THE INHERITANCE AND PHYSIOLOGY OF BORON RESPONSE IN THE TOMATO

Wall , J. R., and C. F. Andrus . (U.S.D.A., U. S. Vegetable Breeding Laboratory, Charleston, S. C.) The inheritance and physiology of boron response in the tomato. Amer. Jour. Bot. 49(7): 758–762. Illus. 1962.—Brittle stem (btl), an abnormal sublethal phenotype in the tomato caused by boron deficiency, was found to be controlled by a single recessive gene. The threshold of boron concentration for brittle-stem expression is not constant but fluctuates and is intimately associated with a number of interrelated environmental factors. Light duration and intensity are especially significant, while temperature and nitrogen, phosphorus, and calcium availability probably contribute to btl expression. It is suggested that when boron supply is limiting, brittle-stem (boron deficiency) symptoms are intensified by any environmental factor or factors which enhance plant growth. Plants of btl/btl genotype contain much less boron in their leaves than do those of the control variety ‘Rutgers’; conversely, these plants contain more boron in their roots when grown in nutrient cultures of high boron content. This finding is discussed in relation to possible modes of gene action.