Establishment of labor-saving, low-cost cultivation combined with sparse planting of paddy rice [Oryza sativa] and short-term seedlings

Sparse planting of rice seedlings at 11-15 hills per m2 (row distance 30cm, hill distance 22.5-30cm) was investigated using short-term seedlings grown by a week shorter than young seedlings to save labor and decrease the production cost of rice cultivation. l. Sparse planting with young seedlings delayed the heading and maturity times by about 1 day compared with standard planting (hill distance 15cm), but yield, visual quality and protein content of hulled rice were almost the same as those obtained by standard planting. 2. Sparse planting with short-term seedlings delayed the heading and maturity times by 1 - 2 days compared with standard planting with young seedlings, but yield, visual quality and protein content of hulled rice were almost the same as those for standard planting. 3. Sparse planting (hill distance 30cm) required about 10 nursery boxes per 10a, which was about 60% of that of standard planting for rice transplantation, and this had a labor- and cost-saving effect. Use of short-term seedlings also allowed further labor-saving. 4. Yield in the basal dressing of whole prescribed nutrients with controlled-release fertilizer was lower than that in the split dressing with quick-acting fertilizer. However, there was not much difference in the required number of days for rearing of seedlings, and planting density. Therefore sparse planting combined with short-term seedlings and the basal dressing of whole prescribed nutrients with controlled-release fertilizer was seemed to be more labor-saving. 5. For transplantation with a hill distance of about 30cm, it is necessary to use a rice transplanting machine adapted for sparse planting. In the case of a common rice transplanting machine it was possible to save labor and cost according to plant density by adjusting the maximum hill distance.