Effects of intercropping on growth, nutrient uptake and rhizosphere environment in plants.

A greenhouse potted experiment was conducted to investigate the interspecific rhizosphere effects on iron(Fe),phosphorus(P),nitrogen(N),potassium(K),calcium(C),zinc(Z),and manganese(Mn)in capsicum(Capsicum annuum var.longunt) plants by intercropping them with maize(Zea mays L.).In addition,we studied plants growth character,the release of phytosiderophores and the ferric reductase activity of roots,pH and acid phosphatases activity in the rhizosphere and bulk soil,the secretion of acid phosphatases in roots,and the available N,P,K contents of rhizosphere soil.The results showed that shoot dry weight of capsicum plants intercropped with maize were decreased by 23.0%,root dry weight were increased by 44.2%;the dry weight of maize shoot and root were increased by 8.7%,22.9% respectively,as compared to monoculture plants.Growing capsicum plants in a mixture with maize,there were 86.4% and 29.8% increase in the ratio of root to shoot and root activities of capsicum respectively;In the case of maize,the ratio of root to shoot and root activities were not significantly affected by intercropping with capsicum.The chlorophyll contents of both capsicum and maize were also increased significantly by intercropping.The concentrations of Fe,Zn and Mn in intercropped capsicum increased by 1.50 fold,1.39 fold and 1.34%,respectively.While the concentrations of Fe,Zn and Mn in maize plants were not significantly affected by intercropping with capsicum.As far as the Ca concentrations of capsicum and maize plants were concerned,monoculture culture exceeded intercropping.Intercropping also improved significantly the K and P concentrations of capsicum and maize,while N concentrations of capsicum and maize were little affected by intercropping.In the intercropping of capsicum/maize,the acid phosphatase activities of the rhizosphere and bulk soil and root secreted acid phosphatase were significantly higher than that of monoculture capsicum and maize.In accordance,the P concentrations of capsicum and maize plants were much higher when they were intercropped with capsicum or maize,respectively.The rhizosphere and bulk soil pH values were not clearly affected by different cropping systems.As compared to their monoculture treatments,the secretion of phytosiderophore from maize roots decreased by 32.8%,but there was no significant difference between two treatments;the ferric reducing capacity of capsicum roots increased by 1.10 fold by the intercropping.The results indicate capsicum/maize intercropping pattern is a promising management practice,contributes to better nutrition of plants with Fe,Zn,P and K,most probably by affecting biological properties and chemical process in the rhizosphere.