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Plant Stages (plant + stage)
Selected AbstractsInfluence of plant species and plant growth stage on Frankliniella occidentalis pupation behaviour in greenhouse ornamentalsJOURNAL OF APPLIED ENTOMOLOGY, Issue 1 2008R. Buitenhuis Abstract The influence of plant stage and plant species on the pupation behaviour of western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), was investigated in flowering and non-flowering potted chrysanthemums and mini roses. On non-flowering chrysanthemums and roses, 92,93% of the F. occidentalis pupated in the soil. On flowering roses, 87% pupated in the soil, and on flowering chrysanthemums only 60% chose the soil as a pupation site and 40% stayed on the plant. This means that, in the presence of flowers, especially complex inflorescences like chrysanthemums, a large proportion of F. occidentalis chooses stay on the plant to pupate. [source] Evaluation of Drought-Related Traits and Screening Methods at Different Developmental Stages in Spring BarleyJOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 5 2008F. Szira Abstract Despite intensive research and breeding efforts, the physiological and quantitative genetic bases of drought tolerance are still poorly understood. The comparison of results obtained from different sources is also complex, because different testing methods may lead to controversial conclusions. This report discusses various drought stress experiments (hydroponics and in soil) in which the plant tolerance was studied at different developmental stages. Tests were performed in the germination, seedling and adult plant stages on the parental lines of five well-known barley-mapping populations. The results suggest that drought tolerance is a stage-specific trait and changes during the life cycle. The effect of drought stress depended not only on the duration and intensity of water deficiency, but also on the developmental phase in which it began. To induce the same type of stress and to obtain comparable tolerance information from the replications, it is recommended that drought stress should be induced at the same growth stage. Correlations between the traits, commonly associated with improved drought resistance (high relative water content under stress, proline accumulation, osmoregulation) with stress tolerance indexes, are also presented, while the advantages and disadvantages of the most frequently used screening methods are discussed. [source] Effect of number of fractionating trays on reactive distillation performanceAICHE JOURNAL, Issue 12 2000Muhammad A. Al-Arfaj Sneesby et al. recently suggested that adding trays in the stripping and rectifying sections of a reactive distillation column can degrade performance. This effect, if true, is not only counterintuitive, but very disturbing because it suggests that the design of reactive distillation columns cannot use conservative estimates of tray numbers, that is, we cannot simply add excess trays, as in conventional distillation. The problem is compounded by the uncertainty in vapor,liquid equilibrium data and tray efficiencies. This implies that developing reactive distillation columns would require extensive experimental work at the pilot-plant and plant stages to find the numbers of stages offering the best performance. Such a scenario would mean long and expensive development programs. This article explores the effect of the number of trays in the rectifying and/or stripping sections of reactive (catalytic) distillation columns. Three reactive distillation systems are used: an ideal hypothetical system, the ETBE system, and the methyl acetate system. Contrary to the published results, it is demonstrated that additional trays do not degrade performance. Two degrees of freedom available in all cases must be carefully chosen for fair comparisons. [source] Induced Resistance by , -Aminobutyric Acid in Artichoke against White Mould Caused by Sclerotinia sclerotiorumJOURNAL OF PHYTOPATHOLOGY, Issue 10 2010Emanuela Marcucci Abstract ,-aminobutyric acid (BABA) was assessed for the ability to protect two artichoke cultivars, C3 and Exploter, against white mould caused by Sclerotinia sclerotiorum, which represents a major problem in the cultivation of this crop in many growing areas of Central Italy. Changes in the activity and isoenzymatic profiles of the pathogenesis-related (PR) proteins ,-1,3-glucanase, chitinase and peroxidase in plantlets upon BABA treatment and following inoculation of the pathogen in plantlets and leaves detached from adult plants were also investigated as molecular markers of induced resistance and priming. BABA treatments by soil drenching induced a high level of resistance against S. sclerotiorum in artichoke plantlets of both cultivars C3 and Exploter with a similar level of protection and determined a consistent increase in peroxidase activity paralleled with the differential induction of alkaline isoenzyme with a pI 8.6. A consistent change was found in Exploter in the peroxidase activity following BABA treatments and pathogen inoculation and was paralleled with the expression of an anionic band in plantlets and both anionic and cationic bands in leaves. Our results showed a correlation between BABA-induced resistance (BABA-IR) and a augmented capacity to express basal defence responses, more pronounced in cultivar C3 and associated ,-1,3-glucanase accumulation in both plantlets and leaves inoculated with the pathogen, whereas chitinase resulted affected only at plantlet stage. The present results represent the first one showing the effect of BABA in inducing resistance in artichoke and associated accumulation of selected PRs. If confirmed in field tests, the use of BABA at early plant stages may represent a promising approach to the control soilborne pathogens, such as the early infection of S. sclerotiorum. [source] Herbivory and Abiotic Factors Affect Population Dynamics of Arabidopsis thaliana in a Sand Dune AreaPLANT BIOLOGY, Issue 5 2005A. Mosleh Arany Abstract: Population dynamics of the annual plant Arabidopsis thaliana (L.) Heynh. were studied in a natural habitat of this species on the coastal dunes of the Netherlands. The main objective was to elucidate factors controlling population dynamics and the relative importance of factors affecting final population density. Permanent plots were established and plants were mapped to obtain data on survival and reproductive performance of each individual, with special attention to herbivore damage. In experimental plots we studied how watering, addition of nutrients, artificial disturbance, and natural herbivores affected survival and growth. Mortality was low during autumn and early winter and high at the time of stem elongation, between February and April. A key factor analysis showed a high correlation between mortality from February to April and total mortality. The specialist weevils Ceutorhyncus atomus and C. contractus (Curculionidae) were identified as the major insect herbivores on A. thaliana, reducing seed production by more than 40 %. These herbivores acted in a plant size-dependent manner, attacking a greater fraction of the fruits on large plants. While mortality rates were not affected by density, fecundity decreased with density, although the effect was small. Adding water reduced mortality in rosette and flowering plant stages. Soil disturbance did not increase seed germination, but did have a significant positive effect on survival of rosette and flowering plants. Seed production of A. thaliana populations varied greatly between years, leading to population fluctuations, with a small role for density-dependent fecundity and plant size-dependent herbivory. [source] Identification of a single dominant allele for resistance to blackleg in Brassica napus,Surpass 400'PLANT BREEDING, Issue 6 2003C.-X. Li Abstract The inheritance of resistance to blackleg (caused by Leptosphaeria maculans) was examined in the F1 and F2 of a cross between highly resistant canola ,Surpass 400' and susceptible ,Westar' in the field. Blackleg-infected canola straw was collected from the field and scattered among plants to increase disease development with the aid of natural rainfall. Disease severity on seedlings was assessed as the average number of lesions on leaves 1 and 2, and on adult plants as the percentage necrosis on a cross-section of stems immediately above the crown. All ,Westar' plants were susceptible (S) and all ,Surpass 400' and F1 plants were resistant (R) at both growth stages. Disease severity on F2 plants segregated 3 : 1 (R : S) as expected for a single dominant resistance allele in both the seedling and adult plant stages. There was a high proportion (91.1%) of matching reactions (R-R and S-S) between seedling and adult plants. ,Surpass 400' is the source of a single dominant allele for blackleg resistance in Brassica napus that is expressed strongly in both seedlings and adult plants. [source] Combination of resistance tests and molecular tests to postulate the yellow rust resistance gene Yr17 in bread wheat linesPLANT BREEDING, Issue 6 2000O. Robert Abstract Yellow rust caused by Puccinia striiformis is a wheat disease of worldwide importance. The Yr17 resistance gene introgressed from Aegilops ventricosa was effective, in France, against all yellow rust isolates until 1998. The SC-Y15 marker is one of three molecular markers closely linked to Yr17. In this paper, results obtained are compared with the molecular marker SC-Y15 and with resistance tests performed at the seedling and adult plant stages on 31 lines from five populations derived from recurrent selection programmes. The resistance tests showed that Yr17 controlled the resistance in seven lines, but that others had additional resistance at the adult stage (18 lines). The molecular test corresponded well with the resistance test in most lines (98% of 156 plants tested), including individual plants that were resistant or susceptible in heterogeneous lines. It also indicated the presence of Yr17 in lines in which it could not be identified by the resistance test because of the presence of other genes. Three of the 156 plants tested appeared to have the gene Yr17 according to the resistance tests, but lacked the molecular marker. These could have resulted from breakage of the linkage, the number being consistent with the estimate of linkage already published. This indicated the need for a resistance test, at least in later stages of breeding programmes, if it is considered essential to have the Yr17 gene present. The use of the selected lines in breeding programmes is also discussed. [source] | ||||||||||