Thursday, 10 November 2005 - 8:30 AM
314-1

Competitive Growth Responses of Three Cool-Season Grasses to Salinity & Drought Stresses.

Mohammad Pessarakli, David Kopec, and Jeffrey Gilbert. University of Arizona, 1140 E. South Campus Dr., Tucson, AZ 85721

Growth responses [shoot & root lengths & DM, & canopy green cover (CGC)] of Creeping bent (Agrostis stolonifera), Rough bluegrass (Poa trivialis), & Perennial rye (Lolium sperenne) were compared under salt & drought stresses in a greenhouse, using hydroponics system. Grasses were grown in 1/2 strength Hoagland solution for 90 d prior to exposure to stress. Then, 24 meq NaCl L-1 culture solution d-1 for each -0.1 MPa osmotic potential (OP) of salinity or 75 & 119 g of PEG L-1 culture solution were added for -0.2 & -0.4 MPa OP of drought stress treatments, respectively. Five treatments [control (no NaCl or PEG), -0.2 & -0.4 MPa OP salinity, & -0.2 & -0.4 MPa OP drought stress were replicated 4 times in a RCB design experiment. Grasses were grown under these conditions for 6 weeks. During this period, shoots were clipped weekly for DM yield, shoot & root lengths were measured, & CGC was evaluated. The clippings were oven dried at 60o C & DM recorded. At the last harvest, roots were also cut, oven dried, & DM recorded. The results showed, all 3 grasses were more severely affected by drought than salinity, bluegrass was the most & bent the least severely affected by either stress. Reductions in CGC due to stresses ranged between 3 - 12, 8 - 36, & 44 - 60% for bent, rye, & bluegrass, respectively. For each grass, the lower values resulted from salinity & the higher ones from drought.

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