ROOT PENETRATION AND SHOOT ELONGATION OF TALL WHEATGRASS AND BASIN WILDRYE IN RELATION TO SALINITY

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Abstract
Tall wheatgrass [Elytrigia pontica (Podp.) Holub Syn: Agropyron elongatum (Host) Beauv. ’Jose’] and basin wildrye [Leymus cinereus (Scribn. & Merr.) A. Love Syn: Elymus cinereus Scribn. and Merr. ’Magnar’] may have potential for increasing forage production once established on saline rangelands. The shoot and root elongation, osmotic adjustment, leaf water stress, and turgor at growth cessation of these grasses in response to drought and salinity were compared in a growth chamber experiment. Seedlings were grown in columns of soil initially saturated with solutions with an electrical conductivity of 1.0, 10, and 20 dS∙m−1 and allowed to grow until desiccated. The greater shoot elongation and root penetration of tall wheatgrass than basin wildrye at all soil salinities corresponds with the higher survival of tall wheatgrass than basin wildrye on a saline soil and on a nonsaline soil in central Nevada. As leaf water potential decreased, both species had similar or higher turgor maintenance in saline than nonsaline soil. But salinity decreased growth of both species, even when no water stress was apparent, and plant and soil water potentials in the saline and nonsaline columns were similar. This suggests that salt toxicity or nutritional imbalances due to accumulated ions, rather than water stress, depressed growth. Plant materials for revegetating saline, arid rangelands should be screened not only for seedling vigor and ability to tolerate or avoid water stress but also for tolerance to salinity.Key words: Drought, osmotic adjustment, turgor, ion toxicity, salt tolerance