Study On The Growth And Physiology Characteristics Of Soybean Intercropped With Maize

In recent years, the development of urbanization and industrialization has drived farmers land area decreased, which has threatened food safety. In order to ensure the sustainable development of agriculture and food security, intercropping planting mode arouse people’s attention once again in our country. Compared with the monoculture, intercropping mode is more stable, more safety. To cultivate and screen crop varieties which is helpful for intercropping and establish the innovation of intercropping mode have very important significance for ensuring food ecurity. In this experiment,47 widely cultivated soybean varieties are selected as matetials.In the backgroup of soybean and corn intercropping, according to different corn planting density, I set different shading intensity. I use principal component analysis and cluster analysis to analysis related character.47 soybean varieties are needed to engage shade tolerance screening, shade tolerant varieties, sensitive varieties, intermediate type varieties are selected out. The selected soybean varieties,including SUXIE 1, AGS91 and JINDA 332 are used to furtherly study growth physiology and yield index under shading condition of different tolerance varieties in order to verify screening test results of different shade tolerant varieties and study the influence of soybean growth physiology and yield under the condition of soybean shading stress for exploring a way to identify the main morphological characteristics of shade tolerant soybean varieties, to provide a theoretical basis and technical support for high yield planting of soybeans and corn intercropping in the production practice. The experimental results showed that:1.The principal component analysis is used to analysis IR(response index) of fourteen traits and yield index,including plant height, seed number per plant, biomass per plant, economic factors, the number of pods per plant, seeds per pod, seed weight per plant, hundred kernel weight, bottom pod height, number of branches, number of main stem section, a seed pods, two seed pods, three seed pods, then I select the first six principal components whose cumulative contribution rate is more than 79.3% as major factor to describe soybean varieties’ biological traits; then I filer out the six key indicators, namely, plant height, seed number per plant, biomass per plant, economic factors, the number of pods per plant, seeds per pod in ord to cluster analysis,47 soybean varieties are divided into three categories:shade-tolerant varieties, sensitive varieties, intermediate varieties.The number of pods per plant, number of branches per plant, grain weight per plant, economic factors of shade-type varieties is higher under intercropping conditions; Pods per plant, grain weight per plant, biomass per plant and other indicators of sensitive varieties are lower under conditions of intercropping;The number of pods per plant, number of branches per plant, grain weight and other indicators of intermediate species under conditions of intercropping are lower, and they are largely affected by shading intensity2. Three different shade tolerance soybean varieties, each is elected as a representative to the next step of a test, the test results show that the effect on the morphology and yield of different tolerant varieties is different under the shade treatment.Under the shade treatment, the three soybean varieties’ plant height increase, dry matter accumulation, the number of branches, leaf area, yield of SUXIE 1 decrease with the increase of shading intensity in growth period. The changes of sensitive varieties AGS91 in each index is opposite of SUXIE 1. While the middle type variety JINDA 332 because of shading degree, influence on each index is not the same, all the indicators of intercropping treatment are better than monoculture, while under the high-intensity shade,all indicators of intercropping one treatment are worse than the contron group treatment.The results also indicate that flower and pod abscission rate of soybean is interrelated to varieties’ patience and planting density, under conditions of shading treatment, SUXIE 1’s flower and pods dropping rate is lower than monoculture, and sensitive cultivar AGS91’ s flower and pods dropping rate is significantly higher than that of monoculture, while the middle type variety JINDA 332’s flower and pods dropping rate is the highest, the intercropping two treatment’ flower and pods dropping rate is lower than that of the control group, and the intercropping one treatment’s flower and pods dropping rate is significantly higher than that of monoculture. Among the different varieties, shade tolerant soybeans have lower plant height, more branch number, smaller leaf area, more biomass accumulation in growth period, compact plant type, earlier blossom podding time, low flower and pod shedding rate. For the yield component factors, shade tolerant soybean’ pod number per plant is not dominant, but grain plump is big,100 seed weight is higher, flower and pods dropping rate is low.3. Shading, significantly increases the content of MDA and H2O2, production rate of O2- in soybean leaves, then increases peroxidation of cell membrane, and the change trend of different tolerance varieties is not the same. Compared with monocropping, the MDA and ROS from SUXIE l’s leaf of intercropping treatment of shade tolerant cultivars increase a little, sensitive varieties increase a lot, facing strong shading effect, intermediate variety -JINDA 332, increase a lot and facing the slight shading, increase a little margin. Shading stress stimulates antioxidant system, makes the activity of SOD, POD and CAT increase in leaves of soybeans increase largely compared with monoculture, the content of antioxidant ASA and GSH increase significantly. Soluble protein content of shade tolerant varieties of SUXIE 1, with the stress level increasing, there is a downward trend.