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breeding effort ( Sraffa, 2005 ; Willcox, 1954 ). Foliar nutrient analysis is a well-established method ( Munson and Nelson, 1990 ) to assist in the diagnosis of nutrient-related problems (deficiencies, toxicities, imbalances, etc.) of both annual and

Open Access

Substrate solution testing is an essential management tool for greenhouse plug production. Current methods of plug solution extraction and testing can be confounded by subjective aspects of their techniques. The press extraction method (PEM) developed at North Carolina State University offers a convenient and timely method of solution extraction. The rooting substrate is brought to container capacity and after a period of one hour, pressing the plug surface with a finger or thumb is sufficient to expel the solution. This series of experiments serves to quantify possible variation that may occur in pH, Electrical conductivity (EC), and nutrient analysis from differing manual extraction forces. A modified press was designed to apply a range of force [53, 71, 89, 106, and 124 N (5.0, 6.7, 8.3, 10.0, and 11.6 lb/inch2)], and sampling protocol consistency was verified. For all three experiments, the range of extraction forces within a single fertilizer rate did not significantly affect solution pH or EC. When testing included a range of fertilizer rates, results were significantly different among the fertilizer rates, demonstrating the method's ability to detect changes in pH and EC resulting from increases in fertility levels. Nutrient analysis (NO3 -, NH4 +, P, K, Ca, Mg, Na, B, Cu, Fe, Mn, and Zn) of solution extracted from two different rooting substrates (peat-based and coir-based) showed no differences within substrates for the range of force treatments.

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evaluations were performed to determine the treatment effects on plant tissues. The evaluations included leaf texture analysis, leaf nutrient analysis, and moisture loss. Sampling for each analysis method started 6 weeks following initiation of treatment

Open Access

site to corresponding N tissue analysis. Materials and methods Tissue sampling and nutrient analysis. The materials selected for this study were obtained from plants at two private farms on Hawai’i Island: Pahala (lat. 19°13′40.2″N, long. 155°28′7.8″W

Open Access

The rhizon soil solution sampler (RSSS) currently is being used for in situ extraction of the soil solution for nutrient analysis of mineral soils used to produce field-grown crops. In this study, laboratory and greenhouse experiments were conducted to test the effectiveness of the RSSS for in situ solution extraction from soilless container root media and to compare an RSSS extraction method for measuring root-medium pH, electrical conductivity (EC), and NO3-N and K concentrations with that measured with the saturated media extract (SME) method. A near 1:1 correlation was found between the pH, EC, and NO3-N and K concentrations measured in the extracted solution of the RSSS and SME method in media without plants and in media from ten species grown using three water-soluble fertilizer concentrations applied by subirrigation. More testing is needed with the RSSS, perhaps using composite samples form several pots for analysis. The RSSS shows promise for nutrient extraction in container-grown crops because it is fast, nondestructive, simple, economical, and has minimal effect on the nutritional status of the medium in the pot.

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Over-fertilization (i.e., the application of fertilizer nitrogen (N) in excess of the tree or vine capacity to use it for optimum productivity) is associated with high levels of residual nitrate in the soil, which potentially contribute to groundwater and atmospheric pollution as a result of leaching, denitrification, etc. Overfert-ilization also may adversely affect productivity and fruit quality because of both direct (i.e., N) and indirect (i.e., shading) effects on flowering, fruit set, and fruit growth resulting from vegetative vigor. Pathological and physiological disorders as well as susceptibility to disease and insect pests also are influenced by the rate of applied N. Over-fertilization appears to be more serious in orchard crops than in many other crop species. The perennial growth habit of deciduous trees and vines is associated with an increased likelihood of fertilizer N application (and losses) during the dormant period. The large woody biomass increases the difficulty in assessing the kinetics and magnitude of annual N requirement. In mature trees, the N content of the harvested fruit appears to represent a large percentage of annual N uptake. Overfertilization is supported by a) the lack of integration of fertilizer and irrigation management, b) failure to consider nonfertilizer sources of plant-available N in the accounting of fertilizer needs, c) failure to conduct annual diagnosis of the N status, and d) the insensitivity of leaf analysis to over-fertilization. The diversity of orchard sites (with climatic, soil type, and management variables) precludes the general applicability of specific fertilization recommendations. The lack of regulatory and economic penalties encourage excessive application of fertilizer N, and it appears unlikely that the majority of growers will embrace recommended fertilizer management strategies voluntarily.

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manures varies with animal type, bedding, storage, and processing. Nutrient analysis of manure may be required by law in some cases, but analysis is always recommended and should include total N, NH 4 -N, P 2 O 5 , and K 2 O. Usually 25% to 50% of the

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chlorophyll content (SPAD)] measurements and foliar nutrient analysis data were collected ( Nemeskéri et al., 2019 ). Leaf greenness, a surrogate measure for chlorophyll content, was assessed using a SPAD meter (SPAD 502 Plus Chlorophyll Meter; Spectrum

Open Access

Yield responses of `Blue Vantage' cabbage (Brassica oleracea L.) to P fertilizer and two commercially available biostimulants—ROOTS and ESSENTIAL-were evaluated on soils very high in P fertility. Head yield was not increased with P fertilizer when cabbage was transplanted into soil with Mehlich-3 soil test P indexes ≥ 112 ppm (112 mg·kg-1). Neither of the biostimlants applied as a root drench at transplanting influenced head yield or plant tissue nutrient analysis.

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Four rates of two slow-release fertilizers were tested for optimum growth of five hosta cultivars: Hosta sieboldiana `Elegans', Hosta plantaginea `Aphrodite', Hosta `Jade Scepter', Hosta `Hadspen Blue', and Hosta `Francee'. Tissue-cultured hostas from 2.5-cm plugs were planted in 6-inch (15-cm) pots filled with a commercial soilless medium, and the slow-release fertilizer was dibbled into the medium at 0, 3, 6, or 12 g/pot. The plants were maintained for 4 months. Root and shoot fresh and dry weights were recorded at the end of the experiment. In addition, foliar nutrient analysis was conducted on `Aphrodite', `Francee', and `Jade Sceptor'. Overall, hostas grew best when the medium was amended with 3 g of either Osmocote 14N-6P-11.5K or Sierrablen 17N-6P-12K slow-release fertilizer.

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