Crops and Soils
Granule size distribution of wheat starch is an important characteristic that may affect the functionality of wheat products. Light intensity is one of the main factors affecting grain yield and quality. Two high-yield winter wheat cultivars were grown under shade to evaluate the effect of low light intensity after anthesis on starch granule size distribution and starch components in wheat grains at maturity. Shading caused a marked drop in both grain yield and starch yield and led to a significant reduction in the proportion (both by volume and by surface area) of B-type starch granules (9·9 μm), with an increase in those of A-type starch granules (>9·9 μm). This would suggest that the production of B-type starch granules was more sensitive to shading than that of A-type starch granules. It was also found that the proportion by volume of A-type starch granules was significantly increased and that of B-type starch granules was significantly decreased by shading at different grain filling stages, especially at middle and late grain-filling stages. However, shading had little effect on the proportional number of B-type starch granules. The present results suggested that, under dim light conditions, the limited substrate for starch accumulation was mainly partitioned towards hypertrophy (larger granules) not hyperplasia (more) of starch granules.
(Received August 30 2009)
(Online publication December 17 2009)