 หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : Trends in Drought Research) ผู้เขียน: Rainer Messmer, Peter Stamp สื่อสิ่งพิมพ์:pdf AbstractDrought is already a major abiotic constraint to global food production. Climate change will further aggravate this situation. Moreover, the expected increase in the world’s population over the next decades will pose huge challenges to food production as the available water per capita decreases. Although several methods have been developed, it remains difficult to judge where water is and whether it will be scare. Technological improvements will allow for more efficient irrigation. At the same time, it is vital to develop genetically improved crops, which produce higher yields under drought conditions. This can be achieved by increasing their yield potential and by reducing the gap between the maximum yield potential and yield under drought. For example, considerable progress has been made in the genetic improvement of temperate and tropical maize. Future progress will depend on newly defined secondary traits involved in the aerial morphology of plants, in the development and the architecture of the root system, and in physiological mechanisms that confer drought tolerance. There are many techniques available to achieve a better understanding of the complex network of plant responses to drought and to manipulate these responses. These techniques include the mapping of quantitative trait loci (QTLs), association mapping, studies of gene expression and genetic transformation. Although it is unlikely that single genes, especially genes protecting primary metabolism, will greatly enhance plant productivity in the field, some results are encouraging. The success of these technologies will depend on a multidisciplinary approach combining physiology, quantitative genetics, genomics and breeding. Moreover, the agronomical, socio-economical and political context must be considered in order to meet the tremendous challenges to crop improvement. |
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หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : Early Hybrid Testing in Tropical Maize: Are Molecular Markers Useful for Selecting the Parental Component?) ผู้เขียน:Pongsai Chuanchai, Tan Xuelin, เอนก ศิลปพันธุ์, ประดิษฐ์ สุทธิพงศ์, Luan Wei, Rainer Messmer สื่อสิ่งพิมพ์:pdf AbstractThe combination of parental lines determines hybrid performance. Two methods for choosing parental components in early-generation hybrid testing were compared in the present study. The S1 lines of two tropical maize populations from Yunnan and Guangxi were selected either based on the yield performance of reciprocal half-sib progeny (conventional method) or the maximization of the genetic distance (GD) between S1 lines, calculated from the allelic information of fifty SSR markers. The GD between the two original populations was low, probably because of the narrow genetic base and only two generations of development. However, the weak positive correlations between the grain yield of F1 hybrids and the GD as well as the specific combining ability (SCA), indicated that selecting the parents of testcrosses based on their genetic distance could help identify optimal genotype combinations. Highyielding F1 hybrids could be undoubtedly produced by conventionally selecting the parents and without costly field testing. As some crosses of S1 lines resulted in high-yielding progeny, the populations from Yunnan and Guangxi could provide additional new heterotic patterns for tropical maize breeding. |