Physiological genetics of salt tolerance in wheat (Triticum aestivum. L.):: Performance of wheat varieties, inbred lines and reciprocal F1 hybrids under saline conditions

Four bread wheat cultivars were studied at two salinity levels. Tobari 66 had the lowest uptake of Na+ and Cl-, and the highest K+/Na+ ratio; Pato had the highest uptake of these ions and Lyallpur 73 was intermediate. Intervarietal differences were greater at higher salinity, suggesting that they were not caused by variation at the Kna1 locus. There were significant differences between inbred lines for Na+, particularly in Blue Silver, suggesting the possibility of selecting genotypes with enhanced tolerance from within existing cultivars. Pato, Tobari 66 and their reciprocal F-1 hybrids were further evaluated at four salinity levels. The hybrids exhibited similar relative grain yield to Tobari, with better Na+ and Cl- exclusion and higher K+/Na+ ratios than Pato. Overall, Tobari had the highest absolute yield under salinity, and the hybrids were closer to Tobari than to Pato. Tiller and grain numbers, 100-grain weight and yield were more affected by salinity than were height, spike length and spikelet number. We conclude that intervarietal variation for salt tolerance in wheat is controlled by genes which could be transferred to sensitive genotypes to improve their tolerance, and that the K+/Na+ ratio of the youngest leaf could be used to screen for salt tolerance.