Yield and Quality Characteristics of Quinoa Grown in Open Field Under Different Saline and Non‐Saline Irrigation Regimes

A possible alternative to minimize the effects of salt and drought stress is the introduction of species tolerating these conditions with a good adaptability in terms of quantitative and qualitative yield. So quinoa (Chenopodium quinoa Willd.) cultivar Titicaca was grown in an open field trial in 2009 and 2010 to investigate the effects of salt and drought stress on quantitative and qualitative aspects of the yield. Treatments irrigated with well water (Q100, Q50 and Q25) and corresponding treatments irrigated with saline water (Q100S, Q50S and Q25S) with an electrical conductivity (EC_w) of 22 dS m^?1 were compared. Salt and drought stress in both years did not cause significant yield reduction, while the highest level of saline water resulted in higher mean seed weight and as a consequence the increase in fibre and total saponin content in quinoa seeds.     

Effects of Increasing Salinity Stress and Decreasing Water Availability on Ecophysiological Traits of Quinoa (Chenopodium quinoa Willd.) Grown in a Mediterranean‐Type Agroecosystem

Quinoa is a native Andean crop for domestic consumption and market sale, widely investigated due to its nutritional composition and gluten‐free seeds. Leaf water potential (Ψ_leaf) and its components and stomatal conductance (g_s) of quinoa, cultivar Titicaca, were investigated in Southern Italy, in field trials (2009 and 2010). This alternative crop was subjected to irrigation treatments, with the restitution of 100 %, 50 % and 25 % of the water necessary to replenish field capacity, with well water (100 W, 50 W, 25 W) and saline water (100 WS, 50 WS, 25 WS) with an electrical conductivity (EC_w) of 22 dS m^?1. As water and salt stress developed and Ψ_leaf decreased, the leaf osmotic potential (Ψ_π) declined (below ?2.05 MPa) to maintain turgor. Stomatal conductance decreased with the reduction in Ψ_leaf (with a steep drop at Ψ_leaf between ?0.8 and 1.2 MPa) and Ψ_π (with a steep drop at Ψ_π between ?1.2 and ?1.4 MPa). Salt and drought stress, in both years, did not affect markedly the relationship between water potential components, RWC and g_s. Leaf water potentials and g_s were inversely related to water limitation and soil salinity experimentally imposed, showing exponential (Ψ_leaf and turgor pressure, Ψ_p, vs. g_s) or linear (Ψ_leaf and Ψ_p vs. SWC) functions. At the end of the experiment, salt‐irrigated plants showed a severe drop in Ψ_leaf (below ?2 MPa), resulting in stomatal closure through interactive effects of soil water availability and salt excess to control the loss of turgor in leaves. The effects of salinity and drought resulted in strict dependencies between RWC and water potential components, showing that regulating cellular water deficit and volume is a powerful mechanism for conserving cellular hydration under stress, resulting in osmotic adjustment at turgor loss. The extent of osmotic adjustment associated with drought was not reflected in Ψ_π at full turgor. As soil was drying, the association between Ψ_leaf and SWC reflected the ability of quinoa to explore soil volume to continue extracting available water from the soil. However, leaf ABA content did not vary under concomitant salinity and drought stress conditions in 2009, while differing between 100 W and 100 WS in 2010. Quinoa showed good resistance to water and salt stress through stomatal responses and osmotic adjustments that played a role in the maintenance of a leaf turgor favourable to plant growth and preserved crop yield in cropping systems similar to those of Southern Italy.     

Soil Type Influences Relative Yield of Barley and Wheat in a Mediterranean-type Environment

In the eastern wheatbelt of Western Australia the yield of barley relative to wheat is influenced by soil type. Field trials studied detailed aspects of growth, development, yield and water use of a range of barley and wheat cultivars on 2 soil types at 2 locations to identify those factors that lead to the differential relative yields.
Barley had greater grain yields than wheat on both fine and coarse textured soils. On both soil types barley had a greater number of mainstem leaves which appeared faster than those of wheat and this was associated with greater tillering (6.5 v. 3.5 shoots/plant), higher GAI and greater dry matter production (845 v. 804 g/ m). The difference in yield between the two species was greater on the fine textured soil (15 v. 7 %). Barley also had greater harvest index than wheat (6—15%), and this combined with greater dry matter production on the fine textured soil led to a larger yield advantage over wheat than occurred on the coarse textured soil. Water use efficiency was greater for barley than for wheat on both soils.
The greater yield advantage of barley over wheat on the fine textured soil was the result of greater biomass production by barley and greater harvest index. Differences in pattern of water use, and water use efficiency of grain production were associated with greater barley yields but are not themselves considered to be the cause of relative yield differences across soil types. The possible implications of factors such as intrinsic nutrient supply on the 2 soil types in relation to observed yield differences are discussed.