A Comparison of Maturation and Composition of ‘Valencia’ Oranges in Some Major Subtropical Zones of the United States1

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Abstract
Comparisons were made of the composition of ‘Valencia’ oranges, Citrus sinensis Osbeck, from orchards in 6 major climatic zones used for citrus culture in the U. S. Six orchards, selected in a compact area in each location, were measured and sampled at intervals during 2 crop seasons. The locations were: Orlando, Fla.; Weslaco, Tex.; Tempe, Ariz.; Indio, Calif.; Riverside, Calif.; Santa Paula, Calif. Statistical evaluations showed that the seasonal trends for most measurements differed significantly among locations. Observations on flowering showed that full-bloom occurred from 1 to 2 months later in the Far-Western locations than in Texas and Florida. The extremes of the interval between an thesis and the beginning of ripening (a 9 to 1 ratio of total soluble solids to acid in juice) varied from 71/2 to 81/2 months in Weslaco, to 14 to 15 months in Santa Paula, but earliness or lateness of maturity could not be relatd in any simple, obvious manner to the characteristic of the seasonal temperature regimes in the 6 locations. In general, rinds were thinner, smoother and slower to color, and fruits larger, and juicier in Orlando and Weslaco than in the Far-Western locations. Total soluble solids and ascorbic acid in juice at comparable stages of maturity were not influenced in a predictable manner by location, although significant differences occurred in a given season. Of the juice constituents, the acids appear to be the most consistently influenced by climatic conditions during the rapid growth and maturation periods of fruit development. The warmer the climate, the more rapid was the rate of decrease of total acid concentration. Seediness of fruit was influenced by both location and season. Measurements of comparable samples of fruit obtained from widely divergent climatic parameters suggest that the numerous growth and metabolic processes involved in ripening of citrus fruits have independent internal controlling mechanisms. Apparently these processes interact in different ways with external environmental factors, and are not dominated by a pervasive, common internal maturity factor.

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