油菜生长过程对核桃凋落叶化感作用的响应

为研究农作物白菜型油菜生长过程对核桃凋落叶化感作用的生理响应，采用盆栽试验，通过设置空白对照CK（不添加凋落叶）和3个凋落叶添加剂量水平:L₆₀（60 g·盆^-1）、L₁₂₀（120 g·盆^-1）和L₁₈₀（180 g·盆^-1），测定盆栽油菜生长中后期的营养生长、生殖生长及生理响应相关指标。结果表明:1）核桃凋落叶分解对油菜中期营养生长（地径、株高）有显著抑制，在后期得到明显减弱，可仍对后期油菜生殖生长（开花性状、结实性状和产量）产生抑制影响；但这种抑制效应不会影响油菜结实种子的萌发。2）油菜生长中期（100 d），随核桃凋落叶剂量增大，油菜叶片中超氧化物歧化酶（SOD）、过氧化氢酶（CAT）活性逐步增强，过氧化物酶（POD）活性无显著变化；丙二醛（MDA）含量仅在L₁₈₀处理下显著>CK（P＜0.05），可溶性糖（SS）含量逐步增加，而可溶性蛋白（SP）含量呈逐步下降；到油菜生长后期（140 d）时，各处理下油菜POD、CAT的活性和SS、SP的含量均逐步下降，MDA含量均显著P<0.05）。3）各核桃凋落叶处理对油菜叶片各类叶绿素均有明显抑制作用,随凋落叶添加量增加，油菜叶片净光合速率（P_n）、气孔导度（G_s）和胞间CO₂浓度（C_i）呈先降后增的趋势。综上所述，核桃凋落叶经土壤分解对油菜中后期生长造成强烈的化感胁迫，其主要通过对油菜的细胞膜造成过氧化伤害，使叶绿素合成受到抑制，光合作用受到影响，进而妨碍其生长及产量品质的形成。

Responses of Physiological Process of Rape to the Allelopathy of Walnut Leaf Litters

In order to study the physiological response of the growth process of cabbage rape (Brassica rapa) to the allelopathy of walnut (Juglans regia) leaf litters,a pot experiment was carried out by adding walnut leaf litter with different dosages:0,60,120,and 180 g per pot (represented by the control,L₆₀,L₁₂₀,and L₁₈₀),respectively.The results indicated that 1) the decomposition of walnut leaf litters significantly inhibited the vegetative growth of B.rapa seedlings,such as plant height and ground diameter,and reproductive growth,such as flowering and fruiting,in the middle and late growth stages of rapeseed.But this inhibiting effect would not be inherited to the second generation of rapeseed.2) At the middle stage of rapeseed growth (100 days),with the increase of walnut litter dose,the activities of superoxide dismutase (SOD) and catalase (CAT) in rape leaves increased gradually.The content of malondialdehyde (MDA) was significantly higher than that of the control only under L₁₈₀ treatment,while the content of soluble sugar (SS) increased gradually,while the content of soluble protein (SP) decreased gradually.At the late stage of rapeseed growth (140 days),POD,CAT,SS and SP of rapeseed decreased gradually in all treatments,and MDA content was significantly lower than the control.3) The treatment of walnut leaf litters obviously inhibited all kinds of chlorophylls in rape leaves.The net photosynthetic rate (P_n),stomatal conductance (G_s) and intercellular CO₂ concentration (C_i) of rape leaves decreased first and then increased with the increase of litter addition.In summary,the withered leaves of walnut caused strong allelopathy stress to the growth of rape in the middle and late growth stages through soil decomposition,which mainly caused peroxidation damage to the cell membrane of rape,so that its chlorophyll synthesis was inhibited,its photosynthetic capacity was affected,and then hindered its growth,yield and quality formation.