Cotton Science 2005，17(2)：88-93
Characterization of Growth-delayed Cotton Cool Damage by Heat Index Abstract: According to data of cotton growth, output and temperature during five stages from Wulanwusu Agro-meteorological Experiment Station in xinjiang in 2003, heat indexes of every growth stages in different sowing times were calculated and analyzed. The results showed that: 1) With prolongation of sowing times heat in the cotton previous growth period rise. By contrast, heat index was also obviously increased. However, in the later period it began decrease. 2) If heat in bud and bloom periods were efficient, heat index would be stable. 3) There was linear correlation between output in different sowing times and heat index in the later growth period. Heat index in the later growth period was closely related to rate of cotton harvested before frost and more influenced on the quality of cotton than output. 4) Due to output reduction heat index in the later below 64 was usually defined as delay cool damage year and below 61.8 more serious year under the sufficient heat condition before blooming. 5) In terms of rate of cotton harvested before frost, heat index in later growth period below 70.9 was regarded as cool damage year and below 63.2 more severe under the sufficient heat condition before blooming in the northern Xinjiang.
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