The major goal for long-term poplar breeding can be formulated as maximizing annual progress in Group Merit Gain at a given annual budget （GMG/Y＊）. To evaluate different breeding scenarios, a deterministic simulato...The major goal for long-term poplar breeding can be formulated as maximizing annual progress in Group Merit Gain at a given annual budget （GMG/Y＊）. To evaluate different breeding scenarios, a deterministic simulator BREEDING CYCLE ANALYZER covering the most important aspects （gain, cost, time, technique, and gene diversity） of a full breeding cycle was used. The breeding strategies considered was based on pairwise crossing of the selected breeding population and balanced within family selection for the next breeding population. A main scenario and a number of alternative scenarios within these constraints were evaluated using estimates of the best available inputs for poplars. In focus was a comparison between three different testing scenarios for selecting the parents mated to create future breeding generations, thus selecting based on phenotype, clone test or progeny test. For the main scenario, the highest GMG/Y, and the optimal selection age for clone, phenotype and progeny strategies were 0.7480 %, 0.6989% and 0.4675%; 7, 6, and 11 years respectively. Clone test was best except when heritability was high, plant price was high or total budget was low; phenotype strategy was the second except for the case of extremely low narrow-sense heritability, for which the progeny strategy was a little more efficient than phenotype strategy. GMG/Y was markedly affected by narrow-sense heritability, additive variance at mature age, rotation age, plant-dependent cost, total budget and the time needed to produce the test plants, while diversity loss and recombination cost had rather weak effect on GMG/Y. Short rotation age and cheap testing cost favoured all three testing strategies. Comparably short rotation age, low plant-dependent cost and high total budget seem to promote early selection for progeny strategy.展开更多
Cross breeding strategies are very efficient for gaining new and superior genotypes. Ninety-eight new white poplar hybrid clones produced from 12 cross combinations within the Section Leuce Duby were studied using gen...Cross breeding strategies are very efficient for gaining new and superior genotypes. Ninety-eight new white poplar hybrid clones produced from 12 cross combinations within the Section Leuce Duby were studied using genetic analysis and seedling tests. We exploited the wide variation that exists in this population and found that the differences among diameter at breast height （DBH）, root collar diameter （RCD） and height （H） were statistically extremely significant. The repeatability of clones of these measured traits ranged from 0.947-0.967, which indicated that these traits were strongly controlled by genetic factors. Based on multiple compari- sons, a total of 25 clones showed better performance in growth than the control cultivar. These 25 clones were from six different cross combinations, which can guarantee a larger genetic background for future new clone promotion projects. This study provides a simple overview on these clones and can guide us to carry out subsequent selection plans.展开更多
基金This study was supported by Kempe Foundation, the ChinaScholarship Council (CSC) and Jiangsu Hi-tech foundation (BG2003306)
文摘The major goal for long-term poplar breeding can be formulated as maximizing annual progress in Group Merit Gain at a given annual budget （GMG/Y＊）. To evaluate different breeding scenarios, a deterministic simulator BREEDING CYCLE ANALYZER covering the most important aspects （gain, cost, time, technique, and gene diversity） of a full breeding cycle was used. The breeding strategies considered was based on pairwise crossing of the selected breeding population and balanced within family selection for the next breeding population. A main scenario and a number of alternative scenarios within these constraints were evaluated using estimates of the best available inputs for poplars. In focus was a comparison between three different testing scenarios for selecting the parents mated to create future breeding generations, thus selecting based on phenotype, clone test or progeny test. For the main scenario, the highest GMG/Y, and the optimal selection age for clone, phenotype and progeny strategies were 0.7480 %, 0.6989% and 0.4675%; 7, 6, and 11 years respectively. Clone test was best except when heritability was high, plant price was high or total budget was low; phenotype strategy was the second except for the case of extremely low narrow-sense heritability, for which the progeny strategy was a little more efficient than phenotype strategy. GMG/Y was markedly affected by narrow-sense heritability, additive variance at mature age, rotation age, plant-dependent cost, total budget and the time needed to produce the test plants, while diversity loss and recombination cost had rather weak effect on GMG/Y. Short rotation age and cheap testing cost favoured all three testing strategies. Comparably short rotation age, low plant-dependent cost and high total budget seem to promote early selection for progeny strategy.
基金National Natural Sciences Foundation of China (Grant No.30571516)National Project of Science and Technology for the 11th Five-Year Plan (Grant No.2006BAD01A1502)
文摘Cross breeding strategies are very efficient for gaining new and superior genotypes. Ninety-eight new white poplar hybrid clones produced from 12 cross combinations within the Section Leuce Duby were studied using genetic analysis and seedling tests. We exploited the wide variation that exists in this population and found that the differences among diameter at breast height （DBH）, root collar diameter （RCD） and height （H） were statistically extremely significant. The repeatability of clones of these measured traits ranged from 0.947-0.967, which indicated that these traits were strongly controlled by genetic factors. Based on multiple compari- sons, a total of 25 clones showed better performance in growth than the control cultivar. These 25 clones were from six different cross combinations, which can guarantee a larger genetic background for future new clone promotion projects. This study provides a simple overview on these clones and can guide us to carry out subsequent selection plans.
