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  • Author or Editor: M.A. Dixon x
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A concern with the greenhouse production of horticultural commodities, particularly those grown in the ground, is the difficulty in managing nutrient runoff. Alstroemeria, a heavy-feeding crop that is nearly always grown in soil, were planted into 26.5-L pots with a medium of LECA. Greenhouse experiments were designed to examine flowering stem production, quality, and nutrient flux under nutrient solution reuse (closed system) and with one of three levels of nutrition (EC of 2.1, 1.6 and 1.1 mS/cm). Plants in the closed treatments were set on troughs sloped towards separate 24-L reservoirs. The control was an open drainage system fed at 2.1 mS/cm. The reservoirs were kept at a constant volume with the addition of water after every irrigation; nutrients were added to restore the EC to demand levels. Stems were harvested twice per week and the nutrient content of the reservoirs were analyzed biweekly by ion chromatography. Data were analyzed as an RCBD with four treatments and blocks. Analysis of data from the preliminary experiment (29 May to 3 Aug. 1998) indicated number of stems and cymes were similar among treatments. Stem length, dry weight, and number of florets were depressed below the control only in lowest fed treatment. Nutrient application was reduced markedly, by up to 1000-fold in the closed vs. the open production system.

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Authors: and

Abstract

Nitrogen, as urea, was applied to filbert (Corylus avellena L.) trees at the rates of 0, .68, 1.36, and 2.72 kg N/tree/year from 1971-1977. Nitrogen applications significantly increased leaf N, yield, and tree size. Leaf P levels were reduced by N applications in all years. Soil pH, measured after 7 years of N application, significantly declined as N application rate increased. Leaf Mn levels were increased by N applications in all years, probably due to the decrease in soil pH. Yields were expressed as a quadratic function of N and the standard ranges for leaf N in filbert were categorized as follows: deficiency (visible symptoms present) < 2.0% dry weight; below normal 2.0 − 2.2%; normal 2.2 − 2.4%; above normal > 2.4%.

Open Access

Abstract

Leaves of red raspberry (Rubus idaeus L. cv. Meeker) were sampled every 2 weeks throughout the growing season at 7 different positions on the cane to determine the time and position of minimum leaf nutrient flux. During the last half of August, the 5th to 12th leaves from the terminal 15 cm of the primocane showed the least variation in nutrient concentrations.

Open Access