Effects of Adjusting Transplanting Dates on Climatic Indices of Growth Stages of Burley Tobacco in Dazhou

Climatic indices of growth stages of burley tobacco in Dazhou were investigated by adjusting transplanting dates. The results showed that delaying transplanting dates could reduce the time of root elongation and maturity, increase the days of vigorous growth stage. The change in transplanting time had the greatest impact on air temperature, followed by soil moisture, humidity, sunshine and the average number of sunshine hours. The effect of transplanting dates on precipitation was not consistent. The air temperature indices, including daily average temperature, accumulated temperature, effective temperature, and sunshine hours, all increased gradually in the vigorous growth stage, and increased first and then decreased in maturity stage with postponement of transplanting dates. Average temperature and effective temperature gradually increased with postponement of transplanting dates in the whole growth period. Accumulated temperature, sunshine hours and soil moisture decreased first and then increased in root elongation growth stage.