Growth responses and inorganic ion regulation of four bermudagrass(Cynodon spp.)cultivars under salinity stress

摘要

The need for salinity-tolerant turfgrasses is increasing owing to increased use of reclaimed or saline water for irrigation.The objective of this study was to investigate the salinity tolerance,growth,and physiological responses of four bermudagrass(Cynodon spp.)cultivars.The salinity treatments were 0,100,200,300,and 400 mmol L?1 NaCl.The reduction in relative shoot growth with increasing salinity in the tested cultivars indicated a salinity tolerance in the order of‘ Riviera’ ＞‘Blackjack’＞ ‘Savannah’＞‘Sundevil 2’.Shoot growth,root growth,and relative water content of shoots and roots of all cultivars were significantly affected by NaCl stress.However,root length and root dry weight of the salt-tolerant cultivars Riviera and Blackjack increased significantly compared with the control.Tissue Na+and Cl– concentrations in all cultivars increased with increasing salinity.Riviera accumulated less Na+and Cl–in leaves and roots and more K+in leaves than the least tolerant cultivar,Sundevil 2.All cultivars had bicellular salt glands on both the abaxial and adaxial leaf surfaces.Riviera excreted more Na+and Cl– than the other cultivars through saltglands.All grasses exhibited complete osmotic adjustment,and osmotic adjustment of Riviera was less than other cultivars under salinity stress.Our results indicate that the salinity tolerance of Bermuda grasses is associated with leaf and root Na+and Cl– regulation,in conjunction with the maintenance of high leaf K+levels and efficient excretion of Na+and Cl– by leaf salt glands.