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  • Author or Editor: George A. Cummings x
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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.

Open Access

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.

Open Access

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.

Open Access

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.

Open Access

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.

Open Access

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.

Open Access

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.

Open Access

Abstract

Irrigation did not influence total yield, growth, or longevity of ‘Elberta’ or ‘Redhaven’ peach trees. Yields were depressed when N was reduced to 0.2 kg/tree (approx 1/2 recommended rate) with both cultivars. Increasing N above the recommended rate did not influence yield. Highest yields were obtained with lightest pruning level but fruit size was reduced. Random tree loss occurred with all treatments but was highest with low N rates.

Open Access