The Research Of Floating Seedling Technology In Shandong Tobacco Area

The tobacco root system was seriously damaged during the heel-in process of the two-stage culture of tobacco seedlings in tobacco planting regions of Shandong .When using the two-stage culture method of seedlings, the recovering stage of tobacco seedlings was very long, and the whole operating process was complicated. This method needed lots of labor and time, and the tobacco seedlings were susceptible to infect various disease, and thus this method was not feasible to cultivate high quality and healthy tobacco seedlings. In this paper, we used the tobacco as experimental material and the floating culture of seedlings were carried out with the two-stage culture of seedlings as control. In the floating culture of seedlings, we specially studied the effects of nutrient solutions with different nutrition composition and different seedling-growing base materials on the quality of tobacco seedlings from floating culture system. Moreover, we also studied the algae control technique and free clipping technology of tobacco leaves in the floating culture of tobacco seedlings. We hoped that this study would provide some ideas for the extend of floating culture of tobacco seedlings, and for the establishment of high-efficiency floating culture technology system of tobacco seedlings in tobacco planting regions of Shandong. The results of this study were as follows:1. The emergence of seedlings was late in floating culture of tobacco seedlings, and the seedlings growed slowly at the early seedling-bed stage, but growed fast at late seedling-bed stage. The tobacco was sowed on February 25th, and the emergence of seedlings in floating culture was delayed about 5 days compared to the two-stage culture, and the date into the Grand Cross was delayed about 7 days. However, the seedlings from the two-stage culture started to be transplanted since the Grand Cross stage. During the heel-in process, the roots of tobacco were seriously damaged, and thus the seedlings grew slowly which needed a short recovering-seedling stage. In contrast, the water temperature in floating culture started to increase, and the water and fertilizer were complemented in time, and the seedlings from floating culture growed rapidly, which resulted in no difference of final seedlings between the two-stage culture and floating culture. The seedlings from floating culture were better than that from two-stage culture in many growth indexes and physiological characteristics.2. Regarding the actual situation of Shandong, many experiments were performed. Through multiple comparisons, we found that the suitable base material was cotton seed shell / mushroom substrate + fine sand + sterile soil, the suitable nutrient solution (N: P: K = 20:10:20), and the suitable nitrogen concentration of 150 mg/kg.3. The effects of various chemicals on algaecide and the emergence of tobacco seedlings were evaluated comprehensively. The copper sulfate, thiophanate-methyl, and hymexazol were thought to be the effective algaecide chemicals in the seedling-bed.4. Sprayings of different types and different doses of chemicals on tobacco and general leaf-cutting acclimatization were done and compared. We found that paclobutrazol 15% wp had the best control effect on tobacco seedlings, and especially when the paclobutrazol was diluted to 2000-3000 times to spray. The inhibitory effect of paclobutrazol on tobacco was short (~30 days), so we could spray it ahead of 30 days before transplanting, which could prevent the excessive growth of tobacco and thus get the strong and healthy seedlings.