Results of 5 different treatment (D1: sandy field with thin plastic cover, D2: sandy field +small shed, D3: sandy field + thin plastic cover+ small shed, D4: sandy field, control 1, and D5: soil field, control 2) experiment were as follows.

• 试验设D1(砂田+地膜)、D2(砂田+小拱棚)、D3(砂田+地膜+小拱棚)、D4(砂田CK1)、D5(土田CK2)5个处理。 试验表明: