Effects Of Silicon And Potassium On Growth And Physiological Characteristics Of Kentucky Bluegrass Under NaCl Stress

Soil salinization is a global problem that affects the agricultural production and environmentbeautification.It is necessary to plant lawn in saline-alkali soil because of the need for citygreening and environmental protection. Kentucky bluegrass is low plant with its strong resistance,wide adaptability, long green period, good quality and beautiful lawn. It plays an important role tobeautify and green the city, improves the ecological environment and the quality of the people’slife. Kentucky bluegrass has been common used in the northern landscaping and movement field.It is an excellent cold season turf grasses and fully affirmed the people.In this paper, we use two varieties of kentucky bluegrass ’Barun’ and ’Midnight’as researchmaterial to study the growth and stress-resistance physiological characteristics of the effects ofdifferent concentrations of KNO₃and K₂SiO₃under NaCl stress of kentucky bluegrass. We set9different treatments and use hydroponic salt stress.The main results were showed as the followingconclusions:1. NaCl stress made the ratio of Na⁺/K⁺unbalance and severely inhibited the growth of thekentucky bluegrass, the plant height, fresh weight and dry weight decreased significantly;NaClstress reduced the content of chlorophyll and water use efficiency in leaves of kentucky bluegrass,it made kentucky bluegrass photosynthetic parameters of Pn, Gs and Tr decrease, Ci increase.Long time NaCl stress made POD, SOD, CAT activity of kentucky bluegrass leaf decrease, butalso damage cell osmotic of kentucky bluegrass, the intracellular concentration of soluble protein,soluble sugar, proline and the amount of electrolyte leakage increased, membrane lipidperoxidation enhance. Comparison of the growth and physiological indices of rate, we concludethat the kentucky bluegrass varieties ’ Barun ’salt tolerance better than’ Midnight ’salt tolerance.2. Under NaCl stress, the effects of different concentrations of KNO₃and K₂SiO₃canalleviate the damage caused salt of kentucky bluegrass, it can be summarized as follows:1)Because of adding KNO₃and K₂SiO₃under salt stress, the imbalance of the proportion of Na⁺/K⁺is improved, it also improve metabolism in vivo environment and reduce the toxicity caused bysalt stress on Kentucky bluegrass.2) Under salt stress, silicon can form a layer of silicon layer onthe plant cell wall to prevent the loss of water, which makes relative water content and water use efficiency of the leaf improve, plant osmotic adjustment ability enhance, electrolyte leakage andmembrane lipid peroxidation decrease.3) Adding KNO₃and K₂SiO₃is conducive to the synthesisof chloroplast and of leaf tissue internal organic osmolytes, improves the adaptive capacity ofkentucky bluegrass chloroplast to salt stress, reduces the degree of toxicity of salinity onchloroplast, increases chloroplast photosynthetic capacity.4) The addition of KNO₃and K₂SiO₃increased the activity of POD, CAT and SOD, decreased reactive oxygen in chloroplastaccumulation, made various enzymatic reaction normal, alleviate the harm of salt stress.In this study, the alleviation of6mmol·L^-1K₂SiO₃on Kentucky bluegrass salt stress effect isthe best, the second is9mmol·L^-1K₂SiO₃and12mmol·L^-1KNO₃,6mmol·L^-1KNO₃eased slightlyto NaCl stress, but no significant differences.The alleviation to salt stress effect of3mmol·L^-1K^-12SiO₃,3mmol·LK₂SiO₃（except for potassium ions） and18mmol·L^-1KNO₃are differentbecause of the different physiological index. At the same time treatment of low concentration Si,addition of K⁺did not increase the content of chlorophyll, Kentucky bluegrass’ water useefficiency, net photosynthetic rate and the activities of antioxidant enzymes, the alleviation ofKentucky bluegrass salt stress is mainly Si function alone, with little relationship to K⁺. The sameconcentration of K⁺, mitigation effect of K₂SiO₃on salt stress is better than the KNO₃. This may bebecause the synergistic effect of potassium and silicon.