Downton W J S, Grant W J R, Loveys B R
CISRO Division of Horticultural Research, GPO Box 350, Adelaide, 5001, Australia.
New Phytol. 1987 Jan;105(1):71-80. doi: 10.1111/j.1469-8137.1987.tb00111.x.
Field studies of the gas exchange of Riesling grape vines (Vitis vinifera L.) showed large diurnal changes in net photosynthesis during the period of rapid sugar accumulation by fruit. The onset of the decline in photosynthesis occurred earlier in the day for vines without fruit. Decreases in photosynthesis were approximately proportional to changes in stomatal conductance. Despite the accompanying large changes in stomatal conductance, changes in intercellular CO concentration were small and mathematical analysis showed that stomatal changes accounted for only 20 to 40% of the change in assimilation rate. The CO compensation point, oxygen enhancement of photosynthesis, light and temperature responses of the leaf did not vary throughout the day. Stimulation of photorespiration was therefore not responsible for the non-stomatal inhibition of photosynthesis. No obvious correlation existed between the decline in leaf photosynthesis and daily changes in leaf water potential. A field study of Colombard grape vines revealed that frequently watered vines which had received irrigation 2 d prior to measurement showed little change in photosynthetic rate over the day compared with vines subjected to a more usual watering cycle, which had last been irrigated 18 d prior to measurement. Possible non-stomatal factors responsible for the reduction in photosynthesis during the day are discussed.
对雷司令葡萄藤（葡萄属）气体交换的田间研究表明，在果实快速积累糖分期间，净光合作用存在较大的昼夜变化。对于无果的葡萄藤，光合作用下降的开始时间更早。光合作用的下降大致与气孔导度的变化成比例。尽管气孔导度随之发生了很大变化，但细胞间二氧化碳浓度的变化很小，数学分析表明，气孔变化仅占同化率变化的20%至40%。二氧化碳补偿点、光合作用的氧气增强、叶片的光响应和温度响应在一天中没有变化。因此，光呼吸的刺激并不是光合作用非气孔抑制的原因。叶片光合作用的下降与叶片水势的每日变化之间没有明显的相关性。对鸽笼白葡萄藤的田间研究表明，与测量前18天进行过更常规浇水周期的葡萄藤相比，在测量前2天接受灌溉的频繁浇水的葡萄藤，其光合速率在一天中变化不大。文中讨论了可能导致白天光合作用降低的非气孔因素。
