Effect of adjusting flue-cured tobacco transplanting time on climate condition of different growth phases.

By setting different transplanting times,the author redistributed such climatic factors as light,temperature and water in tobacco growth period,so as to provide theoretical basis for analyzing the climate cause of strong-flavor tobacco leaves formation and determining suitable transplanting time. The results showed that: when the transplanting time delayed,the daily mean air temperature at the whole growth stage,root-extending stage,vigorous growing stage and mature stage showed increasing trend,and the daily air temperature range at the whole growth stage,vigorous growing stage and mature stage decreased gradually,while the daily air temperature range at the root-extending stage had no obvious changes. When flue-cured tobacco was transplanted in middle Henan province from April 28 to May 24,the daily mean air temperature in the whole growth period was 25. 0 ~ 26. 5 ℃,the active accumulated air temperature was 2249. 80 ~ 2581. 38 ℃ ·d,and the sunshine duration was enough. In the whole growth period of tobacco,the daily mean soil temperature gradually increased,the diurnal soil temperature range,the active accumulated soil temperature and effective accumulated soil temperature were significantly negatively related to the transplanting time,and the regulatory effect of the climate on the active accumulated soil temperature was maximum. Postponing the transplanting time significantly reduced the sunlight time and sunlight intensity in the whole tobacco growth period,and had very great influences on the air temperature and soil temperature at different growth stages of tobacco,which were ideal when the tobacco was transplanted from April 21 to May 12. Delaying the transplanting time had a great moderating effect on the required rainfall by tobacco production in the field,and the rainfalls in the treatments of transplanting on April 28 and May 5 were 428. 5 and 441. 2 mm respectively,which could basically meet the water demand of high-quality tobacco growth. According to the climate moderating effect of different transplanting times,it was more suitable for tobacco to transplant from April 28 to May 5,no later than May 12.