The effect of environment on seed development in sorghum : (Sorghum bicolor (L.) Moench)

Abstract

Small Seed Syndrome (SSS) is a problem that plagues the sorghum breeder, producer, transporter, and processor. Small seed cause a reduction in yield, prices and feed efficiency due to decreases in weight, density, protein content, and starch content. These seed appear fully developed externally except for the smaller size. However, SSS seed have more floury endosperms that lies adjacent to the scutellar region of the embryo and also exhibit differences in physical and chemical characteristics. Temperature treatment both before and after flowering can cause small seed to occur in RS671. Small seed found in greenhouse grown sorghum are not typical of SSS seed. Seed defects caused by temperature treatment after flowering will be reductions in weight per 100 seed, density, and starch content leading to lowered yield. Temperature treatment has its greatest effect on seed development during the first 10 to 12 days after flowering. If the plant has a chance to develop seed and provide photosynthetate for 50% of the grain filling period, many problems are overcome. High temperature (35/25 C) can cause as many, if not more, problems than low temperatures. High respiration rates cause yield reduction in density and starch content. Starch degradation also occurs in normal seed in the higher temperatures. Amylase activity occurs in sorghum seed prior to physiological maturity. The activity is found in the scutellum adjacent to endosperm tissue. Degradation of starch granules and changes in scutellar cell structure occur when amylase activity is high. Low temperatures cause yield loss in density and starch content that is probably due to reduced photosynthetate flow to the seed.