Salinity Tolerance of Muntries (Kunzea pomifera F. Muell.), a Native Food Crop in Australia

Identifying productive food crops that tolerate moderate soil salinity is critical for global food security. We evaluate the salinity tolerance of Kunzea pomifera (muntries), a traditional Indigenous food plant that grows naturally in coastal regions of southern Australia and thrives on relatively low rainfall. A range of saline irrigation treatments were tested on four genotypes: tap water, 50, 200, 300, and 400 mM NaCl [Maarten's Favorite (MF)] and up to 200 mM NaCl (MP1, SES2, and CJ1). After a 10-week saline irrigation treatment at 50 mM NaCl, SES2 appeared to have the highest salt tolerance of all genotypes based on no significant change in the number of secondary branches. At 50 mM NaCl, sodium accumulated significantly in roots but not the leaves of three genotypes, suggesting an active shoot exclusion mechanism. At 200 mM NaCl, plant growth decreased, Na+ and Cl- generally accumulated to significantly higher levels in leaves, compared with 50 mM NaCl, whereas potassium (K+) levels were unchanged. At high NaCl (300 and 400 mM), MF showed severe growth retardation with leaf symptoms appearing in week 9. Our results indicate that two genotypes of K. pomifera, SES2 and CJ1, are moderately salt tolerant based on modest reductions in three growth parameters at 50 mM NaCl, compared with MF and MP1. Further evaluation of the natural diversity of this species should reveal a range of diverse mechanisms of salinity tolerance thus providing a new fruit crop for moderately saline soils. Chemical names: NaCl (sodium chloride).