为探索西北旱区饲用甜高梁最佳灌溉定额和节水效果,进行了覆膜畦灌条件下饲用甜高粱需水规律及优化灌溉制度试验,研究了不同灌溉定额(2400、3 000、3 600、4 200、4 800 m3·hm-2)条件下,饲用甜高粱生育期土壤水分变化情况、农艺性状及生物产量变化.结果表明,甜高梁生育期0～ 100 cm土层含水量随生育期的延长呈先降低后升高的趋势,灌水定额对土壤水分分布的影响发生在播后62d.当灌溉定额小于2400 m3·hm-2时,严重影响甜高粱长势,植株表现为矮小,茎秆增粗,干物质累积量降低.随灌溉定额的降低,甜高粱茎秆汁液的含糖量呈提高的趋势.甜高粱生物产量的增加是由于株高(R2=0.97)、LAI(R2=0.81)、茎节数(R2=0.59)等因素共同作用的结果.从节水和增加生物量角度而言,畦灌条件下,甜高梁在全生育期灌水4次,灌水定额为900 m3·hm-2,灌溉定额为3 600 m3·hm-2的灌溉制度最优.%In order to explore the optimal irrigation quota and water-saving effect suitable for feeding sweet sorghum under condition of border irrigation with mulching,a field experimem was conducted to study the effect of the irrigation quota (2 400,3 000,3 600,4 200,4 800 m3·hm-2 respectively) on soil water content,agronomic trait and biomass.Results showed that soil water content within 0 ～ 100 cm soil layer first increased and then decreased in sweet sorghum growth period,and irrigation quota had significant effect on 0 ～ 100 cm soil moisture distribution at the 62th d after sowing.Irrigation quota which was less than 2 400 m3· hm-2 seriously affected the sweet sorghum growing (such as reducing plant height,enlarging stem stalk,decreasing accumulative dry matter).Sugar content of sweet sorghum stalk juice had a trend of increase with the decrease of irrigation quota.The increase of sweet sorghum biomass was attributed to factors such as plant height,LAI and numbers of stem nodes (R2 =0.97,0.81,0.59 respectively).In conclusion,for watersaving and increasing the biomass,irrigation schedule with irrigation quota of 3 600 m3· hm-2 (irrigation frequency was 4 times) was thereby recommended as the optional practice to increase the biomass (25.29 t· hm-2) and WUE (5.76 kg · m-3) under condition of border irrigation with mulching.
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