Contribution of stem nonstructural carbohydrates to grain yield in new plant types of rice
1998
Egdane, J.A. | Laureles, E.V. | Ito, O. | Khush, G.S. (International Rice Research Inst., P.O. Box 933, 1099 Manila (Philippines))
New plant types (NPT) of rice were developed at IRRI for higher grain yield by incorporating the trait of larger panicle size. However, earlier results showed that NPT lines failed to achieve the targeted yield due to low grain filing, although a significant amount of nonstructural carbohydrates were left unutilized in the stem at maturity. This study evaluated the apparent contribution of nonstructural carbohydrates in the stem before flowering to yield and examined other factors, which may have limited grain production. Five Bulu parents and 28 NPT lines were used. Preliminary results indicate that the carbohydrates in the stem before flowering contributed significantly to the developing panicles during grain filling in NPT lines. There was negative correlation between change in spikelet dry weight during the ripening and panicle number per hill (r=0.59), between change in panicle dry weight during ripening and panicle number per hill (r=0.77), and between spikelet number per panicle and percentage filled grains (r=0.54). A positive correlation between soluble sugar content in the stems at maturity and percentage filled grains (r=0.56) was observed. The assimilates mobilized from the stems of the NPT lines were equivalent to 15-60 percent of grain weight in maturity, indicating that NPT lines rely heavily on the stored carbohydrates to meet the demand of developing panicles during grain-filling period. Further work on the source-sink relationship is required to determine the factors limiting grain filling in terms of supply and consumption of available carbohydrates
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