|其他摘要||Cotton is the main staple crop of Xinjiang. Xinjiang, as the one of the perfect regions to plant cotton, gradually becomes one of the important producing areas of our country. The development of cotton is related to the survival of the downstream industries. Being the largest high-quality cotton-producing area, Xinjiang plays a vital part to ensure the safety of national cotton. At present, the supply of cotton in the world exceeds demand, so it becomes the crucial development direction for cotton industry in Xinjiang to “improve the quality and increase the efficiency”. Xinjiang has become the highest-yield cotton-producing area throughout the world, because the increasing cotton yield has strong support from popularization and application of new technologies, such as excellent varieties, precision seeding technology, drip irrigation technology, integration of water into fertilizer, harvest mechanization technology and so on. The exploration on the mechanism of Xinjiang cotton high-yield in a large area has provided theory support for cotton continuous high-yield of Xinjiang, but correlational research is lack of the systematic research on the individual features and on the ecology and psychology of high-yield population building for theory support. This research takes the providing sustainable high-yield theory and technology for Xinjiang cotton producing as its goal, takes the Xinjiang production and construction corps agricultural division sixteen population s of Xinjiang Academy of Agricultural Sciences' Institute of Economic Crops implementing the creation of the high-yield cotton field with 4000-kilogram lint in a hectare as its research platform, puts the high-yield varieties of 10-108-3 and AY4 as the material, and adopts the root system observation methods in situ in the large field. Then this research will be compared with the artificial climate chamber floating cultivation method. According to the following aspects, photosynthetic characteristics of cotton population, leaf index area, distribution rule of dry matter, and the specification analysis on the individual vegetative organs and reproductive organ development law, this paper will analyze the high-yield cotton population formation characteristics in the south of Xinjiang under different environmental conditions. For the root traits of upland cotton cultivars, agronomic traits of the aboveground part and development characteristics of yield and quality traits, this paper carries out the research on the ecological basis of population development of high-yield cotton, individual development law on the cotton plants of high-yield cotton field, and high yield cotton variety characteristics to demonstrate the Xinjiang cotton high-yield research and control technology. The following main conclusions are reached through 4-year study.
1. The ecological basis of high-yield cotton field in south of Xinjiang
The development progress of cotton in high-yield cotton field has close relations with daily average temperature. High temperature will shorten the growth period and high rainfall will prolong its development progress. These aspects, such as flowering boll opening period of cotton, 20 degrees centigrade of accumulated temperature and sunshine duration, can make great influence on the cotton productivity. The extreme accumulative temperature above 35 degrees centigrade in June has most close relations with seed cotton productivity. Plenty of light will promote the increasing of boll number per plant, which has close relations with the productivity in high-yield fields. The accumulated sunshine duration in October is most close correlated with the seed cotton yield; the accumulated sunshine duration in May, June, July and September also has a great effect on seed cotton yield and the accumulated sunshine duration in August and October has more close relations with the single boll weight. Under the condition of irrigation, the precipitation has less relations with the yield of high-yield cotton field.
2. The screening breeding index and root genetic evolution law of of high yield cotton variety in south of Xinjiang
The plant height growth and leaf age development of high-yield cotton are sooner than the general varieties and the total number of buds and growing bolls and the speed of growing into bolls have great advantage. The seed cotton weight of a single boll plays a key part in the seed cotton yield and the number of bolls on single plant has less effect for this. The seed cotton yield of high-yield varieties has positive correlation with the number of bolls on a single plant, while the number of single plant bolls has negative correlation with the weight of bolls. Because that the number of a single plant bolls increase and the weight of a single boll will decrease; the weight of a boll has positive correlation with the boll shell, weight of cotton seed, weight of fiber and seed number with the correlation coefficient between the ginning outturn and seed index, lint index and fiber weight separately as 0.829, 0.606 and 0.632, and the seed index has positive correlation with seed cotton weight and fiber weight. The root of Adai 80, an introduced variety, develops best and that of the Xinluzhong No.26 develops worst. The root development of improved varieties of the 80’s of home-bred ones is superior to that of the 90’s and there isn’t law in the variable coefficient of root development of the improved varieties from 2000 to 2010. The modern cotton varieties with small root system have made greater yield improvement than the old varieties with large root system, because the modern varieties adapt to the condensed planting to decrease the root redundancy and respiration consumption of root and to distribute more assimilation product to the aboveground parts.
3. The development characteristics of high-yield cotton in the south of Xinjiang
The development progress, bud development and fruit and branches development of high-yield cotton population are different from the development progress of cotton bolls. The transfer characteristics of the period of budding, blossom and boll setting can avoid the phenomenon of boll abscission and hollow branches because of the hot and dry weather. The peak of the population simple leaf and canopy photosynthetic rate of high-yield varieties appears later than that of the general varieties. The maximum canopy photosynthetic rate of high-yield variety, 10-108-3, appears at the early stage of peak-bolling as 27.5μmolm-2s-1. After the peak-bolling, the downtrend of simple leaf net photosynthetic rate becomes relatively flat and that in boll opening stage can maintain 17.3μmolm-2s-1. The respiratory rate and canopy photosynthetic rate can maintain at a relatively low level of 30%-47%, especially in the early period of boll-opening with 30.4%, a low of 2.3-28.1% compared with varieties, 07-16 and China cotton No.1. The leaf characteristics of variety 10-108-3 mentioned above are beneficial to population drafty pervious to light. The peak value of LAI during boll-setting period is 4.4, and after that period it will fall slowly and maintain around 3.1 during boll-opening. The leaf inclination of high-yield variety 10-108-3 will be larger than that of 07-16 and China cotton No.1 during each growth period with average value of 56° and largest value of 68.8°. The fastest period of dry material accumulation is from the full-blossom period and full-boll period with the 10-108-3 speed of dry material accumulation being 480.6kg.hm-2.d-1，reaching 371.8kg.hm-2.d-1 from the later stage of full-boll to the boll-opening period, exceeding the China cotton No.1 and 07-16 separately as 40.8% and 71%. Dry weight of reproductive organs in full-bloom stage covers 44% of that of the whole aboveground parts, 2% and 4% higher separately than 07-61 and the contrast variety ( China cotton No.1), 51% in full-boll period and 63% in boll-opening period,over 10% and 11% separately than those two varieties.
4.The influence and mechanism for cotton physiological indexes under different management methods in cotton region of the south of Xinjiang
Cotton topping is beneficial to the improvement of chlorophyll content in cotton leaves, the increasing of the root shoot ratio, lateral root number and the length of lateral root and the improvement of the ginning outturn of the middle and lower part and the maturity, but it will be bad for the main root length increasing and the the weight increasing of bolls in middle and lower part of the cotton plants, and it has no influence law on the fiber length and specific strength. After cotton topping, the chlorophyll content will be higher than that before cotton topping because the number of branch leaves, leaf number per plant and the single leaf area will be increasing and the leaf area per plant will be increasing too. Five kinds of plant hormones in different positions of the plant under drop irrigation will have visible differences. Spraying DPC and cotton-topping can increase the photosynthetic rate and chlorophyll content and the seed cotton yield before the frost is higher or remarkably higher than that of those cottons without praying DPC and cotton-topping. The leaf branch boll setting percentage is the highest with spraying DPC and cotton-topping and the fruit branch boll setting percentage will be higher without spraying DPC and cotton-topping. The leaf branch boll setting percentage is the lowest and the total number of abscission is the highest when the cotton isn’t tackled through spraying DPC and cotton-topping. At present, we can integrate these two kinds of methods with taking full advantage of the genetic, environmental and ecological resources to mend up the shortcomings of climate resources, to play the inherent potentials of the varieties and to coordinate the cotton individual and community development, playing an important part in Xinjiang cotton yield increasing.|