The Study On The Comprehensive Effect Of The Rice Intercropping With Canna Indica L. And Pontederia Cordata L. Respectively

A rational intercropping could improve the biodiversity in eco-agricultural system,reduce the diseases and pests and improve the rice yield,which has obviously ecological dominance and yield advantages.For now,the domestic and abroad researches on the paddy field intercropping systems are mostly found in China,and those always focus on the researches about the rice-upland crop intercropping.The researches under the paddy field mainly concentrated on the rice-aquatic vegetable intercropping.This paper introduced the aquatic flowers--the Canna indica L.and the Pontederia cordata L.to the paddy field in South China.It started as two different models that was the rice-Canna indica L.intercropping and the rice-Pontederia cordata L.intercropping during the early and late seasons of rice in 2016 and 2017.The experiment set five treatments including the monoculture of rice（CK）,the monoculture of the Canna indica L.（CM）,the monoculture of the Pontederia cordata L.（PM）,the intercropping of the rice-Canna indica L.（RC）,the intercropping of the rice-Pontederia cordata L.（RP）,and each treatment repeated three replicates.Besides,through the laboratory simulation of Cadmium pollution,we studied the effect of different concentrations of Cadmium on the rice-aquatic flowers intercropping.This experiment set five treatments as same treatments as the paddy field experiment,and the input concentration were 0,1,10 and 25 mg·kg^-1.We studied the effects of rice-Canna indica L.and rice-Pontederia cordata L.intercropping on the paddy field microclimate,the controlling of the diseases and pests,the restoration of heavy metal pollution in paddy field and the economical and ecological benefits.The results are showed as follows:1.Compared with the rice monoculture,the rice tiller number,the leaf chlorophyll content,the effective spike number and the yield of the rice-Canna indica L.intercropping and the rice-Pontederia cordata L.intercropping were significantly higher.Under the intercropping pattern,the rice tiller number,the leaf chlorophyll content,the effective spike number and the yield of the outside rows achieved significantly higher than those of the inside rows.The main reason of the yield promotion came from the increasing the yield of outside rows by increasing the effective spike number.During the four seasons’experiments,compared with the monoculture of rice,the per unit yield of the rice-Canna indica L.intercropping and the rice-Pontederia cordata L.intercropping was improved 28.98%and19.78%respectively.The land equivalent ratio of the intercropping was larger than 1,indicates that there was yield advantage in these two intercropping patterns.2.There were controlling effect on the incidence of the rice leaf folder and the sheath blight under the rice-Canna indica L.intercropping and the rice-Pontederia cordata L.intercropping.The rate of the rolling-leaf by the rice leaf folders was decreased significantly by 60.31%and 34.24%respectively,and disease index of rice sheath blight was decreased significantly by 44.03%and 46.18%.In the two intercropping systems,the rate of the rolling-leaf by the rice leaf folders and the disease index of rice sheath blight of outside rows were significantly lower than those of the inside rows.3.The investigation of the field microclimate at rice tillering stage and heading stage showed that field temperature and its difference under the rice-Canna indica L.intercropping and the rice-Pontederia cordata L.intercropping was higher than those under the rice monoculture.The relative air humidity in the group in the two intercropping system was lower than that in the monoculture of rice.The illumination intensity in the two intercropping patterns was higher than that in the rice monoculture.The two intercropping systems promoted the temperature of the rice canopy and the illumination intensity in the paddy field under some conditions,while reduced the relative air humidity,which were beneficial for the rice yield promotion and the controlling of the diseases and pests.4.Under the rice-Canna indica L.intercropping and the rice-Pontederia cordata L.intercropping,the brown rice rate,the white rice rate,the whole white rice rate,the length-width ratio,the TBN and the amylase content were basically higher than those in the rice monoculture.Compared with the monoculture,the brown rice rate and the whole white rice rate showed significant differences.The chalky rice rate under the two intercropping patterns was significantly lower than that in the rice monoculture.The length-width ratio and the TBN under the rice-Canna indica L.intercropping were significantly higher than those in the rice monoculture.It showed that rice quality of the two intercropping patterns was better than that in the monoculture to some extent.5.Compared with rice monoculture,the economic benefit of the rice-Canna indica L.intercropping and the rice-Pontederia cordata L.intercropping was higher.Though the money investment of purchasing the seeding of the Canna indica L.and Pontederia cordata L.was larger,the income of the two intercropping patterns was promoted by 17525.06yuan·hm^-2and 15657.30 yuan·hm^-2respectively.It showed that the intercropping patterns could bring more economic benefits.6.Studies on the rice-Canna indica L.intercropping and the rice-Pontederia cordata L.intercropping under different cadmium pollution indicated that,the distribution of cadmium content in rice plant is:root>stem>leaf>ear,the distribution pattern of cadmium in Canna indica L.and Pontederia cordata L.was as follows:root>stem>leaf,and all organs gradually increased with the increase of cadmium concentration.At the same cadmium concentration,the cadmium content in the two intercropping pattern was all lower than those in the rice monoculture,the height and tiller of rice plant were higher than those in rice monoculture,The above results indicated that intercropping can reduce the adsorption of cadmium by rice and promote the rice growth especially under the intercropping system of rice-Pontederia cordata L.The enrichment factor and the transfer coefficient result indicated that Canna indica L.and Pontederia cordata L.could enrich cadmium with certain concentrations;Canna indica L.is more capable of transferring cadmium to the ground than Pontederia cordata L.Under the current low concentration of farmland cadmium pollution,the rice-Canna indica L.intercropping and the rice-Pontederia cordata L.intercropping has a certain promotion value for agriculture practice.In summary,the rice-Canna indica L.intercropping and the rice-Pontederia cordata L.intercropping have a high comprehensive benefits.