Effect of Salt Concentration, Kind of Salt, and Climate on Plant Growth in Sand Cultures.

Introduction Many western farmers believe that soil alkali is more detrimental to crop growth during the hot weather than during the cooler seasons of the year. Other agricultural workers have noted that damage to crops due to alkali (soil salinity) is more serious in the hot interior valleys than along the coast where the climate is more moderable. It is not definitely known whether or not soil salinity concentrations are comparable between different seasons of the year or between respective areas. Yet, information on this question is pertinent to the development of management practices which would aid in ameliorating soil salinity conditions at different seasons of the year and under different climatic conditions. In order to obtain definite information on this question, the Regional Salinity Laboratory planned a series of experiments to determine the tolerance of crop plants to the salts commonly found in irrigation waters and soils, and to what extent climate modified these effects. This paper presents a resume of the more pertinent results from these experiments conducted during 1939, 1940, and 1941. TRELEASE and LIVINGSTON (10) were among the earliest authors to find that climatic conditions modified the crop growth obtained with the same culture solutions and to suggest that studies should be made on the effect of climate in modifying plant responses. In 1938 AHI and POWERS (1) grew salt grass, alfalfa, and strawberry clover in the same culture solutions in greenhouses held at 55” and 75” F. They found germination and growth to be poorer at the higher temperature. HAYWARD and LONG (6), and WALL and HARTMAN (11) have also published results indicating that climatic factors modify the action of salt on plants. The amount of salt which plants can tolerate in sand cultures under normal climatic conditions has been reported by many authors, and the reader is referred to recent reviews by EATON (5), and HAYWARD and LONG (6). In general, salt tolerant plants can continue growth in nutrient solution at concentrations exceeding 6 atmospheres, while salt sensitive plants may s u c cumb at solution concentrations below 2.5 atmospheres.