关键词: 玉米, 干旱, 秸秆覆盖, 生长发育, 子粒产量

Abstract: Field experiments were conducted during 1994 to 2000 at Xingfu of Taonan city situated in semi-arid areas in western Jilin. Two treatments consisting of cultivation on bare land and cultivation on land covered by straw residues have been designed. Mulching was conducted at the five-leaf stage of maize and with frittered maize and wheat straws at 2~3 cm length. The treatments were arranged in a randomized complete block design with four replications. In every next year, plots were re-randomized to avoid carry-over effects of the previous year's residue materials. Corn residues from the previous year were removed prior to the establishment of the treatments. Maize, Dan Yu 13, was cultivated at 51 000 plants hm^-2 during the last week in April from 1996 to 2000. Fertilizer applying and controlling of diseases, pests and weeds were same in the treated and the check plots. From 1996 to 2000, 10 consecutive plants in each plot were marked at the beginning of the growing season and observed and investigated at different stages of growth and development. Maize ears were harvested after physiological maturity. Analyses of variance were performed and differences between means were tested using the least significant difference test (LSD) at an alpha level of 0.05. The effects of straw mulch on growth, development of maize and water content in soil were deeply investigated under semi-drought condition. Prior to the straw mulching, all the plots had synchronous water content in soil. After the five-leaf stage of maize plant the water content in soil of treatments was significantly higher than that in the checker. The effect lasted until the end of second week of July during the years of experiments. In details, the water content in soil of treatments was 12.86% higher than that in control on 10 June, 7.17% on 25 June and 2.86% on 15 July, respectively. The increased water content in soil was very important for maize because it warranted the need of water for roots and above ground growth and development at its early stage. Straw mulching also directly or indirectly promoted the growth and development of maize at middle and later stages: enhanced the leaf area and the dry weight per plant; contributed to the differentiation and development of female inflorescence; improved the properties of maize ear; increased the grain numbers and grain weight per ear; and finally, increased the grain yield. Therefore, the straw mulching could be used as a main method, not perfect one, in the comprehensively drought-resistant cultivation of maize under drought and semi-drought regions.

Key words: maize, drought, straw mulch, growth and development, grain yield