Tolerancia a la salinidad durante la germinación de semillas provenientes de poblaciones naturalizadas de agropiro alargado (Thinopyrum ponticum)

Abstract

The phenotypic variability among ten adapted populations of tall wheatgrass (Thinopyrum ponticum) germinating under saline stress conditions was evaluated as part of a breeding program. The aim of the breeding program was to provide new cultivars of tall wheatgrass adapted to saline soil conditions. Saline soils represent 8% of the total agricultural soil surface in Argentina. Seeds were sown on towel paper (30 g·m-2 ) and germinated with alternating light and darkness (16 and 8 h, respectively) and temperature (20- 30ºC), under 0, 60, 135 y 220 mM NaCl treatments, equivalent to electric conductivity of 0, 6, 12 y 18 dS·m-1 . Treatments were distributed in a randomized complete block design, with a factorial arrangement of 4 x 11, four salinity treatments x eleven tall wheatgrass populations; four replications were carried out, consisting of 25 seeds per experiment. The germination percentage and germination index were calculated. The results indicated large differences between populations and between treatments for both attributes. The mean germination percentage decreased 4.2, 18.6 and 61.0%, as compared to the control, as electric conductivity increased to 6, 12 and 18 dS·m-1 , respectively. Differences between populations were signifi cant only in 18 dS·m-1 . The germination index had a similar performance with the increase in electric conductivity (y = 28.827x-35.091, R2 = 0.9692). Population number 3 had the best germination and index performance. At 18 dS·m-1 , all populations had a variable number of seeds with germination capacity. Therefore, this electric conductivity could be adequate for a salt tolerance breeding and selection program.