香樟凋落叶分解对几种园地作物抗性生理和土壤氮组分的影响

【目的】探讨香樟(Cinnamomum camphora)凋落叶添加到土壤中对小白菜(Brassica chinensis)、莴笋(Lactuca sativa)、茄子(Solanum melongena)生长和抗性生理的影响以及土壤矿质化氮的动态响应。【方法】采用盆栽试验,以单位面积香樟叶年凋落量作为凋落叶的基本添加量,设不添加凋落叶的对照(CK)和3个凋落叶添加水平,即A₁(25 g/盆)、A₂(50 g/盆)、A₃(100 g/盆),每处理重复5次,处理3种作物共计60盆。处理后,定期对植株生长指标(株高、地径)和抗性生理指标(超氧化物歧化酶、过氧化氢酶、过氧化物酶)和作物所生长土壤的硝态氮、铵态氮含量进行测定。【结果】香樟凋落叶分解对3种作物的地径、株高均有明显的抑制作用,且有随凋落叶添加量的增加而增强并随分解时间的延长而逐渐减弱的效应; 香樟凋落叶分解初期(20～40 d),各水平处理均显著地促进了叶片超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性,抑制了过氧化物酶(POD)活性。凋落叶分解到80 d时,各处理CAT、POD、SOD活性的差异明显缩小; 加入不同量的香樟凋落叶在一定时间(30～50 d)内大幅降低了土壤矿化氮(硝态氮和铵态氮)含量; 不同作物对香樟凋落叶化感作用的敏感程度不同,莴笋最为敏感,其次是小白菜,茄子的耐受性最强,相对更适宜在香樟林间或林缘种植。【结论】香樟凋落叶分解可能降低了土壤氮素的有效性,并对作物造成活性氧伤害,最终限制其生长发育。

Effects of decomposingleaf litter of Cinnamomum camphora on the resistance physiology of three intercropping crops and activity of the organic nitrogen fraction

Objectives] A pot experiment was conducted to investigate the allelopathic effect of decomposing leaf litter of camphor (Cinnamonmm camphora) on the growth and resistance physiology of three recipient crops:cabbage (Brassica chinensis),lettuce (Lactuca sativa) and eggplant (Solanum melongena).Methods]Through potted trial,the annual amount of leaf litter per unit area was uesd as the basic amount of litter in this experiment,four levels of leaf litter addition were applied to the soil (namely A1(25 g/pot),A2(50 g/pot),A3(100 g/pot) and CK (no leaf litter added).Repeated five times for each treatment,the total amount of three crops were 60 pots.After the treatment,on a regular basis,the plant growth index (height and diameter) and resistant physiological index (superoxide dismutase,catalase and peroxidase) and the contents of soil nitrate and ammonium nitrogenfor crop growth were measured.Results] The decomposing camphor leaf litter showed inhibiting effect on ground diameter and height of the three recipient crops.The inhibition effect on the recipient crops was enhanced with the increment of leaf litter,but with the extension of decomposition time the inhibition effect tended to weaken and even showed the promotion effect on recipient crops;At the early stage (20-40 d) of decomposition of leaf litter,the activities of superoxide dismutase (SOD) and catalase (CAT) were inhibited with the increase of leaf litter addition,and the activity of peroxidase (POD) was increased.After 80 d of decomposition,the activity difference of CAT,SOD and POD were significantly decreased.Different addition during a certain period (30-50 d) remarkably reduced the content of soil mineral nitrogen (nitrate nitrogen and ammonium nitrogen).The sensitive levels of different recipient plants to the allelopathic inhibition of decomposing camphor leaf litter were different.The inhibition effect on lettuce was the strongest,while the inhibition effect on eggplant was the weakest.Conclusions] With the extension of decomposition time the inhibition effect tended to weaken.Based on the results above,we concluded that the decomposing camphor leaf litter affected the growth of recipient crops directly or indirectly by releasing allelochemicals,thus the vegetative growth of rccipicnt crops was limited,and accordingly the accumulation of biomass was decreased.