关键词: 叶用莴苣, 叶用莴苣, 高温, 抽薹, 内源激素

Abstract: By using the method of nutrient solution culture and simulated water stress with PEG6000, the effects of two K treatments (3, 0.05 mmol/L) and three water conditions (non-water stress, mild and moderate water stress condition) on physiological and photosynthetic characteristics of sugarcane shoots were studied. Results showed that with the rising of water stress, the biomass, leaf net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr) and the leaf relative water content (RWC) of both the normal and the low K treatments decreased, but the decrease range under the normal K supply was lower than that under the low K supply. Intercellular CO₂ concentration (Ci) went up first and then down under the normal K supply, but declined first and then increased under the low K supply. The water use efficiency (WUE), free proline (Pro) and malondiadehyde (MDA) contents increased with the rising of water stress. Under non-water stress, normal K supply had a little effect on the biomass, Pn, Gs, Tr and the content of Pro, compared with low K supply. Under the water stress, normal K supply increased the biomass, leaf K content, Pn, Gs, Tr and the content of Pro significantly, while reduced the accumulation of MDA. It indicated that normal K level could promote the growth and photosynthesis of sugarcane shoots and reduce the negative effect under drought stress.