Influence of Potassium and Boron on Nutrient-Element Balance in and Growth of Ranger Alfalfa

Abstract

Inadequate supplies of K and B have been associated with short life and low yield of alfalfa in the eastern United States. For this reason, studies of the influence of these two elements on the behavior of this plant are of special interest. This paper is concerned with such studies.Literature review HUNTER, TOTH, and BEAR (9) concluded that when the K content of alfalfa falls below 1 per cent., its Ca exceeds 2 per cent., or its Ca-K equivalent ratio is greater than four, yields are greatly depressed. It was also shown that although the content of the individual cations may vary widely, cation-equivalent summation values tend to be constant under standardized environmental conditions. Such cation interrelationships in plants have received considerable attention (7,19,28).Other work from this station (29) has shown that plants having high cation-equivalent values also tend to have high mineral anion-equivalent values. When alfalfa plants were grown under uniform environmental conditions, except as to the nutrient supply, cation-anion equivalent ratios were essentially constant. This applied, notwithstanding variations in the relative amounts of the different cations in the nutrient medium and regardless of the season of the year. Other workers have noted this phenomenon (17,23).Extensive data on K-B and Ca-B relationships in plants are highly contradictory (5,18,24

Sources and rates of potassium for sweet orange production

“…Other results of leaf analysis demonstrated a significant interaction (p < 0.05) between K and B contents of leaves in both locations, in which leaf B decreased about ten units B with increased K fertilization ( Figure 6A and 6B). Such effect was also described for alfalfa (Wallace and Bear, 1949) and avocados (Jaime et al, 1992), even though no specific mechanism at the plant level was proposed to explain such results. Conversely, K uptake by plants is increased with B supply (Cooper et al, 1952;Schon et al, 1990;Obermeyer et al, 1996;Quaggio et al, 2003;Grassi et al, 2004).…”

Potassium deficiency in pastures

“…Bourdon et al (1948) recorded that yields of clover dropped immediately with potassium deficiency but leaf symptoms did not appear for 12 years. Wallace and Bear (1949) found no symptoms of potassium deficiency in lucerne grown in a deficient soil in autumn although height of growth was reduced. In the present work, deficiency symptoms were absent or difficult to identify in the autumn and winter, but these were also the times of minimum responses.…”

“…During the hot, sunny, and dry weather of autumn, when growth was retarded and the intervals between grazings were longer, plants tended to mature. Such conditions also favour lignification of tissues and carbohydrate synthesis, which has a "dilution" effect in lowering plant cation concentrations (Wallace and Bear 1949).…”

Cation and Anion Relationships in Plants and Their Bearing on Crop Quality1

“…A detailed study of uninoculatecl alfalfa in sand culture (7,8) revealed that cation-anion equivalent ratio values varied from one part of the plant to another. In the leaves, they decreased with increasing K and decreasing Ca.…”