Effects Of Inter-relay Cropping Time With Sweet Potato On Tobacco Yield And Quality

The production of tobacco in Xiangxi mountainous area is restricted by one cropping per year systems. The flue-cured tobacco and sweet potato intercropping is a reasonable planting pattern, however, the intercropping time is not clear. The intercropping time was researched by field experiments in the article. The results are as follows:1. The production and income of sweet potato decreased when the intercropping time decreased. The production and income of sweet potato were highest in the treatment of intercropping at the 40th days after tobacco transplanting, they were 928.45kg/667m2 and 408.52 yuan/667m2 respectively. Correlation between sweet potato production and economic characters was not significant, but stem diameter and upper leaf width was significantly correlated with sweet potato production.2. Weight of single leaf, production and income of tobacco were highest in the treatment of intercropping at 40th days after tobacco transplanted. Average price and rate of first class of flue-cured tobacco were highest in the treatment of intercropping at 50th days after tobacco transplanted, they were respectively 14.36 yuan/kg and 38.04%.3. Total income (flue-cured tobacco income+sweet potato income) in different treatments is different. The highest of income was 2904.44 yuan/667m2 in the treatment of intercropping at 50th days after tobacco transplanted.4. Compared to tobacco monoculture, the width of upper and middle leaf, the length of lower leaf decreased in the intercropping treatments.5. The influence of different intercropping time on tobacco chemical components was different in different position. Total sugar and reducing sugar in middle leaf is higher than upper leaf. Total sugar and reducing sugar decreased with intercropping time decreased. The treatment of intercropping at 50th days after tobacco transplanting is best for higher total sugar and reducing sugar, lower total nitrogen and middle nicotine.