Current And Residual Effects Of Mg, Cl And B And Their Interactions On Flue-cured Tobacco Growth And Soil Nutrient In The Tobacco-rice Continuous Cropping System Of South Anhui Province

More than90%of the flue-cured tobacco was growing in the paddy field of South Anhui (Chizhou) Province. As a crop which should be paid equal attention to yield and quality, the soil nutrient was directly related to the yield and quality of flue-cured tobacco. While they were a wide range of antagonistic and synergistic effect between some elements in soil nutrient. Current and residual effects of Mg, Cl and B and their interactions on flue-cured tobacco physiological characteristics, main agronomic characteristics, dry matter accumulation, economic characteristics and quality, on rice yield and dry matter accumulation, and on the change of soil nutrient was studied by Yunyan87and Jinchou148, through two years’pot experiment. Simultaneously, current effects of Mg, Cl and B and their interactions on flue-cured tobacco main agronomic characteristics, economic characteristics and quality was studied by Yunyan87too, through one year’field experiment. The results were as follows:(1) The pot experiment showed that when B applied-alone increased tobacco output value significantly than Mg or Cl applied-alone, and the effects could be extended to the following year. Mg applied-alone also had positive effects. But both current and residual effects of Cl applied-alone on output value were not significant, whether applied Cl should be decided on soil Cl content and element interactions. If Mg, Cl and B combined application, they had different effects on flue-cured tobacco, current and residual effects were different too.1:1.51was optimal ratio for Mg and Cl, which promoted tobacco absorption of Mg and Cl, and could promote tobacco growth especially in the current year, stimulated significantly the growth of middle leaves (length×width) and output value, which could get46084.11yuan·hm-2. When Mg and B applied-together on the ration of1:0.08, the uptake of Mg in tobacco was increased, but it suppressed the absorption of B, it promoted the tobacco growth, had a trend of increasing the tobacco yield and output value in the current year, and also had positive residual effects which increased significantly tobacco output value, which could get44192.37yuan-hm"2. When Cl and B applied-together on the ration of1:0.05, it promoted tobacco absorption of B, restrained tobacco growth in current year, but residual effects promoted tobacco growth, increased output value to some extent.(2) The pot experiment showed that there was no obvious rule for the content of total N, total P, nicotine, total sugar and reducing sugar in tobacco leaves affected by the different combination of Mg, Cl and B. The current and residual effects of Mg and B had positive effects on the tobacco sensory qualities, while the effect of Cl was worse. When Mg and B applied-together the overall sensory qualities of tobacco was better, But when Cl, B used together or Mg, Cl and B used together, the overall sensory qualities of tobacco performed poor.(3) The pot experiment showed different combinations of Mg, Cl, B had significant effects on rice seed setting rate,1000-grain weight and yield. When Mg and Cl applied-together the yield of the rice was lowest in2010, significantly lower than other treatments except the combination of all the Mg, Cl and B. In2011, the residual effects of Mg, Cl and B to rice were strongly weakened, significant effect only to1000-grain weight, and its effect to yield was not significant.(4) The pot experiment showed that in the current year, the interaction between Mg and B affected the content of available N in soil significantly. When no fertilization of Mg (or B) applied B (Mg), the content of available N in soil increased, but when Mg and B used together, the situation was contrary. The application of Cl relatively decreased the content of soil available P. Through the continuous cropping of tobacco-rice in2010, the content of soil exchangeable Mg increased, the content of available Cl decreased a lot, and available B decreased too. After cultivated flue-cured tobacco of2011, the effects of Mg, Cl, B and their interactions to the available N and available P of soil was not significant, but Mg showed a trend of increasing the content of soil available K.(5) The field experiment showed that B applied-alone had positive effect on output value of flue-cured tobacco. Mg and B applied-together could promote tobacco growth, getting highest output value, significantly higher than that of Mg, Cl and B applied-together. There was no obvious rule for the content of total N, total P, nicotine, total sugar, reducing sugar and Ca in tobacco leaves affected by the different combination of Mg, Cl and B. The sensory qualities of tobacco basically performed the same with pot experiment. In conclusion, we found current and residual effects of Mg, Cl and B and their interactions on. flue-cured tobacco were different. When Mg and B applied-alone, the effects was obvious. The performance of Mg and B applied-together on the ration of1:0.08was best, while C1and B applied-together on the ration of1:0.05was worst. Therefore reasonable fertilization should consider the condition of soil nutrient, nutrient type, composite ratio, the interactions and residual effects.