Salt Tolerance of Mexican Wheat: II. Relation to Variable Sodium Chloride and Length of Growing Season

Abstract

AbstractGermination, seedling growth, and grain production of four short‐season, one intermediate‐season, and three long‐season varieties of Mexican wheat (Triticum aestivum) were studied in relation to variable NaCl salinity. Germination counts after 7 days exposure to NaCl solutions in petri dishes revealed that the wheats as a group are relatively tolerant, germinating freely in the presence of −16‐ to −20‐atm osmotic potential. ‘Nadadores,’ ‘Potam,’ ‘Sonora,’ and ‘Nuri’ were the most tolerant; ‘Ciano,’ ‘Cajeme,’ and ‘Yecora,’ the least at germination. Tolerance at germination was not associated with any obvious properties such as length of growing season or seed hardness. The eight wheat varieties were grown from seedling stage to maturity in sand cultures with a complete nutrient solution containing sufficient NaCl to produce total osmotic potentials of −0.5, −2.5, and −4.5 atm. Leaf samples were collected at spike emergence for chemical analysis including NO3‐N, Cl, and Na. Plots of relative grain yield in relation to osmotic potential of substrate revealed two general relationships, one for the short‐season varieties and one for the long‐season varieties. Fifty percent yield decrements were associated with −3 atm and −6 atm for short‐season and long‐season varieties, respectively. Further, relative grain yields under a given NaCl stress were correlated with the length of the maturity period. Chemical analyses of leaf samples collected at spike emergence showed higher Na and Cl contents in short‐season varieties than in long‐season varieties. Thus, Na and Cl toxicities may be involved in growth depressions. Also, leaf analysis data revealed an inhibitory effect of Cl upon NO3‐N accumulation.