银木凋落叶腐解过程对小白菜生长和抗性生理的影响

Abstract

采用盆栽试验,研究了0(CK)、20(A₁)、40(A₂)和80(A₃)g/盆不同量银木凋落叶在土壤中腐解不同时间(30、40、50、60、70 d)后对受体植物小白菜株高、叶面积、生物量及几种抗性生理指标的影响。同时设置补充试验,采用充分浸泡48 h并蒸煮4 h,再风干后的银木凋落叶,各处理用叶量同上,观测分析蒸煮后的银木凋落叶在施入土壤后对土壤物理性质和受体植物的影响。结果表明:(1)在未蒸煮的试验中,凋落叶在施入土壤70 d内,显著抑制了小白菜的高生长、叶片伸展和生物量;在低凋落叶量、短时间处理下,小白菜叶片超氧化物歧化酶、过氧化物酶和过氧化氢酶活性有所升高,但处理量增大或处理时间延长时,超氧化物歧化酶和过氧化物酶活性降低,70 d时过氧化氢酶活性随着处理量增大受到显著促进(<em>RI</em>>0);在低凋落叶量、短时间处理下,可溶性糖含量显著上升,随着处理时间的延长和处理量的增加,可溶性糖和可溶性蛋白的含量显著降低;银木凋落叶在土壤中的作用强度随分解时间延长呈先强后弱的变化趋势,高凋落叶量处理产生的效应比低凋落叶量处理快且强,对小白菜的综合抑制效应变化趋势为:A₃＞A₂＞A₁;60 d后,各处理的某些指标(生物量、超氧化物歧化酶等)的效应明显减弱以及各处理之间效应差异缩小,可能是由于银木凋落叶在土壤中分解释放的有害次生代谢物质已明显减少;(2)在补充试验中,小白菜试验期内各处理间无明显形态差别,70 d时各处理生物量、形态指标之间无显著差异(<em>P</em>>0.05),表明在凋落叶施入量一定的范围内,土壤物理性质并不是影响小白菜生长的主要因素。综合各项指标可以看出,银木凋落叶在土壤腐解过程中可能对小白菜的生长和抗性生理产生了化感作用。;A pot experiment was carried out to study the effects of addition of leaf litter of <em>Cinnamomum septentrionale</em> on growth and resistance physiology of <em>Brassica rapa</em> during the decomposition process. Each pot contained 8 kg of soil mixed with 0, 20, 40, 80 g leaf litter of <em>C. septentrionale</em> respectively. Seeds of <em>B. rapa</em> were sawed on 13th April, a week later after litter addition. Height, biomass, leaf area and several indexes of resistance physiology were determined at 30, 40, 50, 60 and 70 d after sowing. Supplementary experiment was conducted as following: leaf litter of <em>C. septentrionale</em> after soaking in water for 48 h was steamed for 4 h, and the other methods were the same as above. The results were stated as following. (1) In formal experiment, height and biomass of <em>B. rapa</em> were inhibited significantly in 70 days. The activities of superoxide dismutase (SOD), peroxidase (POD) and catalase activity (CAT) in leaves of <em>B. rapa </em>increased on the condition of low litter content and short time of decomposition, but decreased on that of higher litter content and longer time of decomposition. The activities of CAT went up significantly in 70 d. The content of sugar and soluble protein in leaves of <em>B. rapa </em>increased in low litter content and short time of decomposition, whereas, decreased in that of higher litter content and longer time of decomposition. The affect intensity of leaf litter on <em>B. rapa</em> was from strong to weak in pace with prolonged decomposition time. The compound negative effect of 80 g treatment was the strongest, that of 40 g was weaker, and that of 20 g was the weakest. After 60 days, the discrepancy size of some indicators (e.g. biomass and SOD) of <em>B. rapa</em> among treatments had reduced. This implied that the effects were weakened. The reason might be that the allelochemicals in the litter of <em>C. septentrionale</em> had obviously reduced or almost no longer released. (2)In supplementary experiment, after sowing for 70 d, there was no obvious difference of morphological feature and no significant difference in biomass, height, leaf area between litter addition and control. It indicated that soil physical properties were not influenced obviously and the growth of <em>B. rapa</em> was not affected by addition of litter. On the whole, the leaf litter of <em>C. septentrionale </em>had a fierce allelopathic effect on <em>B. rapa </em>during its initial decomposition process in soil.