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- Author or Editor: George Cummings x
Abstract
Changes in pH and concentration of P, K, Ca and Mg in the soil were monitored during an 8-year period in a blueberry field cleared for cultivation just prior to establishment. The influence of 3 rates of N, P, K and 2 rates of lime upon these parameters, yield, and foliar elemental levels of highbush blueberry (Vaccinium corymbosum L. cv. Wolcott) were determined. Soil pH increased from 3.7 to 4.1 during the study when lime was not applied. Application of N and K increased and P decreased soil pH. Foliar N, P and K reflected the amount applied, but foliar concentration of Ca and Mg was influenced in only 3 years by application of dolomitic lime. Yield was increased by the intermediate level of K (47 kg/ha) and the intermediate and high levels of P (25 and 50 kg/ha) compared with the O rates. Yield was not increased by N above the base rate of 34 kg/ha. Bush mortality was increased by high levels of N (168 kg/ha), P (50 kg/ha) and K (94 kg/ha) compared to the O rates. Increasing N or P delayed but K hastened fruit ripening. Lime application did not influence yield. The effect of treatments upon certain foliar micronutrients are presented and discussed.
Abstract
Chemical analysis of 3 portions (margin, midrib, and petiole) of immature and mature muscadine grape leaves (Vitis rotundifolia Michx. cv. Scuppernong) were carried out from samples collected at six 3-week intervals in 1971. The concentrations of N, Mn, Fe were higher in the leaf blade than in the petioles. Concentration of P, K, Ca, Mg, Cu, and Zn were higher in petioles than in the leaf blades. Difference in elemental concentration in the 2 portions of the leaf blade were evident only with K and Mn. The concentrations of Mg in the 2 portions of the blade were the same early in the season and decreased during the season, but the rate of decrease in the margin portion tended to be more rapid than in the midrib after the second sampling date. The decrease in Mg concentration in the blade coincides with the appearance of visual Mg deficiency symptoms. Seasonal variation was evident for all elements analyzed but slopes of the curves of the different leaf portions for a given element were often quite different. Data are presented for elemental concentration of 3 leaf portions of immature and mature leaves. In all cases, except B, elemental concentrations varied with leaf portions.
Abstract
Effects of soil pH, tillage practices, P application, and the addition of clay at the planting site on tree size, fruit yield, fruit size, and tree longevity of peaches [Prunus persica (L.) Batsch] for 20 growing seasons are reported. Because of widespread tree death, ‘Loring’ trees were removed after 9 years and the orchard replanted to ‘Winblo’. Soil pH below 5.6 resulted in poor tree growth, low fruit yield, and small fruit size compared to trees grown in soils at higher pH. In the final 10 years of the experiment, marked improvement in tree size, fruit yield, fruit size, and longevity were evident as soil pH increased. The effect of 3 tillage practices—normal plow to a depth of 20 cm, normal plow to a depth of 20 cm plus a 75-cm-diameter ⨯ 122-cm-deep hole at the planting site, and deep plowing to a depth of 58 cm—varied with cultivar. Both methods of soil profile modification (which penetrated the A2 horizon) resulted in increased yield and tree size compared to normal plowing to 20 cm with ‘Loring’ during the first 9 years. During the final 10 years, fruit yield was lower and tree death greater in the deep-plow plots, but there were no differences in fruit yield, tree size, or tree longevity between the other tillage treatments. Phosphorus rates (0, 15, and 30 kg/ha annually) or clay additions did not influence tree size, fruit yield, or tree survival. Results of this study lend strong support for the maintenance of soil pH above 5.6 and good evidence that increase in tree growth, fruit yield, and tree longevity is further enhanced when soil pH is maintained above 6.0.
Abstract
Concentration of elements varied widely in different portions of peach trees. Levels of N, P, K, and Zn in the fruit were similar to foliar levels while Cu, Fe, Mn, and especially Mg and Ca were much lower than foliar levels. Concentrations of Ca and Zn in the twigs were similar to those in the foliage. Levels of other elements in the twigs were lower than in the foliage. The lowest concentration of each element except Ca was in the trunk and branches. Concentration of P in the roots was near that of the foliage, while most of the other elements were more abundant in the roots than in the trunk and branches, but less so than in the above ground active metabolic tissue.
Application of either K or Mg increased the concentration in the foliage of the element applied. Antagonistic influence between these 2 elements occurred in the foliage, but not in other tissues. Application of either K or Mg depressed levels of Ca in most portions of the tree. Application of K increased and Mg decreased Mn levels in most portions of the tree. The influence of treatments upon the concentration of other micronutrients was not clear and was usually limited to specific tissue.
Abstract
Concentrations of N, P, K, Ca, Mg, Mn, Fe, Zn and Cu in blueberry fruit (Vaccinium corymbosum L. cv. Wolcott) as influenced by 3 rates of N, P, and K and 2 rates of lime were determined for 2-4 years. Concentration varied among years, but the variation was much less for N, P, K, and Ca than for Mg and the micronutrients. Application of N, P, or K increased the concentration of the element applied. Application of lime did not influence elemental concentrations. Increasing N rates decreased fruit Ca, and P decreased Mn concentrations each year.
Abstract
Muscadine grapes (Vitis rotundifolia Michx. ‘Carlos’) were established in 1972 with 5 soil pH levels, 5.0, 5.5, 6.0, 6.5, and 7.0. An annual N variable of 50 and 83 kg/ha was imposed in 1975. Yields from 1975-1983 were increased by N application and decreased at soil pH 5.0. By 1980, soil Ca and Mg concentrations were increased about 3-times between the lowest and highest pH treatments. With increased soil pH, foliar concentration of Mg, but not Ca, increased whereas K, N, and Mn decreased. Fruit size, soluble solids, acidity, and concentrations of P, Fe, Zn, Cu, and B in the foliage or fruit were not affected by treatments.
Abstract
The application of either N or Mg resulted in marked decreases in keeping quality, firmness, surface color, and to a lesser extent, specific gravity of peaches. The application of K was associated with increases in firmness, keeping quality and color, but a slight decrease in specific gravity of the fruit. The application of lime was not associated with changes in any quality factor determined. The application of P significantly increased firmness. Deviation from normal pruning practices resulted in increases in fruit firmness while irrigation decreased firmness. Treatments that lowered specific gravity usually lowered per cent dry weight. Evidence is presented which indicates that treatment influence upon fruit color was greatly increased in proportion to the number of years a treatment was applied.
Abstract
Nitrogen and P fertilization increased growth of 1 and 2 year-old highbush blueberry plants (Vaccinium corymbosum L., cv Wolcott) at 2 locations in eastern North Carolina. The influence of K upon growth during the years of establishment was not conclusive. Dolomitic lime application prior to establishment raised soil pH from 3.7 and 3.9 to 4.5 and depressed growth.
The influence of treatments upon the foliar contents of N, P, K, Ca, Mg, Fe, Cu, Mn, and Zn was determined. A direct relationship existed between the rate of N, P, or K and the content of these elements in the foliage. The only effects noted from lime application were an increase in P and Ca and decrease in Fe foliar level at one location. Variations in foliar elemental content, induced by treatments, were usually similar at both locations. The level of certain elements in the foliage, however, varied widely with location.
Abstract
We determined the influence of fertilizer and cultural treatments upon peach flesh resistance to browning, soluble solids, titratable acidity, pH, and soluble ninhydrin-positive nitrogenous compounds. Nitrogen, P, K, and lime and severe pruning increased the resistance of macerated fresh fruit to browning. Soil profile modification and Mg application lowered browning resistance. Application of N or lime increased soluble solids in the fruit, but deep tillage decreased them. Soluble solids were higher when pruning was either less or more severe than that normally practiced. Titratable acidity was positively related to the application of P and K, but was decreased by N application. Application of K or lime increased pH whereas changing the N supply yielded inconclusive results. The soluble amino acids of the fruit were positively related to N supply and were reduced by K application. Interrelations of treatment effects upon the various components are discussed.
Abstract
Concentration of N, P, K, Ca and Mg in foliage samples every 3 weeks starting in mid May was determined. Prior to analysis, leaf blades were separated into margin and midrib portions and the petioles of apple (Malus domestica Borkh) and muscadine grapes (Vitis rotundifolia Michx) were removed and analyzed separately. Differences were evident in the concentration of N, K, and Mg between portions of the leaf blade in each of the plants analyzed. Leaf blade portions of highbush blueberry (Vaccinium corymbosum L.) or grape did not differ in P concentration. Changes in the concentration of an element within a portion of the leaf were normally accompanied by similar changes in the other portion or portions. Notable exceptions were the marked increases in grape petiole Ca and Mg during mid and late season with much less change in leaf blade content. Ca appeared to accumulate in the midrib portion to a much greater extent than the leaf margin portion of peach (Prunus perisca (L.) Batsch). The only indication of a late season mobilization of an element from the leaf margin was the decrease in N in the margin and a concurrent increase in themidrib portion of peach leaves.