Date of Award:

5-1959

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Plants, Soils, and Climate

Department name when degree awarded

Soil Science

Committee Chair(s)

R. L. Smith

Committee

R. L. Smith

Committee

Herman H. Wiebe

Committee

Herman B. Peterson

Committee

Norman Bauer

Abstract

Since man first grew crops on calcareous soils he has probably been troubled with what we today call lime-induced chlorosis. This chlorosis has determined whether he grew certain desirable ornamentals or crops or whether he had to substitute others which were less desirable.

Lime-induced chlorosis is spread world wide. It has been reported in the vine and fruit growing regions of Europe, in the chernozem soils of Russia, and many other areas where the rainfall is relatively low and the soil is relatively high in calcium carbonate. In the United States it most frequently occurrs where the average annual rainfall is less than 30 inches. The conditions causing chlorosis are not stable, for it varies from year to year and even from week to week with changing conditions in climate and soil.

An estimated 500,000 acres of crops grown in the western United States on calcareous soils are subject to moderate to severe chlorosis. This physiological malady has challenged the technical ingenuity of outstanding plant and soil scientists. The exact cause or causes have never been isolated; consequently no permanent preventative measures or cures can, as yet, be recommended.

Lime-induced chlorosis, more correctly called lime-induced-iron chlorosis, for iron deficiency symptoms are the characteristics found in the plant, is characterized by an interveinal yellowing of the leaves at the meristematic region combined with reduced vigor of the plant as a whole. Once green, the leaf never turns yellow due to a lack of iron. Thus a leaf chlorotic due to a lack of iron must have always been chlorotic. Even though chlorophyll development is not normal in the chlorotic leaf, unless the condition is critical, the leaf size and stem growth are not seriously effected. If the condition is critical, necrosis will set in and the leaf will drop from the plant. If such a condition is not corrected either through natural or artificial means, some portion or all of the affected plant will die.

The plants susceptible to lime-induced-iron chlorosis are many and varied. Thorne and Wann (1953) have listed a great many plants and their relative susceptibility to lime-induced-iron chlorosis.

Certainly, as pointed out as early as 1879 by Church (1879) and more recently by Thorne and Wann (1950), not all chlorosis in plants is due to iron deficiency. A shortage of such plant nutrients as manganese, nitrogen, zinc, and magnesium will cause chlorosis, a failure of proper chlorophyll formation in the leaves and possibly in the stem of the growing plant.

Lime-induced-iron chlorosis is unique in that, with exceptions, examinations show ample amounts of iron in the afflicted plants for normal plant growth (Wallace, 1928). The iron appears to be inactivated within the plant so as to impair active functioning. Oserkowsky (1933) found a close association between the active iron content of the plant and chlorophyll development.

No single factor has been found to adequately explain this physiological disease although many factors have been associated with it. Thorne, Wann, and Robinson (1950) have observed that calcareous soils characterized by fine texture, high moisture content, poor aeration, and cool temperature intensify the development of chlorosis in plants. Vyunov (1937) presents the hypothesis that all plants having acid root secretions are immune to chlorosis.

Biddulph (1951) and Rediske (1950) found that the pH, iron, and phosphorus content of the growing solution influenced the movement of iron in red kidney beans. Gile and Carrero (1920) observed that excessive uptake of calcium from calcium carbonate by pineapple plants induced chlorosis. Somers and Shive (1942) and McGeorge (1946) found that the pathological symptoms produced when manganese was in excess in the nutrient substrate were identical with those of iron starvation. Hewitt (1948) found that additions of zinc to sand cultures in which he was growing sugar beets induced a type of iron deficiency in the plants. Rediske (1950) has suggested that iron chlorosis might be caused by excessive or toxic quantities of such elements as copper, zinc, and manganese as well as phosphorus.

In the light of these and many other past laboratory observations, it would seem that additional work could be profitably done to determine the individual effects of various nutrient elements on the absorption and translocation of iron. The objective here will be to study the effects of varying levels of pH, phosphorus, copper, manganese, zinc, iron, calcium, and magnesium in nutrient solutions on the translocation of foliar applications of iron and phosphorus.

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