The Experts below are selected from a list of 321 Experts worldwide ranked by ideXlab platform
Gaoming Jiang - One of the best experts on this subject based on the ideXlab platform.
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impacts of Methods and sites of plant Breeding on ozone sensitivity in winter wheat cultivars
Agriculture Ecosystems & Environment, 2009Co-Authors: D K Biswas, J C Yang, Shengbin Chen, Chunming Jiang, K P, S K Adhikary, X Z Wang, Gaoming JiangAbstract:Abstract Development and use of ozone (O3)-resistant crop cultivars are key measures to avoid agricultural yield reduction in a high O3 environment. However, little is known about the impacts of Breeding Methods and Breeding sites on the development of O3 tolerance in winter wheat cultivars. To explore such impacts, 20 Chinese winter wheat cultivars bred using four Breeding Methods (viz. introduction, reselection, conventional Breeding and hybridization) at four Breeding sites having different levels of O3 exposures, were exposed to charcoal-filtered (CF) air or high O3 (82 ppb, 7 h d−1) for 21 days. O3 tolerance of cultivars was assessed by the relative levels of visible injury, growth, gas exchange, dark respiration, antioxidative activities and oxidative modification of proteins and cellular membranes. We found that conventional Breeding and hybridization demonstrated higher potential capacity for O3 tolerance as indicated by a higher level of ascorbate and peroxidase activity in cultivars exposed to CF air. Despite the highest potential capacity for O3 tolerance, hybridization displayed the lowest O3 tolerance as represented by antioxidative activities, oxidative stress, photosynthesis and growth. The causes of higher O3 sensitivity in hybrid cultivars included lower O3 exclusion by stomatal closure, higher reduction in antioxidative activities, higher O3-induced modification of proteins and cellular membranes, lower level of repair of O3-induced cellular damage and higher loss of assimilation rate as well as growth in O3 relative to control plants. Cultivars bred at Breeding sites experiencing higher ambient O3 exposures demonstrated higher potential capacity for O3 tolerance. The observed O3 tolerance in cultivars bred by different Breeding Methods was uncorrelated to ambient O3 levels in Breeding sites as well as to the potential O3 tolerance capacity as observed in CF air. Results from our experiment, therefore, clearly indicated that potential O3 sensitivity would have little use in predicting actual O3 tolerance of winter wheat cultivars. Our findings also suggested that sensitivity to O3 in winter wheat cultivars was related to Breeding Methods, but not to O3 concentrations in Breeding sites.
M.j. Lawrence - One of the best experts on this subject based on the ideXlab platform.
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Quantitative genetics of rice. II. A comparison of the efficiency of four Breeding Methods.
Field Crops Research, 1998Co-Authors: M. Fahim, M.p. Dhanapala, D. Senadhira, M.j. LawrenceAbstract:Abstract A comparison of the efficiency of four Breeding Methods, the pedigree, modified pedigree and bulk Methods, and single seed descent, with a pair of crosses whose potential was assessed in a previous paper, showed that, on average, the F 6 products of the three Methods in which selection had been practiced outscored those produced by single seed descent for most characters for which improvement was sought. However, though the best lines produced by these Methods achieved the desired targets for every character considered singly, none were significantly better than the best single seed descent line for any character in either cross. These results indicate that while it has been possible to practice effective negative selection during the course of inBreeding, by culling plants of poor performance, attempts to carry out positive selection of plants of superior performance were less successful. An audit of the costs incurred in producing the most promising F 6 lines that were extracted by these Methods from each cross revealed that the single seed descent lines were the cheapest and those of the pedigree and modified pedigree Methods the most expensive. These results indicate, therefore, that single seed descent is at least as effective as the other Methods, is less costly and, where three generations can be raised per annum, is more rapid. Comparison of the observed proportions of superior single seed descent F 6 lines, with those predicted from information obtained from the F 3 generation of these crosses showed that for the majority of characters, the former were close to the latter. Single seed descent, therefore, has the further advantage that it is possible to predict the potential of a cross on information obtained from the early generations of the pedigree.
Alexandre Siqueira Guedes Coelho - One of the best experts on this subject based on the ideXlab platform.
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Traditional and Modern Plant Breeding Methods with Examples in Rice (Oryza sativa L.)
Journal of agricultural and food chemistry, 2013Co-Authors: Flávio Breseghello, Alexandre Siqueira Guedes CoelhoAbstract:Plant Breeding can be broadly defined as alterations caused in plants as a result of their use by humans, ranging from unintentional changes resulting from the advent of agriculture to the application of molecular tools for precision Breeding. The vast diversity of Breeding Methods can be simplified into three categories: (i) plant Breeding based on observed variation by selection of plants based on natural variants appearing in nature or within traditional varieties; (ii) plant Breeding based on controlled mating by selection of plants presenting recombination of desirable genes from different parents; and (iii) plant Breeding based on monitored recombination by selection of specific genes or marker profiles, using molecular tools for tracking within-genome variation. The continuous application of traditional Breeding Methods in a given species could lead to the narrowing of the gene pool from which cultivars are drawn, rendering crops vulnerable to biotic and abiotic stresses and hampering future progre...
M. Fahim - One of the best experts on this subject based on the ideXlab platform.
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Quantitative genetics of rice. II. A comparison of the efficiency of four Breeding Methods.
Field Crops Research, 1998Co-Authors: M. Fahim, M.p. Dhanapala, D. Senadhira, M.j. LawrenceAbstract:Abstract A comparison of the efficiency of four Breeding Methods, the pedigree, modified pedigree and bulk Methods, and single seed descent, with a pair of crosses whose potential was assessed in a previous paper, showed that, on average, the F 6 products of the three Methods in which selection had been practiced outscored those produced by single seed descent for most characters for which improvement was sought. However, though the best lines produced by these Methods achieved the desired targets for every character considered singly, none were significantly better than the best single seed descent line for any character in either cross. These results indicate that while it has been possible to practice effective negative selection during the course of inBreeding, by culling plants of poor performance, attempts to carry out positive selection of plants of superior performance were less successful. An audit of the costs incurred in producing the most promising F 6 lines that were extracted by these Methods from each cross revealed that the single seed descent lines were the cheapest and those of the pedigree and modified pedigree Methods the most expensive. These results indicate, therefore, that single seed descent is at least as effective as the other Methods, is less costly and, where three generations can be raised per annum, is more rapid. Comparison of the observed proportions of superior single seed descent F 6 lines, with those predicted from information obtained from the F 3 generation of these crosses showed that for the majority of characters, the former were close to the latter. Single seed descent, therefore, has the further advantage that it is possible to predict the potential of a cross on information obtained from the early generations of the pedigree.
Christian Zorb - One of the best experts on this subject based on the ideXlab platform.
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development of salt resistant maize hybrids the combination of physiological strategies using conventional Breeding Methods
Plant Science, 2009Co-Authors: Sven Schubert, Anja Neubert, Antje Schierholt, Ali Sumer, Christian ZorbAbstract:Abstract According to the two-phase model of growth response to salt stress by Munns, there are two major physiological problems that may limit crop performance under saline conditions. In a first phase, osmotic problems reduce extension growth so that plants show stunted growth and look dark-green in color. In a second phase, ion toxicity develops and growth of sensitive plants is severely inhibited. Based on physiological knowledge, a Breeding program was initiated to improve the salt resistance of maize. First, an efficiently Na + -excluding inbred line (NaExIl) was established that combines superior Na + exclusion at the root surface with low Na + root-to-shoot translocation relative to the parental hybrid Pioneer 3906. Second, out of 200 inbred lines 16 inbred lines were identified with increased osmotic resistance. Crossing of these inbred lines with NaExIl resulted in newly developed hybrids (SR hybrids) that showed significantly improved grain yield performance under saline conditions (EC = 10 dS m −1 ). Whereas osmotic adjustment, turgor, and cell-wall acidification are maintained in the newly developed SR hybrids, cell-wall extensibility still seems to limit extension growth. The newly developed SR hybrids are ideal tools to study physiological traits that may contribute to salt resistance of maize.