GUO Baowei, LI Chao, WEI Huanhe, WANG Zijie, XU Ke, ZHANG Hongcheng, DAI Qigen, HUO Zhongyang, WEI Haiyan
In order to study the differences in grain yield and formation mechanism of indica-japonica hybrids of Yongyou series in different plant height types under the high yield cultivation conditions, a field experiment was conducted with short type (<135cm) including Yongyou1952, Yongyou1956, and Yongyou4395, middle type (140 to 150cm) including Yongyou4340, Yongyou4348, and Yongyou4356, high type (>155cm) including Yongyou4304, Yongyou4306, Yongyou4377, and Yongyou5373. Differences in grain yield and its components, stems and tillers dynamics, dry matter accumulation and translocation, dynamics of leaf area, photosynthetic potential and canopy structure characteristics were analyzed systematically. The two-year results showed that the grain yield of M type was increased by 21.26% and 30.50% compared with the types of S and H, which was mainly attributed to its higher seed setting rate and 1 000-grain weight. From the critical stage of productive tillering to jointing stage, growth rate of the stems and tillers of M type was relatively slow, and after the jointing stage, the number of stems and tillers decreased. The dry matter accumulation of M type was small before heading, which reached 10.51t·hm2 from heading to maturing stage. From heading to maturity, the single stem of M type showed “V” shape change and the maximum output, the maximum output rate and the maximum conversion rate of S type was the highest. In addition, the apparent output, the apparent output rate, and the apparent conversion rate from heading to maturity of M type were the smallest. During grain filling, the leaf area of M type decreased slowly, photosynthetic potential and grain-leaf ratio were higher. Compared with S and H types, the width and size of the top three leaves was appropriate, and the posture by light and canopy light transmittance were both great. M type had large storage capacity depending on reasonable canopy structure and large LAI. The production and transport capacity of the photosynthetic material were strong in the middle and later period. At the same time, it kept the stability of flow capacity, promoted the full capacity, and achieved high yield finally. The findings have important significance for breeding plant height of indica-japonica hybrid rice.