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Plant Height (plant + height)
Selected AbstractsGenetic Diversity and Association Analysis for Salinity Tolerance, Heading Date and Plant Height of Barley Germplasm Using Simple Sequence Repeat MarkersJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 8 2008Lilia Eleuch Abstract The objective of this study was to investigate the genetic diversity of barley accessions. Additionally, association trait analysis was conducted for grain yield under salinity, heading date and plant height. For this purpose, 48 barley genotypes were analyzed with 22 microsatellite simple sequence repeat (SSR) markers. Four of the 22 markers (Bmac316, scssr03907, HVM67 and Bmag770) were able to differentiate all barley genotypes. Cluster and principal coordinate analysis allowed a clear grouping between countries from the same region. The genotypes used in this study have been evaluated for agronomic performance in different environments. Conducting association analysis for grain yield under salinity conditions using TASSEL software revealed a close association of the marker Bmag749 (2H, bin 13) in two different environments with common significant alleles (175, 177), whereas the HVHOTR1 marker (2H, bin 3) was only significant in Sakhar_Egypt with alleles size being 158 and 161. Heading date also showed an association with scssr03907 through the common significant specific allele 111 and EBmac0415 markers in three different agro climatic locations, whereas HVCMA, scssr00103 and HVM67 were linked to heading date in the Egyptian environment only. The plant height association analysis revealed significant markers Bmag770 via the significant allele 152 and scssr09398. [source] Agronomic performance and nutritive value of common and alternative grass and legume species in the Peruvian highlandsGRASS & FORAGE SCIENCE, Issue 2 2009K. Bartl Abstract The agronomic performance and nutritive value of twelve annual and perennial grasses and legumes were analysed in order to define alternatives to local forages for dry-season feeding of ruminants in the Peruvian Andes. There were twelve species and two fertilizer treatments (no fertilizer and a N;P;K fertilizer mainly applied at sowing) in an experiment with a randomized complete block design with three replicates at each of two sites. Plant height, soil cover by forage and weed species, frost damage, dry matter (DM) yield and nutritive value of herbage were evaluated in 2005 and 2006. Among the annual species, Hordeum vulgare L. cv. UNA 80 and ×Triticosecale Wittm. had the highest DM yields when fertilized (8226 and 6934 kg ha,1 respectively). Without fertilizer the alternative cultivars had similar DM yields to that of the local forages. Cultivars of Avena sativa L. had lower concentrations of neutral-detergent fibre (NDF) (557 g kg,1 DM) and higher concentrations of predicted net energy for lactation (5·86 MJ kg,1 DM) than the other annual grass species (625 g kg,1 DM and 5·01 MJ kg,1 DM respectively), while the legumes were superior in concentrations of crude protein (277 g kg,1 DM) and NDF (362 g kg,1 DM). Considering the low agronomic performance of the perennial forages, a mixture of fertilized annual grasses and legumes appears the most appropriate approach to meeting the demand for forage of high nutritive value in the Peruvian highlands. [source] Shrub effects on herbs and grasses in semi-natural grasslands: positive, negative or neutral relationships?GRASS & FORAGE SCIENCE, Issue 1 2008A. Pihlgren Abstract The present study investigated how the abundance and sexual reproduction of herbs and grasses relates to the presence of shrubs of Rosa dumalis in three semi-natural pastures in Sweden. Shrubs may affect grassland plants negatively by competition, positively by serving as grazing refuge, or neutrally. At different distances from shrubs of R. dumalis, data were collected on plant abundance, frequency of reproductive shoots, vegetation height and litter depth. In one grassland, data were collected on seedling density and frequency of reproductive shoots in the presence and absence of grazing. The shrubs functioned as grazing refuges with taller vegetation, deeper litter and higher probability of reproduction by plants. The overall number of plant species remained the same at all distances from shrubs. Most species showed a neutral relationship with shrubs. Proportionately, 0·08,0·26 of the species showed a negative pattern to shrubs and 0·14,0·30 a positive pattern. Seedling density was negatively correlated with litter depth and peaked at 60,90 cm from shrubs. Establishment of seedlings of small-seeded species was negatively related to shrubs probably because of thicker litter layer close to shrubs. The observed patterns were compared with different functional traits, such as Ellenberg values, plant height, growth form and Raunkiaer life form. Plant height from data in the literature was the trait that best explained the relationship of plant species to shrubs because tall species were more common in proximity to shrubs. It was concluded that shrubs increase the heterogeneity in grasslands and that intensive shrub-clearing may negatively affect biodiversity. [source] Growth and chemical composition of wild oat (Avena fatua) under Mediterranean conditionsGRASS & FORAGE SCIENCE, Issue 1 2004M. K. J. El-Shatnawi Abstract Wild oat (Avena fatua) is an annual cool-season species that grows in areas with a Mediterranean climate and has potential as a forage source in Jordan. A field experiment was conducted during the growing seasons of 1999,2000 and 2000,2001 under sub-humid Mediterranean conditions at Samta in the Ajloun Mountains, Jordan. Data on seasonal herbage mass, morphology and chemical composition of wild oat were collected at 60, 80, 100, 120 and 140 days after emergence. Plant height increased rapidly beyond 100 days after emergence. The increase in herbage mass of dry matter was gradual and peaked at 140 days after emergence. The lowest concentration of crude fibre was at 60 and 80 days after emergence, with a range of 201,263 g kg,1 DM. Crude fibre concentrations (610,630 g kg,1 DM) peaked at 140 days after emergence (maturity). In contrast to concentrations of crude fibre, concentrations of crude protein decreased gradually with age. The calcium and phosphorus concentrations were sufficient to meet the maintenance requirements of ewes. [source] Can grazing response of herbaceous plants be predicted from simple vegetative traits?JOURNAL OF APPLIED ECOLOGY, Issue 3 2001Sandra Díaz Summary 1,Range management is based on the response of plant species and communities to grazing intensity. The identification of easily measured plant functional traits that consistently predict grazing response in a wide spectrum of rangelands would be a major advance. 2,Sets of species from temperate subhumid upland grasslands of Argentina and Israel, grazed by cattle, were analysed to find out whether: (i) plants with contrasting grazing responses differed in terms of easily measured vegetative and life-history traits; (ii) their grazing response could be predicted from those traits; (iii) these patterns differed between the two countries. Leaf mass, area, specific area (SLA) and toughness were measured on 83 Argentine and 19 Israeli species. Species were classified by grazing response (grazing-susceptible or grazing-resistant) and plant height (< or > 40 cm) as well as by life history (annual or perennial) and taxonomy (monocotyledon or dicotyledon). 3,Similar plant traits were associated with a specific response to grazing in both Argentina and Israel. Grazing-resistant species were shorter in height, and had smaller, more tender, leaves, with higher SLA than grazing-susceptible species. Grazing resistance was associated with both avoidance traits (small height and leaf size) and tolerance traits (high SLA). Leaf toughness did not contribute to grazing resistance and may be related to selection for canopy dominance. 4,Plant height was the best single predictor of grazing response, followed by leaf mass. The best prediction of species grazing response was achieved by combining plant height, life history and leaf mass. SLA was a comparatively poor predictor of grazing response. 5,The ranges of plant traits, and some correlation patterns between them, differed markedly between species sets from Argentina and Israel. However, the significant relationships between plant traits and grazing response were maintained. 6,The results of this exploratory study suggest that prediction of grazing responses on the basis of easily measured plant traits is feasible and consistent between similar grazing systems in different regions. The results challenge the precept that intense cattle grazing necessarily favours species with tough, unpalatable, leaves. [source] Global patterns in plant heightJOURNAL OF ECOLOGY, Issue 5 2009Angela T. Moles Summary 1. ,Plant height is a central part of plant ecological strategy. It is strongly correlated with life span, seed mass and time to maturity, and is a major determinant of a species' ability to compete for light. Plant height is also related to critical ecosystem variables such as animal diversity and carbon storage capacity. However, remarkably little is known about global patterns in plant height. Here, we use maximum height data for 7084 plant Species × Site combinations to provide the first global, cross-species quantification of the latitudinal gradient in plant height. 2. ,The mean maximum height of species growing within 15° of the equator (7.8 m) was 29 times greater than the height of species between 60° and 75° N (27 cm), and 31 times greater than the height of species between 45° and 60° S (25 cm). There was no evidence that the latitudinal gradient in plant height was different in the northern hemisphere than in the southern hemisphere (P = 0.29). A 2.4-fold drop in plant height at the edge of the tropics (P = 0.006) supports the idea that there might be a switch in plant strategy between temperate and tropical zones. 3. ,We investigated 22 environmental variables to determine which factors underlie the latitudinal gradient in plant height. We found that species with a wide range of height strategies were present in cold, dry, low productivity systems, but there was a noticeable lack of very short species in wetter, warmer, more productive sites. Variables that capture information about growing conditions during the harsh times of the year were relatively poor predictors of height. The best model for global patterns in plant height included only one term: precipitation in the wettest month (R2 = 0.256). 4. ,Synthesis. We found a remarkably steep relationship between latitude and height, indicating a major difference in plant strategy between high and low latitude systems. We also provide new, surprising information about the correlations between plant height and environmental variables. [source] Tolerance to apical and foliar damage: costs and mechanisms in Raphanus raphanistrumOIKOS, Issue 12 2007Elin Boalt To study mechanisms underlying plant tolerance to herbivore damage, we used apical and foliar damage as experimental treatments to study whether there are similar tolerance mechanisms to different types of damage. We also studied whether tolerance to different types of damage are associated, and whether there is a cost involved in plant tolerance to different types of herbivore damage. Our greenhouse experiment involved 480 plants from 30 full-sib families of an annual weed Raphanus raphanistrum, wild radish, which were subjected to control and two different simulated herbivore damage treatments, apex removal and foliar damage of 30% of leaf area. Apical damage significantly decreased seed production, whereas foliar damage had no effect. There was a significant genetic variation for tolerance to foliar, but not apical damage. No costs were observed in terms of negative correlation between tolerance to either damage type and fitness of undamaged plants. Tolerances to apical and foliar damage were not significantly correlated with each other. We observed a larger number of significant associations between tolerance and reproductive traits than between tolerance and vegetative traits. Plant height and leaf size of damaged plants interacted in their association to tolerance to foliar damage. Inflorescence number and pollen quantity per flower of damaged plants were positively associated with tolerance to apical damage. In late-flowering genotypes, petal size of undamaged plants and pollen quantity of damaged plants were positively associated with tolerance to foliar damage. In summary, traits involved in floral display and male fitness were associated with plant tolerance to herbivore damage. [source] Analysis of resistance mechanism to Atherigona soccata in crosses of sorghumPLANT BREEDING, Issue 5 2009A. Anandan Abstract In sorghum, shoot fly resistance is important for grain yield and fodder value. An experiment was conducted to estimate genetic parameters of sorghum for resistance to shoot fly in 50 hybrids, by crossing 5 × 10 genotypes in line × tester manner. Plant height, number of leaves per plant, number of eggs per plant, trichomes on upper and lower surface per unit area of lamina and dead heart per cent were measured on 14 and 21 days after emergence (DAE) and glossiness of leaves was graded on 14 DAE. The correlation between midparent and hybrid performance, GCA : SCA ratio revealed predominance of non-additive gene effects for the traits studied, which could be exploited through hybrid breeding. Of the parents, SPSFPR 94004A and IS 4777 were the best general combiners for shoot fly resistance. Correlation and path analysis revealed the importance of resistance traits and phenol estimation confirms the resistances against shoot fly. [source] Allometric growth relationships of East Africa highland bananas (Musa AAA-EAHB) cv. Kisansa and MbwazirumeANNALS OF APPLIED BIOLOGY, Issue 3 2009K. Nyombi Abstract Highland bananas are an important staple food in East Africa, but there is little information on their physiology and growth patterns. This makes it difficult to identify opportunities for yield improvement. We studied allometric relationships by evaluating different phenological stages of highland banana growth for use in growth assessment, understanding banana crop physiology and yield prediction. Pared corms of uniform size (cv. Kisansa) were planted in a pest-free field in Kawanda (central Uganda), supplied with fertilizers and irrigated during dry periods. In addition, tissue-cultured plants (cv. Kisansa) were planted in an adjacent field and in Ntungamo (southwest Uganda), with various nutrient addition treatments (of N, P, K, Mg, S, Zn, B and Mo). Plant height, girth at base, number of functional leaves and phenological stages were monitored monthly. Destructive sampling allowed derivation of allometric relationships to describe leaf area and biomass distribution in plants throughout the growth cycle. Individual leaf area was estimated as LA (m2) = length (m) × maximum lamina width (m) × 0.68. Total plant leaf area (TLA) was estimated as the product of the measured middle leaf area (MLA) and the number of functional leaves. MLA was estimated as MLA (m2) = ,0.404 + 0.381 height (m) + 0.411 girth (m). A light extinction coefficient (k = 0.7) was estimated from photosynthetically active radiation measurements in a 1.0 m grid over the entire day. The dominant dry matter (DM) sinks changed from leaves at 1118 °C days (47% of DM) and 1518 °C days (46% of DM), to the stem at 2125 °C days (43% of DM) and 3383 °C days (58% of DM), and finally to the bunch at harvest (4326 °C days) with 53% of DM. The allometric relationship between above-ground biomass (AGB in kg DM) and girth (cm) during the vegetative phase followed a power function, AGB = 0.0001 (girth)2.35 (R2 = 0.99), but followed exponential functions at flowering, AGB = 0.325 e0.036(girth) (R2 = 0.79) and at harvest, AGB = 0.069 e0.068(girth) (R2 = 0.96). Girth at flowering was a good parameter for predicting yields with R2 = 0.7 (cv. Mbwazirume) and R2 = 0.57 (cv. Kisansa) obtained between actual and predicted bunch weights. This article shows that allometric relationship can be derived and used to assess biomass production and for developing banana growth models, which can help breeders and agronomists to further exploit the crop's potential. [source] Demographic variation and biomass allocation of Agropyron cristatum grown on steppe and dune sites in the Hunshandake Desert, North ChinaGRASS & FORAGE SCIENCE, Issue 1 2005R. Z. Wang Abstract Demographic and biomass allocation patterns of Agropyron cristatum were measured on steppe and dune sites in the Hunshandake desert of North China in 2001 and 2002. Total plant population, reproductive shoot densities and its differentiation rates were significantly higher in the steppe sites in both years. Plant heights for both vegetative and reproductive shoots were greater in the year with the higher rainfall. The dune sites had a higher biomass allocation to vegetative shoots and roots, while the steppe sites had a higher biomass allocation to reproductive shoots and seed production. It is suggested that the population demography and biomass allocation of the species responded to the differences in the soil variables in the steppe and dune sites. [source] The role of leaf inclination, leaf orientation and plant canopy architecture in soil particle detachment by raindropsEARTH SURFACE PROCESSES AND LANDFORMS, Issue 12 2005Kirsten Foot Abstract A laboratory investigation of the effect of plant architecture on soil particle detachment by rainfall is described. The effects of leaf inclination, leaf orientation, effective canopy area, leaf area index, leaf subcatchment area, lowest canopy area, largest canopy area, canopy overlap area and an alternative leaf area index are examined using artificial plants. Detachment from a 30 cm diameter splash cup filled with sand (150 µm,1 mm particle size) was measured under three types of plant (small leaved, broad leaved and long narrow leaved) for a 10 minute simulated rainstorm of 75 mm/h intensity. There were no significant differences in soil particle detachment between the three plant types or between detachment under the plants and detachment of bare soil. No significant relationships were obtained between detachment and any of the plant parameters. Soil particle detachment by leaf drips can offset any protective effects of the canopy so that detachment does not differ significantly from that on bare soil. Plant architecture significantly affected the distance from the plant stem at which detachment was concentrated even though the canopy diameters of the plants were similar. There would appear to be no advantages in a detailed description of plant architecture and its effects in process-based models of soil erosion. Parameters such as plant height and plant canopy area are sufficient descriptors for modelling plant effects. Copyright © 2005 John Wiley & Sons, Ltd. [source] Life history of the bird cherry-oat aphid, Rhopalosiphum padi, on transgenic and non-transformed wheat challenged with Wheat streak mosaic virusENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 1 2009Edgardo S. Jiménez-Martínez Abstract The life history of the bird cherry-oat aphid, Rhopalosiphum padi (L.) (Hemiptera: Aphididae), was studied via laboratory assays on Wheat streak mosaic virus (WSMV)-infected and non-infected transgenic and non-transformed wheat [Triticum aestivum L. (Poaceae)]. Although R. padi is not a WSMV vector, it is known to colonize WSMV-infected wheat plants. Two transgenic soft white winter wheat genotypes, 366-D03 and 366-D8, that express the WSMV coat protein gene, and the WSMV-susceptible non-transformed cultivar Daws were tested. All genotypes showed disease symptoms when infected with WSMV. Whereas plant height was significantly reduced on virus-infected compared to non-infected plants of all genotypes, virus-infected transgenic plants exhibited lower virus titer and lower disease rating scores than Daws. No significant effects of WSMV infection or genotypes were observed on the length of R. padi nymphal development period, nor on their pre-, and post-reproductive periods. Rhopalosiphum padi reproductive period was significantly longer on Daws infected with WSMV than on non-infected plants of this cultivar. In contrast, there were no significant differences in length of R. padi reproductive period between virus-infected and non-infected transgenic plants within a genotype. Rhopalosiphum padi daily fecundity was significantly lower and adult longevity significantly longer on virus-infected than on non-infected plants of all genotypes. Total aphid fecundity and intrinsic rate of increase were not significantly different among treatments. The percentage of winged aphids that developed was greater on WSMV-infected compared to non-infected plants within a genotype. Results indicate that both virus infection status of plants and wheat genotype influence the life history of R. padi. [source] Determination of essential oil quality index by using energy summation indices in an elite strain of Cymbopogon citratus (DC) Stapf [RRL(J)CCA12]FLAVOUR AND FRAGRANCE JOURNAL, Issue 2 2005Ashok Kumar Shahi Abstract Out of the several accessions of Cymbopogon citratus (DC) Stapf introduced from Central and West India, one accession coded as RRL(J)CCA12, selected through a mass selection technique, was found to have citral (,80%) as the major constituent in its essential oil. Citral has tremendous application in the ,avour and perfume industries. Plant adaptation was judged by quantifying the regression coef,cient (b) value, which was 1.0 using essential oil growth indices. For prediction of essential oil quality index (EOQI), a multiple regression equation was developed for the ,rst time by using essential oil yield/plant and energy summation indices as EOQI (citral %) = 61.6 + 1.09 × essential oil yield/plant (g) - 0.005 × heat use ef,ciency + 0.675 × phenothermal index. For obtaining a better quality of essential oil (citral ,78%), the optimal value of independent variable would be: X1 = 2.49; X2 = 0.018 and X3 = 20.47, where X1, X2 and X3 denote essential oil yield/plant, heat use ef,ciency and phenothermal index, respectively. The validation of the EOQI model is done by correlating the predicted and calculated values of citral (%) which exhibited signi,cant r value = 0.955 at 5% probability level. The thermal requirement of the selectant was ,5500 degree days to exhibit plant maturity in terms of qualitative and quantitative characteristics of its essential oil at 6.0 vegetative lea,ng stage, with attainment of plant height ,1.0 m from previous date of harvest (December 2001). Prediction of essential oil quality by using the mathematical model is helpful for integrating the growth processes and evaluating crop management strategies. Copyright © 2004 John Wiley & Sons, Ltd. [source] Responses of plants in polar regions to UVB exposure: a meta-analysisGLOBAL CHANGE BIOLOGY, Issue 11 2009KEVIN K. NEWSHAM Abstract We report a meta-analysis of data from 34 field studies into the effects of ultraviolet B (UVB) radiation on Arctic and Antarctic bryophytes and angiosperms. The studies measured plant responses to decreases in UVB radiation under screens, natural fluctuations in UVB irradiance or increases in UVB radiation applied from fluorescent UV lamps. Exposure to UVB radiation was found to increase the concentrations of UVB absorbing compounds in leaves or thalli by 7% and 25% (expressed on a mass or area basis, respectively). UVB exposure also reduced aboveground biomass and plant height by 15% and 10%, respectively, and increased DNA damage by 90%. No effects of UVB exposure were found on carotenoid or chlorophyll concentrations, net photosynthesis, Fv/Fm or ,PSII, belowground or total biomass, leaf mass, leaf area or specific leaf area (SLA). The methodology adopted influenced the concentration of UVB absorbing compounds, with screens and natural fluctuations promoting significant changes in the concentrations of these pigments, but lamps failing to elicit a response. Greater reductions in leaf area and SLA, and greater increases in concentrations of carotenoids, were found in experiments based in Antarctica than in those in the Arctic. Bryophytes typically responded in the same way as angiosperms to UVB exposure. Regression analyses indicated that the percentage difference in UVB dose between treatment and control plots was positively associated with concentrations of UVB absorbing compounds and carotenoids, and negatively so with aboveground biomass and leaf area. We conclude that, despite being dominated by bryophytes, the vegetation of polar regions responds to UVB exposure in a similar way to higher plant-dominated vegetation at lower latitudes. In broad terms, the exposure of plants in these regions to UVB radiation elicits the synthesis of UVB absorbing compounds, reduces aboveground biomass and height, and increases DNA damage. [source] Shrub effects on herbs and grasses in semi-natural grasslands: positive, negative or neutral relationships?GRASS & FORAGE SCIENCE, Issue 1 2008A. Pihlgren Abstract The present study investigated how the abundance and sexual reproduction of herbs and grasses relates to the presence of shrubs of Rosa dumalis in three semi-natural pastures in Sweden. Shrubs may affect grassland plants negatively by competition, positively by serving as grazing refuge, or neutrally. At different distances from shrubs of R. dumalis, data were collected on plant abundance, frequency of reproductive shoots, vegetation height and litter depth. In one grassland, data were collected on seedling density and frequency of reproductive shoots in the presence and absence of grazing. The shrubs functioned as grazing refuges with taller vegetation, deeper litter and higher probability of reproduction by plants. The overall number of plant species remained the same at all distances from shrubs. Most species showed a neutral relationship with shrubs. Proportionately, 0·08,0·26 of the species showed a negative pattern to shrubs and 0·14,0·30 a positive pattern. Seedling density was negatively correlated with litter depth and peaked at 60,90 cm from shrubs. Establishment of seedlings of small-seeded species was negatively related to shrubs probably because of thicker litter layer close to shrubs. The observed patterns were compared with different functional traits, such as Ellenberg values, plant height, growth form and Raunkiaer life form. Plant height from data in the literature was the trait that best explained the relationship of plant species to shrubs because tall species were more common in proximity to shrubs. It was concluded that shrubs increase the heterogeneity in grasslands and that intensive shrub-clearing may negatively affect biodiversity. [source] Structural heterogeneity and productivity of a tall fescue pasture grazed rotationally by cattle at four stocking densitiesGRASSLAND SCIENCE, Issue 1 2008Maria Silvia Cid Abstract The spatial heterogeneity in the structure and the productivity of the vegetation was examined in a tall fescue (Festuca arundinacea Schreb.) pasture rotationally grazed at four stocking densities in the Pampean region of Argentina. The examined pasture was grazed at the stocking densities of 3.6, 4.6, 5.6 and 6.6 animals ha,1 with a two-paddock 14-day rotational grazing system. Spatial distribution of plant height was examined as well as the percentages of short patch area (heavily utilized patches) or tall patch area (areas ungrazed or lightly defoliated). In addition, biomass, growth rate and relative growth rate were assessed for both short and tall patches. Grazing generated patchiness in vegetation structure and growth at all stocking densities. Increased stocking density caused an increase in the percentage of the short patch area in the paddocks. Short patches had relatively less live biomass than tall ones, but their relative growth rate was 31% higher than that of tall patches (0.021 ± 0.007 vs 0.016 ± 0.005 g DM g DM,1 day,1). The increase in stocking density enlarged the proportion of short patch areas with higher relative growth rate. The relative growth rate (average between short and tall patches) of the two highest stocking densities was 61.7% higher than that of the low stocking density treatments (0.023 ± 0.006 vs 0.014 ± 0.004 g DM g DM,1 day,1). Although the growth rate of the short patches did not exceed the value of the tall patches, the high value of relative growth rate appeared to indicate a higher photosynthetic capacity of the short patches. Moreover, live biomass did not decrease during the experimental period even in the short patch areas showing that, in the particular conditions of our study, overgrazing did not occur at the range of the stocking density examined. [source] Neotyphodium endophyte infection affects the performance of tall fescue in temperate region AndisolsGRASSLAND SCIENCE, Issue 1 2006M. Hasinur Rahman Abstract A pot experiment was conducted for 75 days to observe the effect of Neotyphodium coenophialum endophyte on three tall fescue (Festuca arundinacea Schreb.) ecotypes grown in two Andisols viz. Black Andisol and Red Andisol. Black Andisol with a naturally low content of P was high in other nutrients such as N, K, while Red Andisol, with a naturally high content of P, was low in other nutrients. Tiller number, plant height, chlorophyll content, shoot dry weight and agronomic efficiency of water use (WUEag) showed higher values in endophyte-infected (E+) plants than noninfected (E,) plants. Plants growing in Black Andisol performed better than those in Red Andisol. Among the three tall fescue ecotypes, one of them (ecotype Showa) had the best performance regardless of soils and endophyte infection. When considering the effect of endophyte infection in different soil conditions, higher WUEag was observed in endophyte-infected plants grown in Black Andisol. Endophyte infection significantly enhanced all plant parameters in Black Andisol but they were reduced in Red Andisol. Our results indicate that infected plants grew better in soil that was naturally low in P whereas uninfected plants had increased vegetative growth in soil that was naturally high in P. In nutrient poor soil with comparatively high P content (Red Andisol) the cost of endophyte infection may override its benefit. The presence of endophyte had a variable impact on plant performance and the effect of endophyte varied with ecotype of grass it infected into. [source] Influences of meteorological and vegetational factors on the partitioning of the energy of a rice paddy fieldHYDROLOGICAL PROCESSES, Issue 8 2005Hiroki Oue Abstract Observations made in a paddy field were analysed to show the influences of meteorological and vegetational factors on the crop's energy budget. Energy budget in the paddy field was characterized by the major partitioning to latent heat flux LE and by the negative Bowen ratio B mostly in the afternoon. Canopy resistance rc, estimated with the Penman,Monteith equation, was related to the influences of solar radiation SR, vapour pressure deficit VPD and plant height. The results demonstrated that rc could not directly account for B but that critical canopy resistance rcc, defined as the canopy resistance when B = 0, could be used to standardize rc, and that rc , rcc proved to be a good parameter to account for B. Influences of bulk stomatal response on energy partitioning were assessed as follows: the Bowen ratio dropped below zero, while the bulk stomatal aperture dwindled with the increase of VPD. In addition, stomata of a big leaf acted to promote the partitioning to LE against the rise of SR in the condition of higher VPD. Copyright © 2004 John Wiley & Sons, Ltd. [source] Impact of Water Stress on Maize Grown Off-Season in a Subtropical EnvironmentJOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 4 2007C. M. T. Soler Abstract During the last decade, the production of off-season maize has increased in several regions of Brazil. Growing maize during this season, with sowing from January through April, imposes several climatic risks that can impact crop yield. This is mainly caused by the high variability of precipitation and the probability of frost during the reproduction phases. High production risks are also partially due to the use of cultivars that are not adapted to the local environmental conditions. The goal of this study was to evaluate crop growth and development and associated yield, yield components and water use efficiency (WUE) for maize hybrids with different maturity ratings grown off-season in a subtropical environment under both rainfed and irrigated conditions. Three experiments were conducted in 2001 and 2002 in Piracicaba, state of São Paulo, Brazil with four hybrids of different maturity duration, AG9010 (very short season), DAS CO32 and Exceler (short season) and DKB 333B (normal season). Leaf area index (LAI), plant height and dry matter were measured approximately every 18 days. Under rainfed conditions, the soil water content in the deeper layers was reduced, suggesting that the extension of the roots into these layers was a response to soil water limitations. On average, WUE varied from 1.45 kg m,3 under rainfed conditions to 1.69 kg m,3 under irrigated conditions during 2001. The average yield varied from 4209 kg ha,1 for the hybrids grown under rainfed conditions to 5594 kg ha,1 under irrigated conditions during 2001. Yield reductions under rainfed conditions were affected by the genotype. For the hybrid DKB 333B with a normal maturity, yield was reduced by 25.6 % while the short maturity hybrid Exceler was the least impacted by soil water limitations with a yield reduction of only 8.4 %. To decrease the risk of yield loss, the application of supplemental irrigation should be considered by local farmers, provided that this practice is not restricted by either economic considerations or the availability of sufficient water resources. [source] Germination of Salicornia bigelovii Ecotypes under Stressing Conditions of Temperature and Salinity and Ameliorative Effects of Plant Growth-promoting BacteriaJOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 3 2007E. O. Rueda-Puente Abstract Salinity is a major stress condition. Salicornia bigelovii is a valuable edible halophyte, considered to be a promising resource for cultivation in arid coastal zones. Its productivity depends on the supplementary provision of nitrogen, for which an option is chemical fertilization. Nevertheless, indiscriminate use of chemical fertilizers contributes to the problem of increased salinity. The inoculation of plant growth-promoting bacteria (PGPB) represents an alternative. Seed ecotypes from four coastal areas [Santa Rosa Chica, Santa Rosa Grande, Santa Cruz and Cerro Prieto (CP), Sonora, México] were collected, in order to inoculate them with two species of PGPB (Azospirillum halopraeferens and Klebsiella pneumoniae). Two germination tests were carried out to study the effect of salinity, temperature regime (night/day) and inoculation with PGPB on germination (percentage and rate), plant height, root length and biomass produced (fresh and dry matter). In the first test, all four ecotypes were considered, whereas in the second test only the CP ecotype was involved because it was found to be the outstanding ecotype in the previous test. Results showed inhibition of germination when salinity was higher in all ecotypes except CP. The CP ecotype showed a decrease of seed germination with an increase in NaCl concentrations at all temperatures tested. However, when it was inoculated with both PGPB, the germination percentage was influenced. [source] Effects of Grazing on Bituminaria bituminosa (L) Stirton: A Potential Forage Crop in Mediterranean GrasslandsJOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 6 2006M. Sternberg Abstract Plant traits of Bituminaria bituminosa, as affected by different intensities of cattle grazing, were studied in a Mediterranean grassland in Israel. B. bituminosa is a widespread Mediterranean perennial legume species that may potentially serve as a fodder crop in Mediterranean grasslands. The aims of the present study were: (i) to evaluate the responses of B. bituminosa to different cattle grazing intensities; (ii) to study functional traits associated with grazing tolerance; and (iii) to evaluate its potential as an alternative forage crop in the region. A total of 100 B. bituminosa plants were monitored in field conditions. During the growing season each individual was sampled five times and the following plant traits were monitored each time: (i) aboveground biomass production, (ii) plant height, (iii) specific leaf area (SLA), (iv) number of flowers, (v) seed mass and size, (vi) tannin concentration in leaves, (vii) total nitrogen in leaves, (viii) fibre concentration in leaves (Neutral Detergent Fiber), and (ix) in vitro dry matter digestibility. The results showed that grazing intensity and history of grazing affected B. bituminosa performance. Plant biomass, height, and flower and seed production were all reduced when plants were exposed to cattle grazing. However, under moderate grazing intensities, its plant cover remained relatively stable indicating a potential tolerance under this stocking rate. The nutritious characteristics of B. bituminosa leaves were good, and the condensed tannins concentration found indicated favourable conditions for digestion. Moreover, the in vitro digestibility studies indicated relatively high values (46,51 %) of digestion. B. bituminosa may be considered as a potential crop for cattle feeding in Mediterranean grasslands. Growing this plant in dense stands in rotational paddocks may provide alternative sources of natural fodder protein, reducing the potential costs of artificial feed supplements. [source] Physiological and Biochemical Responses of Hexaploid and Tetraploid Wheat to Drought StressJOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 4 2000V. Chandrasekar An experiment was conducted to investigate the physiological and biochemical responses of two hexaploids viz., C 306 (water stress tolerant) and Hira (water stress susceptible), and two tetraploids, HW 24 (Triticum dicoccum) and A 9-30-1 (Triticum durum) wheat genotypes to water stress under pot culture condition. Water stress was imposed for a uniform period of 10 days at 50, 60 and 70 days after sowing (DAS) and observations were recorded at 60, 70 and 80 DAS. Total dry matter and plant height were recorded at harvest. Water stress caused a decline in relative water content (RWC), chlorophyll and carotenoid content, membrane stability and nitrate reductase activity and increased accumulation of proline at all stages and abscisic acid (ABA) at 80 DAS in all the genotypes. Both the tetraploids showed a lower reduction in RWC and highest ABA accumulation under water stress. Among the hexaploids Hira showed the most decline in RWC and the lowest ABA accumulation. The tetraploids also showed comparatively higher carotenoid content and membrane stability, closely followed by C 306, while Hira showed the minimum response under water stress. Nitrate reductase activity and chlorophyll content under irrigated conditions were highest in Hira but under water stress the lowest per cent decline was observed in C 306, followed by HW 24, A 9-30-1, and Hira. Proline accumulation under water stress conditions was highest in hexaploids C 306 and Hira and lowest in tetraploids HW 24 and A 9-30-1. Tetraploids HW 24, followed by A 9-30-1 maintained higher plant height and total dry matter (TDM) under water stress and also showed a lower per cent decline under stress than hexaploids C 306 and Hira. From the results it is clear that proline accumulation did not contribute to better drought tolerance of tetraploids than hexaploids. It is also apparent that water stress tolerance is the result of the cumulative action of various physiological processes, and all the parameters/processes may not be positively associated with the drought tolerance of a particular tolerant genotype. [source] Uniformity, Performance and Seed Quality of Soybean (Glycine max (L.) Merrill) Seed Crops Grown from Sub-samples of One Seed Lot Obtained after Selection for Physical Seed AttributesJOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 2 2000R. A. Illipronti Jr In a glasshouse experiment it was examined whether narrow grading and selection from a commercial soybean seed lot cultivar ,IAS-5', could improve the uniformity of the seed crop grown from it and thereby enhance yield, quality and uniformity of seeds produced. The classes created were: Control (original seed lot); Size-graded seeds (projected area measured by image analysis 37,46 mm2); Non-cracked seeds; Yellow seeds; Size-graded sound seeds (size-graded, non-cracked, yellow, non-wrinkled, non-etched). Compared to the control, percentage of emergence, survival and number of yielding plants were enhanced in crops from non-cracked, yellow or size-graded sound seeds. Differences in plant numbers did not result in differences in crop yield. The different seed lots also did not differ in crop uniformity: time interval between stages of plant development, plant height 20 days after sowing, yield components, physical or physiological quality attributes of seeds produced, and respective coefficients of variation were similar. Fewer plants survived in crops showing a larger variation in plant height 20 days after sowing, thus reducing differences in initial plant-to-plant variation. Creating more uniform crops by additional grading or selection of commercial seed lots may therefore not be promising. Zusammenfassung In einem Gewächshausexperiment wurde untersucht, ob Sortierung in engen Werten und Selektion aus einer kommerziellen Sojabohnen-Samenprobe (Kultivar IAS-5) die Einheitlichkeit des Bestandes verbessern und damit Ertrag, Qualität und Einheitlichkeit der Samenproduktion verbessern kann. Die berücksichtigten Klassen waren: Kontrolle (originale Samenprobe); nach Gröie eingeteilte Samen (mit Grenzwerten zwischen 37,46 mm2); nicht geplatzte Samen; gelbe Samen, nach Gröie eingeteilte gesunde Samen (nach Gröie eingeteilt, nicht beschädigt, gelb, nicht runzelige, nicht verätzt). Im Vergleich zur Kontrolle waren Auflaufprozentsatz, Überlebensfähigkeit und Anzahl der Ertrag bringenden Pflanzen bei Beständen aus nicht beschädigten, gelben oder nach Gröie eingeteilten nicht beschädigten Samen erhöht. Unterschiede in der Pflanzenzahl führten nicht zu Unterschieden im Bestandesertrag. Die Unterschiedlichen Samengruppen unterschieden sich auch nicht in der Bestandes-Einheitlichkeit: Zeitintervalle zwischen den Stadien der Pflanzenentwicklung, Pflanzenhöhe zwanzig Tage nach der Aussaat, Ertragskomponenten, äuiere oder physiologische Qualitätseigenschaften der produzierten Samen und Variationskoeffizienten waren vergleichbar. Weniger Pflanzen überlebten in Beständen, die eine gröiere Variation in der Pflanzenhöhe zwanzig Tage nach der Aussaat aufwiesen, wodurch eine Reduzierung der Unterschiede in der Ausgangsvariation von Pflanze zu Pflanze eintrat wurde. Die Erzeugung von mehr einheitlichen Beständen durch zusätzliche Gröieneinordnung oder Selektion von kommerziellen Samenproben könnte daher nicht als zweckmäiig betrachtet werden. [source] Effects of Plant Population Density and Intercropping with Soybean on the Fractal Dimension of Corn Plant Skeletal ImagesJOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 2 2000K. Foroutan-pour Three-year field experiments were conducted to determine whether the temporal pattern of fractal dimension (FD) for corn (Zea mays L.) plant structure is altered by plant population density (PPD) or intercropping with soybean [Glycine max. (L.) Merr.], and how changes in the FD are related to changes in other canopy characteristics. Plants in monocropped corn and intercropped corn,soybean plots were randomly sampled and labelled for later identification. Corn plant structure was photographed from the side that allowed the maximum appearance of details (perpendicular to the plane of developed leaves) and from two fixed sides (side 1: parallel to the row and side 2: perpendicular to the row). Images were scanned and skeletonized, as skeletal images provide acceptable information to estimate the FD of plant structure two-dimensionally by the box-counting method. Differences in the FD estimated from images taken perpendicular to the plane of developed leaves were not significant among competition treatments. An adjustment of corn plants to treatments, by changing the orientation of the plane of developed leaves with respect to the row, was observed. Based on overall FD means, competition treatments were ranked as: high > normal , intercrop , low for side 1 and intercrop > low , normal > high for side 2. Leaf area index (LAI) and plant height had a positive correlation with FD. In contrast, light penetration had a negative correlation with FD. In conclusion, FD provides a meaningful and effective tool for quantifying corn plant structure, measuring the structural response to cultural practices, and modelling corn plant canopies. Zusammenfassung Folgende Ziele der Untersuchungen wurden berücksichtigt: 1) Eine geeignete Methode für die Abschätzung der Anteile (FD) 2-dimensional für Pflanzen mit einer einfachen dreidimensionalen Vegetationsstruktur wie z. B. Mais (Zea mays L.) zu bestimmen; 2) der Frage nachzugehen, ob die zeitlichen Muster von FD bei der Maispflanzenstruktur durch die Bestandesdichte verändert wird (PPD: low, normal und hoch) oder in Mischanbau mit Sojabohnen (Glyzine max. L.) Merr.); und 3) in welcher Beziehung Änderungen in der FD in der Maispflanzenstruktur zu Änderungen in anderen Bestandeseigenschaften stehen. Pflanzen im Reinanbau von Mais und im Mischanbau in Mais-Sojabohnen-Parzellen wurden randomisiert gesammelt und für die spätere Identifikation gekennzeichnet. Die Maispflanzenstruktur wurde von der Seite fotografiert, so dai eine maximale Darstellung der Details (perpendiculär zu der Ebene der entwickelten Blätter) und von zwei festgelegten Seiten (Seite 1: parallel zur Reihe und Seite 2 perpendikulär zur Reihe) verfügbar war. Die Abbildungen wurden gescannt und skelettiert; Skelettabbildungen geben eine akzeptierbare Information zur Abschätzung von FD Pflanzenstrukturen in zweidimensionaler Form über die Box-counting-Methode. Unterschiede in der FD, die sich aus Bildern mit einer perpendikulären Aufnahme zu der Ebene der entwickelten Blätter ergaben, waren nicht signifikant innerhalb der Konkurrenzbehandlungen. Eine Anpassung der Maispflanzen an die Behandlungen durch Änderungen der Orientierung zur Ebene der entwickelten Blätter im Hinblick auf die Reihe, wurde beobachtet. Auf der Grundlage von gesamt FD-Mittelwerten ergab sich, dai Konkurrenzbehandlungen in folgender Reihe auftraten: Hoch (1,192) > (1,178) , zu Mischanbau (1,177) , zu gering (1,170) für Seite 1 und bei Mischanbau (1,147) > gering (1,158) , (1,153) > hoch für Seite 2. Der Blattflächenindex (LAI) und die Pflanzenhöhe hatten eine positive Korrelation zu FD. Im Gegensatz dazu wies die Lichtpenetration eine negative Korrelation zu FD auf. Es kann festgestellt werden, dai FD eine aussagekräftige und zweckmäiige Methode ist, die Maispflanzenstruktur zu quantifizieren, Strukturreaktionen zum Anbauverfahren zu messen und Maispflanzenbestände zu beschreiben. [source] Can grazing response of herbaceous plants be predicted from simple vegetative traits?JOURNAL OF APPLIED ECOLOGY, Issue 3 2001Sandra Díaz Summary 1,Range management is based on the response of plant species and communities to grazing intensity. The identification of easily measured plant functional traits that consistently predict grazing response in a wide spectrum of rangelands would be a major advance. 2,Sets of species from temperate subhumid upland grasslands of Argentina and Israel, grazed by cattle, were analysed to find out whether: (i) plants with contrasting grazing responses differed in terms of easily measured vegetative and life-history traits; (ii) their grazing response could be predicted from those traits; (iii) these patterns differed between the two countries. Leaf mass, area, specific area (SLA) and toughness were measured on 83 Argentine and 19 Israeli species. Species were classified by grazing response (grazing-susceptible or grazing-resistant) and plant height (< or > 40 cm) as well as by life history (annual or perennial) and taxonomy (monocotyledon or dicotyledon). 3,Similar plant traits were associated with a specific response to grazing in both Argentina and Israel. Grazing-resistant species were shorter in height, and had smaller, more tender, leaves, with higher SLA than grazing-susceptible species. Grazing resistance was associated with both avoidance traits (small height and leaf size) and tolerance traits (high SLA). Leaf toughness did not contribute to grazing resistance and may be related to selection for canopy dominance. 4,Plant height was the best single predictor of grazing response, followed by leaf mass. The best prediction of species grazing response was achieved by combining plant height, life history and leaf mass. SLA was a comparatively poor predictor of grazing response. 5,The ranges of plant traits, and some correlation patterns between them, differed markedly between species sets from Argentina and Israel. However, the significant relationships between plant traits and grazing response were maintained. 6,The results of this exploratory study suggest that prediction of grazing responses on the basis of easily measured plant traits is feasible and consistent between similar grazing systems in different regions. The results challenge the precept that intense cattle grazing necessarily favours species with tough, unpalatable, leaves. [source] The effect of pea cultivar and water stress on root and shoot competition between vegetative plants of maize and peaJOURNAL OF APPLIED ECOLOGY, Issue 1 2001Tzehaye Semere Summary 1Improvements in intercrop yields may be achieved through an understanding of yield advantages due to above-ground or below-ground interactions. 2Forage maize and two morphologically contrasting cultivars of pea (leafy cv. Bohatyr and semi-leafless cv. Grafila) were grown alone and in additive mixtures, under two contrasting levels of soil moisture (± water stress). 3The mechanism of competition between maize and pea was studied by separating the effects of root competition and shoot competition, using soil and aerial partitions. Plants were grown in rectangular tanks in a glasshouse. 4Leafy pea cv. Bohatyr was as competitive as maize, both below-ground and above-ground, whereas semi-leafless pea cv. Grafila was less competitive than maize or pea cv. Bohatyr. The greater competitive ability of the leafy pea, both above- and below-ground, was probably due to its greater growth rate, associated with its greater leaf area. 5The competitive ability of maize, relative to peas, was considerably reduced by water stress. Both the root and shoot competitive abilities of pea were greater under water stress, compared with those of maize. 6Relative yield total (RYT) values were significantly greater when maize and pea were subjected to shoot competition only (RYT = 1·76) than when subjected to root competition (RYT = 1·17) or when subjected to both shoot and root competition (RYT = 1·13). This reflects the fact that the effects of root competition were greater than those of shoot competition. 7Root competition decreased the shoot dry weights, plant height and leaf area of both maize and pea, whereas shoot competition had no significant effect on these attributes, indicating that soil resources, i.e. mineral nutrients and water, were more limiting than light. [source] Browsing impact of large herbivores on Acacia xanthophloea Benth in Lake Nakuru National Park, KenyaAFRICAN JOURNAL OF ECOLOGY, Issue 2 2009N. Dharani Abstract Significant differences (P<0.05) were found in growth of plant height, canopy cover and stem diameter of Acacia xanthophloea trees in fenced plot as compared with unfenced plot both in the wet and in the dry seasons. Finding of this study showed that although heavy browsing reduced the height and canopy of trees, it did not kill any trees and seedling regeneration took place simultaneously. Despite the presence of large herbivores that impact some considerable browsing pressure results indicate that the A. xanthophloea habitat type would continue to remain in balance in the presence of recruitment of seedlings and saplings. The conditions at the time of study indicate that the browsing on A. xanthophloea was not significant and was not serious enough to warrant management intervention at present. Résumé Des différences significatives (P<0,05) ont été relevées dans la croissance en hauteur, le couvert de la canopée et le diamètre des tiges d'Acacia xanthophloea dans des parcelles clôturées, comparées à des parcelles non clôturées, en saison sèche comme en saison des pluies. Les résultats de cette étude ont montré que, même si un pâturage intense réduisait la hauteur et la canopée des arbres, il n'en tuait aucun et que la régénération des jeunes plants se faisait simultanément. Malgré la présence de grands herbivores qui exercent une pression considérable, les résultats indiquent que le type d'habitat àA. xanthophloea resterait équilibré grâce au recrutement de jeunes plants et de repousses. Les conditions prévalant au moment de l'étude indiquaient que la consommation d'A. xanthophloea n'était pas significative et qu'elle n'était pas assez grave pour justifier pour le moment une intervention en matière de gestion. [source] Global patterns in plant heightJOURNAL OF ECOLOGY, Issue 5 2009Angela T. Moles Summary 1. ,Plant height is a central part of plant ecological strategy. It is strongly correlated with life span, seed mass and time to maturity, and is a major determinant of a species' ability to compete for light. Plant height is also related to critical ecosystem variables such as animal diversity and carbon storage capacity. However, remarkably little is known about global patterns in plant height. Here, we use maximum height data for 7084 plant Species × Site combinations to provide the first global, cross-species quantification of the latitudinal gradient in plant height. 2. ,The mean maximum height of species growing within 15° of the equator (7.8 m) was 29 times greater than the height of species between 60° and 75° N (27 cm), and 31 times greater than the height of species between 45° and 60° S (25 cm). There was no evidence that the latitudinal gradient in plant height was different in the northern hemisphere than in the southern hemisphere (P = 0.29). A 2.4-fold drop in plant height at the edge of the tropics (P = 0.006) supports the idea that there might be a switch in plant strategy between temperate and tropical zones. 3. ,We investigated 22 environmental variables to determine which factors underlie the latitudinal gradient in plant height. We found that species with a wide range of height strategies were present in cold, dry, low productivity systems, but there was a noticeable lack of very short species in wetter, warmer, more productive sites. Variables that capture information about growing conditions during the harsh times of the year were relatively poor predictors of height. The best model for global patterns in plant height included only one term: precipitation in the wettest month (R2 = 0.256). 4. ,Synthesis. We found a remarkably steep relationship between latitude and height, indicating a major difference in plant strategy between high and low latitude systems. We also provide new, surprising information about the correlations between plant height and environmental variables. [source] Chemical and physical plant defence across multiple ontogenetic stages in a tropical rain forest understorey treeJOURNAL OF ECOLOGY, Issue 4 2009Bruce L. Webber Summary 1Variation over plant ontogeny can play an important role in shaping trade-offs between investing resources in growth, reproduction and defence. Most previous ontogenetic studies on plant defence have compared two life stages, making it impossible to follow complete ontogenetic trajectories for plant defence traits. 2We used the highly defended rain forest understorey tree Ryparosa kurrangii to examine chemical (cyanogen concentrations; CNM) and physical (leaf mass per area; LMA) ontogenetic defence trajectories across multiple stages of development for the first time, using field and glasshouse plants. 3In glasshouse seedlings, total plant cyanide and CNM decreased between cotyledon-bearing and recently autonomous seedlings. In field populations, foliar CNM decreased in a nonlinear fashion and showed a trade-off with LMA through the ontogenetic progression from small seedlings to large mature trees. 4Cyanogenesis was ubiquitous in all individuals tested, with considerable quantitative plasticity in constitutive expression. Environmental influences on defence traits, as measured by foliar nitrogen and potential light availability in the field, had no detectable effect on CNM. Non-cyanide nitrogen (N , NCN)M was negatively correlated with CNM, and NCN was negatively correlated with plant height; therefore, at constant plant height there was no relationship between (N , NCN)M and CNM. LMA was positively correlated with increasing light availability. 5Our results suggest that light and nitrogen availability have no detectable effect on CNM in R. kurrangii and that most of the observed population-level CNM plasticity may be due to underlying genetic and ontogenetic influences. These findings are related to a theoretical model recently proposed for resistance trajectories during plant ontogeny, taking into account the life-history traits of rain forest understorey trees. 6Synthesis. The nonlinear ontogenetic trajectory of plant defence expression observed in this study suggests that ontogenetic defence changes may be strongly influenced by plant life-history traits, the defence(s) examined and the environmental niche the plant occupies. [source] Prediction of species response to atmospheric nitrogen deposition by means of ecological measures and life history traitsJOURNAL OF ECOLOGY, Issue 1 2002Martin Diekmann Summary 1The main objective of this study was to predict the responses of vascular plant species to atmospheric nitrogen deposition and enhanced soil nitrogen levels. The study was carried out in deciduous forests located in three regions of southern Sweden. The abundance of vascular plants, as well as soil pH and nitrogen mineralization rates, were studied in a total of 661 sample plots. 2We calculated an ecological measure (Ndev value) for all species based on their observed vs. expected nitrification ratios at a given soil pH, and compared its accuracy in predicting abundance changes with results using life history traits. Data from long-term field studies and fertilization experiments were used for validation. 3Ndev values were positively correlated between neighbouring regions. Values for the southernmost region (Skåne) were also positively related to the changes in species frequency observed in large-scale flora surveys and permanent plot studies in that area and with species changes reported from Central Europe. Values from one of two other regions were also consistent. Ndev values from Skåne (but no other region) predicted species responses in short-term fertilization experiments. 4No life history trait was as good a predictor as Ndev, although plant height, leaf anatomy, leaf nitrogen concentration and phenology showed significant correlations. Attributes related to taxonomy, life form, relative growth rate and habitat type showed no agreement with the changes in species abundance. 5We predict that species with the following attribute syndrome will increase in abundance in response to enhanced nitrogen levels: those favoured by a high soil nitrification ratio relative to other species at a given soil pH, tall stature, hydro- to helomorph anatomy, high leaf nitrogen concentration and a late phenological development. [source] | ||||||||||||||||||||||||||||