Research On Tobacco Growing Obstacle Factor And Countermeasures Under Years Of Tobacco-potato Crop Rotation In Tobacco-growing Area Of Hezhou

Tobacco-potato crop rotation was one of the main cropping patterns for Hezhou tobacco-growing area, it brought huge benefits for farmer’s income. But after years of crop rotation, the model brought about tobacco obstacle problem, which restricted the healthy sustainable development of tobacco seriously. In order to offer scientific basis and technical measures for solving the actual production problem of He Zhou, this paper aimed at the tobacco obstale problem, which came from tobacco-potato crop rotation for many years, disigned the pot experiments, field experiment and field sampling diagnoses to research the growing obstacle factors of tobacco and the countermeasures. The main results were shown as follows:(1) Growth of tobacco was restrained under the condition of tobacco-potato crop rotation, such as short plant, small stem girth, decreased leaf area, shallowed leaf colour, suffocated photosynthesis, bad root growth and decreased biomass. At the same time, soil microbe quantity declined, microbial activity and biomass C and N decreased, and the fungi/bacteria rised, the soil microbe changed from "bacteria type" to "fungi type" gradually.(2) Planting tobacco in sterilization soil could improve the growth of tobacco root, the photosynthesis and biomass. The effect of different sterilization measures was unlike, which showed that autoclaved sterilization>formalin sterilization>dikesong sterilization> basked soil. Autoclaved sterilization and formalin sterilization could increase soil microbe quantity, microbial activity, biomass C and N, and reduce fungi/bacteria, which closed to the soil of tobacco-rice crop rotation. It indicated that the reducing of soil microbe quantity and activity, the rising of fungi/bacteria were the important reasons of tobacco growing obstacle under years of tobacco-potato crop rotation.(3) Using pot experiment to study the eliminating of tobacco growing obstacle, the results showed that, strong seeding, applying organic fertilizer, microbial organic fertilizer could improve the growth of tobacco, such as Ph, chlorophyll content, root activity and biomass, and the microbe quantity in planting environment was also increased. Applying organic fertilizer enhanced the nutrient content in aerial part and soil microbe quantity, the effect on microbial organic fertilizer was most obvious.(4) The results of field experiment showed that applying microbial organic fertilizer of3750kg/hm2,7500kg/hm2and11250kg/hm2could enhance soil fertility, increase soil microbe quantity, microbial activity and biomass C and N of rhizosphere, then promote tobacco growth, and the growth increased with the increase of the microbial organic fertilizer. Applying sterilizing agent and microbial organic fertilizer could improve ecological environment of rhizosphere soil further, weaken or eliminate the influence of crop rotation on tobacco growth. The effect of different sterilizing agent was unlike, showed that sterilizing agent Ⅰ> sterilizing agent Ⅱ.In a word, the important tobacco growing obstacle factor of tobacco-potato crop rotation in Hezhou were the reducing of soil microbe quantity and activity, the rising of fungi/bacteria, applying sterilizing agent I and microbial organic fertilizer of7500kg/hm2was the effective countermeasure for eliminating tobacco growing obstacle.