6个广西种源荷木光合及保水力的比较

Comparison of leaf photosynthetic capacity and water retention capacity of 6 Schima superba provenances from Guangxi

[目的]评价广西荷木6个种源的光合能力及保水力,以期更好地选择和利用优良种源。[方法]采用列区种植6个广西种源10年生荷木幼林,研究其叶片光合生理、气孔及保水力等指标,并对不同荷木种群进行比较。[结果]6个种源荷木叶片气孔密度在23.4~28.9个·mm^(-2)之间,叶绿素含量在1.342~2.436 mg·g^(-1)之间,叶片暗呼吸速率在0.76~1.84μmol·m^(-2)·s^(-1)之间,光补偿点在11.54~24.63μmol·m^(-2)·s^(-1)之间,光饱和点在1072.87~1607.44μmol·m^(-2)·s^(-1)之间,最大净光合速率在11.14~14.51μmol·m^(-2)·s^(-1)之间。离体24 h后,叶片保水力大小依次为:灌阳>恭城>苍梧>兴业>博白>钦州。总体上,6个广西种源荷木光饱和点、光补偿点、暗呼吸速率、保水力、最大净光合速率均表现为桂北种源(灌阳、恭城、苍梧)高于桂南种源,气孔密度则表现为桂南种源大于桂北种源。荷木胸径、树高与净光合速率呈显著正相关关系。[结论]恭城、苍梧种源保水力较强;博白种源对光照强度的适应能力较强,利用范围较广;钦州种源利用弱光能力较强;桂南种源总体上比桂北种源气孔密度大。荷木生长主要受净光合速率的影响。经度、纬度、年总降雨量、年平均气温等是引起荷木生理及光合特性产生丰富遗传变异的主要环境因素。

[Purpose]Leaf photosynthetic capacity and water retention capacity of 6 Schima superba provenances from Guangxi were evaluated to select excellent provenance for the utilization of S.superba.[Method]Ten-year-old S.superba provenances from Guangxi,which were linearly planted were compared in leaf photosynthetic physiology,stomatal density and water retention capacity.[Result]The leaves of the 6 provenances had 23.4-28.9 stomates per square millimeter,chlorophyll content ranging from 1.342 to 2.436 mg·g^(-1),dark respiration rate ranging from 0.76 to 1.84μmol·m^(-2)·s^(-1),light compensation point between 11.54 and 24.63μmol·m^(-2)·s^(-1),light saturation point between 1072.87 and 1607.44μmol·m^(-2)·s^(-1),and maximum photosynthetic rates ranging from 11.14 to 14.51μmol·m^(-2)·s^(-1).The water retention capacity of leaves in vitro for 24 h followed the order of Guanyang>Gongcheng>Cangwu>Xingye>Bobai>Qinzhou.Generally,the light saturation point,light compensation point,dark respiration rate,water retention rate and maximum photosynthetic rate of S.superba from northern Guangxi provenances(Guanyang,Gongcheng and Cangwu)were higher than those of the southern provenances,while the stomatal density trended conversely.The diameter at breast height and tree height were significant positively correlated with net photosynthetic rate.[Conclusion]S.superba from Guanyang,Gongcheng and Cangwu provenances had greater water retention capacity;the Bobai provenance was highly adaptable to varying light conditions,and able to utilize a wide range of light;S.superba from Qinzhou provenance showed strong ability to use low light.The stomatal density of S.superba from southern Guangxi provenances were greater than those of the northern ones.The growth of S.superba was mainly affected by net photosynthetic rate,and longitude,latitude,annual precipitation and annual average temperature were the main environmental factors causing rich genetic variation in physiological and photosynthetic properties of S.superba.