Effect of Root Zone Warming on Root Growth of Greenhouse-Grown Cucumber

摘要

The experiment was conducted to investigate the effects of rool zone warming on growth of cucumber (Cucumis sativus L.) roots in a greenhouse during winter season. The rool zone was warmed up by 45 deg C water (lowing through the pipe system buried 35 cm deep from the ridge. Soil temperature treatments were 20 deg C, 25 deg C, 30 deg C at 20 cm depth and non-warming. The minimum air temperature during the nighl was set at 14 deg C and the maximum air temperature during the day was at 28 deg C in alltreatments. The cucumber seedlings were planted on Apr. 7. 1994. The average soil temperature in a month after planting at 20 cm depth were 18.2, 21.3, 25.7, and 30.2 deg C at control, 20, 25, and 30 deg C treatments, respectively. The cumulative soil temperature during the same period was 546, 639, 771, and 906 deg C at control, 20, 25, and 30 deg C treatments, respectively. Rooting of the transplanted seedlings was hastened by the root zone warming. In addition, development of lateral roots and growth of hair roots were significantly promoted in 25 and 30 deg C treatments. The water uptake of encumber plants proportionally increased with increasing soil temperature. The amount of xylem exudate collected 30 days after planting for 2 h was 29.0, 34.6,48.6, and 45.7 mL at control, 20, 25, and 30 deg C treatments, respectively.