Abstract/Summary

In Mozambique, rice is one of the staple crops and is among the main sources of carbohydrates for most of the population. Most rice production occurs along the coastal areas. Rice crop is sensitive to salt stress and sea salt intrusion severely limits growth, development and yield of rice in Mozambique. However, scientific evidence on the specific effects of salinity on rice varieties cultivated in Mozambique and the mechanisms that could increase salt tolerance are still scarce. To fill this gap, laboratory experiments in hydroponic system in a growth cabinet were conducted to investigate rice salt tolerance, the effect of priming treatments with inorganic salts (CaCl2, KCl, and KNO3) in mitigating salt stress, and the physiological mechanisms that confer higher salt tolerance. The following parameters were assessed in twelve rice accessions: plant growth (shoot dry weight, percent germination, root and shoot lengths), plant physiology (Na-ions and K-ions), grain yield and grain composition (starch, amylose, protein concentrations). Indica Mozambique (landrace) rice accessions are moderately tolerant and the indica improved (IRRI Lines) are tolerant to salt stress. CaCl2 and KNO3 priming treatments showed potential to alleviate salt stress effects on Indica Mozambique (landrace) by increasing shoot dry weight and salt tolerance, altering Na-ions and K+ /Na+ ratios, and increasing grain protein concentrations. However, these changes were not translated in the increase of grain yield, thus there is a need for further studies to identify the ideal priming inorganic salt concentration and duration suitable for each rice accession, stage of crop growth, level and duration of salinity stress, including the evaluation of more physiological parameters (e.g. Ca-ions, osmolytes, antioxidants, hydrolases). Thereafter, priming approaches with positive significant effects may be adopted by the smallholder farmers to increase rice grain yield and quality, hence contributing to food and nutritional security in Mozambique.