抄録
Water consumption of spring wheat, potatoes, sugar beet, and onions grown in a lysimeter placed inside of a green house was measured using the change of soil water content profiles. The results obtained were summarized as follows :
1) Water consumption per day of each crop gradually increased with crop growth up to August. The increases of water consumption pattern and their volume, however, were different among these crops. Spring wheat showed the largest water consumption,and it reached 12mm«d_1 on July. An irrigation after water stress increased water consumption of potatoes.
2) Total water consumption from initial stage to August showed following order : spring wheat > sugar beetpotatoes > onions. Water consumption of potatoes grown in Volcanic ash soil was about 10%more than that grown in Brown forest soil. There were no differences in water consumption between the wet and dry soil water treatments.
3 ) Soil chemical properties influenced dry matter production of crop and top—root ratio. And it is considered that increase of top—root ratio increased evapotranspiration. That may be one of important facters to explain the difference in total water consumption through the grown period and Apparent Water Requirement (defined as amount of water consumed to produce unit dry weight) between soils.
4 ) Apparent Water Requirement was higher in the dry treatment than the wet one. Therefore this suggests that the crops wasted water in the dry treatment.
