Study On Cadmium Tolerance And Mechanism Of 20 Varieties Tall Fescue

The effect of 10 ?mol"L-1 Cd2+ on 20 Tall fescue varieties were investigate using water culture method.the 20 Tall fescue varieties are divided into 4 kinds.In order to further explore the tolerance mechanism of different varieties of tall fescue to heavy metals,the physiological and biochemical indexes were compared and analyzed.The main results are as follows;1)The 20 Tall fescue varieties are divided into 4 kinds,high-tolerance and high-accumulation:' Arid 3','Extreme','Commander','Escalade','Ecological King','Ky-32','Red Start','Green Label';high-tolerance and low-accumulation:'Gold Crown','Justice','Honky Tonk','Aries';low-tolerance and high-accumulation:'Ruby ?','Coronado TDH';low-tolerance and low-accumulation:'K31','Crossfire ?','Essential','Super Watchdog','Gram villa','Dynamic ?'.2)The total root length,total volume and apical number of 'Commander' were significantly lower than 'Crossfire ?',while the decrease of the total surface area and average diameter was significantly smaller than 'Crossfire ?'.The descending rate of growth rate of root and plant height was 12.78%and 96.80%,respectively.The decrease of'Crossfire ?' was 22.24%and 97.97%respectively,and the difference of plant height was significantly,the difference of root was significantly.The relative conductivity of the five parts such as Root tip,root,stem base,leaf base and leaf tip of 'Commander' is less than 'Crossfire ?r.The transfer coefficient of'Commander' is 0.926,while 'Crossfire ?' is 0.221.,'Commander' performance better in transport capacity of Cd2+Comparative3)Cd2+had a significant effect on the content of endogenous hormones in two cultivars,and the content of IAA in the root of 'Commander' was significantly increased under Cd2+stress,while the content of IAA in 'Crossfire III' was significantly decreased.The content of ABA in the root extract of'Commander' was not significant,while the content of 'Crossfire ?' ABA was significantly increased,and the BR and ZA contents of the two cultivars decreased to a certain extent.In hormone levels,Crossfire ?' is greater stressd The addition of exogenous DMTU and PCIB all inhibited the Cd2+stress,and the inhibition of root elongation was alleviated.DMTU treatment,'Commander' IAA content decreased,and 'Crossfire ?' is increased.ABA content decreased,the difference was significant difference.BR and ZR content increased,the difference was significant difference.The IAA and ABA contents of the two cultivars decreased under the PCIB treatment,and the BR content in the'Commander' tip did not change,and the BR content of'Crossfire ?' decreased ZA showed a certain degree of rise,the difference was significant.4)The effects of Cd2+on the content of antioxidant enzymes in the two cultivars were consistent.Under the Cd2+ stress,the SOD,POD and CAT contents of the two cultivars showed different degrees of increase,the content of H2O2 in the root of the two crosses was significantly increased,and the increase of H2O2 content in the 'Crossfire ?' tip was significantly larger than 'Commander,'Commander'Showing a strong resistance.The addition of exogenous DMTU and PClB all inhibited the Cd2+ stress,and the inhibition of root tip elongation was alleviated,and the contents of SOD,POD,CAT and H2O2 decreased in different degrees.