Research On Nitrogen Fertilizer Replacement And Reduction Technology Of Cherry Tomato

Cherry tomato（Lycopersicon esculentum var.cerasiforme）is both a fruit and a vegetable.It is the main vegetable variety grown in winter in southern provinces（regions）such as Hainan and Guangxi,and is one of the main economic incomes of local farmers.Nitrogen is the most important limiting factor for crop growth and yield enhancement.However,in production practice,the excessive application of nitrogen fertilizer by farmers is prominent,which leads to adverse effects such as low fertilizer utilization rate,decline in yield and quality,soil compaction,and deterioration of agricultural ecological environment.To this end,this paper firstly studies the dry matter accumulation and nutrient requirements of cherry tomato,obtains the optimal fertilization method,obtains the conventional fertilization amount and the optimal fertilization amount through investigation and literature review,and finally obtains the constant phosphorus and potassium when the phosphorus and potassium remain unchanged.Under the premise,different ratios of organic fertilizers to replace chemical fertilizer nitrogen were set,and the effects on crop growth and development,yield and quality were analyzed.The research results are as follows:1.Using the grafted plant of Lefen No.3,which is mainly promoted in Tianyang District,as the material,the accumulation and distribution of dry matter in each organ at different growth stages were analyzed.The growth rate was relatively stable until the seedling stage;the maximum growth rate of dry matter mass per stem was significantly greater than that of roots and leaves,which determined the maximum growth rate of dry matter mass of the whole plant.Leaf dry matter transport rate;from the early fruiting period to the peak fruiting period accounted for 50.76%of the dry matter mass,and the dry matter mass accumulation rate was also the largest in this period,reaching 4.93g·strain^-1·d^-1.It shows that the early growth of cherry tomato should be controlled in the production process,and after flowering,nutrition should be strengthened in flowering period,leaves should be preserved and stems should be promoted,and tomato yield should be improved.2.Determine the contents of nitrogen,phosphorus and potassium in different growth stages of tomato and their accumulation and distribution.It is found that:with the extension of the growth period,the nitrogen content of stems,leaves and fruits presents a decreasing trend;stems,leaves and shoots The accumulation of nitrogen,phosphorus and potassium in organs showed a trend of first rising and then decreasing,and they all reached the maximum in the peak period of fruit;the accumulation of nitrogen,phosphorus and potassium in fruits showed an increasing trend;the total demand for nitrogen,phosphorus and potassium showed a trend of increasing.The law of potassium>nitrogen>phosphorus.It shows that the demand for potassium is the largest in the fruiting period,and it is recommended to apply potassium fertilizer in production.3.Tomato variety of‘Qianxi’was used as the experimental material,four nitrogen application treatments with 0（N₀）,225（N₁）,450（N₂）and 675 kg·hm^-2（N₃）were set up in the field experiments.The results showed that:The fresh matter accumulations of tomato fruit accord with logistic curve and show the change rule of slow-quick-slow.During the quick increasing period,58.32%fresh matter are absorbed.The accumulation amount and the maximum accumulation amount of fresh matter of N₂treatment were significantly higher than that of the other three treatments.（2）The dynamic curve of fruit fresh matter accumulation rate is"inverse parabola".Fruit fresh matter accumulation rate and the maximum rate in increasing gradually period,rapid increasing period,slow increasing period and the duration of growth are 2.01,11.97,3.35,13.65 and 4.63 g·d^-1·plant^-1,significantly higher than that of the other three treatments.（3）With the increase of N dosage,start time,end time,peak time and effective accumulation period of rapid accumulation were gradually increased.In conclusion,it is recommended to apply 450 kg of pure nitrogen per hectare for obtaining higher yield.4.Through the test of the optimal ratio of organic N to replace inorganic nitrogen,it was found that the nitrogen partial productivity of the 36%replacement treatment was the highest,which was 0.230;the vitamin C content of the 36%replacement treatment was greater than that of the other 4 treatments,and the ratio of sugar to acid was also greater than the other 4 treatments.The nitrogen content of the fruits replaced by 18%and 36%was the lowest in the early stage of the results,and the nitrogen content of the replacement of 36%in the peak period was the highest;the nitrogen accumulation in the fruits was analyzed,and there was no significant difference among the five treatments.It is recommended to replace 36%inorganic N with organic N under the condition that the amount of phosphorus and potassium remains unchanged.