Thermal Preservation Effect of Multi-Film Covering and Heating Wire in Plastic Greenhouses in Winter

Tests were conducted on temperature variation pattern in winter in the standard plastic greenhouse under different treatment using inner plastic greenhouse, tunnel, heat preservation cover material, plastic mulch and heating wire. The experiment results showed that by adding each covering, air temperature could increase 1～2 ℃ at night and this effect more obvious during daytime. Using heating wire in the tunnel, the heating effect is better than that of covering. With multi film covering and by using heating wire when needed is an effective way to grow tomato and other thermophile vegetables during whole winter.