摘要
对自然生长在沙丘上的旱生植物沙拐枣、梭梭和防护林带的中生植物沙枣和杨树在大气干燥,土壤干旱下的光合响应机制进行了比较研究。结果表明,4种植物气孔导度的变化主要受空气相对湿度和饱和水蒸汽压差的影响,气孔的关闭是对空气湿度的急剧降低、饱和水蒸汽压差的急剧升高的前馈反应,只是响应程度不同。沙拐枣、沙枣和梭梭具有高光合,杨树为低光合。沙拐枣、梭梭、沙枣的光合速率日变化曲线呈双峰型,有午睡现象出现;杨树的呈单峰型。沙拐枣的午睡主要由非气孔因素引起,光化学效率的降低可能是非气孔因素之一;梭梭的光合午睡也是由非气孔因素引起。而气孔关闭是沙枣光合午睡的一个原因。沙枣的光合速率的日变化曲线与气孔导度的变化呈平行下降趋势,其他3种植物没有表现此现象。4种植物在强光时都发生了不同程度的光抑制,只是出现的时间不同;沙拐枣和沙枣出现低谷后恢复很快,梭梭和杨树起伏比较大,杨树恢复相对较慢,但到晚上都得到恢复。4种植物对沙区高光强表现出不同程度的可调控的保护性机制。
The response mechanism of photosynthesis of Haloxylon ammodendron,Calligonum mongolicum and Elaegnusn Angastifolia, Populus hosiensis under drought stress were comparatively studied. The result showed that the changes of stomatal conductance were mainly controlled by air relative humidity and vapour pressure deficiency. The closure of stomata was the response of rapid decrease of air relative humidity and increase of vapour pressure deficiency. Four plants all showed this feature to different degree. Haloxylonammodendron, Calligonum mongolicum and Elaegnusn Angastifolia have higher photosynthesis rate, however, Populus hosiensis has lower one. The diurnal changes of photosynthesis of Haloxylonammodendron, Calligonum mongolicum and Elaegnusn Angastifolia showed the type of two-peaks and Populus hosiensi showed one-peak. The midday depression of photosynthesis of Haloxylonammodendron, Calligonum mongolicum resulted mainly from non-stomatal factors. The decrease of photochemical efficiency was a possible non-stomatal factor for Calligonum mongolicum. The midday depression of Elaegnusn Angastifolia resulted from the closure of stomata. The diurnal change of photosynthetic rate and stomatal conductance has the same tendency. High irradiances caused the photo-inhibition to the four plants. Calligonum mongolicum and Elaegnusn Angastifolia recovered very quickly, but that of Haloxylonammodendron and Populus hosiensis fluctuated greatly and recovered slowly. However they all recovered in the evening. They all express different adjustable protection mechanism to high irradiances in desert under drought stress.
出处
《中国沙漠》
CSCD
北大核心
2005年第4期587-592,共6页
Journal of Desert Research
基金
国家重点基础研究发展规划项目(G2000048704
G2000018600)资助
