Basic Study on Super Panicle Weight Type Varieties in Rice

本研究旨在阐明水稻超穗重型（SPWT）品种的颖花数、汇容量和籽粒灌浆决定过程的特点。所得结果总结如下：1。高产的半矮型和中秆型SPWT品种由于每m^2的颖花数和1粒体积（重量）均较高，且营养器官向穗间碳水化合物的运输系统良好，因此具有较高的汇容量。穗部不同位置的最终粒重主要取决于籽粒灌浆速率与籽粒灌浆周期的比较，而不考虑包括SPWT.3在内的品种间籽粒大小的较大差异。随移栽至抽穗各阶段施氮量的增加，SPWT品种的籽粒重量减轻，籽粒尺寸减小。糙米的籽粒比越大，籽粒重越大，籽粒重与糙米的体积呈密切正相关关系，而糙米的体积主要与糙米的厚度有关。灌浆期SPWT品种的成熟粒率和千粒重与籽粒根活性（α -萘胺氧化活性）呈显著正相关，且根活性的增加对这些性状的促进作用在穗部下部的劣穗上表现得更明显。

This study was carried out to clarify the characteristics of determining processes of number of spikelets, sink capacity and grain-filling in super panicle weight type (SPWT) varieties in rice. The results obtained were summarized as follows ;1. The high yielding semidwarf and intermediate culmed indica SPWT varieties had higher sink capacity due to higher both components, i.e., number of spikelets per m^2 and 1 grain volume (weight) and good transportation system of carbohydrates from the vegetative organs to the panicle.2. The final grain weight at the different positions in a panicle was mainly determined by the grain-filling rate compared with the grain filling period, irrespective of large differences in grain size among varieties including SPWT.3. With increasing amount of nitrogen application at various stage from transplanting to heading decreased the hull size of SPWT varieties and resulted in lighter grain weight. The unhulled grains with heavier specific weight showed heavier grain weight, and the grain weight closely and positively associated with the volume of brown rice which was mainly related to the thickness.4. The percentage of ripened grains and 1000-grain weight of a SPWT variety were strongly and positively correlated with the root activity (α -naphthylamine oxidizing activity) per grain during grain-filling period, and the promotion of these characters with increasing the root activity were greater in the inferior spikelets located on the lower part of a panicle.