香樟凋落叶分解物对辣椒生长发育的影响

采用盆栽试验,研究了香樟(Cinnamomum camphora)凋落叶(0、25、50、75、100g凋落叶分别与10kg土壤混合)分解过程中对辣椒(Capsicum annuum)及其子代生长发育的影响,并采用气质联用(GC-MS)技术对凋落叶分解前后的萜类物质进行了检测和对比。结果显示:(1)香樟凋落叶分解物显著地抑制了辣椒的叶片数量、整株叶面积以及株高和基径生长,抑制效应随凋落叶剂量的增大而增强,而分解过的凋落叶和塑料片替代凋落叶原样的试验并不抑制辣椒的生长。(2)观察期内(处理45~76d),辣椒的现蕾数、开花数和结实数在各凋落叶处理下均明显低于同期对照;采用指数方程拟合的现蕾、开花和结实动态显示,25g凋落叶处理使辣椒的始蕾期、始花期和始果期分别推迟了0.81、0.17和1.35d,50g处理使这3项参数分别推迟了4.69、5.78和6.27d,而75g和100g处理均使这3项参数推迟10d以上。(3)辣椒的单株果实产量在凋落叶处理下降低29.44%~61.29%,而单果重受到的影响相对较小。(4)辣椒产出的种子千粒重和子代的生长状况并未受到凋落叶分解物的影响。(5)凋落叶的正己烷提取物中萜类占78.05%,而分解后其相对总量下降至40.76%,峰面积下降至原样的约1%。研究认为:香樟凋落叶添加处理对辣椒营养生长和生殖生长产生的明显抑制作用,不是由凋落叶添加对土壤通气透水性或对受体生长造成机械阻隔引起的,其在分解过程中释放樟脑(Camphor)、1,8-桉叶油醇(1,8-cineole)等萜类物质引起化感作用可能才是关键原因。

Effect of Decomposing Leaf Litter of Cinnamomum camphora on Growth and Development of Capsicum annuum

A pot experiment was carried out to investigate the effects of decomposing leaf litter of camphor tree(Cinnamomum camphora) on growth and development of hot pepper(Capsicum annuum) and its progeny.The experiment consisted of four leaf litter treatments(25,50,75 and 100 g of camphor tree leaf litter were separately added to 10 kg of soil) and a control(free of leaf litter).Gas chromatograph-mass spectrometry(GC-MS) was used to identify and compare terpenes existed in the original and decomposed leaf litter.Results showed that:(1)Decomposing leaf litter of camphor tree inhibited the leaf number,leaf area,height and basal diameter of hot pepper sharply,and the inhibition rate increased with the increase of leaf litter.However,in the parallel trial,no significant differences were observed between hot pepper treated with decomposed leaf litter and plastic film in terms of growth status.(2)The numbers of buds,flowers and fruits were all suppressed when exposed to leaf litter during the observation period(45-76 d).Exponential equation was used to fit the budding,flowering and fructification dynamics of hot pepper,and showed that the first bud emerging day,first flower blooming day,and first fruit emerging day were 0.81,0.17 and 1.35 d later than that of control when exposed to 25 g leaf litter,respectively,and those were 4.69,5.78 and 6.27 d later than that of control when exposed to 50 g leaf litter,respectively.More visibly,75 g and 100 g leaf litter both delayed these parameters by more than 10 days.(3)The fruit production of a single plant was inhibited treated with decomposing leaf litter in spite of the doses,with a decreasing amplitude of 29.44%-61.29%,while the single fruit weight was suffered less from the leaf litter.(4)The addition of leaf litter exerted neither significant effect on the 1000-grain weight of the seeds produced by hot pepper,nor on the growth of the progeny.(5)Terpenes represented about 78.05% of the total constituents extracted,and after decomposition,the relative content of which decreased to 40.76%,and most importantly,their absolute peak area decreased to approximately 1% of that in the original sample.The present study revealed obvious suppressive effect of decomposing leaf litter of camphor tree on the vegetative and reproductive growth of the targeted plant.The allelochemicals,e.g.,Camphor and 1,8-cineole released during the decomposition process rather than the alteration of soil and water permeability due to the addition of leaf litter should be responsible for these results.