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A split-plot experimental design was imposed in the year of planting and maintained for the first five growing seasons in a high density apple orchard on M.9 rootstock planted at 1.5 m (within row) × 4 m (between row) in a loamy sand soil susceptible to K deficiency when drip-irrigated. Four N-K fertigation treatments involving low (N1) and high (N2) rates of N combined with 0 (K0) or 15 g K/tree per year (K1) were applied in five replicated and randomized main plot units. Subplots consisted of three-tree plots of each of the apple cultivars Gala, Fuji, Fiesta and Spartan. Soil solution monitoring indicated the maintenance of distinctly different soil solution N and K concentrations in the respective N-K treatments during the study. The most important plant response was prevention of the development of K deficiency by the K1-fertigation treatment. Fertigation of 15 g K/tree generally increased leaf K, fruit K and Mg concentrations, fruit size and yield and fruit titratable acidity and red coloration at harvest for all cultivars. K fertigation also decreased leaf Mg and B concentrations, fruit N, P and Ca concentration and fruit firmness. In addition to leaf K concentrations <1%, K deficiency was associated with fruit K concentrations <100 mg/100 g fresh weight and soil solution K concentration <5 mg·L-1. Increasing the rate of fertigated N when growth was constrained by K deficiency increased leaf N and Mn and decreased leaf P and B, but had no effect on tree vigor or fruit production and quality.

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Strawberry (Fragaria × ananassa Duch.) was grown for two seasons on a fine sand soil to study the plant and fruiting response of three cultivars to K rates of O, 56, 112, 168, and 224 kg·ha-1. `Dover' total fruit yields increased linearly with rate both seasons while the maximum March yield the first season was with 170 kg K/ha. April yields increased linearly with K rate the first season. `Tufts' and `Chandler' responses to K rates were not consistent for monthly or total fruit yield. The average fruit weight of `Dover' and `Tufts' decreased linearly with increasing K rate for March and for the season in 1984, while `Dover' gave a positive linear average fruit weight response to K rate during Apr. 1986. `Dover' leaf K decreased from December to February, and K deficiency symptoms were expressed by February in treatments receiving lower rates of K. Leaf K concentrations of `Dover' correlated well with K rate.

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During the 1992-93 fruiting season, straw berry plants were fertigated weekly with either 0.28, 0.56, 0.84, 1.12, or 1.40 kg/ha/day of K derived from KCl. Other nutrients were applied in the plant bed before fumigation except for N which was applied at 0.84 kg/ha/day by fertigation. Soil moisture in the plant beds was maintained between 10 and 15 cbs. Initial soil K tested medium with the Mehlich I soil test. Seasonal average fruit weight and percent marketable fruit decreased with increasing K rate. Seasonal fruit yields did not increase with K rates above 0.56 kg/ha/day. Leaf K concentrations increased with increasing K rates throughout the harvest season. The leaf K concentrations in the 0.28 K treatment were below 1% during the last month of harvest. K rates did not affect fruit firmness.

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Abstract

Ligustrum lucidum Ait. ‘Compaction’ grown in hydrophilic polymer-amended medium required irrigation less frequently than plants in nonamended medium. Plants contained higher levels of N and K and lower levels of Ca, Mg, and other divalent cations when grown in polymer-amended medium, as compared to controls. Polymer was associated with maintenance of higher pH. With an osmocote rate increase from 15 to 45 g, a polymer × fertilizer interaction was observed. Dry weights of polymer-treated plants decreased and controls increased with increasing fertility.

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Abstract

Ten-week-old pepper plants (Capsicum annuum L. ‘Bell Boy’) were grown at 5 different root-zone temperatures (RZT) (12°, 18°, 24°, 30°, or 36° ± 2°C) for a period of 8 weeks. Maximum shoot dry weight and leaf area were measured at 24° and 30° RZT. Leaf area ratio (LAR) was not significantly affected by RZT treatments. Fruit weight was maximum at 30° RZT, but earliness was delayed at high RZT. Nitrogen, P, and K content of shoots were increased, but Mg and Ca concentrations were reduced at high RZT. Plant photosynthesis was the highest at 36° RZT. Increasing RZT improved both greenhouse or outdoor pepper production.

Open Access

Anatomical differences in leaves of queen palm [Syagrus romanzoffiana (Chamisso) Glassman] showing visible K, Mn, and Fe deficiency symptoms are described. Potassium-deficient leaves showed less organization in the mesophyll than healthy leaves. Adaxial fibers increased in diameter. Chloroplast frequency was reduced overall, but most severely in areas of the leaf showing gross symptoms of the deficiency. Manganese-deficient leaves had reduced chloroplast frequency, especially in tissue near necrotic areas, and thicker and more fibers per unit length. Iron-deficient leaves had few chloroplasts throughout the mesophyll, and also thicker and more fibers per unit length.

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Abstract

Energy dispersive X-ray analysis of Ca and K was conducted in apple (Malus domestica Borkh.) leaves. Larger amounts of Ca and K were detected in the xylem than in the mesophyll tissue. The X-ray images of both the elements increased in intensities in samples from trees receiving gypsum and foliar sprays with CaCl2. Conversion of the X-ray images into graphical data produced a better quantitative comparison of element concentrations. The range of Ca concentration in the xylem of 206 to 350 ppm compared favorably with that reported in the literature for xylem sap of assorted tree species, including apple trees.

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36 and 84 kg·ha −1 of K ( Harkins et al., 2014 ). As the need is greatest during fruiting, K deficiency is common in years of high production, with symptoms including reduced growth, followed by chlorosis and necrosis in the leaves, and shortening of

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Dr. Robert K. Soost, 88, Professor Emeritus in the Department of Botany and Plant Sciences, University of California (UC)–Riverside, died on 8 Mar. 2009. Dr. Soost was internationally known for his work in citrus breeding. His research included a

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plants can provide a theoretical basis for revealing the breeding system and genetic breeding of angiosperms, which will further guarantee the breeding success of these species, thereby increasing the species continuity. C. weiningensis Y.K. Li

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