Post-tsunami collection of polyembryonic mango diversity from Andaman islands and their ex situ reaction to high sodium in sodic soil

Abstract: The study includes collection of polyembryonic mango types from tsunami affected areas of the South Andaman district where trees are under natural selection pressure for salt tolerance and screening of collections against high sodium in sodic soils ex situ. Forty two accessions were located and collected on the basis of phenotypic expression and indentation level in tsunami. Out of which 15 diverse polyembryony types from different locations were evaluated for survival and growth in sodic soils of pHe 9.51 and sodium (Na+) 21.20 meq/L at Lucknow. The mortality percentage and relationship between the salt tolerance potential of the selections and Na+ / K+ ratio, root length and shoot length were investigated. Based on mortality in ex situ screening, collected types were classified into different groups. An increase in pH and Na+ concentrations led to higher mortality (96.67 -100.00 %) in polyembronic seedlings when compared to salt tolerant types (3.33-16.678 %). Six accessions GPL-1, GPL-3, ML-3, ML-4, ML-2 and GPL-4 exhibited tolerance to high soil sodium content and pH. Accessions GPL-1 and ML-2 collected from sites affected by inundation of sea water during tsunami under acid saline soil conditions were found to have the highest tolerance level. These accessions accumulated comparatively higher amounts of K+ ions in leaves than other accessions. They also had lower Na+ / K+ ratio which was even lower than the other tolerant collections. The collections demonstrated an increase in the root and shoot length and significant negative correlation with mortality of the seedlings (r= 0.97 and 0.98, respectively). The study revealed the importance of natural selection of mango polyembryony seedlings for salt tolerance and scope of its utilization.