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This technical report series captures and documents the work in progress of the Iraq Salinity Project, in its seven research themes, working at the regional, farm and irrigation system scales. Technical reports feed into the Iraq Salinity Assessment, a synthesis and solutions to solving the problem: Situation Analysis (Report 1); Approaches and Solutions (Report 2) and Investment Options (Report 2).

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Field evaluation of germplasm for performance under water and heat stress is challenging. Field environments are variable and unpredictable, and genotype × environment interactions are difficult to interpret if environments are not well characterised. Numerous traits, genes and quantitative trait loci have been proposed for improving performance but few have been used in variety development. This reflects the limited capacity of commercial breeding companies to screen for these traits and the absence of validation in field environments relevant to breeding companies, and because little is known about the economic benefit of selecting one particular trait over another. The value of the proposed traits or genes is commonly not demonstrated in genetic backgrounds of value to breeding companies. To overcome this disconnection between physiological trait breeding and uptake by breeding companies, three field sites representing the main environment types encountered across the Australian wheatbelt were selected to form a set of managed environment facilities (MEFs). Each MEF manages soil moisture stress through irrigation, and the effects of heat stress through variable sowing dates. Field trials are monitored continuously for weather variables and changes in soil water and canopy temperature in selected probe genotypes, which aids in decisions guiding irrigation scheduling and sampling times. Protocols have been standardised for an essential core set of measurements so that phenotyping yield and other traits are consistent across sites and seasons. MEFs enable assessment of a large number of traits across multiple genetic backgrounds in relevant environments, determine relative trait value, and facilitate delivery of promising germplasm and high value traits into commercial breeding programs.

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Atriplex nummularia with one root half in 10 mm NaCl maintained net photosynthesis, shoot growth and shoot water potential even when the other root half was exposed to 670 mm NaCl, a concentration that inhibits growth by 65 % when uniform in the root zone. Given the likelihood of non-uniform salinity in many field situations, this situation would presumably benefit halophyte growth and physiology in saline environments.

Salinity and waterlogging (root-zone hypoxia) are abiotic stresses that often occur together on saltland. It is widely recognised that these two factors interact to increase Na+ and/or Cl– concentrations in shoots, which can have adverse effects on plant growth and survival. This review expands on this understanding, providing evidence that the adverse effects of the interaction are also associated with a disturbance to plant K+ homeostasis. This conclusion is based on a comparative analysis of changes in ion concentrations and growth reported in the literature between species (glycophytes vs halophytes) and within a single species (Hordeum marinum L.). Comparisons between species show that hypoxia under saline conditions causes simultaneous increases in Na+ and Cl– concentrations and decreases in K+ concentrations in shoots and that these changes can all be related to changes in shoot dry mass. Comparisons between accessions of a single species (Hordeum maritima L.) strengthen the argument, with increases in Na+ and decreases in K+ being related to decreases in shoot relative growth rate.