硅提高高羊茅耐盐性的生理生态机制研究

The improvement of salt tolerance of turf grasses is one of important way to face the secondary salinization of soil in the turf management.Our previous studies have showed that addtion of silicon increased the emergence rate and the rate of survival seedling; however, its physiological and ecological mechanisms are still well-known. In this study, the water culture experiment will be carried out to determine the effect of addition of silicon on seed germination, seedling growth, cell membrane and activity of antioxidant enzymes under the different salt concentration conditions for disclosing the physiological mechanism of higher emergence rate of tall fescue caunsed by silicon. The scanning electron microscopy and Energy Dispersive X-ray will be used to silicon deposit position and deposit amount in leaves, stems and root of tall fescue growing in different salt concentration conditions with pot experiment, and the relationships between silicon deposit amount and biomas, tillers per plant, leaves longth and width, leaf number, and leaf area will be simulated and determined to select morphologic indexes which indicates the higher salt tolerance of tall fescue.This study further determine the response of stomatal structure and density, photosynthetic performance, relative water content and water saturation，soluble sugar and abscisic acid contents, activites of SOD, POD and CAT, N, P, K and Na contents of tall fescue leaves gorwing in the different salt concentration conditions to addition of silicon, disclosing the physilogical and ecological mechanism of stronger salt tolerance of tall fescue caused by addition of silicon, which will provide scientific theory for control secondary salinization of soil by application of silicon in the turf management.

提高草坪草耐盐性是应对草坪绿地土壤次生盐渍化的重要途径之一。前期研究发现，盐生境下硅可提高高羊茅的出苗率和保苗率，然而其生理生态机制尚不清晰。本项目通过水培实验研究不同盐浓度胁迫下硅对高羊茅种子萌发、幼苗生长，细胞膜和抗氧化酶活性的影响，查明硅提高高羊茅种子发芽率的生理机制；采用扫描电子显微镜和能量分散X 射线技术，分析盆栽条件下不同盐浓度胁迫时高羊茅根、茎和叶中硅的沉积位置和沉积量，阐明这种沉积特征与其生产力和坪用性状间（分蘖数、叶宽、叶长、株高、叶片数和叶面积）的关系，确定硅提高坪用高羊茅耐盐性的主要形态学指标；通过分析不同盐浓度胁迫条件下高羊茅叶片气孔结构和密度、光合特征、相对含水量、叶片水分饱和度、可溶性糖和脱落酸含量，SOD、POD和CAT活性，氮磷钾钠含量对硅的响应，揭示硅提高坪用高羊茅耐盐性的主要生理生态机制，为采用硅应对草坪绿地土壤次生盐渍化提供科学理论依据。

提高草坪草耐盐性是应对草坪绿地土壤次生盐渍化的重要途径之一，盐生境下硅可提高高羊茅的耐盐性，然而其生理生态机制尚不清晰。本项目通过水培实验，查清了不同盐生境下高羊茅（抗性强的XD和抗性弱的K31）出苗率、保苗率、株高、分蘖数、叶片数、叶长、叶宽、地上含水量、地上生物量、根系生物量、根冠比、根系总表面积、根系体积、根系总长对硅的响应的分异。添加硅显著提高盐浓度100-200mmol/L时XD的出苗率和保苗率，而添加硅显著提高K31出苗率和保苗率的盐浓度为100mmol/L（P<0.05）；盐浓度≤50mmol/L时添加硅显著增加了XD分蘖数和叶片数（P<0.05）；盐浓度≤100mmol/L时加硅显著增加了XD的株高、叶长、地上生物量，而盐浓度为150mmol/L、200mmol/L时，加硅显著增加了K31的株高、叶长、地上生物量（P<0.05）；添加硅在盐浓度≥200mmol/L时显著增加了K31的地上含水量（P<0.05）；盐浓度≤150mmol/L时，硅显著提高了XD根系生物量，根系表面积和根系总长（P<0.05）；添加硅显著增加了≤150mmol/L时XD的地下地上生物量比，以及盐浓度100mmol/L时K31地上地下生物量比（P<0.05）。明晰了不同盐生境下高羊茅水分调节、渗透调节、酶活性调节，离子调节以及光合特征对硅的响应。盐浓度≤200mmol/L时添加硅显著增加高羊茅幼苗的生物量、SOD、CAT、POD、降低相对电导率、丙二醛、脯氨酸、可溶性糖含量（P<0.05）；加硅显著降低了≥200mmol/L时K31的可溶性糖含量，以及盐浓度250mmol/L时K31的脯氨酸含量（P<0.05）；添加硅均显著降低盐浓度≥150mmol/L时K31和XD的丙二醛含量（P<0.05）；添加硅显著提高盐浓度≤100mmol/L时XD的Pn、Gs、Ls，降低Ci、Tr（P<0.05）。添加硅显著提高盐浓度＜50mmol/L时K31的 Pn、Gs、Ls，降低了Ci、Tr（P<0.05）；添加硅显著降低盐浓度150mmol/L和200mmol/L时高羊茅体内Na+含量，而显著增加高羊茅体内K+含量（P<0.05）。上述结果表明，硅通过提高盐生境下高羊茅体内抗氧化系统酶活性，改善渗透调节物质含量，增加对水分和矿质元素的吸收利用，保持体内离子稳态的途径，从而维持较高的叶片光合