棉铃对位叶氮浓度与纤维品质指标的关系

 【目的】研究棉铃对位叶氮浓度与纤维品质指标的关系，为不同开花期棉铃纤维品质形成的氮素营养监测提供理论依据。【方法】在大田栽培条件下，以高品质棉(科棉1号)和常规棉(美棉33B)品种为材料，分别于江苏南京（118°50′E，32°02′N，长江流域下游棉区）和江苏徐州（117°11′E，34°15′N，黄河流域黄淮棉区）设置不同氮素水平(低氮：0 kgN?hm-2;中氮：240 kgN?hm-2;高氮：480 kgN?hm-2)试验，研究棉铃对位叶比叶重（LMA）、氮浓度（单位干重氮含量，NM;单位叶面积氮含量，NA）对氮素水平的响应，并初步探索了棉铃对位叶NA与纤维品质指标的关系。【结果】（1）棉铃对位叶NA蕴含了NM和LMA的双重信息，具有对氮素水平及开花期均较为敏感的特性，在氮素处理间差异性达显著水平，随开花期的推迟呈现出逐步上升趋势。（2）随着棉铃对位叶NA平均值的增加，棉纤维品质关键指标(纤维长度、比强度、马克隆值、整齐度)的变化趋势均为开口向下的抛物线型。（3）低氮与中氮处理间棉铃对位叶NA平均值的差距随着开花期的推迟逐渐扩大，而高氮与中氮处理间的差距逐渐缩小，相应氮素处理间纤维比强度和马克隆值的差距亦呈现出同样的变化趋势。【结论】棉铃对位叶NA与棉纤维品质指标的关系密切，可作为今后从氮素营养角度实时监测预报棉纤维品质优劣的一个重要生理指标。

Relationship Between Nitrogen Concentration in the Subtending Leaf of Cotton Boll and Fiber Quality Indices

【Objective】 To investigate the relationship between nitrogen concentration in the subtending leaf of cotton boll and fiber quality indices, and to provide theoretical basis for monitoring nitrogen status in fiber quality formation of bolls with different anthesis dates. 【Method】 Field experiments were carried out in Nanjing (118o50′E, 32o02′N) and Xuzhou (117°11′E, 34°15′N), representing different ecological conditions in the middle lower reaches of Yangtze River Valley and the Yellow River Valley in China. Two cotton cultivars and three nitrogen application levels were applied. The three N levels were 0, 240 and 480 kgN?ha-1, representing low, medium and high nitrogen level, respectively, and the two cultivars were KC-1 and AC-33B with different fiber quality indices. Responses of LMA (leaf mass per unit leaf area) and nitrogen concentration (NM, nitrogen content per unit leaf mass; NA, nitrogen content per unit leaf area) in the subtending leaf of cotton boll to nitrogen application levels were studied, and the relationships between nitrogen concentration and fiber quality indices were firstly groped. 【Result】 (1) NA in the subtending leaf of cotton boll contained both the information of LMA and NM, possessed the special sensitive characteristic in response to nitrogen application levels and anthesis dates. It can reflect the increasing trends with anthesis date postponing and significant difference in nitrogen treatments. (2) With the average values of NA increasing, the changing trends of pivotal quality indices (length, strength, micronaire and uniformity) of cotton fiber according with the curve of parabola with peak value. (3) With anthesis date, postponing, the difference of NA between low-nitrogen and medium-nitrogen treatments enlarged gradually, on the contrary, the difference between high-nitrogen and medium-nitrogen treatments diminished gradually, fiber strength and micronaire also showed similar trends between corresponding nitrogen treatments. 【Conclusion】 NA in the subtending leaf of cotton boll is tightly related to fiber quality indices formation. As the corresponding relationships between NA and fiber indices are not affected by cotton varieties and ecological sites, it is proposed that NA in the subtending leaf of cotton boll could be used as a practical physiologic index for timely monitoring nitrogen status for fiber quality in the future.