水热胁迫对3个树种苗期部分光合特性的影响

Effects of High Temperature and Soil Water Stress on Photosynthetic Responses of Three Tree Species

在人工气候箱中40℃高温下设计3个土壤水分梯度(分别为田间持水量的70%、55%、40%,即正常水分、轻度胁迫、重度胁迫),采用盆栽试验,模拟干热河谷车桑子(Dodonaea viscosa)、赤桉(Eucalyptus camaldulensis)、大叶相思(Acacia auriculiformis)苗期的光响应曲线和CO2响应曲线。结果表明:3个树种苗期的最大净光合速率均随水分胁迫加剧而下降,羧化效率、光呼吸速率均为先升后降,车桑子和赤桉各指标变化平缓,大叶相思对胁迫最为敏感。非直角双曲线模型较好地拟合了3个树种的光合特征参数。

Three kinds of seedlings were exposed to watering regimes（ 70%,55% and 40% of filed water holding capacity） under short-term high temperature（ 40 ℃） to study the changes of the photosynthetic light and CO2 response curve in dry-hot valley. The results showed that the maximum net photosynthetic rate（ Pmax） were decreased with the soil water content decreased in three seedlings under short-term high temperature; the carboxylation-efficiency（ CE） and photo-respiration rate（ Rp） were increased firstly and decreased under short-term high temperature with soil water content decreased. The photosynthesis indices of Dodonaea viscose and Eucalyptus camaldulensis were changed slowly and gently,however,the photosynthesis indices of Acacia auriculiformis were changed sensitively with soil water content. The results fitted by nonrectangular hyperbolic model in three kinds of seedling.