The Changes and Affecting Factors of Stem-sheath Reserve Contents of Rice during Grain Filling
LIANG Jiansheng;CAO Xianzu;ZHANGo Haiyan; SONG Ping;ZHU Qingsen(Jiangsu Agricultural College. Yanzhou 225001;Seed Company of Jingjiang City, Jingjiang, Jiangsu 225000)
Investigstions were carried out on the changes of leaf-sheath and stem reserve contents and effects of leaf-cutting, spikelet-thinning and hormones on the contents, translocation and residual ratio of these reserves during grain filling in rice varieties of Yanjing 235(sink-limiting type) and Shanyou 63 and Yayou 2(source-limiting type). The leaf-cutting and spikelet-thinning treatments delayed or accelerated the grain-filling processes of weak grains in all tested varieties, respectively, but had little influences on those of strong grains. The accumulation peaks of leaf-sheath and stem reserves of Yanjing 235 were about 5 days earlier than those of Shanyou 63and Yayou 2, and the amount of reserves per unit sink capacity of Yanjing 235 was also higher. The translocation of reserves of Yanjing 235 to grains took place at heading stage, which was about 5 days earlier than the other two varieties, and ended at about 10 days after heading. The stimulation of spikelet-thinning on starch accumulation of leaf-sheath and stem of Yanjing 235 was higher than that of Shanyou 63 and Yayou 2, but its effects on translocation and residual ratio of stem-sheath reserves of Shanyou 63 and Yayou 2 were much significant than that of Yanjing 235.The effects of leaf-cutting were contrary to those of spikeletthinning. The contents,translocation and residual ratio of leaves,sheaths and stem of all rice tested varieties were markedly influenced by ABA treatments, depending on the treated sites of rice. 4-Pu 30 treatment significantly enhanced the accumulation, translocation and residual ratio of stem-sheath reserves irrespectives of the treated sites. The roles of stem-sheaths reserves in the early development of grains were also discussed.