棉花不同叶位主茎叶衰老特征的研究

 在大田条件下，研究了棉花不同叶位主茎叶在盛铃末期的衰老状况。以转基因抗虫棉33B为材料，测定全部主茎叶的主要生理生化指标，以分析不同部位叶片衰老的差异。结果表明，（1）盛铃末期是主茎功能叶片从旺盛生理功能到衰老的转折时期；（2）从主茎上部第1叶到下部的第10叶叶绿素含量、蛋白质含量、SOD活性呈下降趋势，MDA含量、POD活性呈上升趋势；（3）盛铃期调控棉花叶片的衰老应以主茎中部轻度衰老叶片为诊断和调控主体。

Studies on the Characteristics of Leaf Senescence at Different Stem Positions of Cotton

In recent years, with the generalization of transgenic cotton, premature senescence is aggravated, which has become a main factor for the production of cotton. Characteristics of leaf senescence for main stem of different positions were studied in the later full boll stage of cotton in the field. With Bt-transgenic cotton 33B as experimental plant, by researching into the change trends of contents of chlorophyll and MDA in functional leaves on main stem in the whole growing period, the turning point from blooming to senescence was found in 2005. Hereby in 2006 the physiological characteristics (Chlorophyll, Protein, MDA, SOD, POD) of all leaves at the different stem positions on the cotton plant were researched into in the turning period, and then the differences in senescence between leaves were analyzed. The results showed, (1) The turning point from blooming to senescence is at the later full bolling stage; (2) The Chl content, Pro content and SOD activity decreased with the change of leaf position from stem top to bottom, while the MDA content and POD activity increased; (3) All of the main stem leaves can be separated into three parts on the basis of physiological index changes: bloom leaves (the first leaf and the second leaf on the top), light senescence leaves (the third leaf to the eighth leaf ), heavy senescence leaves (the ninth leaf and the tenth leaf), (4) The middle leaves (light senescence leaves) should be mainly diagnosed and regulated at the full bolling stage, which can postpone the leaf senescence, even the whole plant senescence.