覆膜滴灌对日光温室甜瓜土壤环境及产量的影响

为探明不同覆膜滴灌条件下,大棚甜瓜土壤水、热等环境因素变化对脲酶及甜瓜产量的影响,该文采用正交试验设计,研究了日光温室内不同覆膜方式(全覆膜、半覆膜、无膜)、灌水下限(田间持水量的60%、70%、80%)、滴灌毛管密度(1管1行、3管4行、1管2行)以及3种因素的交互作用下的土壤水、热、pH值等的变化,以及对甜瓜土壤脲酶活性及甜瓜产量的影响。结果发现,半膜覆盖、80%田间持水量的灌水下限、1管2行滴灌毛管密度等的甜瓜根区土壤水分分布均匀、土壤温度较高、pH值较低,可显著提高土壤脲酶活性；60%田间持水量下限处理脲酶活性在果实膨大期和成熟期高,70%田间持水量下限处理在苗期高,80%田间持水量下限处理在各个生育阶段都最高；半膜覆盖、1管2行和80% 田间持水量下限组合和半膜覆盖、3管4行和70%田间持水量下限组合的甜瓜产量分别为34.46、31.27 t/hm²,显著高于全膜覆盖、1管1行和80% 田间持水量下限组合的28.02 t/hm²；半膜覆盖、1管2行和80% 田间持水量下限组合甜瓜的可溶性糖和可溶性固形物含量高,有机酸含量低。在陕西关中地区的日光温室栽培甜瓜,建议采取半膜覆盖,1管2行的滴灌管密度,灌水量下限分别为苗期70%、开花坐果期80%、果实膨大期80%和成熟期60%田间持水量。

Effects of drip irrigation under plastic film on muskmelon soil environment and yield in greenhouse

Soil urease is the key enzyme of soil nitrogen cycle, which is the important indicator to measure soil quality and fertility and can significantly affect the material and energy exchange between plant and soil and plant production especially in the plastic greenhouse.In order to investigate the effects of different drip irrigation with plastic mulched on muskmelon soil environment, soil urease and melon production in plastic greenhouse, a test was conducted in a sunlight plastic greenhouse in Dazhai Village, Dazhai Town, Yangling City, Shaanxi Province, China from April to July, 2014.The test was designed according to orthogonal experiment with 3 factors and 3 levels, using orthogonal table L₉(34), which contained 3 factors including the film covering (P), the drip line density laying (T) and the irrigation low limit (L).The film covering was divided into 3 levels, i.e.the full film covering(PF), the half film covering(PH) and the no film covering(PN).The drip line density laying was divided into 3 kinds of layout, i.e.1 pipe for 1 line(T1), 3 pipes for 4 lines(T3/4) and 1 pipe for 2 lines(T1/2).The irrigation low limit was divided into 60%(L₆₀), 70%(L₇₀) and 80%(L₈₀) of field capacity respectively, which corresponding upper limit was 65%, 75% and 85% of field capacity.And there were 9 tests in all: PFT1L₈₀(Treatment 1), PNT1/2L₇₀(Treatment 2), PNT3/4L₈₀(Treatment 3), PHT1/2L₈₀(Treatment 4), PFT1/2L₆₀(Treatment 5), PFT3/4L₇₀(Treatment 6), PNT1L₆₀ (Treatment 7), PHT3/4L₆₀(Treatment 8), and PHT1L₇₀(Treatment 9).Each treatment was repeated by 3 times and had 27 test plots in all.The soil environment factors, such as soil moisture content, soil temperature and soil pH value were measured.And the urease activity, the melon yield and the fruit quality of melon under the changes of the soil environment factors were also measured, and the fruit quality of melon contained the soluble sugar, soluble solids and the organic acid.And the response of soil urease to different environmental factors change and the response of the melon yield and the fruit quality to the soil urease were analyzed.The results showed that the different film covering, drip line density laying and irrigation low limit could create significantly different soil moisture distribution, soil temperature and soil pH value, which led to the different soil urease activities and melon yield.The root zone soil of muskmelon had better water distribution uniformity, higher soil temperature and lower soil pH value and could significantly increase soil urease activity under the condition of half covering, 80% field capacity and 1 pipe for 2 lines.The urease activity of the treatment of 60% field capacity was high in fruit swelling and mature periods, while that of the treatment of 70% field capacity was high in seedling period, and that of the treatment of 80% field capacity was always the highest in each stage.The muskmelon yields were 34.46 and 31.27 t/hm² respectively under the combination of half covering, 80% field capacity and 1 pipe for 2 lines and the combination of half covering, 70% field capacity and 3 pipes for 4 lines, which was significantly higher than the yield 28.02 t/hm² under the condition of full covering, 80% field capacity and 1 pipe for 1 line.In addition, the different film covering, drip line density laying and irrigation low limit had also significant effects on the melon fruit quality.The half film covering had the same soluble sugar level with the full covering, and was 14.26% lower than the full covering in soluble solids content but its organic acid content was the lowest.And the 1 pipe for 2 lines had the most amount of TSS(total soluble solid) which was 3.93% and 25.94% higher than 1 pipe for 1 line and 3 pipes for 4 lines respectively.And the 1 pipe for 2 lines had the lowest organic acid content which was 27.58% and 39.51% lower than 1 pipe for 1 line and 3 pipes for 4 lines respectively.And the 80% field capacity had the lowest organic acid content while had the same soluble sugar and soluble solids level with the 60% and 70% field capacity.Therefore, the film covering mode of half covering and the drip irrigation pipe density of 1 pipe for 2 lines would be recommended for melon cultivation in the greenhouse in Guanzhong region of Shaanxi Province, and the irrigation low limit should be 70% field capacity in seedling period, 80% field capacity in flowering period and fruit swelling period, and 60% field capacity in mature period.