Effects of rootstock and environment on the composition of oranges and grapefruit

Abstract

Abstract does not appear. First page follows. Introduction The influence of different rootstocks on important citrus varieties is being studied in a long-term experiment at this station. The present paper deals with rootstock effects on fruit composition. The effects on growth and yield of the trees in the same plots are being investigated by other workers cooperating in this project. On the basis of results with soil and fertilizer studies, rootstock differences may be expected to have less effect on the fruit than on the foliage. But even small differences in composition may appreciably affect fruit quality, which is of immediate practical importance to the grower. Unfortunately, edible quality is a subjective judgment not closely correlated with anyone quantitative test. Flavor varies not only with concentration of total soluble solids and with relative amounts of sugar and acids, but also with other, independent variables. Differences in amounts of aromatic substances, for example, may cause noticeable differences in palatability in oranges with the same concentration of total soluble solids. But though chemical composition is difficult to relate directly to fruit quality, especially in citrus, it does measure quantitatively certain pertinent characteristics. It is of further interest scientifically for the light it throws on the physiological activities in budded citrus trees. The effect of rootstock on the composition of citrus fruits has been studied in various parts of the world, notably in Australia (31),5 South Africa (29), South America (33), and the United States (20), (23). Reports on some of these investigations are brief and limited in experimental data, while others are more extended.