Effects Of Slow-Release Fertilizer On Nutrient Uptake,Yield And Quality Of Eggplant In Substrate Culture

The imbalance between soil nutrient supply and absorption leads to the problem of low utilization rate and consequently affects vegetable production.Solving this problem may contribute to achieving China’s agricultural modernization. Slow/controlled release fertilizers function in concert with plant nutrient absorption.It is reported that slow/controlled fertilizers release nutrients into the soil and as a consequence have a positive effect on enhancing crop growth and yield.In view of this, a field experiment was carried out to investigate the effect of slow/controlled fertilizer on quality,marketable yield, nitrogen,phosphorus and potassium distribution rate,fertilizer utilization rate, and photosynthesis of eggplant(Solanum melongena L.).Three different fertilizer types(urea, release period of 3-4 month and 8-9 month release fertilizer) and zero doses of NPK-fertilizers were applied to the crop in a randomized complete block design with three replicates. Results showed that as follows:1. Sustained release period of different fertilizer could effectively improve the eggplant growth status of plant height,stem diameter, chlorophyll, root activity,expressed as compared with other treatments,stained release period of 3-4 months of fertilizer has significantly effect on plant height of eggplant growth later period.Slow release fertilizer significantly better than ordinary fertilizer and slow-release period of 8-9 months.In a sustained period of 3-4 months of slow-release fertilizer in the early days of eggplant stem diameter was significantly higher than other treatments,then all treatments showed no significant differences between the results of 3-4 months,to the late,slow release fertilizer treatment was slightly higher than that of other treatments;root activity in the fruiting period performance for the release period of 3-4 months of slow release fertilizer treatment was significantly higher than that in ordinary fertilizer and 8-9 months of slow release fertilizers.2. Sustained release period in different fertilizer application on eggplant quality was significantly better than the ordinary fertilizer. Compared with other treatments,sustained release period of 3-4 months of fertilizer could make the Vc content of eggplant significantly increased 43.3%-47.8%,Free amino acids significantly increased to 34.2%-117.1%;nitrate content on 8-9 months release period of slow release fertilizer reached 196.3mg·kg-1,was the lowest, compared to release 3-4 slow-release fertilizer,urea treatment and the control,the nitrate content of eggplant respectively decreased 38.6,47.1 and 32.1mg·kg-1.3. Different release period of slow release fertilizer could significantly increase the yield of eggplant.The results show that different fertilizer has different results,release period of 3-4 months of slow-release fertilizer in eggplant fruit weight and yield per plant was highest, sustained period of 8-9 months of slow release fertilizer secondly,compared to other treatment, yield per plant increased by 28.3%-58.4%.The fruiting period sampling period before,all fertilizer treatments of eggplant shoot dry weight almost identical trend,after the full fruit period for common fertilizer treatment decreased significantly, the dry weight of the release period of 3-4 months increased obviously.The last harvest period, sustained release period of 3-4 months of fertilizer basically maintained at a stable level, 8-9 release period of slow release fertilizer is gradually increased,the more gentle finally,with 8-9 month slow-release fertilizer on eggplant dry weight increased and reached the maximum value.4. With different release period fertilizer could obviously improve the net photosynthetic rate,transpiration rate and stomatal conductance of eggplant.Compared with other treatments, eggplant leaf net photosynthetic rate of the release period of 3-4 months of slow release fertilizer increased by 2.6% and 30.5%.the transpiration rate and net photosynthetic rate showed the same trend on the whole fertilizer treatments.The release period of 3-4 months Slow release fertilizer and ordinary fertilizer treatment that were higher than the release period of 8-9 months of fertilizer and control,and the difference was significant.The stomatal conductance of the release period of 8-9 months treatment and the release period of 3-4 months treatment is significantly higher than the common fertilizer and the control,the difference between two kinds of slow-release fertilizer of 8-9 months release period treatment and the 3-4 months treatment was not significant.5. On the absorption of nitrogen phosphorus and potassium elements,the test results showed that the different release duration,slow release fertilizer could significantly increase phosphorus and potassium apparent utilization rate of the eggplant,with slow-release fertilizer of 8-9 months release period is highest,compared with the lowest treatment of ordinary urea,the apparent phosphorus and potassium utilization rate respectively increased 10.72 and 63.47 %.6. The influence of the available nutrient content and enzyme activity.The results showed that,two kinds of slow release fertilizer could significantly increase the nutrient content of available NK.Compared with other processing, overall, in addition to hormone had no obvious effect on phosphorus release,two different period of release fertilizer are effectively increased available nutrient content in the matrix, and through the tests also found that,in the 3 kinds of matrix effects on enzyme activity,to the release period of 8-9 months the invertise activity of slow release fertilizer treatment the highest 3-4 months,slow release fertilizer secondly, ordinary fertilizer was the lowest,and the fertilization treatments was significant difference.Slow release fertilizer release period of 3-4 months(2.70 mg·g-1·h-1) processing matrix urea activity was significantly higher than the other, was increased by 14.8%-69.8% compared with other treatments,it shows two kinds of slow release fertilizer in improving the effect of catalase active matrix is not significant.