벼 조기초관폐쇄성의 품종 변이 및 수량과의 관계

Genotypic Variation of Rapid Canopy Closure and Its Relationship with Yield of Rice

Rapid canopy closure (RCC) is one of the physiological attributes that may enhance genetic yield po-tential of rice (Oryza sativa L.) in a growing season. Crop growth before canopy closure could be described by an exponential equation of y = α･exp(β･t) where α is the crop leaf area index (LAI) or shoot dry weight (DW), t is the thermal time, β is the LAI or DW at the beginning of the exponential growth and is the relative growth rate of LAI (m2 m-2℃-1) or DW(gg-2℃-1). Field experiment using 22 cultivars revealed that the exponential growth phase before canopy closure can be divided into two sections; an earlier section during which crop dry weight and LAI of varieties are highly dependent on α and a second section where crop dry weight and LAI are highly dependent on β. Grain weight had significantly positive correlation with α parameter and dry weight and LAI during early exponential phase. The parameter β of the exponential growth curve had positive and significant correlation with the LAI and dry weight during the late exponential growth phase, grain number per unit area, and grain yield. There was genotypic difference for RCC parameters, α and β, indicating the possibility of genetic improvement for these traits.