Effect of silicon on the growth of rice plant at different growth stages

Abstract

Rice plants (Oryza sativa L. cv. Akebono) were cultured in Kimura B solution. The effect of silicon on plant growth and the characteristics of the uptake and distribution of silicon at different growth stages were studied from both aspects: the addition and removal of silicon during the vegetative, reproductive and ripening stages. When silicon was removed during the reproductive stage, the dry weights of straw (stem+leaf blade) and grain decreased by 20 and 50% respectively, compared with those of the plants cultured in the solution with silicon throughout the growth period. Conversely, when silicon was added during the reproductive stage, the dry weights of straw and grain increased by 243 and 30%, respectively, over those of the plants cultured in a solution devoid of silicon throughout the growth period. The effect of silicon on the dry weights of straw and grain was small when silicon was either added or removed during the vegetative and ripening stages. The percentage of filled spikelets remarkably increased or decreased when silicon was added or removed during the reproductive stage. The 1,000-grain weight was hardly influenced by the addition or removal of silicon regardless of the growth stage. About 66% of silicon in the whole plant and 70 to 75% of silicon in the leaf blades were absorbed during the reproductive stage. About 75% of silicon in the panicle was absorbed during the ripening stage although no beneficial effect was detected in this experiment. Forty to 50% of the silicon absorbed during the vegetative and reproductive stages was present in the leaf blades, whereas only 20 to 30% of silicon absorbed during the ripening stage was present in the leaf blades. Based on these results, it is concluded that the supply of silicon during the reproductive stage is most important for plant growth.