Abstract:

Widespread cultivated early maturing upland cotton varieties bred in Xinjiang in different decades (1990s, 2000s and 2010s) were used as experimental materials under mulching drip irrigation conditions. Canopy openness, mean foliage titled angle and canopy light distribution at different growing stages were measured to analyze cotton canopy structural characteristics, which provides a theoretical basis for breeding new cotton varieties and optimizing cultivation management. In the cotton varieties replacement process with yield increase, there was no significant difference in growth stage among different decades, and the growth stage of varieties grown in 2010s was relatively long. In the growth period from full boll stage to boll opening stage, the canopy openness was more reasonable and the light absorption rate was higher for the varieties in 2010s than in 1990s and 2000s; in the late growth period, the canopy openness and canopy light absorption rate for the varieties in 2010s were averagely 1.06% to 5.94% higher than those in 1990s and 2000s. Furthermore, dry matter accumulation of varieties in 2010s was averagely 11.51% to 15.59% higher than that in 1990s and 2000s, with an increasing trend in various organs. There was a consistent changing trend in leaf inclination angle for different varieties, but with a great difference among varieties and closely relating to leaf size. Therefore, with cotton varieties replacing, the appropriate leaf area index and canopy openness at the middle and later stages of cotton growth have been up to about 90% of light absorption now and got more dry matter accumulation, resulting in increased yield.

Key words: Upland cotton, Early maturing variety, Variety renew, Canopy structure, Yield, Xinjiang