Effect of Various Ranges of Controlled Air Temperatures on the Early Growth of Sago Palm (Metroxylon sagu Rottb.) Seedlings

抄録

The present study evaluated the effect of various ranges of controlled air temperatures (day-night air temperature; 23-15°C, 27-19°C, 31-23°C, and 35-27°C) on the growth and nutrient status of sago palm seedlings. Seedlings grown at the air temperature of 31-23°C displayed the highest plant length increment, while at the highest air temperature (35-27°C), the seedlings showed the lowest plant length increment. Delay in new leaf emergence was more pronounced at the lower air temperatures (23-15°C and 27-19°C) than at the higher ones (31-23°C and 35-27°C) and the production of new leaves declined when the air temperature decreased. The highest and lowest temperatures reduced the SPAD values almost simultaneously but the reduction was more pronounced at the highest temperature. The maximum leaf area was observed at the air temperature of 31-23°C, followed by 35-27°C. The seedlings showed a higher value of shoot dry weight as the air temperature increased, up to 31-23°C when the maximum value of the shoot dry weight was recorded. The highest (35-27°C) and the lowest (23-15°C) air temperatures inhibited root growth, though the number of adventitious roots was not affected. The maximum value of the root dry weight was recorded at the air temperature of 27-19°C. Growth at the air temperature of 31-23°C led to the highest uptake of N, P, K, and Ca, while the uptake of Mg was the highest at 27-19°C. The optimum air temperature range required for adequate growth is probably within 31 to 23°C. In this air temperature range, the maximum number of leaflets, leaf area, and uptake of N, P, K, and Ca could be obtained.