陆地棉棉铃对位叶碳氮变化特征与其生物量关系的研究

在大田栽培条件下,选用科棉1号和美棉33B两个棉花品种,于江苏南京、徐州进行施氮量(0、240、480kg.hm-2)试验,研究棉铃对位叶碳氮变化特征与棉铃(棉子、纤维)生物量的关系。结果表明:棉铃对位叶全碳、全氮含量变化可用函数Y=at2+bt+c〔Y(%):全碳或全氮含量,t(d):铃龄,a、b、c:参数〕拟合,碳氮比变化可用Logistic方程拟合。进一步分析棉铃对位叶碳氮变化的特征值发现:(1)棉铃对位叶全碳含量达到最小值的时间早、最小含量值高,则可提高棉铃、棉子、纤维生物量快速累积持续期间的平均速率,但缩短了棉铃和纤维生物量快速累积持续期,延长了棉子生物量快速累积持续期。(2)棉铃对位叶全氮含量达到最小值的时间晚,则可延长棉铃和纤维生物量快速累积持续期;全氮最小含量值高,则可延长棉子生物量快速累积持续期。(3)棉铃对位叶碳氮比快速增长持续期长、快速增长平均速率小,则可延长棉铃及纤维生物量快速累积持续期。可见,棉铃对位叶碳氮变化特征与棉铃生物量的关系密切,可通过调控棉铃对位叶碳氮含量及其比值促进棉铃发育。

Changes of Carbon and Nitrogen in the Subtending Leaf of Cotton Boll and Its Relationship to Biomass of Cotton Boll, Seed and Fiber

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.