Study On Optimization Of Substrate Ratio And Application Rates Of Nitrogen,Phosphorus And Potassium In Soilless Culture Of Eggplant

Based on the"sand:slag=2:1（V:V）"substrate formula,in order to optimize the substrate ratio,the effects of different proportions（10%,20%,30%,40%and 50%）of mushroom residue on the growth,yield and quality of eggplant were studied using’Blita’eggplant variety as material.On this basis,according to the amount of nitrogen,phosphorus and potassium required for the unit yield of eggplant,the effects of different levels of nitrogen,phosphorus and potassium on the growth,yield,quality and rhizosphere microenvironment of eggplant were studied in order to provide theoretical basis and technical guidance for the scientific management of nitrogen,phosphorus and potassium nutrients of eggplant in substrate culture.The main results are as follows:1.In winter-spring and autumn-winter crops,the contents of chlorophyll a,chlorophyll b,Pn,root activity and root volume of eggplant were higher under the same condition of adding10%mushroom residue.Within a certain range,quality of eggplant was improved with the increasing of the proportion of mushroom residue,but beyond this range,the quality is decreased.In winter-spring crop,the contents of soluble sugar and free amino acid in pulp of eggplant increased significantly with the additions of 20%,30%and 40%mushroom residue.The contents of ascorbic acid in pulp and anthocyanin,flavonoids and total phenol in peel of eggplant were higher under adding 40%mushroom residue.In autumn-winter crop,the contents of soluble sugar,soluble protein and free amino acid in pulp were higher under adding 30%mushroom residue.The ascorbic acid content was significantly higher under adding 40%mushroom residue.The contents of flavonoids and total phenol in peel were higher under adding 10%mushroom residue.In both crops,the yield of addi ng 10%mushroom residue was the highest.In summary,it is beneficial to the growth and yield formation of eggplant by adding 10%mushroom residue in both winter-spring and autumn-winter crops.While adding 30%or 40%mushroom residue were favorable for the fruit quality forming of eggplant.2.In autumn-winter crop,the contents of chlorophyll a,chlorophyll b,carotenoid and Pn of eggplant leaves increased first and then decreased with the increase of nitrogen,phosphorus and potassium,and they were higher under 80%of dosage(N 231.5 kg·hm^-2,P₂O₅ 271.9 kg·hm^-2 and K₂O 557.6 kg·hm^-2),which were 27.6%,27.4%,29.8%and 21.2%more than the contrast,respectively.With the extension of growth period,the activity of NR in eggplant leaves was increased first and then tended to be gentle,and the activities of NiR,GS,GDH,GOGAT and soluble protein content were all increased first and then decreased.After 65 days of planting,the activities of NR,GS,GDH,GOGAT and the content of soluble protein and the gene expressions of NR,NiR,FD-GOGAT,GDH1 and GDH2 in eggplant leaves increased first and then decreased with the increase of nitrogen,phosphorus and potassium.The activities of NR and GDH and the gene expressions of NiR,GDH1 and GDH2were higher under the treatment of 80%of dosage.The activities of GS,GOGAT and the contents of soluble protein and nitrate nitrogen were higher at 100%of dosage.The activities of NiR,GS,GDH,GOGAT and the contents of soluble protein and nitrate nitrogen in leaves were significant positive correlations with yield.3.In winter-spring crop,the root activity,total root length and root surface area of eggplant increased first and then decreased with the increase of nitrogen,phosphorus and potassium,and they were higher under the treatment of 60%of dosage,which increased by109.2%,49.2%and 46.5%than the contrast,respectively.After 90 days of planting,the numbers of microorganisms and the activities of sucrase,catalase and alkaline phosphatase in rhizosphere substrate of eggplant were also increased first and then decreased,they were higher under the treatment of 80%of dosage.The urease activity was higher under the treatment of 100%of dosage.The contents of available nutrients in the substrate increased with the increase of nitrogen,phosphorus and potassium.There was a significant positive correlation between the number of bacteria and the enzyme activities in rhizosphere substrate.The urease activity was significantly positively correlated with the contents of available nutrients.The activities of catalase and alkaline phosphatase were significantly positively correlated with the contents of available phosphorus and available potassium.The microbial quantities,enzyme activities and available nutrient contents in rhizosphere substrate were positively correlated with root activity.4.In autumn-winter crop,the dry matter accumulation of eggplant increased first and then decreased with the increase of nitrogen,phosphorus and potassium,and it was higher under the treatment of 80%and 100%of dosage.The absorption of nutrient uptake was potassium>nitrogen>phosphorus.The partial factor productivities from applied nitrogen,phosphorus and potassium were decreased with the increase of nitrogen,phosphorus and potassium.In 80%to 100%of dosage,the partial factor productivity from applied nitrogen was 388.24⁴89.12 kg·kg^-1,the partial factor productivity from applied phosphorus was330.54⁴16.43 kg·kg^-1,and the partial factor productivity from applied potassium was161.20²03.07 kg·kg^-1.5.In both crops,the yield,the contents of soluble sugar and soluble protein in eggplant pulp and the contents of quality indicators in eggplant peel increased first and then decreased with the increase of nitrogen,phosphorus and potassium.In winter-spring crop,the yield of fertilization treatments increased by 101.1%²12.9%compared with no fertilization,and the treatment of 80%of dosage was higher,which was 212.9%more than the contrast.In autumn-winter crop,the yield of fertilization treatment increased by 48.2%⁸3.9%compared with no fertilization,the treatments of 80%of dosage and 100%of dosage were higher,which were 83.9%and 82.5%more than the contrast,respectively.6.Comprehensive analysis of the above results,under the condition of adding 10%mushroom residue,from the perspective of saving fertilizer and water without affecting yield,quality and soil microenvironment,the optimum fertilizer dosage for autumn-winter crop（125d）is N 180.6²25.7 kg·hm^-2,P₂O₅ 212.1²65.1 kg·hm^-2,K₂O 434.9⁵43.7 kg·hm^-2,and for autumn-winter crop（155 d）,it‘s N 231.5²89.4 kg·hm^-2,P₂O₅ 271.9³39.9 kg·hm^-2,K₂O557.6⁶97.1 kg·hm^-2.