Referring to corn breeding literature at home and abroad,the possible ways to improve the efficiency of maize breeding were discussed.The results showed that through the summary and reflection on breeding objectives a...Referring to corn breeding literature at home and abroad,the possible ways to improve the efficiency of maize breeding were discussed.The results showed that through the summary and reflection on breeding objectives and strategies,and improvement and optimization of breeding techniques and methods,as well as adjustment and simplification of experimental design and implementation,the breeding cost would be greatly reduced,and the breeding efficiency would be improved.展开更多
Before farmers can benefit from new improved maize varieties with novel genetic information, new maize varieties have to undergo performance testing, registration and approval. The registration procedures require that...Before farmers can benefit from new improved maize varieties with novel genetic information, new maize varieties have to undergo performance testing, registration and approval. The registration procedures require that new maize varieties must pass the tests for value for cultivation and use （VCU） and standardized tests for distinctness, uniformity and stability （DUS）. To meet the minimum requirements for variety release, public and private sector maize breeding programs routinely assemble breeding nurseries and evaluate variety performance in National and Regional Performance Trials （NRPT） with the objective of generating important agronomic data to identify the best maize varieties for release. In spite of intensive variety evaluation in regional and national trials, only few maize varieties have been registered and released annually in sub-Saharan Africa （SSA） denying farmers access to new improved varieties. The purpose of this study was to identify constraints hampering the registration and release of elite maize gennplasm and make recommends on how to quicken the deployment of elite germplasm to smallholders＇ farmers. A survey was conducted on the varietal testing and release systems in 14 selected countries （Angola, Benin, Ethiopia, Malawi, Ghana, Mali, Mozambique, Nigeria, Tanzania, Kenya, South Africa, Uganda, Zambia, and Zimbabwe） in SSA. The results from the study show that regulations on variety testing and release procedures in the various countries are overlapping and rigid hindering the deployment and commercialization of new improved maize germplasm. The study also showed that varietal release rates fluctuated between countries with South Africa having the highest number of varietal release rates per year and some countries failing to release a single variety per year.展开更多
The main objective of this study was to evaluate the impact of adopting improved maize varieties on crop yield in Uganda using propensity score matching （PSM） algorithms to control for hidden selection bias. The stu...The main objective of this study was to evaluate the impact of adopting improved maize varieties on crop yield in Uganda using propensity score matching （PSM） algorithms to control for hidden selection bias. The study employed cross-sectional household data collected in 2005/2006 by the Uganda Bureau of Statistics （UBOS） across the country. Data were divided into two parts; the full sample and smallholder farmer sub-sample （those that cultivated less than 5 acres or 2 Hectares of maize in 2004 and 2005）. Then estimation was made of the difference in yields between the adopters and non adopters, the average treatment effect on the treated （ATT） for the full sample and smallholder farmer sub-sample. Matching methods were used to control for hidden selection bias and the standardized bias measure was used to check for the quality of matching. The results indicate that adoption of improved maize seed had a robust positive and significant effect on yields obtained by farmers. The results were consistent for both the full and smallholder farmer sub-samples. Sensitivity analysis using Rosenbaum bounds indicated that the ATT results were fairly robust to hidden selection bias. That is, the results were not sensitive to unobserved selection bias. Therefore it is confidently asserted that the estimated average difference in maize yields between the adopters and non-adopters was due to the effect of planting improved maize seed.展开更多
基金Supported by National Science and Technology Support Program(2007BAD69B05)~~
文摘Referring to corn breeding literature at home and abroad,the possible ways to improve the efficiency of maize breeding were discussed.The results showed that through the summary and reflection on breeding objectives and strategies,and improvement and optimization of breeding techniques and methods,as well as adjustment and simplification of experimental design and implementation,the breeding cost would be greatly reduced,and the breeding efficiency would be improved.
文摘Before farmers can benefit from new improved maize varieties with novel genetic information, new maize varieties have to undergo performance testing, registration and approval. The registration procedures require that new maize varieties must pass the tests for value for cultivation and use （VCU） and standardized tests for distinctness, uniformity and stability （DUS）. To meet the minimum requirements for variety release, public and private sector maize breeding programs routinely assemble breeding nurseries and evaluate variety performance in National and Regional Performance Trials （NRPT） with the objective of generating important agronomic data to identify the best maize varieties for release. In spite of intensive variety evaluation in regional and national trials, only few maize varieties have been registered and released annually in sub-Saharan Africa （SSA） denying farmers access to new improved varieties. The purpose of this study was to identify constraints hampering the registration and release of elite maize gennplasm and make recommends on how to quicken the deployment of elite germplasm to smallholders＇ farmers. A survey was conducted on the varietal testing and release systems in 14 selected countries （Angola, Benin, Ethiopia, Malawi, Ghana, Mali, Mozambique, Nigeria, Tanzania, Kenya, South Africa, Uganda, Zambia, and Zimbabwe） in SSA. The results from the study show that regulations on variety testing and release procedures in the various countries are overlapping and rigid hindering the deployment and commercialization of new improved maize germplasm. The study also showed that varietal release rates fluctuated between countries with South Africa having the highest number of varietal release rates per year and some countries failing to release a single variety per year.
文摘The main objective of this study was to evaluate the impact of adopting improved maize varieties on crop yield in Uganda using propensity score matching （PSM） algorithms to control for hidden selection bias. The study employed cross-sectional household data collected in 2005/2006 by the Uganda Bureau of Statistics （UBOS） across the country. Data were divided into two parts; the full sample and smallholder farmer sub-sample （those that cultivated less than 5 acres or 2 Hectares of maize in 2004 and 2005）. Then estimation was made of the difference in yields between the adopters and non adopters, the average treatment effect on the treated （ATT） for the full sample and smallholder farmer sub-sample. Matching methods were used to control for hidden selection bias and the standardized bias measure was used to check for the quality of matching. The results indicate that adoption of improved maize seed had a robust positive and significant effect on yields obtained by farmers. The results were consistent for both the full and smallholder farmer sub-samples. Sensitivity analysis using Rosenbaum bounds indicated that the ATT results were fairly robust to hidden selection bias. That is, the results were not sensitive to unobserved selection bias. Therefore it is confidently asserted that the estimated average difference in maize yields between the adopters and non-adopters was due to the effect of planting improved maize seed.
