SALINITY AND GERMINATION IN Agropyron desertorum ACCESSIONS

Abstract

Salinity is an important factor limiting germination and emergence of crested wheat-grass [Agropyron desertorum (Fisch. ex Link) Schult.] on desert range sites. The objectives of this research were to examine germination characteristics of A. desertorum on saline media and to identify accessions with high salinity resistance at germination. Reductions in percent germination by NaCl solutions was relatively small between 0 and −0.6 MPa (92 to 85%), but more pronounced between −0.6 and −1.5 MPa (85 to 26%). Germination rate index (GRI) and maximum germination rate d−1 declined linearly from 0 to −1.5 MPa. Seventy-one accessions were evaluated for salt resistance in NaCl at −0.9 MPa. Accessions were identified with high relative germination (percent germination at −0.9 MPa divided by the distilled water controls) and high percent germination and GRI at −0.9 MPa. In most cases, accessions with high salt resistance, determined as high relative germination or percent germination at −0.9 MPa, were the same accessions with high relative GRI or GRI at −0.9 MPa. Maximum germination rate d−1 did not consistently identify salinity resistant accessions. Separation of high and low salt resistant accessions observed at 22 °C and −0.9 MPa for relative germination and GRI was also observed at −1.5 MPa, but not at −0.3 MPa. Separation of accessions with high and low salinity resistance was maintained at alternating daily temperatures of 15 °C (16 h)/25 °C (8 h), and at 12 °C constant temperature. In some cases, CaCl2 solutions at −0.9 MPa inhibited germination more than NaCl at −0.9 MPa. However, accessions showing differences in salt resistance on NaCl solutions showed the same qualitative separation on CaCl2 and in 1:1, NaCl:CaCl2 solutions. Accessions potentially useful for improving germination under saline conditions were identified and are available for field testing and further selection.Key words: Crested wheatgrass, plant stress resistance, salinity, salinity resistance