Selection of lines with high and low sodium transport from within varieties of an inbreeding species; rice (<i>Oryza sativa</i> L.)

Abstract

summary Varieties (including designated cultivars) of Asian rice (a predominantly inbreeding species) show large individual variability in sodium transport and salinity resistance. Recurrent selection has been carried out over five generations with populations of Oryza sativa L. cv. IR36 and cv. IR20. Large numbers of individuals were exposed to a low concentration of NaCl in solution culture, and their sodium uptake determined non‐destructively by sampling the third leaf. The range of sodium concentrations in the leaf was two or three orders of magnitude. Individuals showing both high and low extremes of sodium uptake were selected and allowed to self‐pollinate. The sodium uptake by the progeny was measured in the same way, and the selection repeated. Significant differences in the frequency distribution of sodium transport between the selected lines were evident in both varieties after three cycles of selection. The lines continued to segregate in the fourth and fifth generations by which time the high and low selected lines showed substantial differences in sodium uptake. It is concluded that useful genetic diversity for sodium uptake and hence salt resistance exists within modern rice varieties.