Effect of releasing cotton seedling by turn-over plastic film on micro-ecological system in plastic-mulched cotton field

The effect of turn-over plastic film from narrow row(cotton seeding row) to wide row(space between cotton seedling row) to release cotton seedling on microecological system was investigated using comparison with withholding and holing plastic film to release seedling(control). The results show that effective coverage rate of plastic film increases by 30% ~ 45% in turnover plastic film to release cotton seedling, compared with withholdingholing plastic film to release seedling, as it strengthens regulating effect on moisture-temperature in cotton fields. After seedling release by turn-over plastic film, the soil temperature increases in wide rows, and become stabe in narrow row; the soil water content reduces below that in the control; but steam movement increases compared with the control. This is beneficial to preventing seedlings from outgrowth and developing of microbes which strengthens root nutrient absorption, but more importantly, to reducing soil bulk density by 0.12 g·cm^-3. Light reflection, light strength near soil surface increase and cotton plant photosynthetic rate increases as well, which prevents aphis gossipii glover migration.