Growth of tomato (Lycopersicon esculentum Mill.) plug transplants in a closed system at relatively high air current speeds -- a preliminary study -

摘要

Growth and its uniformity of tomato (Lycopersicon esculentum Mill., cv. Momotaro) plug transplants, with fully expanded cotyledon, in 128-cell plug trays were investigated in the wind tunnel at air current speeds of 0.5 and 1.0 m s~(-1). The plug transplants were grown at PPF of 375 #mu#mol m~(-2) s~(-1) as measured at the canopy surface and provided by fluorescent lamps, with air temperature of 26 deg C, and CO_2 concentration of 1000 #mu#mol mol~(-1). The results showed that dry mass of the plug transplants on Day 6 at air current speed of 0.5 m s~(-1) was similar to that at 1.0 m s~(-1) (119 +- 35 and 120 +- 39 mg per transplant, respectively). Net photosynthetic rates of plug transplants on Days 2, 4 and 6, respectively, were 10, 16 and 24 #mu#mol m~(-2) s~(-1) at 0.5 m s~(-1); and 7, 15 and 23 #mu#mol m~(-2) s~(-1) at 1.0 m s~(-1). The differences in CO_2 concentration between windward and leeward end of the plug tray at air current speeds of 0.5 and 1.0 m s~(-1) were about 2 and 1 #mu#mol mol~(-1), respectively. The differences in water vapor concentration were 0.7 and 0.4 mmol mol~(-1), respectively. Dry mass of plug transplants was significantly lower at rear half of the plug tray than at front half of the plug tray. The reason for this significant difference requires further investigation.