Study On Water And Fertilizer Regulation Technology For Melon Under Drip Irrigation

As a high input and high technology industry,the corresponding supporting facilities of facility agriculture are becoming more and more perfect with the development of modern agriculture.However,due to the lack of corresponding efficient water and fertilizer control technology,the facility system cannot play its proper role.In order to ensure high quality and high yield of crops,improve water and fertilizer utilization rate,and avoid wasting resources,the appropriate water and fertilizer regulation scheme of water and fertilizer integration facilities for melon is explored,in this study,a greenhouse pot experiment was carried out with different irrigation threshold levels（W1:75%θfc、W2:65%θfc、W3:55%θfc）and different topdressing levels（F1:1050kg/hm2、F2:735 kg/hm2）,by setting conventional spraying compound fertilizer coupled with flooded irrigation as the control,the melon growth,yield,water and fertilizer use efficiency,and quality were studied.The main research results are as follows.To analyze the effects of different water and fertilizer treatments on plant growth,the plant height and stem diameter significantly increased with the increasing of fertilizer application.After the vine extension stage,the plant stem diameter under W2 was significantly higher than W1 and W3.The chlorophyll content was measured by Soil and Plant Analyzer Development（SPAD values）.The SPAD values showed a distribution regular of W2>W1>W3 at the fruit swelling stage,while the SPAD values decreased with the lower limit of irrigation at all other reproductive stages and with the decrease of fertilizer application.The photosynthetic characteristics of the leaves showed different trends at different top application levels,with W2>W1>W3 at high top application levels and W2>W3>W1 at low top application levels.The fertilization level had no significant effect on the flowering and fruit harvest time,but the high irrigation threshold could make the crop enter the maturity stage early and improve the market value at harvest period.The dry matter size and maximum leaf area of all parts of melon showed a tendency to decrease with the lower limit of irrigation and to increase with the amount of top application.To analyze the effects of different water and fertilizer treatments on melon fruit,the larger the amount of irrigation,the faster the increase in the longitudinal and transverse diameter of the fruit during dynamic changes in fruit size.The greater the amount of irrigation water and fertilizer application,the greater the fruit morphological indexes increased,and the maximum fruit indexes in the water-fertilizer integration treatment W1F1 increased the fruit longitudinal diameter,transverse diameter,and flesh thickness by 19.8%,21.2%,and 13%compared to CK.Mature hardness showed a pattern of decrease with increasing irrigation lower limit,topdressing level had no significant effect on it.The highest yield was found in W1F1,which was 35.5%higher than that of W3F2 and not significantly different from that of W2F1.Reducing the amount of fertilizer was beneficial to the accumulation of melon quality.The high irrigation amount significantly reduced the accumulation of reducing sugar and soluble solids,the accumulation of VC and soluble protein increased first and then decreased with the decrease of irrigation amount.The ranking result of the comprehensive quality evaluation was that W2F2 was the best and W2F1was the second.In the study of the effects of different water and fertilizer treatments on water and fertilizer utilization rate and substrate,water use efficiency（WUE）gradually increased and fertilizer partial productivity（PFP）gradually decreased with the reducing of irrigation threshold.The maximum value of WUE was W3F1,which was 1.58 times that of CK,the maximum value of PFP was W1F1,which was 28.4%higher than that of the CK.The lower limit of irrigation and the level of fertilization had a significant effect on the nutrients available nitrogen and available phosphorus in the substrate,and the difference between the water and fertilizer integration facilities and CK available nitrogen was greater than that of available phosphoru.There was no significant negative effect of kitchen waste organic fertilizer on the EC value of the substrate,and the treatment with the largest EC value,W1F1,was only 8%higher than CK.The pH values of treatments with kitchen waste organic fertilizer were significantly different from those of CK.Kitchen waste organic fertilizer was effective in reducing the pH value of the substrate and improving the chemical properties of the substrate.If only the market value is considered,the W1F1 scheme can be used as the water and fertilizer regulation scheme.When considering plant growth status,yield,quality and water and fertilizer utilization,the indicators were evaluated comprehensively by the affiliation function method and entropy TOPSIS method.Both evaluation ranking results have a pattern of 65%θfc>55%θfc>75%θfc,while the affiliation function method favors low fertilization levels and the entropy TOPSIS method prefers high fertilization levels,but the optimal solution for both is W2F1.Therefore,the water and fertilizer regulation scheme of W2F1 is more suitable for the planting of protected melon in Changshu area.