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Tottori University (2013)

Study on physiological and adaptational responses of turfgrasses to salinity stress

Xu, Ran

Titre : Study on physiological and adaptational responses of turfgrasses to salinity stress

Auteur : Xu, Ran

Université de soutenance : Tottori University

Grade : Doctoral Thesis 2013

Sommaire partiel
Increased need for salt-tolerant turfgrasses continues due to increased use of recycled saline water for turfgrass irrigation in the arid and semiarid regions. Turfgrasses growing on saline environments suffer from salinity stress. This study was conducted to determine the salinity tolerance, growth and physiological responses of Kentucky bluegrass (KBG), Tall fescue (TF) and four bermudagrass cultivars (Riviera, Blackjack, Savannah and Sundevil 2). KBG and TF were subjected to 0, 50, 100, 150 and 200 mmol L−1 NaCl and bermudagrass cultivars were treated with 0, 100, 200, 300, and 400 mmol L−1 NaCl. Salinity tolerance was assessed according to the turf quality, leaf firing and relative shoot growth. The ranking of salinity tolerance was bermudagrass > Tall fescue > Kentucky bluegrass. Salinity tolerance among Bermudagrass cultivars was Riviera > Blackjack > Savannah > Sundevil 2. KBG, TF and bermudagrass cultivars exhibited differential physiological and adaptational response to salinity stress. Maintenance of relatively stable root growth of TF and root growth stimulation of bermudagrass was a potential adaptive mechanism for salinity tolerance. The most salt-tolerant Riviera has the most significant root growth under moderately salinity among bermudagrass cultivars. Root growth stimulation can increase in root/shoot ratios, and therefore increase in water absorption/transpiration area to resist saline osmotic stress. Complete osmotic adjustment was observed in all turfgrasses studied in this study. Saline ions (Na+ and Cl–) were predominant solute for osmotic adjustment. These saline ions regulation may be one of key mechanisms of salinity tolerance in turfgrasses. The Na+ and Cl– concentrations in root were higher than those in shoot or leaf in all turfgrasses. The root Na+/shoot Na+ ratio of TF was higher than that of KBG. The root Na+/leaf Na+ ratio of Riviera was the highest among bermudagrass cultivars. Root plays an important role in limiting the transport of Na+ to the shoot in turfgrass. The exclusion of saline ions from shoot reduces the toxicity to plant growth, which associate with salinity tolerance of turfgrasses studied in this study.

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