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以巨桉幼树为对象,研究了不同施肥水平(每株施用含N、P2O5和K2O各15%的复合肥0、90、180和270g)下巨桉叶片的气孔导度(Gs)、胞间CO2浓度(Ci)、净光合速率(Pn)、蒸腾速率(Tr)、水分利用效率(WUE)和叶面饱和水汽压亏缺(Vpdl)日变化,及其叶绿素含量变化,探讨巨桉光合特性与施肥和环境因素之间的关系.结果表明:各处理巨桉叶片Pn的日变化呈“单峰”形曲线,峰值出现在14:00,未出现光合“午休”现象;Gs、Tr和Vpdl的日变化与Pn相同,而Ci的最低值出现在14:00;WUE的日变化呈“双峰”形曲线,峰值分别出现在10:00和14:00.与对照处理相比,施肥处理叶片Gs、Pn、Tr、WUE及叶绿素a、叶绿素b和总叶绿素含量平均值分别增加4.6%～15.9%、7.8%～21.8%、4.8%～11.6%、3.2%～8.8%、15.5%～62.0%、14.5%～44.5%和15.3%～57.1%,且随施肥量的增加而增加;而叶片Ci和Vpdl平均值分别降低1.7%～4.6%和6.4%～15.2%,且随施肥量的增加而降低.气温、相对湿度(RH)和光合有效辐射(PAR)与Gs、Pn和Tr,Gs与Pn和Tr均显著相关.施肥可以促进巨桉生长、提高水分利用效率和增加生物固碳能力;气温、RH、PAR和Gs是影响巨桉光合作用和蒸腾作用日变化的主要因素.
In this study, the stomatal conductance (Gs) of E. grandis under different fertilization levels (0, 90, 180 and 270 g with 15% N, P2O5 and 15% (Ci), net photosynthetic rate (Pn), transpiration rate (Tr), water use efficiency (WUE) and leaf water vapor pressure deficit (Vpdl) The results showed that the diurnal variation of Pn in leaves of Eucalyptus grandis showed “unimodal” curve with the peak at 14:00 and no photosynthesis “midday break ” appeared. The daily changes of Gs, Tr and Vpdl were the same as that of Pn, while the lowest value of Ci appeared at 14:00. The diurnal variation of WUE was “bimodal” and the peaks appeared at 10:00 and 14:00 respectively. Compared with the control, the average values of Gs, Pn, Tr, WUE, chlorophyll a, chlorophyll b and total chlorophyll content increased by 4.6% -15.9%, 7.8% -21.8%, 4.8% -11.6%, 3.2% 8.8%, 15.5% -62.0%, 14.5% -44.5% and 15.3% -57.1%, respectively, and increased with the increase of fertilization rate. The average value of Ci and Vpdl decreased by 1.7% -4.6% and 6.4% -15.2% , And with the increase of fertilizer (RH) and photosynthetically active radiation (PAR) were significantly correlated with Gs, Pn and Tr, Gs and Pn and Tr fertilization could promote the growth of Eucalyptus grandis, improve water use efficiency and increase bio-carbon sequestration Ability; temperature, RH, PAR and Gs were the main factors affecting diurnal changes of photosynthesis and transpiration of E. grandis.