Effects Of Adding Silicon On Banana Nitrogen Nutrition And Resistance To Fusarium Wilt

Banana,as an important economic fruit crop and crop in the world,was a major pillar industry in Hainan.Banana was an accumulation plant of silicon.The infection rate of banana Panama disease was related to nitrogen and silicon level.The absorption of nitrogen affected the absorption and distribution of silicon.In the acidic soil of Hainan,the available silicon level of the soil was low,developing the effects of applying silicon fertilizer at different nitrogen supply levels on the growth,nutrient absorption and disease resistance of different varieties of bananas had guiding significance for the rational application of silicon and nitrogen fertilizer and the stable development of bananas.In this paper,the effects of adding silicon on the growth,nitrogen metabolism and fusarium wilt resistance of different varieties of banana were studied by sand culture and soil culture respectively at 2 nitrogen levels.The main conclusions were as follows:1.In both sand culture medium and soil culture medium,addition of silicon significantly affected the absorption and distribution of biomass,nitrate nitrogen content,nitrogen,phosphorus and silicon nutrients of bananas.Response characteristics of different varieties were different.Under the two conditions,the biomass of banana root under the condition of high nitrogen supply level was lower than that under the condition of normal nitrogen supply level.Addition of silicon increased the nitrogen content of banana roots under normal nitrogen supply level,while the silicon supply level under high nitrogen level did not affect the absorption of phosphorus by banana roots.2.Under the condition of soil culture medium,the activity of polyphenol oxidase(PPO)and peroxidase(POD),the content of total phenol and lignin in banana leaves were related to the level of nitrogen and silicon supply and the quantity of pathogens in soil.With the addition of sterilized soil and the same nitrogen supply level,the leaf PPO activity of Brazil decreased significantly by 18%and 24%with the increase of silicon supply level.Under normal nitrogen supply level conditions(0.5g/kg).leaf POD activity of Brazil and Baodao increased significantly by 67%and 1.08 times with the increase of silicon supply level,while leaf PPO activity and POD activity of Red Banana did not change significantly between the two silicon supply levels.Compared with the addition of sterilized soil,the leaf PPO activity of Brazil was significantly decreased with the addition of unsterilized soil and the same nitrogen and silicon level,while the leaf PPO activity of Baodao was significantly increased,but the change oi Red Banana was not significant.The total phenol content in leaves of the three varieties bananas with high nitrogen supply level(1.0g/kg)increased by 15%,34%and 38%respectively with the silicon supply level increasing,and the change law was opposite after adding unsterilized soil.At the same nitrogen supply level,the cauloid lignin content of Red Banana increased significantly with the increase of silicon supply level,up to 24%and 34%,respectively.Under the condition of high nitrogen supply level(1.0g/kg),Brazil showed the same law with Red Banana.The cauloid lignin content of Baodao was significantly higher under the condition of adding unsterilized soil and normal nitrogen supply(0.5g/kg)than that under the condition of adding sterilized soil and the same silicon level,which were increased by 16%and 42%respectively.Under the condition of adding sterilized soil and high nitrogen supply(1.0g/kg),silicon increased the disease resistance of Brazil and Red Banana by increasing the content of pseudostem lignin and total phenol in leaves,and enhanced the disease resistance of Baodao by increasing the activity of leaf PPO and POD.3.Increasing the silicon supply level could reduce the number of fusarium oxysporum in the rhizosphere soil of bananas,and different varieties of bananas had different responses.Under the condition of normal nitrogen supply(0.5g/kg)and adding sterilized soil,the quantity of fusarium oxysporum in rhizosphere of Brazil and Baodao decreased by 89%and 95%with the increase of silicon supply level,and by 79%and 63%with the increase of silicon supply level under the condition of adding unsterilized soil.The number of fusarium oxysporum in the rhizosphere soil of Red Banana with high nitrogen supply(1.0g/kg)and unsterilized soil decreased by 56%with the increase of silicon supply level.4.Silicon and nitrogen supply levels and medium conditions affect banana's absorption and distribution of silicon and nitrogen.Under the condition of 200mg/L and 400mg/L nitrogen supply in sand culture and 0.5g/kg and 1.0g/kg nitrogen supply in soil culture,the biomass,silicon content and nitrogen content of the two media have significant differences between the silicon levels.In conclusion,under different nitrogen supply levels,silicon significantly affected the growth of bananas,the absorption and distribution of nitrogen and phosphorus and silicon nutrients,lignin content,total phenol content,polyphenol oxidase,peroxidase activity,the number of rhizosphere soil pathogens,and the response mechanism to silicon and disease resistance of different banana varieties were different.