Since 1982, the technique of using cold screen and polyethylene membrane as double arch covers for breeding rice seedlings on the upland nursery has been Studied. The results showed that the cold screen was suitable ofr breeding rice seedlings on the upland rice nursery. The range of the network necessary was between 10 and 12. The light transmission ratio and the wind reducing rate of the network in above range are 85—88% and 14—23% respectively. The quality of spray for controlling weed and diseases was satisfactory. The results of the field and middle experiments carried out in Jilin and Heilongjiang provinces proved that the technique was characterized by fine warmth keeping, light transmission and wind-proof efficiencies. The method was not only Simple but also Safe and applicable. It increased the seedling, s resistance to damping-off and withered shoot of rice plant, and provided uniform and healthy seedling for transplant.
The technique is most suitable for breeding seedlings on upland Nursery in coid area, especilly for breeding seedling of middle and small shoot.