小麦进化过程中叶片气孔和光合特征演变趋势

Evolutional trends of leaf stomatal and photosynthetic characteristics in wheat evolutions

根据小麦属内种间的进化关系选取21种小麦品种为实验材料,研究了小麦进化过程中气孔特征和光合特征的演变趋势。结果表明,无论是A,B,D染色体组还是A,G染色体组,气孔长度、宽度、周长、面积均随倍性水平的升高而呈增大趋势,而气孔指数无显著变化;A,B,D染色体组气孔密度随倍性升高呈减少趋势。二倍体小麦的Pn值最高,六倍体小麦的Fv/Fm值较高,二倍体小麦叶片叶绿素含量显著高于四倍体和六倍体小麦。不同倍性小麦的净光合速率与气孔导度间均存在极显著相关关系,表明气孔传导力是小麦光合能力的主要限制因素之一。气孔导度与单一气孔特征之间无显著相关关系。A,B,D染色体组不同倍性小麦叶片气孔密度差异显著,其大小顺序为二倍体>四倍体>六倍体;A,B,D染色体组不同倍体小麦叶片的气孔长度、宽度、周长、面积差异显著,顺序均为六倍体>四倍体>二倍体,气孔密度降低可能是A,B,D染色体组六倍体小麦光合能力降低的原因。随着倍性的升高,小麦的抵抗光抑制能力越强,因此光化学能转换效率可能不是小麦进化过程中光合能力变化的原因。A,B,D染色体组中二倍体的叶绿素含量显著大于四倍体和六倍体,而A,G染色体组中倍体间叶绿素含量差异不显著,说明叶绿素的降低可能是A,B,D染色体组六倍体光合能力降低的原因之一。

According to the evolution relationships among Triticum varieties, 21 wheat varieties were chosen as research materials in this experiment to determine the evolutional trends of stomatal and photosynthetic characteristics. The results showed that as ploidy increase, the stomatal length, width, girth and area were found to increase. The stomatal density was found to decrease in A, B, D genomes ; however, no differences were found in stomatal indices among ploidies indicating that the stomata became larger but were less in evolution progress. The Diploidy had the highest Pn, which was less in Hetraploidy, and was the least in Hexaploidy. On the contrary, the Hexaploidy had the highest values in Fv/Fm. The Diploidy had the highest chlorophyll content. The net photosynthetic rate had significant correlationship with stomatal conductivity, however, no significant relationship was found among stomatal conductivity and any stomatal characteristics, indicating that the stomatal conductivity is one of the factors limited the photosynthetic rate while the single stamatal characteristics is not the reason that inducing the photosynthetic rate change. The stomatal density showed significant differences among ploidy materials in A, B, D genomes and the trend of genotype was in order of 2n 〉 4n 〉 6n ; the stomatal length, width, girth and area showed significant differences among ploidy materials and the trends of genotype was in the order 6n 〉 4n 〉 2n. The results indicate that the low density might induce the low conductivity and low photosynthetic ability in Hexaploidy. Furthermore, the Diploidy had higher values in chlorophyll content of flag leaf area among ploidy materials in A, B, and D genomes, indicating that higher chiorophyll content might be a reason for higher photosynthetic ability in Diploidy wheat species.