Growth analysis of a sorghum hybrid and its parents

Growth rate, leaf area index, net assimilation rate, and distribution of dry matter among aboveground plant parts were determined for sorghum [Sorghum bicolor (L.) Moench] hybrid ‘RS 610’ and its parents throughout the growing season in a replicated field experiment. Dry weight and leaf area were measured twice weekly before flowering and weekly thereafter. The hybrid developed faster than its parents. It had greater leaf area than its parents until 1 week prior to flowering, and less leaf area than its parents thereafter. The hybrid had greater total dry weight than its parents throughout the growing season. The crop growth rate (CGR) of the hybrid was greater than that of either parent from emergence to panicle initiation, while net assimilation rate and relative growth rate did not differ among genotypes at this period. RS 10 outyielded its parents in grain, and had more kernels per panicle than the female parent, but did not differ from the male parent in this characteristic. The yield superiority of RS 610 was attributed mainly to the combination of the high CGR of the female parent during grain filling with the effective conversion of dry matter to grain of the male parent. More rapid seedling growth and a longer grain filling period were also advantages of the hybrid over its parent

Beta-decay half-lives and beta-delayed neutron emission probabilities of nuclei in the region below A=110, relevant for the r-process

Measurements of the beta-decay properties of r-process nuclei below A=110 have been completed at the National Superconducting Cyclotron Laboratory, at Michigan State University. Beta-decay half-lives for Y-105, Zr-106,107 and Mo-111, along with beta-delayed neutron emission probabilities of Y-104, Mo-109,110 and upper limits for Y-105, Zr-103,104,105,106,107 and Mo-108,111 have been measured for the first time. Studies on the basis of the quasi-random phase approximation are used to analyze the ground-state deformation of these nuclei.Comment: 21 pages, 10 figures, article accepted for publication in Physical Review

Beta-decay of nuclei around Se-90. Search for signatures of a N=56 sub-shell closure relevant the r-process

Nuclear structure plays a significant role on the rapid neutron capture process (r-process) since shapes evolve with the emergence of shells and sub-shells. There was some indication in neighboring nuclei that we might find examples of a new N=56 sub-shell, which may give rise to a doubly magic Se-90 nucleus. Beta-decay half lives of nuclei around Se-90 have been measured to determine if this nucleus has in fact a doubly-magic character. The fragmentation of Xe-136 beam at the National Superconducting Cyclotron Laboratory at Michigan State University was used to create a cocktail of nuclei in the A=90 region. We have measured the half lives of twenty-two nuclei near the r-process path in the A=90 region. The half lives of As-88 and Se-90 have been measured for the first time. The values were compared with theoretical predictions in the search for nuclear-deformation signatures of a N=56 sub-shell, and its possible role in the emergence of a potential doubly-magic Se-90. The impact of such hypothesis on the synthesis of heavy nuclei, particularly in the production of Sr, Y and Zr elements was investigated with a weak r-process network. The new half lives agree with results obtained from a standard global QRPA model used in r-process calculations, indicating that Se-90 has a quadrupole shape incompatible with a closed N=56 sub-shell in this region. The impact of the measured Se-90 half-life in comparison with a former theoretical predication associated with a spherical half-life on the weak-r-process is shown to be strong

Alternate cytoplasms and apomixis of sorghum and pearl millet

Cytoplasmic-nuclear male sterility (CAdS) has been an important factor in the improvement o f sorghum and pearl millet by increasing yield, expanding production, and stimulatingresearch and breeding. The identification o f alternate sterility-inducing cytoplasms and their emerging deployment hold promise for further advances. Current research to determine the cause and control o f CMS in these species could lead to greater efficiency and effectiveness in using CMS to select parents andproduce hybrids. Apomixis, although not now used with either sorghum or pearl millet, has the potential to be as important as male sterility in these species. Potential sources have been identified and research is in progress on characterization, introgression, and enhancement. The ability to perpetuate hybrid vigor by self-pollination could be very important in some o f the major sorghum and millet growing areas