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不同播期对棉花出苗早晚、苗病和生长发育均有不同的影响。在一定播期范围内,播种早晚主要影响出苗和苗期的长短,对现蕾以后的生育进程作用较小。而播种过早,苗病重,生育慢,不利于全苗壮苗,易形成老苗、出现后期早衰;过晚播种,就降低了地膜覆盖的效用。温度是决定播期的主要条件,统计分析表明,膜内外5厘米地温存在着高度的相关性,据此推算,当露地5厘米地温稳定通过11℃时,膜下5厘米地温可达13—14℃,已能满足棉种发芽出苗的要求,可视为棉花地膜覆盖播种适期的温度指标。综合考虑以上因素,结合我省气侯特点,提出棉花地膜覆盖适宜播种期范围为4月5日—15日,一般比露地直播提早5—10天播种为宜。
Different sowing dates have different effects on cotton seedling emergence, seedling disease and growth and development. In a certain range of sowing date, sowing sooner or later mainly affect the length of emergence and seedling stage, less effect on the reproductive process after budding. The sowing premature, severe disease, slow growth, is not conducive to all seedlings strong seedlings, easy to form old seedlings, there premature aging late; sown too late, reducing the effectiveness of plastic film coverage. The temperature is the main condition that determines the sowing date. Statistical analysis shows that there is a high degree of correlation between the 5 cm soil temperature inside and outside the membrane. According to the above calculation, when the 5 cm ground temperature is stable through 11 ℃, the ground temperature of 5 cm below the membrane can reach 13-14 ℃, has been able to meet the germination of cotton seed germination requirements can be considered cotton mulching sowing appropriate temperature indicators. Considering the above factors, combined with the characteristics of the climate in our province, put forward the suitable sowing period of cotton mulching coverage for the April 5 -15 days, generally 5-10 days earlier than the opencast sowing sowing is appropriate.