Effects Of N,P,K Fertilization Levels On Nutrient Accumulation And Quality Of Tomato

The vegetable industry is a pillar industry for the development of China’s agriculture and rural economy in addition to the grain industry.In the process of vegetable planting and production,facility vegetables are widely used due to intensive production methods,and the high yield and efficiency of tomatoes are favored by consumers.In this study,different levels of N P and K fertilizer,which were no fertilizer was used as the control(CK),increase of N fertilizer by 20%(T2),increase of K fertilizer by 20%(T3),and increase of N and K fertilizer by 20%(T4)based on the recommended fertilization and kept P fertilizer constant,respectively,were applied on tomato.The effects of different N,P,and K fertilization levels on the yield,quality and soil environment of tomatoes were studied.The results showed that:1.Tomato plant height and stem thickness change with S-shaped curve along with growth period.The plant height was higher in T4 treatment,which was 37.59% higher than that of the control treatment;the stem diameter was the largest in T3 treatment,which was 47.39% higher than that of the control,the difference was significant.In the case of the same potassium fertilizer,increasing the level of nitrogen fertilizer application increased the dry and fresh weight of the plant,and increasing application of potassium fertilizer had a more significant increase in the dry and fresh weight of the plant under the same nitrogen fertilizer condition,and the T4 treatment has the best effect.The dry and fresh weight of tomato plants gradually increased with the growth stage.At the harvest stage(120d),the fresh and dry weight of the tomato plants in the T4 treatment increased by 74.22% and 64.49%,respectively,compared with the control treatment,which was a significant difference.The increase rate of dry and fresh weight of tomato plants in each treatment gradually decreased with the growth stage.In the case of the same potassium fertilizer,increasing the level of nitrogen fertilizer and potassium fertilizer application increased the dry and fresh weight of the plant,and the increase of the single fertilization level will not increase the dry and fresh weight of the plant significantly,and the T4 treatment has the best effect.From the perspective of the proportion of dry matter in roots,stems and leaves of each treatment,the proportion of dry matter of leaves and stems accounting for 56.30%-61.01% and 29.89% of the total dry matter accumulation of plants.The proportion of root dry matter accounted for 8.57% and 10.63% of the total dry matter accumulation of plants.2.The number of flowers per plant of tomato is the highest in T1 treatment,and the fruit setting rate is the highest in T3 treatment(72.6%).Under the same nitrogen fertilizer level,increasing potassium fertilizer increased the fruit setting rate and yield of tomatoes,but under the same potassium fertilizer level,increasing nitrogen fertilizer has little effect on tomato fruit setting and yield,and high nitrogen and high potassium fertilizer levels decreased the tomato yield.The tomato yield of T3 treatment reached 9168.31 kg,which was 65.73% higher than that the control treatment,and the difference was significant.The longitudinal and transverse diameters of tomato fruit were the largest in T3 treatment,but the fruit type index of each treatment was not significantly different.The firmness of the fruit between the fertilization treatments was significantly higher than that of the control treatment.The content of soluble solids in the fruit was the highest in the T3 treatment(8.62%),which was significantly different from the control treatment.The fruit water content was highest in T2 treatment,followed by T3 and T4 treatments,which was significantly higher than that in the control treatment.There was no significant difference of the Vc content in tomato fruits with different treatments.The highest content of nitrite in tomato was found in CK;followed by T2 treatment.The highest content of nitrate was found in T2,followed by T4.The absorption and transformation of nitrogen reduces the content of nitrate and nitrite in the fruit.T3 treatment has the highest soluble sugar content,which is 42.32% higher than that in the control treatment.The highest organic acid content in tomato was found in T1 treatment,which is 18.87% higher than that in the control treatment,and the difference is significant.The sugar-acid ratio in tomato of the T3 treatment is the largest(6.60),which is increased by 48.31% compared with the control treatment,and the difference was significant.The metal content of tomato fruits is lower than the national standard,which indicated that the quality of tomato reaching the standard of pollution-free vegetables.3.The content of chlorophyll a in each fertilization treatment increased firstly and then decreased slowly with the growth period prolonged;the content of chlorophyll b as well as chlorophyll a+b gradually increased with the growth period prolonged.The chlorophyll content of each fertilization treatment was significantly higher than that of the control treatment during the whole growth period.In the full season of tomato growth(60 days),the content of proline in tomato leaves increased with the increase of potassium fertilizer,and the malondialdehyde decreased with the increase of potassium fertilizer.The superoxide dismutase activity is not obvious changed,but high nitrogen and potassium reduced the content of catalase.In the late growth period(120d),the proline content in tomato leaves increased with the increase of potassium fertilizer;the activity of superoxide dismutase was highest in the T2 treatment;the difference of catalase in each treatment was not significant.4.The content of N,P,and K of tomato in each treatment followed the role of T3>T2>T1>T4>CK.Judging from the ratio of nitrogen accumulation in fruits,roots,stems and leaves of each treatment,the nitrogen content of fruits,leaves,stem and roots accounting for 70.07%-72.78%,12.48%-15.23%,12.06%-14.27% and 1.56%-3.16% of the total N content in tomato,respectively.Phosphorus contents in fruit,leaves,stem and root accounted for 51.08%-59.60%,17.35%-29.96%,11.98%-21.20% and 2.98%-5.54% of the total P content in tomato,respectively.Potassium content in fruit,leaves,stem and root accounted for 63.22%-66.77%,9.94%-15.60%,17.71%-24.73% and 1.45%-2.39% of the total K content in tomato,respectively.Fertilization can significantly improve soil fertility.The content of soil available nitrogen in T3 treatment is the highest(557.80 mg/kg),which is 46.25% higher than that in the control;and the highest content of available phosphorus was found in T4 treatment;the content of available potassium is not significantly different from each fertilization treatment,but significantly higher than the control treatment.From the perspective of soil p H and electrical conductivity,reasonable fertilization treatments can reduce soil electrical conductivity.The conductivity of each fertilization treatment is significantly lower than that of the control treatment;the p H value of each treatment has no significant difference.5 Increasing application of nitrogen fertilizer increased the activities of soil urease,phosphatase and invertase.The activity of catalase was increased as the application of potassium fertilizer increasing,but it significantly reduced the activity of invertase.The soil urease and phosphatase activities of each treatment showed a trend of firstly increasing and then decreasing with the growth period of tomato prolonged,but the urease of the control treatment showed a decreasing trend with the growth period.