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The aim of this research was to determine the effects on growth variables and leaf mineral concentration of tomato plants watered with nutrient solutions containing amino acids. Two separate experiments were then carried out to achieve this goal. In the first experiment, plants were watered with seven different nutrient solutions consisting of half-strength Hoagland solution supplemented with single (Alanine, Serine, Phenylalanine, Tyrosine) or combined (Ala + Ser; Phe + Tyr) amino acids, each at 0.2 mM of concentration. The control nutrient solution did not have any amino acids added. Relative to the control, growth variables were not affected by the presence of amino acids. In general, the mixture of Ala + Ser increased the leaf Ca 2+ concentration, and the aliphatic amino acid treatments favoured an increase in leaf K + , Fe, Cu, and Mn concentrations. In addition, amino acids with hydroxyl groups in their structure, Ser and Tyr, increased Mg 2+ concentration. In the second experiment, the nutrient solutions were supplemented with 0.05 mM of the same amino acids (T1). Control plants were irrigated with amino acid-free nutrient solution (T0). The concentration of Ca 2+ , K + , Mg 2+ , Fe, Cu, and Mn in the leaf also increased due the amino acids treatment. Chlorophyll contents in the leaves and amino acids compositions in the xylem sap and leaf water relation were also determined. In conclusion, the data reported in the two experiments point out that the application of amino acids to the nutrient solution has a beneficial effect on the leaf mineral status and on the chlorophyll concentration of the leaves.Additional key words: amino acid fertilization; biofertilizer; hydroponic culture; Solanum lycopersicum L. ResumenEfectos de la aplicación de amino ácidos en la solución nutritiva sobre la composición mineral y el crecimiento de plántulas de tomate En este trabajo se estudiaron los efectos sobre el crecimiento y la concentración mineral de hojas de plantas de tomate cultivadas con soluciones nutritivas con distinta composición en aminoácidos. Para ello se plantearon dos experimentos. En el primero las plantas se regaron con siete soluciones nutritivas 1/2 Hoagland que diferían en la composición de los aminoácidos, todos ellos a una concentración total de 0,2 mM (Ala, Ser, Fen y Tir aplicados de forma individual, dos con la combinación Ala+Ser y Fen+Tir, un control sin aminoácidos). Las variables de crecimiento no mostraron diferencias entre los tratamientos; sin embargo, se observaron cambios en las concentraciones de nutrientes aunque los efectos dependieron de los aminoácidos utilizados. La mezcla de Ala + Ser aumentó la concentración de Ca 2+ , mientras que los tratamientos de aminoácidos alifáticos favorecieron un aumento de K + , Fe, Cu y Mn, y aquellos con grupos hidroxilo (Ser y Tyr) aumentaron el Mg 2+ . En el segundo experimento las plantas se regaron con disolución 1/2 Hoagland (T0) o con disolución 1/2 Hoagland más una mezcla de los 4 aminoácidos (0,05 mM) ensayados (T1). En este experiment...

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The use of almond by products as substrate in greenhouses for growing vegetables has a great economic interest. The objective of this work was to assess the use of two almond by-products (almond shell-AS and almond hull-AH), which had been previously conditioned without composting, as substrates for pepper (cv. Caprino F1) production and to study their effects on the yield, fruit size, and fruit mineral content. Physical, physico-chemical, and chemical characteristics of the almond by-products were determined both initially and during the pepper growing season. Initially, all values of the parameters studied -except sulfur and iron-differed significantly between the two substrates. During cultivation, the 18 substrate parameters and variables tested -except bulk density-exhibited significant variations with time for AS; the same occurred for AH, exceptions being pH, total nitrogen N t , N-NH 4 , bulk density, and manganese. The changes in both substrates for the K, N, and S concentrations were significant. The nutrient levels in AH were higher than for AS. The almond shell and almond hull substrates produced slight decreases in total fruit yield with respect to the control (0.79 and 3.22 for AS and AH, respectively), with a lesser decrease for AS, due to reductions in the number of fruits per plant rather than to reductions in individual fruit weight. The plants grown on the AS and AH substrates showed a decrease in total fruit yield, due to reductions in the number of fruits per plant rather than reductions in individual fruit weight.

The effects of calcium deficiency on the appearance of ''glassiness'' or ''watercore'' and texture evolution in cantaloupe muskmelon (Cucumis melo L.) and on polygalacturonase (PG) and b-galactosidase activities and their relation to ethylene production were studied. Watercore increased in melons cultivated with calcium-deficient nutrient solutions, as did ripening, which could be related to their lower calcium content. Whole fruit firmness and flesh firmness decreased from 34 days after set (DAS) in control melons, while in calcium-deficient fruits, the softening process had begun before day 33 after fruit set, both parameters being significantly lower in these. The activity of b-galactosidase increased during melon ripening, reaching maximum values two days earlier in melons grown with calcium-deficient solutions than in control ones. However, no PG activity was detected in control melons, but this activity increased during ripening in melons grown with low and removed calcium solutions, a fact that positively correlated with decreased fruit firmness. Ethylene production rate increased sharply as fruit ripened, which could be responsible for the increase in b-galactosidase activity and so for fruit softening. However, the higher softening and glassiness incidence observed in melons irrigated with calcium-deficient solutions could be due to PG activity.Se ha estudiado el efecto de la deficiencia de calcio en la aparicio´n de vitrescencia y en la evolucio´n de la firmeza en melo´n Cantalupe (Cucumis melo L.), ası´como en la actividad de los enzimas poligalacturonasa (PG) y b-galactosidasa y su relacio´n con la produccio´n de etileno. La aparicio´n de vitrescencia aumentod urante la maduracio´n en todos los melones cultivados con disoluciones nutritivas deficientes en calcio, lo que podrı´a relacionarse con su menor contenido en calcio. La firmeza del fruto entero y de la pulpa disminuyo´a partir de los 34 dı´as desde el cuaje (DAS) en los melones control, mientras que en los frutos deficientes en calcio, el proceso de ablandamiento habı´a comenzado antes de los 33 DAS, siendo ambos para´metros significativamente ma´s bajos en estos frutos. La actividad b-galactosidasa aumento´durante la maduracio´n del melo´n, alcanzando valores ma´ximos dos dı´as antes en los melones cultivados con disoluciones deficientes en calcio que en los controles. No se detecto´actividad PG en los melones control, sin embargo esta actividad aumento´durante la maduracio´n en los melones cultivados con disoluciones deficientes en calcio, lo que se correlaciono´positivamente con el ablandamiento de los frutos. La tasa de produccio´n de etileno aumento´ra´pidamente con la maduracio´n, lo que pudo ser responsable del aumento en la actividad b-galactosidasa y del ablandamiento del fruto. Sin embargo, la incidencia de vitrescencia y el mayor ablandamiento de los melones cultivados con disoluciones deficientes en calcio podrı´a deberse a la actividad poligalacturonasa.