棉 花 学 报    Cotton Science   2010，22（3）：209-216

Changes of Carbon and Nitrogen in the Subtending Leaf of Cotton Boll and Its Relationship to Biomass of Cotton Boll, Seed and Fiber
ZHAO Xin-hua^1,2, QU Lei¹, CHEN Bing-lin¹, ZHOU Zhi-guo^1*
(1.Nanjing Agricultural University/Key Laboratory of Crop Physiology & Ecology, Ministry of Agriculture, Nanjing 210095, China; 2. Cotton Research Institute of CAAS, Anyang, Henan 455000, China)

Abstract: Two cotton cultivars (KC-1, AC-33B) were used, with three nitrogen application rates (0, 240, 480 kg·hm^-2), standing for low, moderate and high nitrogen levels, respectively, in field experiments in Nanjing (118°50′E, 32°02′N, middle lower reaches of Yangtze River Valley) and Xuzhou (117°11′E,34°15′N, Yellow River Valley), Jiangsu Province, which stand for the different ecological conditions, to investigate the relationship between the changes of carbon and nitrogen in the subtending leaf of cotton boll and biomass of cotton boll. The results showed that the changes of total carbon and total nitrogen content in subtending leaf of cotton boll could be simulated with quadratic: Y=at²+bt+c (Y stands for the total carbon or total nitrogen content (%), t stands for boll age (d)). And the changes of C/N ratio could be simulated with Logistic equation. Correlation analysis indicated:(1) The average rate of cotton boll, seed and fiber biomass during the speedy accumulation period could be improved, the duration of cotton boll and fiber biomass could be shortened and the duration of the seed biomass speedy accumulation could be prolonged when the date of reaching the minimum content of the total carbon was earlier and the minimum content of the total carbon was higher. (2) The period of cotton boll and fiber biomass speedy accumulation could be prolonged as the date of reaching the minimum content of the total nitrogen was later. And the minimum content of total nitrogen was higher, which resulted in prolonging the cotton seed biomass speedy accumulation period. (3) The duration for cotton boll and fiber biomass speedy accumulation could be prolonged by lengthening the speedy increasing duration and slowing the average rate of C/N ratio increase during the speedy increasing period. Therefore, the changes of carbon and nitrogen in the subtending leaf of cotton boll is tightly related to the cotton boll biomass, boll development could be improved by adjusting the content of carbon and nitrogen and the C/N ratio in the subtending leaf.
Key words：Gossypium hirsutum L.; subtending leaf of cotton boll; changes of carbon and nitrogen;
cotton boll; biomass            [Full Text, 397KB]