Water use and growth of rice (Oryza sativa L.) cultivated on saline soils with various amounts of soil and water

Salinity stress as well as water stress impairs crop production in saline soil. This study was conducted to examine the relationship between water use, which may depend on root growth, and dry matter production in rice. Paddy soil of 1~10 kg was put in appropriate pots. A definite amount of NaCl solution corresponding to 50% of soil weight was applied to establish saline soil containing NaCl at 0 (control), 1 and 2 g kg^-1. Seedlings of salt-tolerant cultivar IR4595-4-1-13 and normal cultivar Nipponbare were transplanted to the pots which were not irrigated thereafter. Shoot and root dry weight on the day when leaf ceased to elongate increased as soil amount increased, and decreased as soil salinity increased. Shoot growth decreased with the increase of plant sodium concentration. The amount of soil water increased with the increase in soil weight and salinity, indicating that evapotranspiration was decreased due to soil salinity. Shoot dry weight increased in proportion to the evapotranspiration. Soil water content was low in the control which had vigorous root growth, and high in the high-salinity soil which had poor root growth. It was concluded that rice shoot growth on saline soil increased in proportion to evapotranspiration and poor root growth may be responsible for reduced evapotranspiration.