降冠对核桃'云新高原'光合性能的效应OA

This research aimed to clarify the effects of crown-decreasing on photosynthetic performance of Juglans regia'Yunxingaoyuan',providing a basis for the industrial popularization and application of the crown-decreasing technology in J.regia cultivation.Crown-decreasing was performed on the J.regia'Yunxingaoyuan'trees entering full fruiting period,the photosynthetic pigment contents of the leaves were determined by using spectrophotometry,the photosynthetic and chlorophyll fluorescence parameters of the leaves were measured by using portable photosynthetic apparatus,and the comprehensive ranking of the leaf photosynthetic performance was evaluated by using membership function.The results indicated that the area,chlorophyll a content([Chl a]),chlorophyll b content([Chl b]),total chlorophyll content{[Chl(a+b)]},carotenoid content([Car])and the initial fluorescence(F0)of the leaves of the 4.0 m crown height plants were the highest,i.e.,about(77.4378±10.7445)cm2,(2.3780±0.1483)mg/(g·FW),(0.9775±0.1091)mg/(g·FW),(3.3565±0.2376)mg/(g·FW),(0.6391±0.0426)mg/(g·FW)and 110.0982±6.5923,respectively,the[Chl a]/[Chl b],maximum fluorescence yield(Fm)and the maximal photochemical efficiency of PSⅡ(Fv/Fm)of the leaves of the check(CK)plants with 8.0-9.0 m crown height were the highest,i.e.,approximately 2.8662±0.1448,917.8035±10.2468 and 0.8928±0.0032,respectively,whereas the[Chl(a+b)]/[Car],net photosynthetic rate(Pn),stomatal conductance(Gs),intercellular CO2 concentration(Ci)and transpiration rate(Tr)of the leaves of the 3.6 m crown height plants were the highest,i.e.,roughly 5.5542±0.6019,(14.3004±1.8561)μmol/(m2·s),(0.081±0.0064)mol/(m2·s),(719.4092±153.8605)μmol/mol and(2.3070±0.1348)mmol/(m2·s),respectively.The differences of the area,[Chl a],[Chl b],[Car],F0 and Fv/Fm among the plants with different crown heights all reached significant levels,the differences of the[Chl(a+b)],Pn,Gs,Tr and Fm all reached extremely significant levels,but those of the[Chl a]/[Chl b],[Chl(a+b)]/[Car]and Ci did not reach any significant levels.In brief,the comprehensive ranking of the photosynthetic performances of the leaves was as:3.6 m crown height＞4.0 m crown height＞4.4 m crown height＞CK.Thus,the 3 crown-decreasing treatments can all improve the photosynthetic performance of J.regia'Yunxingaoyuan'leaves,when the crown height is decreased to 3.6 m,the leaf photosynthetic performance is the best.