中文摘要：

【目的】探明棉铃对位叶氮浓度对棉纤维比强度形成的影响。【方法】以纤维比强度差异较大的3个棉花品种为材料,设置不同施氮量处理以形成不同的棉铃对位叶氮浓度,研究棉纤维加厚发育过程中棉铃对位叶氮浓度的动态变化及其与纤维中糖类物质及纤维比强度间的关系。【结果】棉铃对位叶氮浓度随铃龄的变化符合幂函数曲线YN=αt-β;在棉纤维加厚发育过程中,纤维中蔗糖、β-1,3-葡聚糖和纤维素含量随棉铃对位叶氮浓度的增加呈抛物线型变化,蔗糖、纤维素累积与纤维比强度形成的最佳棉铃对位叶氮浓度变化曲线相吻合,β-1,3-葡聚糖累积与纤维比强度形成的最佳对位叶氮浓度差异较大。【结论】棉铃对位叶氮浓度反映了棉铃发育的氮营养状况,在棉纤维加厚发育过程中,均存在一个有利于蔗糖、β-1,3-葡聚糖、纤维素累积及高强纤维形成的最佳对位叶氮浓度。棉纤维中较高的蔗糖和纤维素含量有利于纤维比强度的形成;棉纤维加厚发育前期较高的β-1,3-葡聚糖含量有利于纤维比强度的形成,后期则对纤维比强度形成的作用降低。不同品种纤维比强度形成的对位叶适宜氮浓度差异较大,进一步说明对位叶氮浓度影响棉花纤维加厚发育和比强度的形成。

英文摘要：

【Objective】 The objective of the experiment is to clarify the effects of the subtending leaf nitrogen concentration on strength formation of cotton fiber.【Method】 Five nitrogen rates were applied to set up varying leaf-nitrogen content treatments and three cotton cultivars with a great difference in fiber quality were employed.The study focused on the relationship between nitrogen concentration in subtending leaf of boll and the content of saccharide compounds,and their relationship with fiber strength formation.【Result】 Results showed that the changes of optimal nitrogen concentration in subtending leaf of cotton boll followed the equation：YN=αt-β（YN is nitrogen concentration in the subtending leaf of cotton boll（%）;t is boll age（d）;α and β are the parameters）.At fiber thickening stage,the content of sucrose,and cellulose all changed as a parabola-like curve according to the increasing nitrogen content in the leaf subtending boll.The curve of the leaf nitrogen for fiber strength increasing was very close to the curve of the optimum leaf nitrogen for sucrose or cellulose accumulation,while it was significantly apart from the curve of the leaf nitrogen for β-1,3-glucan accumulation.【Conclusion】 The nitrogen content of the leaf subtending bolls reflects the special nitrogen status for fiber development precisely.At fiber thickening stage,there exists an optimum leaf nitrogen curve for sucrose,β-1,3-glucan and cellulose accumulation and for fiber strength formation.The higher the sucrose exist,the higher fiber strength formed.At the early stage of fiber thickening,higher content of β-1,3-glucan is benefit for fiber strength formation,while at later stage,the higher content of β-1,3-glucan will make less contribution to fiber strength formation.It is concluded that the optimum leaf nitrogen content for fiber strength formation in different cotton culitivars is different,and the nitrogen concentration in the subtending leaf of cotton boll affects obviously the cotton fiber thicken