Diurnal and seasonal stomatal behaviors of rice plants grown in controlled environment

Abstract

The diurnal and seasonal changes of stomatal movement of rice (Oryza sativa L.) plants were studied in the controlled environment. The results showed that the diurnal patterns of stomatal behavior were shown in the seasonal fashions. A decreasing trend of stomatal diffusive conductances were observed in the vegetative growth phase followed by a dramatic increase of conductance began at Leaf 16 stage, which is concurrent to the panicle formation period. Stomatal conductances were dropping after heading as plant aged. Such phenomenon can be clearly discerned by plotting the data at 0800, 1400 and 2000 h. It is suggested that the indicated behavior of stomata may be a compromise of its own economy by optimizing photosynthetic capacity in the sacrifice of transpiration loss because of the elevated demand of photosynthetic assimilates for reproduction. 本文旨在觀測水稻(Oryza sativa L.)葉片氣孔在控制環境下每日遇期性及季節性之變化。結果顯示，水稻葉片在恆常狀況下具有週期性之氣孔運動，且此種每曰週期之行爲具有季節性變異。在營養生長期間，氣孔傳導度隨株齡（以葉齡表示）之增加呈現下降趨勢，直至第16齡期間突然明顯地升高。由於此時期恰爲穗形成期，故此一現象可能爲稻株追求高光合成需要所作之自身調節。氣孔傳導度自抽穗開花後便逐漸降低。