The effects of pre-sowing magnetic treatments on growth and yield of tomato (cv Campbell-28) were investigated under field conditions. Tomato seeds were exposed to full-wave rectified sinusoidal non-uniform magnetic fields (MFs) induced by an electromagnet at 100 mT (rms) for 10 min and at 170 mT (rms) for 3 min. Non-treated seeds were considered as controls. Plants were grown in experimental plots (30.2 m(2)) and were cultivated according to standard agricultural practices. During the vegetative and generative growth stages, samples were collected at regular intervals for growth rate analyses, and the resistance of plants to geminivirus and early blight was evaluated. At physiological maturity, the plants were harvested from each plot and the yield and yield parameters were determined. In the vegetative stage, the treatments led to a significant increase in leaf area, leaf dry weight, and specific leaf area (SLA) per plant. Also, the leaf, stem, and root relative growth rates of plants derived from magnetically treated seeds were greater than those shown by the control plants. In the generative stage, leaf area per plant and relative growth rates of fruits from plants from magnetically exposed seeds were greater than those of the control plant fruits. At fruit maturity stage, all magnetic treatments increased significantly (P < .05) the mean fruit weight, the fruit yield per plant, the fruit yield per area, and the equatorial diameter of fruits in comparison with the controls. At the end of the experiment, total dry matter was significantly higher for plants from magnetically treated seeds than that of the controls. A significant delay in the appearance of first symptoms of geminivirus and early blight and a reduced infection rate of early blight were observed in the plants from exposed seeds to MFs. Pre-sowing magnetic treatments would enhance the growth and yield of tomato crop.

The effects of pre-sowing magnetic treatments on the growth and yield of tomatoes (cv. Vyta), cultivated late in the season, were studied under field conditions. Tomato seeds were exposed either to a 120 mT dynamic magnetic field (induced by an experimental electromagnet) for 10 min or to a 80 mT field for 5 min. Non-treated seeds were used as controls. Plants were grown in experimental plots (20.2 m 2 ) and cultivated according to standard agriculture practices. At physiological maturity, the plants were harvested from each plot and the number of fruits, mean fruit weight, fruit yield per plant and fruit yield per area determined. In the nursery stage, the treatments led to a significant increase in root length, fresh and dry root weight, stem length, fresh and dry stem weight, leaf area and foliole dry weight. During the vegetative stage, the leaf, stem and root relative growth rates of plants derived from magnetically-treated seeds were greater than those shown by control plants. In the generative stage, the relative growth rate of the fruits belonging to the 'magnetically treated plants' was greater than that of control plant fruits. At the fruit maturity stage, the magnetically treated seeds produced plants with significantly more fruits (17.9-21.3%), with a significantly greater mean fruit weight (22.3-25.5%), and with a greater fruit yield per plant (47.3-51.7%) and per area (48.6-50.8%) than did the control plants. Pre-sowing magnetic treatments would appear to enhance the growth and yield of tomatoes cultivated late in the season.Additional key words: dry matter increase, Lycopersicon esculentum, magnetic field, stimulating effect. ResumenIncremento del crecimiento y rendimiento del tomate por tratamientos magnéticos de semillas en época tardía Se estudiaron los efectos de tratamientos magnéticos presiembra sobre el crecimiento y rendimiento del tomate (cv Vyta), cultivado en período tardío en condiciones de campo. Las semillas de tomate se expusieron a campos magné-ticos de 120 mT durante 10 min y 80 mT durante 5 min en un eletroimán experimental, utilizando simultáneamente semillas sin tratamiento como control. Las plantas se sembraron en parcelas experimentales (20,2 m 2 ) y se cultivaron de acuerdo con las prácticas agrícolas normales. En la madurez fisiológica, se determinó el número de frutos por planta, la masa promedio de los frutos y el rendimiento por planta y área. En la etapa de semillero, los tratamientos indujeron un incremento significativo de la longitud, masa fresca y seca de la raíz, longitud; masa fresca y seca del tallo; área foliar y masa seca foliar por foliolo. Durante la etapa vegetativa, las tasas relativas de crecimiento de las hojas, tallos y raíces fueron significativamente superiores en los tratamientos magnéticos que en el control, mientras que en la etapa generativa, solamente resultaron significativas las tasas de crecimiento relativo de los frutos. En la etapa de madurez de los frutos, los resultados revelaron que ambos tratamientos magnéticos incrementaron signi...

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Influence of pre-sowing magnetic treatments on plant growth and final yield of lettuce (cv. Black Seeded Simpson) were studied under organoponic conditions. Lettuce seeds were exposed to full-wave rectified sinusoidal non uniform magnetic fields (MFs) induced by an electromagnet at 120 mT (rms) for 3 min, 160 mT (rms) for 1 min, and 160 mT (rms) for 5 min. Non treated seeds were considered as controls. Plants were grown in experimental stonemasons (25.2 m(2)) of an organoponic and cultivated according to standard agricultural practices. During nursery and vegetative growth stages, samples were collected at regular intervals for growth analyses. At physiological maturity, the plants were harvested from each stonemason and the final yield and yield parameters were determined. In the nursery stage, the magnetic treatments induced a significant increase of root length and shoot height in plants derived from magnetically treated seeds. In the vegetative stage, the relative growth rates of plants derived from magnetically exposed seeds were greater than those shown by the control plants. At maturity stage, all magnetic treatments increased significantly (p < 0.05)--plant height, leaf area per plant, final yield per area, and fresh mass per plant--in comparison with the controls. Pre-sowing magnetic treatments would enhance the growth and final yield of lettuce crop.

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