Root growth, architecture, and ion uptake of alfalfa and triticale irrigated with brackish groundwater and reverse osmosis concentrate

Abstract

Soil salinity is a major environmental constraint for agricultural production, especially in arid and semiarid regions of the world. Salts in irrigation water and soil can potentially harm plant root growth. To date, more research has been devoted to aboveground biomass production. This study is aimed at determining the impacts of irrigating with brackish groundwater (BGW) and reverse osmosis (RO) concentrate on the root and shoot biomass, root/shoot ratio (R:S), and root system architecture (RSA) of alfalfa (Medicago sativa L.) and triticale (× Triticosecale Wittm. ex A. Camus). Two replicated experiments were conducted in the Fabian Garcia Science Center (FGSC) greenhouse from 7 Oct. 2017 to 7 Jan. 2018 in Las Cruces, NM, USA. After 90 d, roots were scanned using a WinRHIZO image analysis system and the data were analyzed. In both the species, RO and BGW + NaCl increased root Na + and Clconcentrations. Triticale behaved more like a root Na-retaining species than alfalfa but with an associated decrease in total root biomass. Irrigation with BGW in alfalfa increased root length and the number of forks and crossings, whereas RO irrigation increased root length density (RLD). Unlike alfalfa, triticale root architectural parameters were largely unaffected by salinity. However, RO and BGW + NaCl waters promoted significantly (p ≤ .05) higher shoot biomass in triticale than the control and BGW alone. Our findings recommend BGW for alfalfa irrigation, and triticale as a potential future forage crop for dry and saline conditions. INTRODUCTIONSoil salinity is recognized as a critical problem in arid and semiarid regions of the world (Ladeiro, 2012). Globally, 4 million km 2 of land is affected by natural salinization, and >75 million km 2 is affected by human-induced salinization