| Based on the achievements in physiological and ecological mechanisms of cotton fiber development and fiber quality formation, the experiments conducted in the lower reaches of Yangtze River Valley (Nanjing) and the Yellow River Valley (Xuzhou, Anyang) in2005,2007, and2009, we quantify the effects of fruiting branches, weather (temperature and solar radiation, using PTI as an composite indicator), and N supply on cotton fiber development and quality formation. Using agricultural model principle and systematic analysis method, we developed simulation model for cotton fiber quality formation.These models were tested with the field experimental data collected from different sits. Meanwhile, a cotton fiber quality regional distribution and appraisal system based on model and GIS was built, which including both the cotton fiber formation model and integrated fiber quality model. The main results are as follows:1. Effects of fruiting branch position, temperature-light factors and nitrogen rates on cotton fiber elongationCotton bolls developed in the middle-branch position produced longer fiber than that in lower-and upper-branch positions, but the dynamic changes of fiber length were not significant among different fruiting branches. PTI can be an indicator assessing temperature-light effect during cotton fiber elongation period. The maximum elongation rate (Vmax) and duration of fiber speedy elongation period (T) were linearly corelated with PTI, while the theoretical maximum of cotton fiber length (Lenm) was quadratic with PTI. The longest Lenm was obtained at PTI of335MJ m-2in cotton fiber elongation period, when Vmax was1.3mm d-and T was16d. There exists an interaction between N fertilization and PTI on fiber elongation. As N fertilization increased, values of PTI for obtaining the longest Lenm decreased. And when PTI was greater than240MJ m-2(237.6and241.6MJ m-2for Kemian1and NuCOTN33B, respectively), NA under240kg N ha-1was more suitable for the elongation of cotton fiber; while PTI was less than that value, NA under480kg N ha-1was more appropriate.2. Effects of fruiting branch position, temperature-light factors and nitrogen rates on cotton fiber strength formationAn interaction between fruiting branch and temperature was observed. Cotton bolls in the Middle-branch produced stronger fiber than that in Lower-and Upper-branch when temperature-light factor was optimal. While temperature-light decreased, fruiting-branch effects are not significant. Development of cotton fiber strength can be divided into rapid and steady growth period, cultivar difference in cotton fiber strength may come from difference in steady growth period. The strongest Strobs was obtained at PTI of291MJ m-2. N fertilization significantly affects formation of cotton fiber strength and has a compensatory effect on PTI. As N increased, PTI for obtain the highest Stro\>s decreased. NA under240kg N ha-1is more suitable for cotton fiber strength when PTI was greater than104MJ m-2; when PTI is less than that value, NA under480kg N ha-1is more appropriate. Fruiting-branch significantly affects formation of cotton fiber strength and there is interaction between fruiting-branch and temperature-light factor. Temperature-light factor and nitrogen rate significantly influence cotton fiber strength formation, nitrogen has a compensate effect on temperature-light factor.3. Effects of fruiting branch position, temperature-light factors and nitrogen rates on cotton fiber fineness, maturity and micronaire formationThe final fiber fineness, maturity, and micronaire were not significant among different fruiting branches. PTI can be an indicator assessing temperature-light effect during cotton fiber secondary wall synthesis period. It significantly related to eigen values of cotton fiber fineness (FinObS), maturity (Matm), and micronaire (Micm). Cottin fiber fineness and micronaire were quadratic with PTI, while cotton fiber maturity was linearly corelated with it. The lowest Finobs was obtained at PTI of310.0and318.1MJ m-2for Kemian1and NuCOTN33B, respectively, in cotton fiber secondary wall synthesis period. Range of1.60-1.75for cotton fiber maturity was obtained at PTI range of211.5-299.7MJ m-2for Kemian1and233.2-301.4MJ m-2for NuCOTN33B. Range of3.7-4.2for cotton fiber micronaire was obtained at PTI range of14.8-103.8MJ m-2for Kemian1and58.7-127.8MJ m-2for NuCOTN33B. N fertilization affects cotton fiber fineness, maturity, and micronaire by influencing subtending leaf N per unit area (NA). And there exists an interaction between NA and PTI. When PTI was less than63.1,144.3,61.5MJ m2,480kg N ha-1was more appropriate for cotton fiber fineness, maturity, and micronaire formation.4. Modeling cotton fiber quality formationThe simulation of cotton (Gossypium hirsutum L.) fiber quality is still an area of great uncertainty, especially in their formation process. The aim of this study was to develop a model for simulating cotton fiber quality formation for explaining the effect of genotype, weather (temperature and solar radiation), and crop management N supply. The duration of fiber elongation for fiber length formation and secondary wall synthesis for fiber strength, fineness, maturity and micronaire formation were determined as proportional to the boll physiological developmental time (PDT), which was simulated as a function of temperature, radiation, and N. The interactive effect of temperature and radiation on cotton fiber quality was modeled as a function of the integrated photo-thermal index, the product of thermal effectiveness and radiation (PTI). The subtending leaf N concentration per unit area of cotton boll (NA) was used as the indicator of boll N nutrition. The changes of NA with boll development, N application rate, and boll position were simulated by a semi-empirical formula. Based on the relations between the actual and critical NA, the nitrogen response functions for the formation of different fiber quality parameters were quantified, accounting for the interactive effects of N nutrition and PTI on fiber quality. Calibration and validation of the model were made using fiber quality data obtained from three years with two sowing dates and three or four N application rates at three locations in China. The average RMSE for fiber length, strength, fineness, maturity, and micronaire predictions were1.03mm,2.20cN tex-1,372m g-1,0.11and0.3, respectively. The proposed model well explained the observed genotypic and environmental variations in fiber length, strength, fineness, maturity and micronaire formation of cotton in China.5. Cotton fiber quality regional distribution and appraisal system based on model and GISIn order to predict and access the cotton fiber quality formation and their spatial distribution, taking MapObjects as investigative platform, using C#, then based on process-based model of the cotton fiber quality (CFQ), the regional distribution and appraisal System of CFQ is developed. By inputting the parameters of cotton species characteristic, climate and nitrogen application rate, it can analysis and estimate cotton fiber quality formation and their spatial interpolation. In the same time, each station of224 cotton lords in the Yellow River reaches and the Yangtze River reaches and eco-sites of Jiangsu province can be calculated and predicted for that year and next year a lord to cotton fiber length,strength, micromaire and integrated fiber quality. Showing the result by using the form, carve and chart, and automatically make the matic map. The case study of the system with the datasets in33eco-sites of Jiangsu province indicated that the system operates easily, runs reliably, estimates the space expression of result accurately and chooses the stations flexibly. This system can provide science basis for economy sustainable development in the cotton district. |
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