Effects Of Controlled-release Fertilizer On Yield, Quality And Nutrient Absorption And Nutrient Use Efficiency Of Tomato In Substrate Culture

The abuse in the use of chemical fertilizers in vegetable crop production is one of the major challeges that limits the utilization rate of the fertilizer, destroys the balance between soil nutrient supply and absorption, and results in low crop productivity. Numerous studies showed that the nutrient release characteristics of controlled fertilizers were in accordance with the plant nutrient absorption capacity. However, the applications of controlled fertilizers on tomato have rarely been reported. We conducted all experiment including six fertilization treatments: including Treatment I(No N fertilizer, CK), Treatment II(fertilizing chemical, CF), Treatment III(the content of nutrient is same as CF, CRF),Treatment IV(reduced by 20%decrement of nitrogen controlled-release fertilization, CRF20), Treatment V(reduced by 40 %decrement of nitrogen controlled-release fertilization, CRF40), Treatment VI(reduced by 60 % decrement of nitrogen controlled-release fertilization, CRF60) on the development, productivity, and quality of tomato, and the appropriate ratio of CRN was determined by considering comprehensive performances, in order to provide a theoretical basis for the application of controlled fertilizer in tomatoes cultivated in substrate. The research results were as follows:1、The variation trends of the plant height and stem diameter in all treatments were consistent in the early growth period of tomato. Fifty days after transplanting, plant height and stem diameter in the treatments of controlled fertilizers were significantly higher than CK, with CRF20 and CRF40 were better.2、The CRF2 and CRF40 treatments improved the rate of photosynthesis of tomato, the actual photochemical efficiency(ФPSⅡ)and net photosynthetic rate(Pn) better than the other treatments at early stage of fruiting and at the peak fruiting period.3、Controlled releace fertilizers significantly increased the yield of tomato and improved the fertilizers use efficiency. The yield under CRF20 and CRF40 were significantly higher than those of the other treatments. The increase was 10.68% and 36.03%. Respectively compared with CF. The N ultilization efficiencies increased by decreasing N application rate. CRF60, which had the is highest N ultilization efficiencies in all treatments was up to 50.5%4、With regard to quality, compared with CF, Controlled fertilizers increased the content of Soluble sugar and decreased organic acid and Nitrate content, CRF60 had the highest soluble sugar content, while CRF640 had the highest VC content and the least content of Nitrate. The CRF40 treatment gave fruits with the best quality.5、The trend of the available N and K content in the substrate of the controlled fertilizers treatments were similar. After 50 days, there was a highest content of available N and K, however, the content of available P steadily increased. CF significantly increased substrate content of available P. After 75 days there was a highest content in all treatments. During the whole growth period, the content of available N and K of the CRF、CRF20、CRF40 treatments were significantly higher than CF and basically satisfied the demand for NPK nutrition in tomatoes throughout the growth period.