Response of malt barley grain quality characteristics to increasing irrigation water salinity

Abstract

Premiums are offered for high quality grain, but producers of malting barley are often confronted with marginal soils and water scarcity. Irrigation water quality is often low, primarily due to high salt loads. This study determined the effect of irrigation water salinity (ECi) on grain quality characteristics of malt barley evaluated in a lysimeter-based trial over two seasons. The trial involved five ECi levels (1. 5, 4. 5, 6, 9 and 12 dS m−1), and two different soil types (Bainsvlei and Clovelly). Grain yields, 1 000 seed mass (TSM, g), germination characteristics, and crude proteins (CP) were determined. Salinity levels of greater than 6 dS m−1 decreased TSM but had no significant effect on germination characteristics, while CP content of the grains significantly increased above the required range (between 9% and 11.5%) for malting. Increasing ECi reduced malt extract potential for all treatments, most noticeably at 9 and 12 ECi dS m−1. There were significant relationships between salinity and germinative characteristics as well as the malt extract proxy (germination index). The study shows that premium quality barley grain cannot be produced when salinity exceeds 6 dS m−1 and that the Clovelly soil would be a better fit for producing barley irrigated with saline water.