| The irrigation management is closely associated with the water consumption property of plants.Optimization of crop irrigation system reduce the crop water consumption,which has been an effective strategy to balance the storage and utilization of groundwater resource in North China Plain.In this study,using a muskmelon cultivar referred to as Xizhoumi 25 specified by low water consumption as the material,the responses of plant growth traits,physiological parameters,water consumption characterization,yield and fruit quality traits of muskmelon to irrigation mode,root space,and water contents of wetted soil were investigated under greenhouse condition,during the 2013-2016 growth seasons.The irrigation indices for water-saving and high-quality irrigation schedule were established for muskmelon grown under the greenhouse condition.The main results are as follows:1 The effects of four irrigation methods,including furrow irrigation without mulch coverage,furrow irrigation with mulch coverage,drip irrigation without mulch coverage,and drip irrigation with mulch coverage on yield,melon quality and water consumption characterization for muskmelon grown in sunlight greenhouse were studied.Results indicated that the plant water consumption intensities were 0.95-1.12mm·d-1,1.65-1.89 mm·d-1,1.90-2.24mm·d-1 and 1.85-1.99 mm·d-1 at first vine elongation stage,flowering and fruit setting stage,fruit expansion stage,and mature stage,respectively,with the highest shown at fruit expansion stage.Compared with other three irrigation modes,drip irrigation with mulch coverage displayed the lowest water consumption intensity,being decreased by 15.20%,6.45%and 11.04%compared with furrow irrigation without mulch coverage,furrow irrigation with mulch coverage,drip irrigation without mulch coverage,respectively.The total evaporation amounts during whole growth season for muskmelon varied from 10.45 mm to 59.75 mm.Compared with irrigation without mulch coverage,the irrigation modes with mulch coverage significantly decreased the evaporation intensity and evaporation amount during growth stages.Of which,the evaporation intensity was 0.03～0.25 mm·d-1 for those grown under irrigation with coverage whereas that was 0.48～0.96 mm·d-1 for those grown under irrigation without coverage.The evaporation amount under former condition was decreased by 75%with respect to that under later case.The treatment of drip irrigation with mulch coverage led to the highest yield and water use efficiency for muskmelon plants,with the increase extents of 39.7%,10.4%and 22.4%on yield and 67.2%,19.8%,and 39.3%on water use efficiency compared with treatments of furrow irrigation without mulch coverage,furrow irrigation with mulch coverage,drip irrigation without mulch coverage,respectively.Compared with irrigation without mulch coverage and that with furrow pattern,the irrigation with mulch coverage and that with drip both significantly increased the plant height,stem diameter,leaf area index,and leaf net photosynthetic rate,and elevated the biomass accumulation of aerial organs and melon.In addition,the irrigation with coverage significantly increased the longitudinal diameter,fresh weight,and total soluble sugar content of fruits,and improved fruit quality of melon at maturity.Compared with furrow irrigation,drip irrigation increased the fruit fresh weight together with no significant difference on sugar acid ratio trait between the two irrigation methods.In comprehensively considering behaviors on water use efficiency,fruit yield,and quality of melon,it was concluded that drip irrigation with mulch coverage is suggested to be a suitable mode for muskmelon grown in greenhouse with purposes of water-saving,high yield and elite melon quality.2 The root restriction treatments combining two forms of stopping roots(gauze cloth and plastic cloth)and six restriction root depths(10,20,30.40,50,60 cm)were set up under drip irrigation with coverage.The effects of above treatments on plant water consumption,dry matter accumulation,yield,and melon quality were determined.Results indicated that the plant height,stem diameter,leaf area index,dry matter weight of vegetative organs,fruit biomass,fresh weight of fruit and yield were all not affected by 10-60 cm gauze cloth that restricts root depth elongation.The treatment of 10-60 cm plastic cloth significantly reduced the dry matter weight of above ground organs,fruit biomass,fruit fresh weight and yield.Additionally,the treatment of 10 cm gauze cloth and that of 10 cm plastic cloth increased the water use efficiency by 10.9%and 8.1%compared with control,respectively.Treatments with gauze cloth stopping roots with depth more than 20 cm unaltered the water use efficiency compared with control.However,the treatments restricting roots with plastic cloth of 40-60 cm significantly reduced water use efficiency.The treatments with 10-30 cm root stopping by gauze cloth and those with 20-30 cm restriction by plastic cloth increased the total soluble sugar content and acid-to-sugar ratio of melon fruit.Compared with control,the melon longitudinal diameters and fresh weight per melon were significantly decreased under treatments with stopping root by plastic cloth.Therefore.gauze separation with 10-20 cm depth can promote the water use efficiency and melon quality without yield loss.It was thus concluded that the planned wetted soil depth is 10-20 cm for muskmelon cultivation under greenhouse condition.3.Based on negative pressure infiltration irrigation to precisely control the moisture content in the planned wetted soil depth,five water supply suctions(5,10,15,20,25 kPa corresponding to soil water contents of 95.6-97.7%,79.0-80.0%,70.2-73.7%,59.2-66.7%and 48.8-55.7%of field capacity,respectively)during flowering and fruit setting period and fruit expanding to mature period on water consumption,yield and melon quality were studied.Results indicated that the water supply suction range of 5-15 kPa during the flowering and fruit setting period benefited the yield formation and quality improvement.Under condition of water supply suction of 20 kPa,the yield,water use efficiency,melon diameters,and total soluble sugar content of melon were significantly reduced compared with control.In comprehensively consideration of behaviors of yield,water use efficiency,and melon quality,the suitable water supply suction for the muskmelon grown is 15 kPa during flowering and fruit setting period under greenhouse condition,which corresponded to the soil water contents of 70.2-73.7%.5-10 kPa of water supply suction at fruit elongation to maturity benefited to the melon yield formation,soluble sugar accumulation,and vitamin C synthesis.Likewise,treatments of 10 and 15 kPa of water supply suctions reduced plant water consumption and enhanced plant water use efficiency.Together,10 kPa(i.e.,soil contents 79.0-80.0%of field capacity)at fruit elongation to maturity was suggested to be the best for comprehensively improving yield,water use efficiency,and the melon quality for muskmelon grown under greenhouse condition.4.The water requirement amount for muskmelon was shown to be 10.6-28.1%of that of other field crops,and the unit water production benefit is 7.1～67.7 times of other crops.Muskmelon cultivation under sunlight greenhouse had high yield and economic output,suggesting that it has improved economic benefit.Adoption of water-saving irrigation method together with optimized wetting depth during irrigation and accurately control of soil water content at the planned wetted soil depth,the water consumption of muskmelon could be further reduced,which benefits improvement of the water productivity and fruit quality by which to elevate high-quality and water-saving production of muskmelon in North China plain. |
