Emergence, height, and yield of tall, NewHy, and green wheatgrass forage crops grown in saline root zones

Abstract

The salinity tolerance of a crop relates to its inherent ability to yield economic product while subjected to root-zone salinity. Tall wheatgrass [Thinopyrum ponticum (Podp.) Liu & Wang, previously Agropyron elongatum (Horst.) Beauv.] ranks as one of the most salt-tolerant forage crops, but producers feeding or grazing livestock with it often report of its poor palatability. NewHy [Elytrigia repens (L.) Nevski × Pseudoroegneria spicata (Pursh.) A. Love] and green wheatgrasses (Elymus hoffmannii Jensen and Asay) are new forages with potentially better palatability. In order to determine the responses of these forages to saline rooting media, two tests were conducted in Canada’s Salinity Tolerance Testing Facility. The plants were grown in sand tanks flushed four times daily with hydroponic solutions consisting of nutrients and salts dominated either by chloride ions measuring from 1.5 to 48 dS m-1 or by sulphate ions from 1.5 to 50 dS m-1. In the chloride test, maximum emergence-survival, emergence rate, and emergence at the time of maximum rate for Orbit tall wheatgrass differed significantly from green wheatgrass (Breeding Strain A6) and NewHy. The maximum percent emergence and survival within the range of test salinity levels averaged 93, 88, 86% for tall, NewHy, and Strain A6 wheat grasses, respectively. In the sulphate test, maximum percent emergence-survival averaged 94, 91, and 87% for Orbit tall wheatgrass and green wheatgrass breeding strains A6 and S2 across the eight salinity levels of the test. Relative crop heights at harvest did not differ significantly among the test forages in either test. In the chloride test, shoot biomass yields relative to the salt-free production analysed by the modified-discount equation resulted in salinity-tolerance-indices of 11.2, 5.7, and 12.9 for tall, NewHy, and green wheatgrasses, respectively. In the sulphate test, salinity-tolerance indices for the tall wheatgrass, A6 and S2 green wheatgrass strains registered 11.7, 12.8, and 12.5, respectively. This and the covariance yield analyses based on paired t-tests lead to the inference that the salinity tolerance for both strains of green wheatgrass equalled that of the Orbit tall wheatgrass and exceeded that of the NewHy. Producers will soon have the option of growing AC Saltlander, a variety of green wheatgrass (Strain S2), which has just been released for commercialization and seed increase. Key words: Salt tolerance, salt resistance, salinity, tall wheatgrass, green wheatgrass, NewHy, crop response to salinity