Field Configuration Technology Of Intercropping Between Flue-cured Tobacco And Vegetable Soybean And Its Effects On The Yield,the Quality And The Occurrence Of Diseases And Pests

Flue-cured tobacco is one of the most important cash crops in China, and it has become a primary route of increasing farmers’income in Liangshan Prefecture. In Recent years, with the development of sole cropping and uniform variety cropping from flue-cured tobacco plantation area, the obstacles from continuous tobacco cropping became more and more grave, and use efficiency of arable land continued to decline, the yield and quality of flue-cured tobacco decreased, the biodiversity went down in the field, the diseases and pests take place frequently, the economic benefit from planting flue-cured tobacco fallen, then affected the sustainable development of tobacco industry. To overcome obstacles from continuous tobacco cropping, preserve the ecological environment, raise the plant areas of food and cash crops and achieve the sustainable development of tobacco and soybean industry, the vegetable soybean was interplanted on tobacco ridge under the premise of no change to the existing flue-cured tobacco cultivation techniques, and these research theory and technique including crop cultivation, soil fertilizer science, phytophysiology and plant protection were used to study the field configuration technology of intercropping between flue-cured tobacco and vegetable soybean and its effects on the yield, the quality and the occurrence of diseases and pests. At the same time, the action of microorganism under the intercropping system between flue-cured tobacco and vegetable soybean were clarified, and a high-yield cultivation configuration technology of relay intercropping of flue-cured tobaccos and vegetable soybean was initially formed in this paper. The main research results were as follows:1. Field Configuration Technology of Flue-cured Tobacco and Vegetable Soybean Intercropping.In the mode of the intercropping between flue-cured tobacco and vegetable soybean, the yields of early and medium-mature vegetable soybeans were slightly low, while the yields of Tiefeng 29 and screw soybeans with late-mature properties were relatively high. The performance of Tiefeng 29 in the sowing dates in two experimental years of 2011-2013 was the most stable, and had significantly difference compared with other varieties. With the delay of sowing date, the growth period of vegetable soybean was markedly shortened, so the number of main stem sections reduced, the plant height lowered, and the diameter of stem and number of effective branches first increased but later decreased; At the same time, the total number of pods in a single plant, the number of effective pods, the fresh weight of 100 pods, the yield of fresh pod, the total number of particles in a single plant, the fresh weight of 100 particles, the yield of fresh particle and other yield traits showed a law of first increase and later decrease, and the best results were achieved in B3 sowing date. The effects of different varieties of vegetable soybean and planting dates on the plant height, the stem circumference, and the number of effective leaves, the leaf length, the leaf width, the maximum leaf area and other major agronomic traits of flue-cured tobacco was relatively small. However, the indicators such as weight of single flue-cured tobacco leaf, yield, output value, average price and ratio of middle and upper-level tobacco leaves showed a trend of first increase and later decrease with the delay of sowing date of vegetable soybean. The matching result of sowing date and variety showed that A6B3 (Tiefeng29, planting when first picking the lower leaves of flue-cured tobacco) was the best, and the yields of fresh pods and fresh particles were respectively up to 10280.79kg/hm2 and 5431.92 kg/hm2. Meanwhile, under this combination, the growth of flue-cured tobacco plant was good and the agronomic indicators were reasonable and balanced, so the optimal output value of flue-cured tobacco was obtained.With the increase of planting density, the plant height of soybean significantly increased, the stem diameter reduced, the nodes number of main stem almost remained, the number of effective branches significantly decreased, and the quantity of dry matter accumulation of overground part significantly decreased. The total number of pods in a single plant, the number of effective pods, the fresh weight of 100 pods, the total number of particles in a single plant and the weight of 100 particles decreased, while the yields of fresh pods and particles first increased and later decreased, and the treatment of 225.000 plants per hm was the best. Under different plant-row spacing, with the decrease of row spacing, the plant height and the diameter stem of soybean increased, the number of main stem sections remained, the number of effective branches decreased, and the dry matter accumulation quantity of overground part increased. The total number of pods in a single plant, the number of effective pods, the fresh weight of 100 pods, the total number of particles in a single plant, the weight of 100 particles and the yield of fresh particles increased. The treatment with 22cm of row spacing was the best, followed by the row spacing of 27.5cm, with insignificant difference, while the difference with the row spacing of 55.0cm was evident compared with 22cm and 27.5cm of row spacing respectively. Among the combinations of density and plant-row spacing allocation, A2B3 (density of 225,000 plants per hm, with 22.0cm of row spacing) was the best, had significant difference compared with other combinations.The effects of planting density and plant-row spacing of soybean on the plant height, the stem circumference, the number of effective leaves, the leaf length, the leaf width, the maximum leaf area, the weight of single leaf, the yield and other indicators of flue-cured tobacco was relatively small, but the ratio of high-mid grade leaves of flue-cured tobacco was increased to a certain extent. The A2B3 was the greatest.In summary, the treatment with the density of 225,000 plants per hm2 and row spacing of 22.0 cm was more conducive to optimizing the population structure of vegetable soybean as well as promoting the quality improvement of flue-cured tobacco, so it could be further applied.Moreover, the interaction experiment of different varieties of flue-cured tobacco and different varieties of vegetable soybeans showed that, the effects of different varieties of flue-cured tobacco on the growth of vegetable soybean was relatively small, and the differences among the three flue-cured tobacco varieties widely used in local areas were not at the significant level.2. Effects of Flue-cured Tobacco and Vegetable Soybean Intercropping on the Occurrence of Diseases and Pests.Compared with single planting, in the periods of picking tobacco leaves and main growth period of vegetable soybean, the quantities of bacteria and actinomycetes in rhizosphere soil under tobacco and soybean intercropping significantly increased, but the fungus quantity decreased, and the overall performance of quantity was bacteria> actinomycetes>fungus. With the increase of intercropping years, the quantities of bacteria and actinomycetes increased, while the quantity of fungus decreased, and the occurrence of main soil-borne diseases reduced, such as tobacco bacterial wilt, tobacco black root rot, tobacco black shank and soybean root rot. Canonical correlation analysis showed that within a certain range, the occurrence degree of tobacco bacterial wilt and tobacco black root rot reduced with the increase of bacteria quantity in the rhizosphere soil of flue-cured tobacco, and the occurrence of tobacco black shank dropped off with the increase of actinomycetes quantity. In addition, simple correlation analysis showed that the occurrence degree of soybean root rot was in significant negative correlation with quantity of actinomycetes, B/F value and A/F value.Compared to single planting, the quantities of bacteria and actinomycetes on phyllosphere under tobacco and soybean intercropping markedly increased, the fungus quantity decreased and the overall quantity performance was bacteria>fungus> actinomycetes. With the increase of intercropping years, the quantities of bacteria and actinomycetes went up, while the fungus quantity fallen down, and the occurrence degree of diseases such as tobacco brown spot, tobacco mosaic virus and tobacco powdery mildew, and soybean anthracnose, soybean powdery mildew, soybean frogeye leaf spot and soybean mosaic virus were alleviated, but there were no significant changes in tobacco wildfire disease and tobacco weather fleck.The canonical correlation analysis between leaf disease and phyllospere microorganism showed the occurrence of tobacco brown spot reduced with the quantity-increase of actinomycetes, bacteria and total quantity of three kinds of microorganisms on phyllospere, and the occurrence of tobacco powdery mildew reduced with the decrease of fungus quantity; the anthrax disease and the mosaic virus occurring on soybean reduced with the quantity increase of bacteria and total quantity of three kinds of microorganisms; the occurrence degree of soybean frogeye leaf spot and soybean powdery mildew went down with the quantity increase of actinomycetes and A/F value.Compared with single planting, the proportion of phytophagous arthropod in the intercropping area reduced, and the types, the individuals’number and the ratio of natural enemies, the species richness, the community diversity, the community evenness significantly increased, while the community dominant concentration index reduced, indicating that the communities in the intercropping area were relatively stable. The increase of intercropping years helps to increase the species richness, the diversity, the stability and the evenness of community, and decrease the dominance and dominant concentration of pest sub-community. The change in A3 (flue-cured tobacco relay strip intercropping with soybean for three years) was the largest, indicating that the increase of intercropping years was more conductive to balance of species and stability of community structure, as well as reduction in the damage of pest to tobacco.3. Effects of Flue-cured Tobacco and Vegetable Soybean Intercropping on the Quality of Flue-cured Tobacco.The quantities of ammonifier, nitrobacteria, nitrite bacteria and free-living nitrogen fixing bacteria raised largely, while the number of the denitrifying bacteria declined compared with those in case of single planting, and the change magnitude was larger with the increase of intercropping years, indicating that the tobacco/soybean relay strip intercropping systems had increased the nitrogen utilization of tobacco. Meanwhile, the tobacco/soybean relay strip intercropping significantly increased the contents of organic matters, total potassium and available potassium, reduced the contents of total nitrogen, available nitrogen, total phosphorus and available phosphorus in soil. The increase of intercropping years had no significant influence on the contents of total nitrogen and total phosphorus as well as pH value, but it increased the contents of total potassium and available potassium to some extent, reduced the content of available nitrogen, and slowed down the decline rate of available phosphorus.Tobacco and soybean intercropping had no significant influence on nitrogen/nicotine ratio of the flue-cured tobacco leaves, but it could significantly increase the contents of total sugar, reducing sugar and potassium, increase the ratio of sugar/nicotine and potassium/chlorine, reduce the contents of total nitrogen, total alkali and chlorine, and balance the tobacco quality. When the intercropping years increased, the above effects were more significant. The overall performance was A3 (flue-cured tobacco relay strip intercropping with soybean for three years)>A2(flue-cured tobacco relay strip intercropping with soybean for two years)>A1 (flue-cured tobacco relay strip intercropping with soybean for one year). The A3 on the quality of flue-cured tobacco was the most significant.Though mutual canonical correlation analysis of functional microorganism related to nitrogen metabolism in rhizosphere soil, soil nutrients and flue-cured quality, the results showed that, within a certain range, the contents of available phosphorus, available potassium and total potassium increased with the decrease of quantities of denitrifying bacteria and nitrobacteria in soil, while the content of organic matters and the pH value increased with the increase of quantities of ammonifier and free-living nitrogen fixing bacteria. The contents of total alkali and chlorine in flue-cured tobacco leaves reduced with the increase of contents of organic matters, total potassium and available potassium; the ratio of nitrogen/nicotine decreased with the increase of contents of total phosphorus and available phosphorus in soil; the content of reducing sugar decreased with the increase of pH value; the content of potassium increased with the increase of total potassium; the content of total sugar increased with the increase of quantities of ammonifier and nitrite bacteria; the potassium/chlorine ratio in flue-cured tobacco leaves reduced with the increase of quantity of free living fixed nitrogen.