Studies On The Evaluation Of Turf Quality And Physiological And Biochemical Mechanisms Of Cold Resistance In Bermudagrass Cultivars

To understand the relationship and its variation between bermudagrass cultivars with cold resistance, physiological and biochemical substance,Provide a theoretical basis and foundation for the Hunan transitional turfgrasses winter maintenance management,at the same time, providing a theoretical reference for the future introduction of exogenous plant growth regulators control and prolong the lawn green period. In this study,we use different Bermudagrass turf grass in Hunan province is widely used as the test material, such as four hybrid bermudagrass cultivars Tifsport,Tifway,Tifeagle and Tifgreen,one common bermudagrass cultivars baodinggouyagen. Comparative analysis of the five Bermudagrass cultivars phenology; Leaf length, leaf width, stem diameter and internode length Morphometry; Fresh weight and dry weight of roots;The differences between Turf color, density, homogeneity, texture, green period, coverage, Lawn strength, Resistance to trampling, Lawn resilience and Turf speed.And use mathematical statistics to evaluate each bermudagrass comprehensive turf quality. Also,we comparative analysis of many indicators of five Bermudagrass cultivars under low temperature stress of natural and artificial control.such as:Conductivity, chlorophyll content, MDA content, SOD, POD, CAT and APX activities, ABA, IAA, tZR and GA3 content, and soluble sugars, starch and fructans content were investigated for the five bermudagrass cultivars.The main results of this study are as follows:1.The turning green period of tested five Bermudagrass cultivars are concentrated in late March, range up to 10 d or more; Turning yellow period appear in the December, range up to 20 d; Green period of different Bermudagrass cultivars followed by Sort are:Tifsport,Tifeagle, Tifgreen, Tifway,baodinggouyagen.External morphological of teated five Bermudagrass cultivars have obvious differences, leaves of baodinggouyagen are longest and widest,Respectively 5.3 cm and 2.63 mm; leaves of Tifgreen narrowest for 1.28 mm, and best texture.The lawn texture and creeping characteristics of four hybrid bermudagrass cultivars special to perform better, but Baodinggouyagen external morphology is rough, turf quality is poor.Underground biomass of different bermudagrass cultivars have obvious differences, root system of Tifsport and Tifeagle are more developed, Baoding root biomass lower.There are obvious turf characteristics differences in lawn color, density, homogeneity, cover, lawn strength, trampling resistance, resilience, speed turf among five bermudagrass cultivars.In this study,using a 5-point level scored 10 primary quality indicators index of lawn and integrated primary and secondary index weights conversion came to the conclusion lawn Composite Index, according to LCI evaluation criteria for quality test grasses make a final evaluation.Results obtained:five different vultivars of bermudagrass turf LCI grades are, Tifsport, Tifgreen and Tifeagle V grade, outstanding; Tifway grade ?; Baoding Bermudagrass grade ?.2. Under natural and artificial low temperature control stress conditions,the conductivity of 5 Bermudagrass cultivars are increasing with low temperature gradually deepening, and conductivity if Tifway is higest and has obvious differnces with others 3 Hybrid Bermudagrass cultivars under cold damage and freezing conditions.It shows that ability of 5 Bermudagrass cultivars to maintain the stability of the cell membrane structure are obvious differnces,Tifsport,Tifgreen and Tifeagle are stronger.Chlorophyll content of 5 bermudagrass cultivars are decreasing with temperature gradually lowered, among them, chlorophyll content of Baoding with largest decline, Decrease of chlorophyll content reached 28.55% and 41.54% when low temperature stress switch to suboptimal temperature from the optimal temperature; chlorophyll content of Tifsport with smallest decline, Chlorophyll content decreased by only 9.41% when temperature switch to suboptimal temperature from the optimum temperature; chlorophyll content of Tifeagle with smallest decline under manual control low temperature, chlorophyll content decreased by only 21.01% when temperature switch to suboptimal temperature from the optimum temperature.3. Under natural and artificial low temperature control stress process, there is result of 5 Bermudagrass cultivars that the antioxidant enzymes (content) activity as MDA,SOD, POD, CAT, APX are rising with the deepening degree of low temperature stress,but when freeze comes Baoding's each test indicators are significantly decreased,when freeze comes there is just CAT activity declined rapidly of Tifway.Antioxidant enzyme system can help plants to remove harmful substances at low stress conditions, decreased activity will affect plant to clear the body's harmful substances thus affecting plant.Integrated natural and manual low temperature stress MDA content and antioxidant enzyme activities of different vultivars of bermudagrass,we believe that Tifgreen, Tifeagle and Tissport three cultivars resistance to cold is hard,Baoding and Tifway resistance to cold is weak.4. Under natural and artificial low temperature control stress process,5 Bermudagrass cultivars tested ABA content are increased with low temperature stress gradually depth; While its IAA, tZR, GA3 content was decreased with low stress deepened.But,under low temperature stress Tifsport and Tifgreen can maintain IAA, tZR, GA3 content to a high level and thus its strong cold resistance. Under natural and artificial low temperature control stress process,5 Bermudagrass cultivars tested soluble sugar content are increased with low temperature stress gradually depth;but, soluble sugar content of baodinggouyegen decreased rapidly when low temperature switched to frost damage from cold damage environment; Starch content of 5 Bermudagrass cultivars presents a trends fall-up-down; 5 Bermudagrass cultivars tested Fructan content are increased with low temperature stress gradually depth;The total non-structural carbohydrates of each bermudagrass cultivars (TNC) content is generally on the rise,However, Baodinggouyagen is decreased significantly in TNC content under FREEZING stress.5. Under natural and artificial low temperature control stress process,5 Bermudagrass cultivars tested ABA content are increased with low temperature stress gradually depth; While its IAA, tZR, GA3 content was decreased with low stress deepened.But,under low temperature stress Tifsport and Tifgreen can maintain IAA, tZR, GA3 content to a high level and thus its strong cold resistance. Under natural and artificial low temperature control stress process,5 Bermudagrass cultivars tested soluble sugar content are increased with low temperature stress gradually depth;but, soluble sugar content of baodinggouyegen decreased rapidly when low temperature switched to frost damage from cold damage environment; Starch content of 5 Bermudagrass cultivars presents a trends fall-up-down; 5 Bermudagrass cultivars tested Fructan content are increased with low temperature stress gradually depth;The total non-structural carbohydrates of each bermudagrass cultivars (TNC) content is generally on the rise,However, Baodinggouyagen is decreased significantly in TNC content under FREEZING stress.