Abstract
Experiments were conducted in a Bangkok clay soil to investigate the influence of N rate, light intensity, tiller separation, and plant density on the yield and yield attributes of parent and clone plants of transplanted rice. Application of 75 kg N and 120 kg N ha-1 resulted m similar yields. The 50% reduction of light intensity reduced grain yield to 43.5% compared with normal light intensity. Separation of more than 4 tillers hill-1 had an adverse effect on the mother crop. Nitrogen fertilizer had no influence on grain weight, per cent filled grains, and panicle size of the mother crop, but increased N produced a higher number of tillers. Reduction of light intensity and higher tiller separation adversely affected grain weight and panicle number. Variation of N rate and light intensity of the mother crop had no influence on grain yield, grain weight, and panicle number of clonal tillers transplanted with 75 kg N ha-1 and with normal light intensity. The clonal tillers produced higher yields than the nursery seedlings, and transplanting 2 clonal tillers hill-1 resulted in almost the same yield as 3 clonal tillers and 4 clonal tillers hill-1. A single clonal tiller had the capacity to produce 4.5 t ha-1 grain yield. Yield components of clonal tillers, i.e., panicle number and grain weight, had no influence due to variations of N and light intensity of the mother crop, but higher densities of clonal tillers transplanted per hill gave lower panicle number and grain weight.
