Abstract
Rooted cuttings of carnation, cultivar ‘Yosooi’, were planted 12 times a year at the intervals of about a month from Jan. 26, 1969. They were grown in a greenhouse. Two to three weeks after planting the plants were pinched, and three lateral shoots were allowed to grow on each of the plants. Water was applied to them by subirrigation method. The amount and feature of consumptive water use of the carnation plants, thus cultured, were studied.
The duration from pinching to flowering time, the fresh weight and leaf area of a shoot at the flowering time changed with the cultivation season, having drawn wavelike curves. They were the smallest when the plants were pinched in May, and were the greatest when pinched in October.
The total amount of transpiration during the period from pinching to flowering changed seasonally. and that of water consumption (transpiration plus soil evaporation) changed also seasonally. The curves of their seasonal changes had two peaks and two bottom levels. When the plants were pinched in June and October, the total amount of transpiration and that of water consumption showed the upper extremes. They became the lowest when the plants were pinched in August and January. The plants pinched in June showed the greatest amount of water consumption of 523mm, and those pinched in January showed the smallest one, 375mm.
The amount of transpiration per day increased as the plants grew, and it was greatly affected by weather conditions. Therefore, the amount of transpiration changed in parallel with that of pan evaporation. The amount of transpiration per leaf area in the plants which were at the middle stage of growth, budding stage, showed seasonal change in parallel with that of pan evaporation. The maximum amount of transpiration per leaf area was observed in mid August. The amount of transpiration per day in that time was 2.24mm. The minimum one, 0.35mm per day, was observed in mid December.
The ratio of transpiration per leaf area to pan evaporation (transpiration ratio) of the plants at the middle stage of growth was smaller in spring, and it was 0.30-0.35cm3/cm2•cm. In summer, the transpiration ratio was 0.40 to 0.45cm3/ cm2•cm. In autumn and winter it was the greatest in the year, and was 0.50cm3/ cm2•cm. On the basis of the transpiration ratio, daily amount of water consumption of greenhouse carnations in various seasons were calculated.
