The Boron Content of Oranges

“…The leaves at the higher borax applications resembled those shown in figure 8. The data (table VIII) show no relation of the boron applied to the soil and that found in the peel, although the boron in the pulp appears to show a relation to the borax applied (18,24 Summary Gum was sometimes found in the peel of lemon and orange and also about the core in orange fruits produced by trees grown in solution cultures lacking boron. The vessels of the woody tissues in such trees were often filled with gum; exudations occurred at cut surfaces and in some cases the gum protruded through the bark.…”

Section: Boron In Citrus Leaves and Fruits In Orchardsmentioning

confidence: 99%

Boron in Citrus Trees

Haas¹

1945

Plant Physiol.

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IntroductionDuring the past twenty-five years attention has been given to the effects of boron on trees. Practically all soils in southern California were then considered to be alkaline in reaction and under such conditions boron availability might be interfered with. Recenitly, however, it was found that soils in healthy citrus orchards are generally acid (11) at some time during the year; some soils are becoming so acid as to require calcium carbonate. Also recently (10) it was shown that most citrus soils in southern California contain adequate amounts of available boron.Boron is an essential element for citrus (8). The response of olive trees to applications of boron to the soil (25) has afforded an opportunity for studying adjoining citrus trees in low-boron areas. Excessive-boron areas on the other hand are numerous. Use was made of trees growing in both of these and in healthy areas in supplementing studies of trees growing under controlled conditions in artificial cultures. In Rhodesia (18) a condition known as "hard fruit" in navel orange trees was corrected by applications of boron to the soil. Translucent spots, such as were found in artificial cultures (13), were noted and in addition there were deposits of gum around the fruit axis and in the albedo of the rind. No corky split veins were observed in the leaves. In Florida (22) grapefruit trees were grown in (coarse builders' sand) cultures and when the trees were boron-deficient, the fruit showed brown discolorations in the albedo but no gum was noticed around the axis of the fruit such as was described in Rhodesia. In Florida but not in Rhodesia there was observed a thickening of the midrib and veins, the midrib of the old leaves becoming corky (1) on the dorsal surface. Other observations (3, 4) in Florida groves revealed symptoms similar to those reported from Rhodesia but the symptoms were not consistent over a period of time in the same grove, disappearing rather quickly when a resumption of rains ended a period of unusual drought. This HAAS: BORON IN CITRUS TREESacidification with dilute HCl, heating of the solution on the hot plate and filtering through the original funllel, the volume was brought near 100 ml. and completed when cool. Usually 5-and not over 25-ml. aliquots were pipetted in duplicate to porcelain dishes as described elsewhere (10) to omit the boron. Otherwise, flowering was scant and of the fruits that set there was an excessive premature abseission, gum exudations being, frequently seen at the tip of flower pedicels after the abscission of the flowers. Some of the fruits from boron-deficient trees contained gum in the albedo of the rind although the number of fruits without such gum was by far the greater. PLANT PHYSIOLOGYIn figure 1 are shown some external effects of boron deficiency in lemon and orange fruits. In severe cases under glasshouse conditions, gum may be forced through the peel (lemons) or accumulate about the core (navel oranges) until the gum protrudes through at the blossom end. When fruits of boron-d...

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Sand- und Wasserkulturversuche über die Wirkung des Bors auf Keimung und Jugendwachstum einiger Kulturpflanzen

Scharrer

Schropp

1933

Z. Pflanzenernaehr. Dueng. Bodenk.

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The Boron Content of Oranges

Cited by 4 publications

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Accumulation of Boron by Reciprocally Grafted Plants

Accumulation of Boron by Reciprocally Grafted Plants

Boron in Citrus Trees

Sand- und Wasserkulturversuche über die Wirkung des Bors auf Keimung und Jugendwachstum einiger Kulturpflanzen

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