[Ecological regionalization of national cotton fiber quality in China using GGE biplot analysis method]. / 利用GGEåŒæ ‡å›¾åˆ’åˆ†æˆ‘å›½æ£‰èŠ±çº¤ç»´å“è´¨ç”Ÿæ€åŒº.

The distinctive regional characteristics of cotton fiber quality in the major cotton-producing areas in China enhance the textile use efficiency of raw cotton yarn by improving fiber quality through ecological regionalization. The "environment vs. trait" GGE biplot analysis method was adopted to explore the interaction between conventional cotton sub-regions and cotton fiber quality traits based on the datasets collected from the national cotton regional trials from 2011 to 2015. The results showed that the major cotton-producing area in China were divided into four fiber quality ecological regions, namely, the "high fiber quality ecological region", the "low micronaire ecological region", the "high fiber strength and micronaire ecological region", and the "moderate fiber quality ecological region". The high fiber quality ecological region was characterized by harmonious development of cotton fiber length, strength, micronaire value and the highest spinning consistency index, and located in the conventional cotton regions in the upper and lower reaches of Yangtze River Valley. The low micronaire value ecological region composed of the northern and south Xinjiang cotton regions was characterized by low micronaire value, relatively lower fiber strength, and relatively high spinning consistency index performance. The high fiber strength and micronaire value ecological region covered the middle reaches of Yangtze River Valley, Nanxiang Basin and Huaibei Plain, and was prominently characterized by high strength and micronaire value, and moderate performance of other traits. The moderate fiber quality ecological region included North China Plain and Loess Plateau cotton growing regions in the Yellow River Valley, and was characterized by moderate or lower performances of all fiber quality traits. This study effectively applied "environment vs. trait" GGE biplot to regionalize cotton fiber quality, which provided a helpful reference for the regiona-lized cotton growing regions in terms of optimal raw fiber production for textile industry, and gave a good example for the implementation of similar ecological regionalization of other crops as well.

[Ecological regionalization of cotton varieties based on GGE biplot].

By using the heritability-adjusted GGE biplot analysis method, and taking the trial sites Anqing, Nanyang, Huanggang, Jingzhou, Wuhan, Xiangyang, Changde, Yueyang, Nanjing, Nantong, Yancheng, Jiujiang, Jianyang, Shehong, and Cixi as the representative cotton-planting areas in the Yangtze River basin, the ecological regionalization of cotton varieties in the basin was made based on the lint cotton yield, and the regionalization results were adjusted by the information ratio (IR) method, aimed to provide scientific basis for the selection of cotton varieties in the cotton-planting areas of the basin. The cotton-planting areas in the Yangtze River basin could be divided into three ecological regions, i.e., the "Sichuan basin cotton region" with Jianyang and Shehong as the representative, the "Nan-Xiang basin cotton region" with Xiangyang and Nanyang as the representative, and the "majority complex cotton region in the Yangtze River basin" including all the other sites in the basin.

[Modeling of cotton boll maturation period and cottonseed biomass accumulation].

Field experiments with different maturity cotton cultivars and sowing dates were conducted at different sites to quantitatively study the effects of cultivar characteristics, weather conditions (air temperature and solar radiation), and crop management variable (N application rate) on the cotton boll maturation period and cottonseed biomass accumulation. The cotton boll maturation period was simulated by using the scale of physiological development time. Based on the hypothesis of sink-determined, the cottonseed biomass accumulation model was then developed. The subtending leaf N concentration of cotton boll was simulated with a semi-empirical equation, and used as the direct indicator of the N nutrition effect on cottonseed growth and development. The model was tested by independent field data obtained in the Yellow River Valley (Xuzhou and Anyang) and the lower reaches of Yangtze River Valley (Huaian) in 2005. The simulated values of boll maturation period showed reasonable agreement with observed values, with a root mean square error (RMSE) of 2.25 days for cultivar DSC-1, of 2.61 days for cultivar KC-1, and of 2.75 days for cultivar AC-33B. The RMSE of cottonseed dry mass prediction was 9.5 mg x seed(-1) for KC-1 and 8.2 mg x seed(-1) for AC-33B, indicating that the model had a good prediction precision.

[Effects of air temperature on enzyme activities of cotton plants related to saccharide metabolism of cotton fiber].

Taking two cotton cultivars with different fiber strength (KC-1, average fiber strength 35 cN x tex(-1); and AC-33B, average fiber strength 32 cN x tex(-1)) as test materials, a field experiment with two planting dates (25 April and 25 May) was conducted in Nanjing of Jiangsu (lower reaches of Yangtze River Valley) and Xuzhou of Jiangsu (Yellow River Valley) to study the dynamic changes of plant sucrase, sucrose synthase, sucrose phosphate synthase, and beta-1,3-glucanase activities during the development of cotton fiber at different air temperatures and their relationships with fiber length and strength. In the development period of fiber elongation, sucrase and beta-1,3-glucanase activities were higher; while during the period of fiber thickening, sucrose synthase and sucrose phosphate synthase activities increased rapidly and were high, but sucrase and beta-1,3-glucanase activities had a rapid decrease. The higher sucrase activity in fiber elongation development period favored the fiber length development, while the rapid increase of sucrose synthase and sucrose phosphate synthase and the rapid decrease of sucrase and beta-1,3-glucanase activity favored the development of fiber strength. For cotton variety KC-1, the sucrase and beta-1,3-glucanase activities in its early development period and the sucrose synthase and sucrose phosphate synthase activities in its middle and later development periods were all higher than those of AC-33B. In this study, 23.3 degrees C was the optimal temperature for high strength fiber formation, and 23.3 degrees C - 25.5 degrees C was the optimal temperature for long length fiber formation.

[Roles of nitrogen fertilization in regulating the physiological bases of fiber specific strength formation in cotton bolls bloomed at different dates].

To study the roles of nitrogen fertilization in regulating the physiological bases of fiber specific strength formation in cotton bolls bloomed at different dates (July 15, July 25, and September 10; expressed as PSB, SB, and AB, respectively), field experiments were conducted in two sites with different ecological conditions, i.e., Nanjing (middle lower reach of Yangtze River Valley) and Xuzhou (Yellow River Valley). Three treatments (0, 240, and 480 kg N x hm(-2)) were installed. The results showed that comparing with applying optimum nitrogen (240 kg N x hm(-2)), no N application decreased the N content and increased the C/N in the leaves subtending cotton bolls significantly, and the effects increased with postponing blooming date, which, to a great extent, led to the decreases of the capabilities of the leaves subtending cotton bolls bloomed at SB and AB in the accumulation and transportation of photosynthetic products, the relative growth rate of fiber in cotton bolls, and the activities of key enzymes (sucrose synthetase and P-1,3-glucanase) during the middle-later period of fiber development, and also, the decline of cellulose speedily accumulating duration in cotton fiber and of the fiber specific strength in the bolls bloomed at SB and AB. On the contrary, applying high nitrogen (480 kg N x hm-2) increased the N content but decreased the C/N in the leaves subtending cotton bolls significantly, and the effects decreased with postponing blooming date, which decreased the distribution proportion of photosynthetic products to fiber, the key enzyme activities during the early-middle period of fiber development, and the momentary rate of cellulose accumulation in the fiber of the bolls blooming at PSB and SB, resulting in a significant decrease of the fiber specific strength. It was suggested that appropriate N application could regulate the 'source-sink' relation of cotton, and benefit the high fiber specific strength formation in cotton bolls bloomed at different dates.

[The inheritance of an ultra-dwarf plant mutant from upland cotton].

The inheritance of an ultra-dwarf plant mutant from upland cotton (Gossypium hirsutum L.) was studied, which showed that the mutant was controlled by single recessive quality gene. This gene was denominated as du tentatively. No similar mutant has been found in upland cotton. The mutation could not normally flower and produce bolls under natural conditions, and its mature height was only 10.5 cm. When treated with exogenous GA3, it could normally flower and boll, and plant height could reach 57.8 cm finally.