Effect of nitrogen application and leaf removal on the metabolism of carbohydrate in leaves and stems of rice plants at ripening stage.

摘要

Nitrogen top dressing and leaf removal were carried out on rice cv. Hitomebore immediately after heading and on cv. Akitakomachi before heading, respectively. With N top dressing, the increasing rate of both total dry weight and panicle weight was initially slower and then became faster reaching an approximate 30% increase in final total dry weight. Sucrose content in leaf blades changed little in top dressed plants during ripening, whereas in untreated controls it decreased from the middle to lateripening stages. The amount of sucrose in the stems was initially smaller in top dressed than control plants but it increased after mid-ripening. The amount of starch in the stems decreased from the beginning of ripening in controls, whereas with top dressing, the amount of starch decreased slightly at the beginning of ripening and then largely increased during mid-ripening. Removal of lower leaves other than flag leaf, and flag and second leaves, respectively, affected panicle weight with only about a10% decrease, but the dry weight of the lower part of the stems decreased considerably. The N content in both leaf blades and stems increased, but sucrose content decreased following leaf removal. Sucrose content in the neck internode of the panicles was smaller than in other internodes and leaf blades. The contents of non-structural carbohydrate and starch in both leaf blades and the neck internode of the panicles were smaller than those in the lower part of the stems, which were decreased by leaf removal.