Effect of global warming on climate feasibility index and available field days of flue-cured tobacco

In order to study the effects of global warming on the adaptability of flue-cured tobacco and available field days in Bijie tobacco-growing region, climate date for 1971?2010 in Bijie tobacco-growing region were used to analyze the trend and characteristics of climate change in the last 40 years. The analysis determined climate feasibility index (CFI) of flue-cured tobacco, the relationship between available field days and temperature and the trends of change in these factors. The results showed that average annual temperature in Bijie tobacco-growing region steadily increased at 0.38 ℃ 10a^-1. The average annual rainfall in the last 40 years in Bijie tobacco-growing region was 1 047.78 mm, with 527.03 mm during tobacco growing period. Average annual sunshine duration in Bijie tobacco-growing region in the last 40 years was 1 318.20 h, with 632.70 h during tobacco-growing period. Sunshine duration gradually decreased during 1971-2010 in Bijie tobacco-growing region due to global warming. CFI increased gradually from 1970 to 2010, with a average annual CFI of 0.62. The start of period with average daily temperature ≥13 ℃ occurred early by about 30 d (average of 7.5 d 10a^-1) during the 40 years. Then the end day of period with average daily temperature ≥18 ℃ (which is the harvest stage of flue-cured tobacco) delayed by about 27 d (average of 6.75 d 10a^-1) after 40 years of global warming. The trend in flue-cured tobacco available field days in the last 40 years steadily increased by 58 d (an increase of 14.5 d 10a^-1) with increasing annual average temperature. Although global warming reduced rainfall and shortened the sunshine duration in Bijie tobacco-growing region, CFI of flue-cured tobacco increased. This was conducive for the proper growth of flue-cured tobacco due to increasing available field days in the Bijie tobacco-growing region.