Quantitative effects of cultural practices on growth and yield of forage rice having short panicles

Cultivation of forage rice for whole-crop silage has been increasing in Japan and will be important in Asia. In this study, effects of cultural practices on growth and yield of a forage rice cultivar "Tsukisuzuka" havingshort panicle 1allele were analysed quantitatively using linear mixed model. The contribution of basal dressing to dry yield per 1 g/m(2)nitrogen fertilizer was larger than that of topdressing. In addition, topdressing 30 and 20 days before heading was considered to have the disadvantage of increasing risk of lodging and panicle weight respectively. Effects of weather elements on growth of forage rice were also speculated. In tested fields, high solar radiation at seedling and tillering stage was considered important for the high yield. As the number of continuous cropping cycles increased, growth of forage rice got worse. And application of compost improved growth of forage rice. Elemental analysis of soil and plants revealed that this continuous cropping obstacle was likely to attributed to deficiency of potassium. In addition, potassium deficiency increased panicle weight of a forage rice cultivar havingshort panicle 1allele. Therefore, control of potassium nutrition will be useful for both sustaining productivity (sufficient application of potassium) and seed production (restriction of potassium). These findings will be useful for improvement of cultivation method of forage rice.