Abstract
Using “seed-mat” consisting of a molded rice-hull mat with hardened rice seeds and cover soil glued on it,we are trying to raise rice seedlings without nursery boxes. The objective of this paper is to elucidate the kind of sheet for the covering of nursery bed,and the amount of cover soil and water supply at the beginning of seedling raising appropriate for no-box nursing. The molded rice-hull mat was placed on plain-woven sheets,nonwoven sheets,perforated sheets,doubled perforated sheets and polyethylene multch. Water absorption and retention of the mat were better on the less water-permeable sheets. Seedling emergence rate was higher and dry weight of seedlings was heavier on the less permeable sheets. Because polyethylene mulch could cause poor seedling emergence if water supply is excess,seedlings were raised on polyethylene mulch with or without low-density holes with cover soil of 300 g, 400 g and 500 g, and water supply of 1.5L and 3 L. Seedling emerged hardly with 3 L of water,and 500 g of soil on the non-perforated sheet,whereas seedlings emerged and grew well with 1.5L of water. Seedling length and dry weight seemed to be better on the non-perforated sheet than on the perforated sheet. These results suggest that non-perforated polyethylene mulch,covered with 300 g to 400 g of soil and 1.5 L of water is appropriate for no-box nursing.
