林(果)粮间作中树木枯落叶对小麦发芽期和苗期的化感效应

树木枯落叶对作物的化感效应是建设林(果)粮间作复合体系所要考虑的重要问题之一。本研究采用陕西关中地区常见的12种树木枯落叶经室内混土分解培养后的不同浓度水浸提液作为培养基质,进行室内小麦种子萌发和生长试验,探讨了林(果)粮间作树种枯落叶对小麦的化感效应。结果表明:(1)杜仲处理和元宝枫处理促进了小麦幼苗苗高生长,提高了CAT活性,却降低了根系活力;泡桐处理和杨树处理促进了小麦种子萌发和幼苗生长;花椒处理抑制了小麦幼苗根长、生物量、CAT活性和根系活力;核桃处理在高浓度时明显抑制了小麦发芽速度指数、根长、CAT活性和叶绿素含量;梨树处理对小麦发芽速度指数、根长和叶绿素含量表现为低促高抑;苹果处理提高了小麦发芽速度指数、幼苗苗高、生物量和叶绿素含量;柿树处理和枣树处理抑制了小麦幼苗根长和生物量;桃树处理和杏树处理对小麦种子萌发表现为低促高抑。(2)统计学主成分分析表明,整体上对小麦发芽和生长起明显促进作用的树种是泡桐、苹果和杨树,其次是杏树和元宝枫;整体上对小麦发芽和生长起到明显抑制作用的树种是柿树、核桃和枣树,其次是花椒和桃树;而梨树起到低促高抑的作用,杜仲则相反。

Allelopathic effects of tree-leaf litter on the germination and seedling phase of wheat in inter-planted systems of trees (fruits trees) and grain crops

Allelopathic effects of tree-leaf litter on crops is one of the most important considerations in constructing inter-planting systems of trees or fruits trees and grain crops. In this study, a bench-scale experiment was conducted on wheat seed germination and growth under different concentrations of water extracts from decomposed leaf litter (the culture substrate) of 12 different trees in Guanzhong (Shaanxi Province). Nine index indicators (including germination ratio, germination rate, shoot height, root length, shoot dry weight, root dry weight, CAT activity, root activity and chlorophyll content) of wheat were measured and the allelopathic effects of the tree-leaf litter on wheat discussed. The results were as follows: (1) While Eucommia ulmoides and Acer truncatum stimulated shoot height growth and CAT activity of wheat, they inhibit root activity. Also Paulownia fortunei and Populus canadensis stimulated wheat seed germination and seedling growth. Then Zanthoxylum bungeanum inhibited seedling root length, biomass, CAT activity and root activity of wheat. Furthermore, Juglans regia significantly inhibited seed germination rate, root length, CAT activity and chlorophyll content at high concentrations. Pyrus bretschneideri was inhibitory to seed germination rate, root length and chlorophyll content at high concentrations but stimulatory at lower concentrations. Malus pumila stimulated seed germination rate, shoot height, growth biomass and chlorophyll content. Diospyros kaki and Ziziphus jujuba inhibited seedling root length and biomass. Also Prunus persica and P. armeniaca inhibited seed germination at high concentrations but stimulated it at low concentrations. (2) Based on comprehensive analysis of allelopathic effects, P. fortunei, M. pumila and P. canadensis significantly stimulated wheat seed germination and growth, followed by P. armeniaca and A. truncatum. Then D. kaki, J. regia and Z. jujuba significantly inhibited wheat seed germination and growth, followed by Z. bungeanum and P. persica. On the contrary, P. bretschneideri inhibited wheat seed germination and growth at high concentrations but stimulated them at low concentrations. The effect was the direct reverse for E. ulmoides.