Abstract
Soil salinity is a major problem in arid and semi-arid regions, causing land degradation, desertification, and subsequently, food insecurity. Salt-affected soils and phosphorus (P) deficiency are the common problems in the sub-Sahara, including the Southern region of Morocco. Soil salinity limits plant growth by limiting water availability, causing a nutritional imbalance, and imparting osmotic stress in the plants. The objective of this study was to determine the positive effects of P on growth and productivity and understand the major leaf mineral nutrient content of quinoa (Chenopodium quinoa Willd.) cv. “ICBA Q5” irrigated with saline water. A field experiment applying three salinity (Electrical Conductivity, EC) levels of irrigation water (ECw = 5, 12, and 17 dS·m−1) and three P fertilizer rates (0, 60, and 70 kg of P2O5 ha−1) were evaluated in a split-plot design with three replications. The experiment was conducted in Foum El Oued, South of Morocco on sandy loam soil during the period of March–July 2020. The results showed that irrigation with saline water significantly reduced the final dry biomass, seed yield, harvest index, and crop water productivity of quinoa; however, P application under saline conditions minimized the effect of salinity and improved the yield. The application of 60 and 70 kg of P2O5 ha−1 increased (p < 0.05) the seed yield by 29 and 51% at low salinity (5 dS·m−1), by 16 and 2% at medium salinity (12 dS·m−1), and by 13 and 8% at high salinity (17 dS·m−1), respectively. The leaf Na+ and K+ content and Na+/K+ ratio increased with irrigation water salinity. However, the leaf content of Mg, Ca, Zn, and Fe decreased under high salinity. It was also found that increasing P fertilization improved the essential nutrient content and nutrient uptake. Our finding suggests that P application minimizes the adverse effects of high soil salinity and can be adopted as a coping strategy under saline conditions.
Highlights
The results showed that the highest dry biomass yield was recorded under the highest irrigation water salinity (EC 17 dS·m−1 )
This study quantified the responses of quinoa to different levels of irrigation water salinity and phosphorus fertilizer rates
This research highlighted the great potential of improving quinoa yield through the application of the optimal amount of phosphorus fertilizer in salt-affected areas
Summary
Soil salinization is a global problem affecting agricultural productivity, and saltaffected soils have been spread over 100 countries. Of the total cultivated land, 227 Mha is irrigated, and out of those, 20% is salt-affected [1,2]. Out of the nonirrigated cultivated land, an additional 2.5% suffers from salinity [3]. Soil salinization is expanding at a rate of 1–2 million ha·year−1 globally, offsetting a significant portion of crop production and making land unsuitable for cultivation. As soil evaporation greatly exceeds precipitation, crop production mostly depends on irrigation and is vulnerable to soil salinity [4]
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