薏苡拔节期光合作用日变化特征研究

Diurnal Changes in Photosynthetic Rate of Job’s-Tears (Coix lacryma-jobi) at the Jointing Stage

以西农薏苡二号为材料,利用LI-6400型便携式光合测定仪,研究拔节期薏苡光合速率的变化及其环境影响因素。结果表明,薏苡净光合速率为10.4￣29.8μmol/(m2·s),净光合速率、气孔导度和蒸腾速率的日变化均呈单峰曲线,净光合速率的峰值出现在上午11:00时,中午11:00￣15:00时的平均净光合速率比上午9:00￣11:00时和下午15:00￣17:00时的平均净光合速率高7.8μmol/(m2·s)和6.6μmol/(m2·s)。气孔导度和蒸腾速率的峰值均出现在15:00时。影响光合速率的主要因素是光照和温度。薏苡光合作用的最适温度为31￣37℃,相对湿度33%￣44%,光合有效辐射在470￣710μmol/(m2·s)。

With the help of LI-6400 portable photosynthesis analyzer, we investigated the diurnal changes of photosynthetic rate and environmental effect in Xinong NO.2 Job＇s-tears （Coix lacryma-jobi） at the jointing stage. A net photosynthetic rate （NPR） within the range of 10.4-29.8μmol/（m^2·s） was observed. The net photosynthetic rate, stomatal conductance and transpiration rate showed a single peak curve pattern with no pronounced decline at noon. A peak value of NPR occurred at 11：00 h and the average photosynthetic rate during 11：00-15：00 h was higher than that of 9：00-11：00 and 15：00-17：00, by 7.8μmol/（m^2·s） and 6.6μmol/（m^2·s） respectively. Diurnal maximal value of stomatal conductance and transpiration was seen at 15：00 h. Temperature is the main factor affecting photosynthetic rate. Job＇stears exhibited an optimal photosynthesis at the temperature of 31-37℃, relative humidity of 33%-44% and a photosynthetically active radiation of 470-710μmol/（m^2·s）.