Changes of Carbohydrates in Pepper (Capsicum annuum L.) Leaves and Flowers under Different Irradiance and Night Temperature Regimes

Abstract

We investigated the effect of night temperature and irradiance in changes of carbohydrates concentrations in peppers to elucidate the relationships between environmental conditions and amount of carbohydrates. A factorial experiment was conducted with two levels of irradiance conditions, 30 and 180 Wm-2, and two levels of night temperature conditions, 13±1 and 18±2℃. The amount of carbohydrates increased with increasing irradiance. Change of carbohydrates concentrations in leaves were constantly maintained regardless of irradiance levels during night time, in comparison with carbohydrates concentrations in flowers. This suggests that carbohydrates formed in the leaves were preferentially used to maintain leaves and then carbohydrates remaining in leaves might be expected to translocate to sink organs, such as flowers. In peppers, the critical temperature is generally 18℃ for flowering and fruit setting, but when the plant is under low irradiance, normal development of flowers was expected to be possible by controlling the night temperature below the critical value. However, low night temperature combined with high irradiance caused swelling of the flowers which might decrease the viability and germinability of the flowers.