毛竹快速生长期光合蒸腾日变化特征

摘要

Moso bamboo(Phyllostachys edulis)can complete its growth in a vary short period, called the rapid growth period. To reveal the flow direction of nutrient transport during the rapid growth period and to analyze characteristics of daily variation for bamboo's gas exchange parameter, a Li-6400XT photosynthesis system was used to measure leaves' gas exchange parameter of three-year-old and five-year-old bamboo. Results indicated that:(1)In the early stage of the rapid growth period, light saturation point(LSP)of three-year-old bamboo was higher than five-year-old bamboo. During the middle and later stages of the rapid growth period, however, five-year-old bamboo's light saturation point was overtake three-year-old bamboo.(2)The net photosynthetic rate(Pn)of three-year-old bamboo was not significantly different within the different stages of the rapid growth period(P>0.05); whereas, five-year-old bamboo's net photosynthetic rates were significantly lower(P<0.05) in its early stage compared to its middle and later stages. In addition, the net photosynthetic rate was highly correlated to bamboo's age(P<0.01, r=0.131)and growing stage(P<0.01, r=0.166).(3)Transpiration rate (Tr)was highly significant and correlated(P<0.01,r=0.688)to its net photosynthetic rate and different stages of the rapid growth period, but was not significantly correlated to bamboo's age(P>0.05, r=0.201).(4)Leaf water use efficiency of bamboo was higher(P<0.01)in the morning than that in the afternoon, and signifi-cantly greater(P<0.01)in the middle period than that in early and later periods. WUE for five-year-old bam-boo was also significantly(P<0.05)than three-year-old bamboo. This study indicated that the process of nu-trient and water transfer from grow-up bamboo to young bamboo through bamboo rhizomes appeared most dras-tic in the middle stage of the rapid growth period, and five-year-old bamboo was the origin of nutrient trans-portation towards young bamboo with younger bamboo being the main source of nutrients throughout its rapid growth.%毛竹Phyllostachys edulis新竹会在极短时间内完成其整个成竹生长,这个过程被称为快速生长期.为揭示毛竹新竹在快速生长期间从竹笋成长为幼竹这一过程中不同竹龄母竹对新竹的营养传输流向以及自然状态下毛竹气体交换参数的日变化特征,利用Li-6400XT光合仪,分别对3年生和5年生毛竹在快速生长期间叶片的气体交换参数进行测定.结果表明:①快速生长前期,3年生毛竹的光饱和点(LSP)高于5年生毛竹,而在中期和后期5年生毛竹的LSP高于3年生毛竹;②3年生毛竹的净光合速率(Pn)在不同生长时期之间差异不显著(P>0.05), 5年生毛竹的净光合速率在快速生长前期显著低于中期和后期(P<0.05).净光合速率与竹龄(P<0.01, r=0.132)和生长时期(P<0.01,r=0.164)的相关性极显著;③蒸腾速率(Tr)与净光合速率极显著相关(P<0.01,r=0.688),与生长时期极显著相关(P<0.01,r=0.201),而与竹龄的相关性则不显著(P>0.05); ④水分利用效率(EWUE)总体表现为上午高于下午(P<0.01),快速生长中期显著高于前期和后期(P<0.01), 5年生毛竹高于3年生毛竹(P<0.05).研究表明:成竹通过竹鞭向新竹输送养分和水分的这个过程在快速生长中期最为剧烈.5年生毛竹是对新竹的营养传输的源头,也是新竹快速生长最主要的养分来源.