Abstract:

【Objective】 The objectives of this study were to investigate the influences of row-spacing on photosynthetic characteristics and yield structure of two winter wheat cultivars with different spikes types to provide a theoretical basis for super-high-yield wheat cultivation. 【Method】 Field experiments were conducted from 2006 to 2008 to study the regulatory effect of five different allocations of row-spacing on grain yield components, photosynthesis and senescence characteristics using two different wheat cultivars including JM 20, a multiple-spike cultivar and SN 8355, a large-spike cultivar. Ten-treatment combinations were arranged in a completely randomized block design with three replicates. 【Result】 The results showed that the equal and narrow row-spacing increased the canopy apparent photosynthesis (CAP) and leaf area index (LAI) from spike-forming to 7 days after anthesis, and then the relationship reversed. Wide spacing form had higher flag leaves photosynthetic rate (Pn) than other treatments, and the increased range was gradually getting biger over time. The antioxidative enzymes activity had a similar trend with Pn in different treatments of row-spacing, but had an opposite trend with MDA. SN 8355 delayed senescencing and the photosynthetic rate was better than JM 20 at the later period of grain-filling. The correlation between photosynthetic rate and grain yield was not significant, and it showed a great difference between CAP and yield components at different growth stages. Pn and CAP had a significant positive correlation from 14 days after anthesis. 【Conclusion】 The row-spacing could adjust yield components and finally affect the grain yield. Wide row-spacing could improve the photosynthesis characteristics and delay the senescence. Different varieties have to match with different row-spacing allocations to reach their maximal yields.

Key words: winter wheat, row-spacing, variety types, canopy apparent photosynthesis, yield components, correlation