棉 花 学 报 Cotton Science 2007，19(1)：23-27
Characteristics of Fiber Quality in High Quality Upland Cotton in Different Latitudes Abstract：Light and temperature play direct roles in the differentiation and development of cotton fiber ，thus produce significant effects on fiber quality. As one of the most important high-quality cotton producing provinces，Jiangsu paid great attention to cotton fiber quality. To some extent，Jiangsu Province is a narrow belt from south to north，varies from 30°45′to 35°20′in latitude. Based on light and temperature conditions in different latitudes，Jiangsu was divided into the South cotton region and the North cotton region with Huaihe and Subei Canal as the border. But，up to now，no systematic research has been conducted on the effects of light and temperature on cotton fiber quality in different latitudes. With the development of cotton breeding technology，some high-quality cotton cultivars have been introduced into cotton plantation in this region in recent years. But fiber quality was quite unstable because of different conditions in different places. The objective of our research is to determine the effects of light and temperature on fiber quality in high-quality cotton in Jiangsu. With high-quality upland cotton Kemian1，a widely-extended high-quality cotton cultivar as the tested material ，the characteristics of fiber quality in four regions with different latitudes，including Pizhou (34°40 ′)，Huai'an (33°40′)，Yangzhou (32°24) and Qidong (31°48′) were studied in 2003 and 2004. Seeds were sowed on April 5 in nutritional pots in seedling beds，and seedlings were transplanted into open field on May 15 with a planting density of 30，000 plants per hectare. 300 kg nitrogen，120 kg P2O5，240K2O were applied per hectare. Other cultural practices were recommended local standards. Bolls formed before July 21 were tagged as pre-summer bolls. Bolls formed between July 21 and August 15 were tagged as mid-summer bolls.Bolls formed between August 16 and August 31 were tagged as early autumn bolls. Those between September 1 and September 20 were tagged as late autumn bolls. All bolls were collected within one week after boll opening so as not to influence fiber quality very much. Fiber quality indices，including fiber length，length uniformity，strength，stretching rate，micronaire，yellowness degree，reflection rate and average yarn index were detected on HVI system. Fiber length，stretching rate and yellowness degree tended to decrease from the north to the south. Fiber strength，micronaire value and length uniformity tended to increase as latitude decreased. But no significant differences were found in fiber reflection rate and average yarn indices in different latitudes. Fiber quality varied significantly in different years. Due to bad weather in 2003，cotton fiber quality were worse than those in 2004. Of all cotton fiber quality indices，fiber length，strength were relatively stable. Micronaire value was quite high in both years. Emphasis should be placed on the optimization of micronaire value to improve cotton fiber quality.
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