Reduced sterility in the EMF line subjected to rising temperatures at anthesis in the greenhouse was attributed to an earlier flowering time compared with Koshihikari. The EMF trait of wild rice is effective in mitigating anticipated yield loss due to global warming by escaping high-temperature stress at anthesis during the daytime.

No abstract

No abstract

No abstract

Increasing leaf photosynthesis offers a possible way to improve yield potential in rice (Oryza sativa L.). Carbon isotope discrimination (Delta(13)C) has potential as an indirect selection criterion. In this study, we searched for quantitative trait loci (QTLs) controlling Delta(13)C, and assessed their association with leaf photosynthesis. Substitution mapping by using chromosome segment substitution lines (CSSLs), that carry segments from the indica cultivar Kasalath in the genetic background of the japonica cultivar Koshihikari, identified genomic regions affecting Delta(13)C on chromosomes (Chr.) 2, 3, 6, 7, and 12. One of the CSSLs, SL208, in which most regions on Chr. 3 were substituted with Kasalath segments, showed higher leaf stomatal conductance for CO(2) (g (s)) and Delta(13)C than Koshihikari during the vegetative stage although leaf photosynthetic rate did not differ between them. These results suggest an association between Delta(13)C and g (s). To test this association, we performed a QTL analysis for Delta(13)C at vegetative and heading stages in an F(2) population derived from a cross between SL208 and Koshihikari. The results confirmed a QTL controlling Delta(13)C on the long arm of Chr. 3. By using a near-isogenic line specific to Hd6, we ruled out the possibility that variation in Delta(13)C was generated through the pleiotropic effect of heading date.

No abstract

Increasing the biomass productivity of rice is a critical research target for improving the yield potential. This paper reviews ecophysiological studies on biomass production as affected by agronomic techniques and cultivars. In addition, we examined the effects of the planting pattern on the biomass production using cv. Takanari, a high-yielding and lodging resistant cultivar. The results showed that greater biomass production and grain yield were observed in plants with the combination of one plant per hill, high hill density and square hill arrangement. The factors responsible for high biomass production in this combination are; (1) vigorous tiller increase at the tillering stage resulting in higher capture of solar radiation, (2) erect leaves in the canopy after the panicle formation stage resulting in an improved light-intercepting character or smaller extinction coefficient, and (3) larger nitrogen accumulation during the ripening period resulting in a smaller decline of photosynthesis as well as a smaller midday and afternoon depression of photosynthesis possibly related to the larger water uptake ability of roots owing to better root-system development. Our results implied that an improvement in biomass production and yield is possible by optimizing the planting pattern and nitrogen management using high-yielding and lodging resistant cultivars in transplanted and direct-sown rice.

No abstract