| The experiment was conducted in the scientific farm of Shandong Agricutural University from 2007 to 2008. L28 was used and 3 types of Controlled release N fertilizer treatments were applied under field condition. Effect of Controlled Release N Fertilizer on spatio-temporal distribution of cotton bolls and fiber quality, soil nutrient dynamic change and its physiological basis was studied. The main results were as follows:1. Effect of controlled release N fertilizer on growth and developmentComparing with CK2, Treatment T1 decreased leaf area per plant, functional leaf area, dry weight and plant height on Jun 17, but its effects on leaf number per plant at seedling stage and plant height on Jul 2 and Sep 15 were insignificant. Treatment T2 increased functional leaf area and fruiting branch number on Jul 2, but its leaf numbers per plant, leaf area per plant, dry weight and plant height of different stage were insignificant. Treatment T3 improved the growth of cotton at seedling stage and the budding of cotton, and then the plant height on Jul 20 and Sep 15 were significantly increased. But the difference of finally fruit node and fruiting branch numbers was insignificant between CRF treatment and CK2 treatment. 2. Effect of controlled release N fertilizer on physiological characteristic of cotton leavesNitrogen nutrition had an obvious effect on functional leaf physiological characteristic at different stage of cotton. N application enhanced the content of chlorophyll, improved the PSⅡ(Fv/Fo) activity, maximum photochemical efficiency (Fv/Fm), photochemical quenching co-efficient (qP), actual quantum efficiency (ФPSⅡ), and photosynthetic rate (Pn) of cotton leaf. N application could promote N metabolism through increasing the activity of NR, enhance total N, P and K content, but decrease nitrate N content. Treatment T1 didn't have an obvious influence on functional leaf physiological characteristic on Jun 15. Treatment T3 represented better than others at different stage of cotton, it was an extremely great advanced on July 17.There was an obvious effect of nitrogen nutrition on leaf physiological characteristic at later stage of cotton. Comparing with CK2, controlled release N fertilizer treatments had significant effect on leaf physiological characteristic at later stage of cotton, controlled release N fertilizer treatments increased the chlorophyll fluorescence dynamics parameters, Fv/Fm, Fv/Fo, qP andФPSⅡ, which improve the Pn of cotton leaf consequently. Controlled release N fertilizer treatments increased the content of soluble sugar, proline and soluble protein, enhanced SOD,POD activities and decreased the accumulation of MDA at the leaf age of 45 and 60 days, which was beneficial to lower active oxygen injury to cell envelope. Controlled release N fertilizer treatments increased NR activity, meanwhile it decreased the content of nitrate N, but it promoted the absorption of N and K. Treatment T1 and T3 were an extremely great advanced.3. Effect of controlled release N fertilizer on soil nutrient dynamic change N application increased the content of nitrate N, ammonia N and available N in 0-40cm soil. Comparing with CK2, soil available N content on Oct 15 of treatment T1 and T3 in 0-20cm soil were increased by 12.59% and 6.99%, in 20-40cm soil, by 11.12% and 5.56%, respectively. N application increased the content of available P and available K at latter stage of cotton. Comparing with CK2, soil available P content on Oct 15 of treatment T1 and T3 in 0-20cm soil were increased by 9.27% and 8.27%, available P content on Oct 15 of treatment T1 and T3 in 20-40cm soil were not increased obviously. soil available K content on Oct 15 of treatment T1 and T3 in 0-20cm soil were increased by 3.37mg/kg and 5.64mg/kg, in 20-40cm soil, by 2.96mg/kg and 5.00mg/kg, but available K content on Oct 15 of in 0-20cm and 20-40cm soil had insignificant difference between treatment T2 and CK2.4. Effect of controlled release N fertilizer on spatio-temporal distribution of cotton bolls and cotton bolls qualityComparing with CK2, for treatment T1, bolls retained intensity in the Jul 11 to 20 and boll weight in the Aug 21 to 31 were increased, but lint percentage in the Aug 21 to 31 was decreased. For treatment T2, bolls retained intensity in the Jul 11 to 20 was increased, but decreased in the Aug 21 to 31, boll weight in the Aug 21 to 31 was increased, but decreased in the Aug 11 to 20. For treatment T3, bolls retained intensity in the Jul 11 to 20 and the Aug 21 to 31 were increased, boll weight in the Aug 11 to 31 was increased. But bolls retained intensity and bolls quality in the other blooming date didn't have significant difference in the three CRF treatments.Comparing with CK2, for the treatment T1, bolls retained intensity and bolls weight on 3-5 fruit node of super fruiting branch were increased, but its lint percentage was decreased. For the treatment T2, bolls weight on 3-5 fruit node of basal fruiting branch was increased, lint percentage on 1-5 fruit node of super fruiting branch was decreased. For the treatment T3, bolls retained intensity on 1-2 fruit node of middle fruiting branch and 1-5 fruit node of super fruiting branch was increased, but lint percentage on 3-5 fruit node of basal fruiting branch and 1-2 fruit node of super fruiting branch. But bolls retained intensity and bolls quality in other fruiting branch difference of three CRF treatments was insignificant. 5. Effect of controlled release N fertilizer on fiber quality of spatio-temporal distribution of cotton bollsComparing with CK2, for the treatment T1, fiber strength in the Jul 21 to 31 was enhanced, micronaire in the Aug 11 to 31 was augmented, fiber maturity in the Aug 1 to 20 was improved, strength in the Jul 21 to 31 was enhanced. For treatment T2, fiber micronaire in the Aug 11 to 20 was augmented. For the treatment T3, fiber length in the Aug 21 to 31 was increased, strength in the Jul 21 to 31 and Aug 21 to 31 was enhanced, micronaire in the Aug 1 to 31 was augmented, maturity in the Aug 1 to 20 was improved. But there was not an obvious influence of controlled release N fertilizer on fiber uniformity in different blooming date.Comparing with CK2, for the treatment T1, fiber strength of 3-5 fruit node on basal and middle fruiting branch was enhanced, micronaire of 1-5 fruit node on super fruiting branch was augmented, maturity of 3-5 fruit node on basal fruiting branch was improved, uniformity of 3-5 fruit node on middle fruiting branch was improved. For the treatment T2, fiber micronaire of 1-5 fruit node on super fruiting branch was augmented, fiber maturity of 1-2 fruit node on super fruiting branch was improved. For the treatment T3, fiber strength of 3-5 fruit node on basal and middle fruiting branch was enhanced, micronaire of 3-5 fruit node on middle fruiting branch and 1-5 fruit node on super fruiting branch was augmented, maturity of 1-2 fruit node on super fruiting branch was improved, uniformity of 3-5 fruit node on middle fruiting branch was improved. But there was not obvious influence on fiber length of different fruiting branch.6. Effect of controlled release N fertilizer on yield, yield components N application increased bolls per plant and boll weight, and then it increased seed cotton yield and lint cotton yield, but there was not an obvious influence on lint percentage. Comparing with CK2, the bolls per plant increase of treatment T1 was 0.77, boll weight increase was 0.09g per boll, seed cotton yield and lint cotton yield were increased by 6.2% and 6.4 %, respectively, but it had no effect on lint percentage. Seed cotton yield of treatment T2 were increased by 6.2%, but there was not an obvious influence on yield components and lint cotton yield of treatment T2. Bolls per plant increase of treatment T3 was 0.84, seed cotton yield and lint cotton yield were increased by 5.0% and 4.31%, but there was no significant difference of lint percentage.7. Effect of controlled release N fertilizer on Nitrogen use efficiency Comparing with CK2, according to the seed cotton yield and lint cotton yield, PFPN and AEN of treatment T1 and T3 were significantly enhanced, but there was no significant difference between treatment T2 and CK2. T2 treatment was the lowest among the three CRF Treatments.
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