Effects of Day Length on Gas Exchange Characteristics in Crassulacean Acid Metabolism Plant, Dendrobium Ekapol cv. Panda

[摘要] Effects of growth day length on gas exchange characteristics were investigated in a crassulacean acid metabolism (CAM) plant, Dendrobium Ekapol cv. Panda. Long (16h) and short (10h) day lengths were treated for 57 to 60 days in a growth chamber set at day/night temperatures of 30/25°C. As a control, plants were grown under natural conditions (light period was 12h). The data showed that the diurnal CO2 exchange of D.Ekapol was classified as typical crassulacean acid metabolism type, an obligate CAM. The CO2 balance of each phase was affected by the day length treatments. The CO2 balances of short-day-length grown plants were increased in phase 1, whereas those of long-day-length grown plants were increased in phases 2 and 4. The CO2 balance of whole day and diurnal malate fluctuation was increased in natural and short-day-length grown plants. The activity of phosphoenolpyruvate carboxylase did not response to the day length treatments. However, susceptibility of phosphoenolpyruvate carboxylase to malate was detected clearly in phase 4 and at the beginning of phase 1 under different day length. It was suggested that the difference between treatments was related to the changes in the CO2 exchange rate in those phases.

[学科分类] 农业科学（综合）

[关键词] Crassulacean acid metabolism;拡散伝導度;Day length;CAM型光合成;Dendrobium Ekapol cv;デンドロビウム (Dendrobium Ekapol cv. Panda);Panda;日長;Leaf conductance;ホスホエノールピルビン酸カルボキシラーゼ;Malate susceptibility;リンゴ酸感受性;Phosphoenolpyruvate carboxylase