不同栽植密度库尔勒香梨光合及叶绿素荧光特性比较

为给库尔勒香梨高效栽培提供理论依据,采用Li-6400光合仪及FMS-2脉冲调制式荧光仪对6种栽植密度库尔勒香梨叶片进行光合及荧光参数的测定,分析其差异。结果表明:株行距3.0 m×5.0 m的净光合速率(P_n)最大,PSⅡ最大光能转化效率(F_v/F_m)较小。株行距5.0 m×6.0 m的P_n最小,F_v/F_m较大。各密度的P_n及气孔导度(G_s)日变化呈"双峰"曲线,蒸腾速率(T_r)呈"单峰"或"双峰"曲线,细胞间隙CO_2浓度(C_i)及F_v/F_m呈"先下降后上升"趋势。栽植密度较大的3个果园,P_n、G_s及气孔限制值(L_s)随栽植密度的增大而增加,C_i随栽植密度的增大而减小;密度较小的3个果园,P_n、G_s、L_s及C_i规律与之相反。株行距3.0 m×5.0 m梨园光合作用较强,耐光抑制能力较弱;株行距5.0 m×6.0 m梨园光合作用较弱,耐光抑制能力较强。株行距3.0 m×5.0 m为较适栽植密度。

Comparisons of photosynthetic characteristics and chlorophyll lfuorescence characteristics in Korla fragrant pear trees under different planting densities

In order to provide a theoretical basis for cultivation techniques which can improve yield and quality of Korla fragrant pear, some photosynthetic and lfuorescence parameters of Korla fragrant pear under six kinds of planting density were determined by using Li-6400 photosynthesis system and FMS-2 pulse modulated lfuorimeter, and were compared and analyzed. The results showed that the net photosynthetic rate (Pn) of the 3.0 m×5.0 m treatment was the maximum, and the maximal efifciency of primary conversion of light energy of PSⅡ (Fv/Fm) was the minimum. The 5.0 m×6.0 m treatment had the minimumPn and higherFv/Fm. The diurnal variation ofPn and the stomatal conductance (Gs) of each density treatment was a double-peak curve, that of the transpiration rate (Tr) was a single-peak or a double-peak curve, and those of both the intercellular CO2 concentration (Ci) andFv/Fm were the trends of ifrstly decreased and then increased. With the increase of planting density,Pn,Gs and the stomatal limitation value (Ls) were increased andCi was decreased in the three orchards with higher planting density. The regulars ofPn,Gs,Ls andCi were on the contrary in the three orchards with lower planting density. The photosynthesis in the orchard under 3.0 m×5.0 m density was stronger, and the inhibitory ability to light was weaker. The photosynthesis in the orchard under 5.0 m×6.0 m density was weaker, and the inhibitory ability to light was stronger. The more suitable planting density was 3.0 m×5.0 m.