土壤盐分胁迫对假俭草、结缕草光合作用的影响

对两种暖季型草坪草假俭草和结缕草在不同浓度土壤盐分胁迫下的光合作用变化作了初步研究。结果表明，土壤盐分胁迫对两种暖季型草坪草的Pn、Ci、Gs、Tr、WUE和呼吸速率产生了显著的影响：随盐分胁迫程度的加大，Pn、Gs逐渐下降，其中Pn的降低速度假俭草大于结缕草，而Gs的降低速度结缕草大于假俭草；Ci的变化，盐分胁迫下假俭草与对照相比得到了明显的增加，结缕草则相反，表现为随土壤盐分胁迫强度的增加不断下降；假俭草净光合速率降低是由非气孔因素所致，结缕草是由气孔因素所致，认为两种草坪草净光合速率下降的内在原因可能是因光抑制和光氧化现象所引起；两种草坪草随土壤盐分胁迫的加强，Tr均呈下降趋势，两个草种不同盐分胁迫下的蒸腾速率下降速度大小与气孔导度一致；两种草坪草由于耐盐能力不同，WUE变化趋势不同．假俭草随盐分胁迫不断下降，而结缕草则相反，均有所增加，这一点与两者的耐盐能力相一致。

Effects of Soil Salt Stress on the Photosynthesis of Zoysiagrass and Centipedegrass

Photosynthesis changes in two warm-season grasses Centipedegrass and Zoysiagrass under soil salt stress with different concentration were studied. The results showed: effects of soil salt tress on the Pn, Ci, Gs, Tr, WUE and respiratory rate were remarkable. With the deepened soil salt stress, Pn and Gs trended to decreased gradually but the decreasing speed of Pn in Centipedegrass was higher than that in Zoysiaagrass, on the contrary, the decreasing speed of Gs in Zoysiagrass was higher than that in Centipedegrass. The content of Ci in Centipedegrass was higher with soil salt stress than that in the control, while on the contrary in Zoysiagrass. These showed the decrease rate of photosynthesis in Centipedegrass resulted from the non-stomatal factor, while in Zoysiagrass resulted from the stomatal factor. The internal cause of the decrease of net photosynthesis rate might be photo-inhibition and photo-oxidation. With the deepened soil salt stress, Tr trended to decrease in the two grasses, the decreasing speed of Tr accorded with Gs under salt stress with different concentration. The ability of salt tolerance and the changing trend of WUE were different in the two turfgrasses, with the deepened soil salt stress, the ability to salt tolerance and WUE trended to decrease gradually in Centipedegrass, while on the contrary in Zoysiagrass, these accorded with the ability of salt tolerance of the two turfgrasses.