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Harvest Index (harvest + index)
Selected AbstractsLeaf Carbon Isotope Discrimination and its Relation with Qualitative Root Traits and Harvest Index in Sugar Beet (Beta vulgaris L.)JOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 5 2003J. T. Tsialtas Abstract Twenty commercial sugar beet varieties were grown at two sites in central Greece during the 2001 growing season (March to October), in a completely randomized block design with three replications. Carbon isotope discrimination (,) in sugar beet leaves was found to be affected by site and marginally by variety. No relation was found between fresh root yield and ,, but significant correlations were found between , and sucrose content (positive) and between , and root ,-amino-N (negative). Also, the harvest index, determined at one site, was negatively correlated with ,. [source] Effects of Deficit Irrigation and Salinity Stress on Common Bean (Phaseolus Vulgaris L.) and Mungbean (Vigna Radiata (L.) Wilczek) Grown in a Controlled EnvironmentJOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 4 2010M. Bourgault Abstract As water for irrigation purposes becomes increasingly scarce because of climate change and population growth, there is growing interest in regulated deficit irrigation (RDI) as a way to improve efficiency of water usage and farm productivity in arid and semi-arid areas. Salinity is also becoming an important problem in these same regions. Experiments were performed to investigate the effects of RDI and salt stress on two legumes crops, common bean (Phaseolus vulgaris L.) and mungbean (Vigna radiata (L.) Wilczek); previous work showed contrasting responses to RDI by these two crops under field conditions. The seed and biomass yields of both crops were reduced as a result of increasing water deficit stress; however, mungbean was able to maintain the same proportion of its biomass in reproductive structures and maintain its harvest index under stress, whereas common bean's decreased. In addition, photosynthesis in mungbean was higher than in common bean and higher at the same levels of transpiration. Finally, salinity stress did not affect the water potential, harvest index or the specific leaf weight of either crop. There were no interactions between salinity and crops or RDI levels, which suggest that the two crops do not differ in their response to salinity stress, and that RDI levels do not modify this response. [source] Root Distribution of Drought-Resistant Peanut Genotypes in Response to DroughtJOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 2 2008P. Songsri Abstract The ability of a plant to modify its root distribution to exploit deeper stored soil water may be an important mechanism to avoid drought. This study aimed at assessing root distributions, variations in root length density (RLD) and percentage of root distribution, and the relevance of root traits for yield of drought-resistant peanut genotypes under different available soil water levels. The experiment was conducted in the dry season during the years 2003/04 and 2004/05. Eleven peanut genotypes (ICGV 98300, ICGV 98303, ICGV 98305, ICGV 98308, ICGV 98324, ICGV 98330, ICGV 98348, ICGV 98353, Tainan 9, KK 60-3 and Tifton-8) and three soil moisture levels [field capacity (FC), 2/3 available soil water (AW) and 1/3 AW] were laid out in a split-plot design with four replications. Roots were sampled by a core sampler at 37, 67 and 97 days after sowing (DAS). Root length was determined by a scanner and the WINRHIZO Pro 2004a software. RLD was calculated as the ratio of root length (cm) and soil volume (cm3). Graphical illustration of root distribution was constructed by merging RLD in the first and second soil layers (0,40 cm) as upper roots and pooling RLD at the third, fourth and fifth layers (40,100 cm) as lower roots. Pod yield, biomass and harvest index (HI) were recorded at harvest. A drought tolerance index (DTI) was calculated for each parameter as the ratio of the parameter under stress treatment to that under well-watered conditions. Variations in RLD in 40 to 100 cm layer (RLD40 to 100 cm) were found under well-watered conditions, and the peanut genotypes could be readily identified as high, intermediate and low for this trait. Changes in RLD in the 40 to 100 cm soil layer were found at 2/3 AW and were more evident at 1/3 AW. ICGV 98300, ICGV 98303, ICGV 98305, ICGV 98308 and KK 60-3 were classified as drought responsive as they increased RLD in the deeper subsoil level in response to drought. In general, RLD under drought conditions was not related to biomass production. The ability to maintain the percentage of RLD (DTI for %RLD) was related to pod yield, DTI for pod yield and DTI for HI. ICGV 98300, ICGV 98303, ICGV 98305 exhibited high DTI (RLD40 to 100 cm) which may explain their high pod yield, DTI (PY) and DTI (HI). Based on these observations we classified them as drought-avoiding genotypes. [source] Yield Responsiveness in Two- and Six-Rowed Barley Grown in Contrasting Nitrogen EnvironmentsJOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 3 2006S. Arisnabarreta Abstract Two- and six-rowed barley with different intrinsic ability to produce tillers and kernels per ear, would differ in responsiveness to nitrogen availability with environmental improvements. Two field experiments were carried out to elucidate how nitrogen supply (N40 and N150) affects yield and its components in two- and six-rowed barley. High nitrogen increased aboveground dry matter at anthesis, by improving cumulative solar radiation intercepted by the crop, determining an increased dry-matter production at maturity without changes in harvest index. In both barley types, variations in grain yield were explained by changes in kernels per unit land area rather than by differences in the average kernel weight. However, changes in the number of kernels were due to variations in the number of ears per m2 in two-rowed barley and the number of kernels per ear in six-rowed barley. Ears per unit area showed a greater responsiveness in two- than in six-rowed barley due to a higher nitrogen supply treatment, associated with their intrinsic higher tillering capacity, while the number of kernels per ear was more responsive in six- than in two-rowed types. The fact that responses to nitrogen by the number of kernels per unit land area in two- and six-rowed barley is better explained by different yield sub-components, allows the speculation that the critical period for yield determination would differ between barley types. [source] Leaf Carbon Isotope Discrimination and its Relation with Qualitative Root Traits and Harvest Index in Sugar Beet (Beta vulgaris L.)JOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 5 2003J. T. Tsialtas Abstract Twenty commercial sugar beet varieties were grown at two sites in central Greece during the 2001 growing season (March to October), in a completely randomized block design with three replications. Carbon isotope discrimination (,) in sugar beet leaves was found to be affected by site and marginally by variety. No relation was found between fresh root yield and ,, but significant correlations were found between , and sucrose content (positive) and between , and root ,-amino-N (negative). Also, the harvest index, determined at one site, was negatively correlated with ,. [source] Screening for Drought Resistance of Rice Recombinant Inbred Populations in the FieldJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 10 2007Gui-Hua Zou Abstract In a 2-year experiment, 187 genotypes were grown under well-watered and drought stress conditions, imposed at panicle initiation stage. The relationship of genotypic variation in yield under drought conditions to potential yield, heading date and flowering delay, reduction in plant height, and to a drought response index (DRI) was detected. Grain yield under drought stress conditions was associated with yield under well-watered conditions (r = 0.47**, and r = 0.61** during 2 years of tests). The delay of heading date ranged from ,1 (no delay) to 24 days, and was negatively associated with grain yield (r = ,0.40*), spikelet fertility percentage (r = ,0.40**), harvest index (r = ,0.58**), but positively associated with yield reduction percentage (r = 0.60**). The reduction in plant height was negatively associated with grain yield (r = ,0.24**, and r = ,0.29**), spikelet fertility percentage (r = ,0.23**, and r = ,0.21*), harvest index (r = ,0.37**, and r = ,0.54**), and positively associated with yield reduction percentage (r = 0.58**, and r = 0.58**) in 2003 and 2004, respectively. The DRI of genotypes was strongly associated with grain yield (r = 0.87**, and r = 0.77**), fertility percentage (r = 0.66** and r = 0.54**), harvest index (r = 0.67** and r = 0.61**), and negatively associated with grain reduction percentage (r = ,0.70**, and r = ,0.73**) under drought stress. The results indicate that genotypes with drought resistance can be identified by measuring yield potential, delay in flowering, reduction in plant height, or DRI under test environments of well-watered and drought stress. [source] Yield assessment of integument-led seed growth following targeted repair of auxin response factor 2PLANT BIOTECHNOLOGY JOURNAL, Issue 8 2008Rhiannon Hughes Summary It is becoming increasingly vital to improve the yield of seed crops to feed an expanding population and, more recently, for biofuel production. One strategy to increase the yield is to increase the seed size, provided that there is not a concomitant decrease in seed number. In a previous study, we described a mutant in the AUXIN RESPONSE FACTOR 2 (ARF2) gene which produced extra cells in the seed coat and, subsequently, enlarged seeds. However, arf2 mutant plants also show severely reduced self-fertility caused, in part, by over-elongated sepals that prevent flower opening. As a low seed set increases individual seed size, a meaningful comparison of the yield in arf2 and wild-type plants could not be conducted. In this study, we show that targeted expression of wild-type ARF2 in the sepals and petals of arf2-9 mutant flowers restores flower opening and dramatically increases seed set. The restored plants retain both enlarged integuments and increased seed size, reinforcing previous evidence that arf2 mutations increase seed weight through their effect on integuments and not only via reduced fertility. We also show that the measurement of the harvest index in Arabidopsis is useful in assessing the impact of introduced traits on the yield. [source] Mitigation of establishment of Brassica napus transgenes in volunteers using a tandem construct containing a selectively unfit genePLANT BIOTECHNOLOGY JOURNAL, Issue 1 2006Hani Al-Ahmad Summary Transgenic oilseed rape (Brassica napus) plants may remain as ,volunteer' weeds in following crops, complicating cultivation and contaminating crop yield. Volunteers can become feral as well as act as a genetic bridge for the transfer of transgenes to weedy relatives. Transgenic mitigation using genes that are positive or neutral to the crop, but deleterious to weeds, should prevent volunteer establishment, as previously intimated using a tobacco (Nicotiana tabacum) model. A transgenically mitigated (TM), dwarf, herbicide-resistant construct using a gibberellic acid-insensitive (,gai) gene in the B. napus crop was effective in offsetting the risks of transgene establishment in volunteer populations of B. napus. This may be useful in the absence of herbicide, e.g. when wheat is rotated with oilseed rape. The TM dwarf B. napus plants grown alone had a much higher yield than the non-transgenics, but were exceedingly unfit in competition with non-transgenic tall cohorts. The reproductive fitness of TM B. napus was 0% at 2.5-cm and 4% at 5-cm spacing between glasshouse-grown plants relative to non-transgenic B. napus. Under screen-house conditions, the reproductive fitness of TM B. napus relative to non-transgenic B. napus was less than 12%, and the harvest index of the TM plants was less than 40% of that of the non-transgenic competitors. The data clearly indicate that the ,gai gene greatly enhances the yield in a weed-free transgenic crop, but the dwarf plants can be eliminated when competing with non-transgenic cohorts (and presumably other species) when the selective herbicide is not used. [source] Inheritance of useful traits in cassava grown in subhumid conditionsPLANT BREEDING, Issue 2 2006N. T. Cach Abstract A diallel study among nine parental clones of cassava was conducted in the subhumid environment on the northern coast of Colombia. Analysis of variance suggested significant effects for the six variables analysed: fresh-root yield, harvest index, root dry matter content, height of first branching, reaction to thrips and plant-type scores. General and specific combining ability effects and their interaction with the environment were significant for most of the variables as well. Results suggested that dominance plays a particularly important role in the cases of fresh-root yield and harvest index but had relatively little importance in the reaction to thrips, dry matter content or height of first branching. Specific breeding approaches are suggested for these traits, depending on the relative importance of additive or non-additive effects in their inheritance. The correlations among different traits were also analysed and in several cases their magnitude reached statistical and biological significance. [source] Genetic dissection of cotton physiological responses to arid conditions and their inter-relationships with productivityPLANT CELL & ENVIRONMENT, Issue 3 2004Y. SARANGA ABSTRACT Testing of the extent to which different complex traits share common genetic control provides a means to distinguish associations that are truly diagnostic of genetic potential for improved adaptation to abiotic stress, from incidental phenotypic correlations. In two generations of progeny from a cross between Gossypium hirsutum and Gossypium barbadense, quantitative trait loci (QTL) mapping was used to evaluate correspondence in genetic control of selected physiological measures and productivity under water-limited and well-watered environments, respectively. A total of 33 QTLs were detected for five physiological variables [osmotic potential (OP), carbon isotope ratio (,13C; indicator of water use efficiency), canopy temperature, chlorophyll a and b], and 46 QTLs for five measures of crop productivity [dry matter, seed cotton yield (SC), harvest index, boll weight, and boll number]. QTL likelihood intervals for high SC and low OP corresponded in three genomic regions, two of which mapped to homoeologous locations on the two subgenomes of tetraploid cotton. QTLs for ,13C showed only incidental association with productivity, indicating that high water use efficiency can be associated with either high or low productivity. Different cotton species have evolved different alleles related to physiological responses and productivity under water deficit, which may permit the development of genotypes that are better-adapted to arid conditions. [source] | ||||||||||