不同成熟度桑叶分区位置的叶绿素荧光参数与叶绿素相对含量分析

Analysis of Location-based Chlorophyll Fluorescence Parameters and SPAD Value of Mulberry Leaves with Different Maturity

桑叶中的叶绿素含量可以反映桑树的光合作用能力及植株的营养健康状态。选择不同成熟度的桑叶并将桑叶沿主叶脉两侧对称划分后细分成6个区域,采用叶绿素荧光仪和叶绿素计测定叶绿素荧光参数与叶绿素相对含量(SPAD值),并将桑叶各分区与全叶、不同成熟度全叶之间的指标数据进行T检验和方差分析及聚类分析,由此确定桑叶叶绿素荧光参数与SPAD值测定的最佳叶片及区域,建立起快速准确的测定技术。各项分析表明:桑叶的SPAD值与叶绿素荧光参数中的光化学淬灭系数qL之间关系密切,桑叶光合活性的高低与叶绿素含量有较强的相关性;叶绿素荧光参数中的最大光合效率F v/F m与实际光能转换效率Y(Ⅱ)之间关系密切,二者之间存在较强的相关性;叶绿素荧光参数F v/F m、Y(Ⅱ)与非光化学淬灭系数NPQ存在一定的相关性,桑叶的光保护能力受光合效率的影响。初步确认叶色饱满、叶位偏中下部的成熟叶片是检测桑树植株叶片叶绿素的最佳材料,具体测定位置以叶片中部主叶脉两侧区域和中后部叶缘附近区域为宜。

The chlorophyll content in mulberry leaves can reflect the photosynthetic capacity of mulberry trees and the nutritional health of plants.Mulberry leaves with different maturity were selected and divided symmetrically along both sides of the main vein and subdivided into six regions.Chlorophyll fluorescence parameters and SPAD value(relative content of chlorophyll)were measured by chlorophyll fluorometer and chlorophyll meter,and the index data between each region of mulberry leaves and whole leaves with different maturity were tested by T test,variance analysis and cluster analysis,so as to determine the best leaves and regions for measuring chlorophyll fluorescence parameters and SPAD value of mulberry leaves,and establish a fast and accurate measurement technology.The results showed that there was a close relationship between SPAD value of mulberry leaves and chlorophyll fluorescence parameter qL,and there was a strong correlation between photosynthetic activity of mulberry leaves and chlorophyll content.There was a close relationship between the maximum photosynthetic efficiency F v/F m and the actual light energy conversion efficiency Y(Ⅱ)in chlorophyll fluorescence parameters,and there was a strong correlation between them.Chlorophyll parameters F v/F m,Y(Ⅱ)had certain correlation with non-photochemical quenching coefficient NPQ,and the light protection ability of mulberry leaves was affected by photosynthetic efficiency.Mature leaves with full leaf color and lower middle position were the best materials to detect chlorophyll in mulberry leaves,and the specific locations were the areas on both sides of the main vein in the middle of the leaves and the areas near the middle and rear leaf edges.