Efficiency Of Seed Production Research Articles

Developing eui-cytoplasmic male sterile lines and applying them in hybrid rice breeding

In hybrid rice development, a serious problem associated with cytoplasmic male sterile (CMS) lines is poor panicle exsertion, which reduces outcrossing rate and hybrid seed production. Gibberellic acid (GA3) has been routinely used to solve this problem. Other problems arise from application of GA3, however, including increased costs, reduced seed quality, and possible environmental hazards. Rugter and Carnahan (1981) reported a recessive mutant that can cause elongation of the uppermost internode, referred to as the eui-1 gene. Since eui can play the same role as GA3 when transferred into CMS lines, this finding has attracted much interest in the development of CMS lines. We generated eui mutants through irradiation on both maintainer (B) and restorer (R) lines and transferred eui-1 into CMS lines in China to improve hybrid rice seed production efficiency (Yang 1998). We report here the discovery of a new eui gene, referred to as eui-2 (t), and the development of several B and R lines with the eui gene (designated as eA and eR), as well as the development of several hybrids with eui CMS lines.

F1 Seed Production Efficiency by Using Photoperiod-sensitive Cytoplasmic Male Sterility and Performance of F1 Hybrid Lines in Wheat.

Photoperiod-sensitive cytoplasmic male sterility (PCMS) caused by Aegilops crassa cytoplasm to common wheat (Triticum aestivum) under long-day conditions (≥15 h light period) has been reported as a new means of producing hybrid wheat, that is a “two-line system”. The PCMS Iine is Inaintained by self-pollination under short-day conditions (≤14.5 h light period), and F1 seeds can beproduced by outcrossing of the PCMS Iine with a pollinator under long-day conditions. A cross pollination study for producing F1 seeds was carried out using three PCMS Iines and three restorer lines under a long-day condition at Tanno, Hokkaido, Japan. Seed setting rate was 14-33%, and 19-55 g/m2 F1 seeds with 47-88% hybrid purity were obtained. Variation in seed setting rate attributable to male parents was highly significant. High seed setting rate was achieved by using a pollinator taller than the PCMS Iine. Shriveled and preharvest sprouting kernels were found in the out-crossed F1 seeds, resulting in lower volume weight and germination rate than the selfed seeds of original cultivars of the PCMS Iines. A field test of evaluating four F1 hybrids with high hybrid purity (>65 %) was conducted under a short-day condition at Kasai, Hyogo, Japan. All F1 hybrids exhibited higher grain yield than their respective better-parent because of more spikelet number/ear and higher 1000 grain weight. The top F1 hybrid yielded 40% more than the mid-parent and 37% more than the better-parent, suggesting a possibility of the practical use of this system for hybrid wheat breeding. F1 hybrids tended to show higher volume weight than their parental cultivars. This indicates that grain quality of the F1 hybrids with the Ae. crassa cytoplasm is not inferior to those of parental cultivars with the wheat cytoplasm.

Nitrogen Economy, Seed Production Efficiency and Seed Vigour of Panicum maximum by Intercropping of Pasture Legumes

A field experiment was conducted to evaluate the performance of pasture legumes (Desmanthus virgatus, Sesbania aegyptica, Macroptelmm autropurpureum, Desmodium tortuosum, Stylosanthes hamata used as in intercropped element) in terms of nitrogen economy, seed production efficiency and seed vigour potential of Panicum maximum– a grass based management maintained for 1986–88 at Research Farm, Indian Grassland and Fodder Research Institute, Jhansi under rainfed condition. Nitrogen economy under these intercropped pasture legumes was estimated on equating its value against nitrogen treatment i.e. 0, 10, 20, 30 and 40 kg N/ha. Among five intercropped legumes, Stylosanthes hamata and Macroptelium autropurpureum intercropping doubled the seed yield; S. aegyptica and M. autropurpureum brought out 46–55 per cent increase in biomass production over control value of 41.7 kg seed and 223.4 q biomass/ha respectively. These treatment showed 20–40 kg N/ha nitrogen equivalent value. Further more increased seed yield of Panicum maximum under intercropping was attributed to its better ear production, spike length and potential sink strength. Germination potential of harvested Panicum seeds under different treatments did not show variation among themselves. Potential seed production performance of Panicum maximum in the first year as compared to subsequent years might be due to its general transcript of plants and have some interaction with rainfall.

Seed Production Efficiency of Timothy (Phleum pratense L.) in Dung Patches

Seed Production Efficiency of Timothy (Phleum pratense L.) in Dung Patches

THE SEED PRODUCTION CAPACITY AND EFFICIENCY OF RED PINE CONES (PINUS RESINOSA AIT.)

The seed capacity of red pine cones varies from about 30 to over 110, depending on the size of the cone and its position in the tree crown, and is determined by the number of ovules that are structurally complete at the time of pollination. These ovules occur in a central "productive" region and constitute less than one-half of the total. The remaining ovules, most: of which are in the proximal part of the cone, never become structurally perfect, and do not contribute to seed production. Abortion of ovules in the productive region usually reduces seed production efficiency to 50–60%, and is accompanied mainly by withering of the nucellus in the first year and failure to produce archegonia early in the second year. The extent of ovule abortion during the first year varies indirectly with cone size, seed capacity, and height in tree.