天竺桂凋落叶对凤仙花生长和光合特性的影响

采用盆栽实验,通过向土壤(每盆8kg)中添加0g·pot-1(CK)、20g·pot-1(L)、40g·pot-1(M)和80g·pot-1(H)天竺桂(Cinnamomum japonicum)凋落叶,模拟其自然分解对凤仙花(Impatiens balsamina)生长和光合特性的影响。结果显示:(1)添加天竺桂凋落叶M和H处理下,凤仙花生物量和地径均显著降低,而株高无明显变化;其叶绿素含量受到显著抑制,净光合速率(Pn)和水分利用效率(WUE)显著低于CK,而气孔导度(Gs)、胞间二氧化碳浓度(Ci)和蒸腾速率(Tr)3个气体交换参数显著高于CK。(2)Pn-PAR曲线和Pn-Ci曲线拟合表明,凤仙花在光饱和以及CO2饱和状态下的最大净光合速率(Pn max)、表观量子效率(AQY)、暗呼吸速率(Rd)、RuBP羧化效率(CE)和光呼吸速率(Rp)均随添加天竺桂凋落叶处理量的增加而呈下降趋势。(3)添加天竺桂凋落叶36d和67d时对凤仙花生长影响不明显,而处理58d时有明显抑制作用。研究表明,在模拟天竺桂凋落叶自然分解的土壤环境中,凤仙花的光合色素含量降低,抑制了其光合能力,对环境适应能力降低,导致凤仙花的生长受到抑制。

Effects of Cinnamomum japonicum Leaf Litter Addition on the Growth and Photosynthetic Characteristics of Impatiens balsamina

In order to investigate the effects of Cinnamomum japonicum leaf litter addition on the growth and photosynthetic characteristics of Impatiens balsamina,we conducted a pot experiment.Four litter addition treatments 0(CK),20(L),40(M),80(H) g·pot^-1 were applied.The results showed that the biomass and basal diameter of I.balsamina decreased significantly in M and H treatments,but no obvious change was observed in plant height among all the treatments.Chlorophyll contents of both M and H treatments were significantly inhibited.In treatments M and H,both net photosynthetic rate(P_n) and water use efficiency(WUE) were significantly lower than that of CK,while the three gas exchange parameters,stomatal conductance(G_s),intercellular CO₂ concentration(C_i) and transpiration rate(T_r) were notably higher than those of CK.P_n-PAR curve and P_n-C_i curve showed that under the saturation of light and CO₂ conditions both maximum net photosynthetic rates(P_{n max}) declined with the increasing amount of litter leaf addition,apparent quantum efficiency(AQY),dark respiration rate(R_d),RuBP carboxylation efficiency(CE) and light respiration rate(R_p) decreased as well.After adding C.japonicum leaf litter 36 and 67 days,no obvious effects were witnessed on the growth of I.balsamina,whereas inhibitory effect was observed obviously after 58 days.Overall,C.japonicum leaf litter addition reduced the content of photosynthetic pigments of I.balsamina,inhibited photosynthetic capacity,weakened adaptability to the environment,restraining the growth of the plant ultimately.