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Title: ANALYSIS OF HIGH WHEAT YIELDS IN NORTHWEST CHINA

Author
item Sinclair, Thomas
item QIN-AN, BAI - CHINESE ACADEMY OF SCIENC

Submitted to: Agricultural Systems
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/1/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary: Wheat yields of over 200 bu A-1 have been reported for specific farms in northwest China. Yields on the Xiangride Farm in 1978 were the highest reported at nearly 250 bu A-1. A mechanistic model of wheat development and growth was used to determine those factors that resulted in these extremely high yields. The weather was an important factor in achieving the high yields. The weather in this region is cool throughout the season and wheat is grown as a full-season crop. The long growing season is coupled with very high solar radiation levels so that an extraordinary amount of light energy is available to the crop. In addition to important weather advantages, wheat varieties developed for this region were found to be well adapted to take advantage of the cool temperature climate, particularly the grain growth traits. However, the highest yields were obtained with a variety that appeared to be vulnerable to low temperatures late in the season. More recently selected varieties have decreased this risk, but they also have decreased yield potential.

Technical Abstract: Grain yields of over 14 Mg ha-1 were reported in 1978 for spring wheat (Triticum sativa L.) grown in Northwest China. Understanding the circumstances under which this record yield was achieved may be useful in defining the key factors which lead to high grain yields and in determining the limits to wheat yield. A relatively simple, mechanistic model was used to simulate the record yield. Various crop traits were adjusted in the model to match observed crop growth. Leaf development was adjusted by changing the length of a phyllochron to 78 TU based on independent data. Two adjustments in the description of grain fill were required to match simulation results with the observations. These adjustments, which involved lengthening the grain-fill period and decreasing the grain growth rate, seemed to be a result of low temperatures during grain development and of unique cultivar traits. The weather which was characterized by cool temperatures and high levels of solar radiation, proved to be especially important in allowing a full-season crop to achieve record yields. These simulations led to important suggestions for examining the interaction between cool temperature regimes and developmental traits of wheat cultivars.