人工四倍体桑树品种鄂桑2号的光合特性研究

Study on Photosynthetic Characteristics of Esang 2,an Artificial Tetraploid Mulberry Variety

多倍体桑树品种具有生长势旺、叶片肥大、叶质优良等特点。采用LI-6400型便携式光合系统测试人工诱变培育的四倍体桑树品种鄂桑2号和二倍体桑树品种湖桑32号植株的各项光合生理参数及其变化规律,分析多倍体桑树品种高产、优质的光合生理机制。测试结果:四倍体和二倍体桑树的叶片净光合速率(Pn)日变化都呈双峰曲线,但出现峰值的时间不同;光补偿点(LCP)为鄂桑2号[55.89μmol/(m2·s)]>湖桑32号[39.90μmol/(m2·s)],光饱和点(LSP)为鄂桑2号[1 332.44μmol/(m2·s)]<湖桑32号[1 572.06μmol/(m2·s)];鄂桑2号和湖桑32号叶片的净光合速率、表观量子效率(AQY)、羧化效率(CE)、气孔限制值(Ls)差异不显著,而光合能力(Pm)和二磷酸核酮糖(RuBP)最大再生速率差异均达显著水平(P<0.05),且鄂桑2号<湖桑32号;鄂桑2号叶片Pn的季节变化动态为10月8日>8月12日>9月22日>9月13日>8月30日,而湖桑32号叶片Pn的季节变化动态为10月8日>9月13日>9月22日>8月12日>8月30日,各测定时期湖桑32号叶片的Pn均大于鄂桑2号;鄂桑2号与湖桑32号不同叶位叶片的Pn差异不显著(P>0.05);鄂桑2号的叶面积及叶绿素含量均大于湖桑32号,且第5、7、9、11位叶均达差异显著水平(P<0.05)。鄂桑2号叶片的光合性能低于湖桑32号,但其叶绿素含量与叶面积显著高于湖桑32号,这可能是鄂桑2号高产的重要因素之一。

Polyploid mulberry varieties have strong growth vigor, big and thick leaves, excellent leaf quality and other valuable traits. In present study, LI-6400 portable photosynthesis system was employed to measure various photosynthetic physiological parameters and their variation regularities in Esang 2, a tetroploid mulberry variety obtained from artificial mutation and cultivation, and in Husang 32, a diploid mulberry, to analyze the photosynthetic physiological mechanism of high yield and quality of polyploid mulberry. The results indicated that the diurnal variation of net photosynthetic rate （Pn） of both tetraploid and diploid mulberry leaves was in double-curve form, but the peak value appeared at different hours. Liqht compensation point （LOP） of Esana 2 f 55. 89 mol/（ m2·S higher ＂332[39.90mol/（m2 .s）], and light saturation point （LSP） of Esang 2[ 1 332.44 mol/（ m2 -s） ] was lower than that of Husang 32 [ 1 572.06 mol/（ m2.s） ]. The net photosynthetic rate, apparent quantum yield （AQY）, carboxylation efficiency （ CE）, volume of stoma restriction （ Ls） had no significant difference between Esang 2 and Husang 32. The photosynthetic capacity （Pro） and max regeneration velocity of ribulose-1,5-bisphosphate （RuBP） had significant difference （ P 〈0.05）, both of which were lower in Esang 2 than in Husang 32. Pn seasonal variation of Esang 2 was in order of October 8th 〉 August 12th 〉 September 22nd 〉 September 13th 〉August 30th, while that of Husang 32 was in order of October 8th 〉September 13th 〉September 22nd 〉August 12th 〉August 30th. Besides, Po value of Husang 32 was higher than that of Esang 2 on each survey date. Pn of differ- ent leaf position in Esang 2 and Husang 32 had no significant difference （P〉0.05）. However, both leaf area and chlorophyll content of Esang 2 were higher than Husang 32, being significantly different in the 5th, 7th, 9th and 1 lth leaf position （P〈0.05）. It was found that the photosynthetic performance of Esang 2 was lower than Husang 32, but its chlorophyll content and leaf area were significantly higher than Husang 32, which is probably one of the important reasons leading to high yield of Fsang 2.