Screening And Application Techniques Of Controlled-release Fertilizers For Floating Tobacco Seedlings

Floating seedling breeding is the main method for breeding flue-cured tobacco in China.It has always used floating liquid fertilization.However,this method has many disadvantages such as frequent application of fertilizers,irregular nutrient supply,low fertilizer utilization rate,and environmental pollution.In this study,the controlled release fertilizers in tobacco floating seedlings are screened,and the amount of fertilizers and the height of fertilization are set.The effects of the treatments on the emergence rate of tobacco,the agronomic traits of tobacco seedlings,the seedling tobacco seedlings CAT(catalase),and SOD are investigated.The effect of(superoxide dismutase)activity provides theory and practice for the development and application of tobacco floating seedling controlled-release fertilizer technology.The test results are as follows:(1)When the controlled release time is 6 months,the application rate is 0.3~0.5 g/hole,and the application rate is 2~3 cm above the bottom of the hole,the seedling emergence rate of the tobacco seedlings is better than the conventional nutrient solution treatment,and the emergence rate reaches 90%.The controlled-release fertilizer with a controlled release time of 3 months is significantly different from the controlled-release fertilizer with a controlled release time of 4 months and 6 months.Its seedling emergence rate is less than 50%,which is not conducive to the emergence of floating seedling tobacco seeds.The controlled-release fertilizer with a controlled release time of 4 months has less than 90% of the emergence rate of tobacco seedlings,which is not enough for production.(2)With controlled-release time of 4 months and 6 months of controlled-release fertilizer,tobacco seedlings are better than nutrient solutions in agronomic traits such as maximum leaf area,plant height,and stem diameter.The agronomy traits of the tobacco seedlings with controlled release time of 6 months and 0.3 g/hole are inferior to those of the conventional nutrient solution treatment,indicating that the supply of nutrients in the later period is insufficient to meet the normal growth of tobacco seedlings.When the amount of fertilizer is 0.5 g/hole,the agronomic traits of tobacco seedlings are better than those of nutrient solutions.(3)The effect of controlled-release fertilizer treatment on the root system of tobacco seedlings at 4 and 6 months of controlled release time is significantly different from that of conventional nutrient solution treatment.The root condition of controlled-release fertilizer treatment is better than that of conventional nutrient solution treatment.The release of fertilizers promote the growth of tobacco seedling roots;controlled-release time of 4 months controlled-release fertilizer has a better effect on the roots of tobacco seedlings than 6 months.(4)The controlled release fertilizer has a higher CAT and SOD activity than the nutrient solution for 6 months.When the fertilization height is 2~3 cm,the CAT and SOD activities of tobacco seedlings are 0.7 g/point>0.5 g/point>0.3 g/point,and the CAT and SOD activities in 0.5 g/point are compared with the conventional nutrient solution.The difference is not significant.(5)The release curve of nitrogen,phosphorus,and potassium in controlled-release fertilizers in still water and in floating plates show an "S" pattern overall.The initial release is relatively slow,the release in the medium term is faster,and the release is slowest in the later period.The release rates of nitrogen,phosphorus and potassium from three controlled-release fertilizers show a release time of 3 months> 4 mo nths> 6 months.The release rates of nitrogen,phosphorus,and potassium in controlled-release fertilizers at controlled release time of 3 months and 4 months are higher than those of 6-month controlled-release fertilizers,and the rapid release rate is the main reason that affected the emergence rate of tobacco seeds.The seedling emergence rate,agronomic traits,root conditions,and CAT and SOD activities are comprehensively considered: Controlled release fertilizers with controlled release time of 6 months,0.5 g/point for fertilization,and 2~3 cm for fertilizer treatment.The indicators are better than the nutrient solution treatment,can meet the nutrients required for the normal growth of tobacco seedlings,and promote the growth of tobacco seedlings,and can replace the conventional nutrient solution as nutrient supplying fertilizer for floating flotation of tobacco.