核桃光合日变化的特征研究

Study on Diurnal Changes of Photosynthetic Characteristics of Juglans regia

以"辽核4号"核桃品种为试材,采用Li-6400便携式光合测定仪,研究了核桃品种的光合日变化规律。结果表明:核桃净光合速率(Pn)日变化呈现"双峰"型曲线,峰值分别出现在10:00左右和16:00左右,且首次峰值比第2次峰值高出48.40%,最大光合速率为6.1125μmol·m-2·s-1,14:00有明显"午休"现象;核桃蒸腾速率(Tr)日变化也呈现"双峰"型曲线,峰值分别出现在10:00左右和14:00左右,且首次峰值低于第2次峰值,最大蒸腾速率为1.7989mmol·m-2·s-1;核桃在午间净光合速率(Pn)和气孔限制值(Ls)均呈现下降趋势,而胞间CO2浓度(Ci)升高,因此非气孔限制因素是影响核桃光合作用的主要限制因素。

Taking Juglans regia ＇Liaohe 4＇ as material,diurnal changes of photosynthetic characteristics were studied by Li-6400 portable photosynthesis analyzer. The results showed that the diurnal changes of the net photosynthetic rate（Pn） in the cultivar exhibited double peak curve at 10.00 and 16：00 respectively and the prime peak was 48. 40% higher than the second peak, the maximum photosynthetic rate was 6. 1125 μmol . m-2 . s -1 significant midday depression phenomenon occurred at 14：00 the diurnal changes of the transpiration rate （Tr） in the cultivar displayed double peak curve at 10：00 and 14：00 respectively and the first peak higher than the second peak,the maximum transpiration rate was 1. 7989 mmol. m 2 . s-1 during midday,net photosynthetic rate （Pn） and stomatal limitation value （Ls） of walnut generally displayed a declining trend, however, intercellular CO2 concentration （Ci） increased. Therefore, non-stomatal limitation was the major factor influencing photosynthesis of Juglans regia.