Allelopathy Of Different Agroforestry Systems In The Weibei Area Of Shaanxi

.Relationship between species in agroforestry systems of modern agroforestry systems not only has become one of the core research, but also has become the design of business models of agroforestry important factors considered. Allelopathy is one of the relationships between species in agroforestry systems. It is an indispensable part in agroforestry systems can not be ignored. In this paper, common forest-crop intercropping and fruit-crop intercropping agroforestry systems in Weibei area has been as the objects. Determinate the allelopathy of water extract from 15 kinds of leaf litter on seed germination and seedling growth of 4 crops (wheat, rape, corn, soybean); allelopathy of leaf litter of different tree on biochemical indexes such as root activity, cell membrane permeability and catalase activity of three of the 4 crops .The main conclusions are as follows:(1) Except water extract of Pyrus, Prunus salicina, Malus, Prunus, Ebenaceae and Eucommia at 0.1g/mL make inhibition of seed germination of wheat, the other concentration have no significant effect on seed germination. Water extract of Ejuglans, Zanthoxylum, Paulownia, Prunus persica, Prunus armeniaca,Cerasus, Acer truncatum and Zizyphus have no effect on the seed germination of wheat. Slightly different stages of seed germination is (Ejuglans, Zanthoxylum, Pyrus, Ebenaceae, Toona, Cerasus, Zizyphus, Acer truncatum, Prunus salicina, Malus pumila and Morus alba the allelopathy showed dual effects promoting in low concentration(≥0.02g/mL)and inhibiting in high one(<0.02g/mL)in seedling growth stage. Eucommia showed significant inhibition on wheat seedling height, root length and three biochemical indicators.(2) Prunus armeniaca, Zizyphus and Cerasus 0.005g/mL ~ 0.1g/mL concentration of litter extract have varying degrees of inhibition on seed germination. Water extract of Cerasus litter at 0.1g/mL has the most significant inhibitory effect on rape. Ejuglans, Pyrus, Prunus salicina, Malus pumila, Prunus persica, Paulownia, Morus alba, Ebenaceae and Eucommia showed dual effects promoting in low concentration(≥0.02g/mL)and inhibiting in high one(<0.02g/mL)in seedling growth stage. In the seedling growth stage, the effects of Pyrus, Prunus salicina, Malus pumila, Prunus persica, Paulownia, Morus, Ebenaceae and Eucommia on rape seedlings similar to the effect on seed germination. Most water extracts showed dual effects promoting in low concentration(≥0.02g/mL)and inhibiting in high one(<0.02g/mL). Treated by 0.005g/mL extracts the experimental values are higher than the control value. Prunus salicina significantly inhibited seedling growth of rape. Within the 0.005g/mL ~ 0.1g/mL, the inhibition gradually increased.(3) After treatment of leaf litter extract from Ejuglans, Zanthoxylum, Pyrus, Toona, Malus pumila, Morus, Acer truncatum and Prunus armeniaca at a low concentration (<0.02g/mL), seed germination of maize was enhanced. The high concentration(≥0.02g/mL) is opposite. Treated by 0.005g/mL extracts the experimental values are higher than the control value. Prunus salicina, Paulownia, Ebenaceae and Prunus persica litter extract in 0.005g/mL ~ 0.1g/mL concentration range inhibited the seed germination. The effect of Ejuglans, Zanthoxylum, Pyrus, Toona, Morus, Malus, Acer truncatum and Prunus armeniaca on the seedling growth is consistent with the effect of seed germination. Prunus salicina, Paulownia, Ebenaceae and Prunus persica litter extract showed dual effects promoting in low concentration(≥0.02g/mL)and inhibiting in high one(<0.02g/mL)in seedling growth stage. In seed germination and seedling growth stage, the effect of Eucommia basically showed inhibition, and inhibited slightly higher than the other species.(4) The seed germination and seedling growth was inhibited to varying degrees of leaf litter extract from Ejuglans, Tooan and Eucommia. With the extract concentration increased, the inhibitory effect of three extracts of soybean has enhanced. Eucommia has the most significant inhibition. By 0.1g/mL concentration of extract treatment, soybean can not be grown seedlings, growth stop at seed germination stage. The effect of Zanthoxylum, Malus pumila, Morus, Prunus armeniaca, Acer truncatum, Zizyphus and Cerasus showed dual effects promoting in low concentration(≥0.02g/mL)and inhibiting in high one(<0.02g/mL)on seed germination. When the concentration is 0.005g/mL, seed germination of soybean has weakly promoted. Zanthoxylum, Malus pumila, Morus, Prunus armeniaca, Acer truncatum, Zizyphus and Cerasus on the seedling growth is consistent with the effect of seed germination.