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试验地设在甘肃张掖地区农科所果园第四区,土壤为绿州沙漠土,土体结构为匀质砂壤,土层厚1米左右,pH8.04。该地区年降水量129毫米,从11月到翌年2月四个月的土壤温度均在0℃以下,冻土深1米左右,是典型的干旱、寒冷地区。试验材料为2年生杜梨(P.betulaefo-lia),株行距2×4米。第7～11行覆膜,共125株;第1～6行不覆膜为对照,共150株。地膜为聚氨乙烯塑料薄膜,宽0.85米,厚0.14厘米。地膜于1986年11月15日覆盖。越冬情况于1987年3月29日进行了调查,出现秋梢受冻干枯(对照1株,覆膜2株),1～3根新梢受冻(对照5株、覆膜
The experiment was located in the fourth area of the orchard of Zhangye Prefecture in Gansu Province, with the soil being the desert soil of the state of Greenzhou. The soil structure was homogeneous sandy soil with a thickness of about 1 meter and pH value of 8.04. The annual precipitation of 129 mm in this area, from November to February the following February the soil temperature in February are below 0 ℃, frozen soil about 1 meter deep, is a typical drought and cold areas. The test material was 2-year old P.betulaefo-lia with a spacing of 2 × 4 meters. Lines 7 to 11 covered a total of 125 lines; lines 1 to 6 covered no control, a total of 150 lines. Plastic film is a polyethylene plastic film, width 0.85 meters, 0.14 cm thick. Mulch was covered on November 15, 1986. The overwintering situation was investigated on March 29, 1987, and the autumn shoots were withered and withered (1 in control and 2 in coated), and 1 to 3 new shoots were frozen (control 5,