Abstract:

In a field test on the experimental farm of Gansu Agricultural University in Zhangye, Northwest China, the characteristics of colony canopy architecture was investigated in spring wheat under the treatments of controlled traffic tillage with straw mulching in ridge (CTS), controlled traffic tillage without mulching in ridge (CT), controlled traffic tillage with film mulching in ridge (CTP), and conventional cultivation (LT, control). The plant height, leaf distribution, leaf area index, light intercept and capture ratio, and photosynthetic rate were measured at a thesis stage. Compared with LT, the plant height was 2.09, 3.27, and 5.65 cm lower in CTP, CTS, and CT, respectively, and there was a significant difference between CT and LT treatments. Under the treatments of CTP and CTS, an approximate ratio of 3:2:1 was observed in the relationship among the distance between flag leaf and the second leaf from top, and the distance between the second and the third leaf from top. Such ratio was optimal for the uniform distribution of light in the wheat colony. The leaf area index was in the order of LT>CTP>CTS>CT, especially from June 25 to July 15. Controlled traffic tillage reduced leaf area apparently, however, mulching in ridge alleviated such influence. In terms of the distribution of incident light within layers of wheat canopy, although wheat colony intercepted the most lights in treatment LT (97.2%), the light distribution varied sharply in the flag leaf layer (77.34%), the second leaf layer (12.17%), and the third leaf layer (7.17%), indicating an incompact colony canopy configuration and low photosynthetic rate. However, the light distribution in the three leaf layers was relatively well-proportioned in CTP and CTS, with only 8.03% and 11.23% of light penetration, respectively. The photosynthetic rate of flag leaf was higher in treatment CT than in other treatments at anthesis stage, but treatment CT had the highest penetration ratio of light and the smallest leaf area index among the four treatments. The results showed that treatments CTP and CTS were in favor of better colony architecture and solar energy use efficiency, resulting in yield promotion in spring wheat. In contrast, the colony configuration was too compact in treatment LT and too incompact in treatment CT to obtain high yield.

Key words: Controlled traffic tillage, Film mulching, Straw mulching, Canopy architecture