Evaluación de sistemas de implantación y variedades de tuna (Opuntia ficus-indica)

The vegetative growth and productivity of four prickly pear varieties grown under two planting systems (single cladode and double cladode) was evaluated over a period of five years (1995-1999) in the San Juan province of Argentina. The three Argentine varieties examined (possibly ecotypes of the variety known locally as "yellow prickly pear without spines") came from the Santiago del Estero, Córdoba and San Juan provinces. The fourth variety used was "Gialla" from Italy. The double cladode plants reached a greater photosynthetic area and total cladode number than the single cladode plants. The double cladode system produced earlier fruits and the highest yields from the second year onwards. "Gialla" gave the highest fruit yields, and showed the greatest vegetative growth. No differences were observed between the Argentine varieties in terms of yield and plant growth. Planting double cladodes significantly improved fruit production and vegetative growth in the Gialla variety. Most of the fruit produced (80%) by the national varieties fell into the medium (96-140 g) and large (> 140 g) categories, while "Gialla" produced mostly medium and small sized fruits ( 80%) se concentró en las categorías mediana (96 a 140 g) y grande (> 140 g) en las variedades nacionales, y en las categorías mediana y chica (< 96 g) en "Gialla"

Assessment of prickly pear (Opuntia ficus-indica) varieties and their possible planting systems

El crecimiento vegetativo y la productividad de cuatro variedades de tuna y dos sistemas de implantación, cladodio doble y cladodio simple, fueron evaluados durante cinco años (1995-1999) en la provincia de San Juan (Argentina). La procedencia de tres de las variedades (posibles ecotipos dentro de la variedad conocida localmente como "tuna amarilla sin espinas"), fueron las provincias de Santiago del Estero, Córdoba y San Juan. La restante variedad fue "Gialla", procedente de Italia. Las plantas formadas a partir del sistema cladodio doble presentaron mayor superficie fotosintética y número total de cladodios. Esrte sistema de plantación ocasionó una entrada anticipada en la etapa productiva y mayores rendimientos a partir del segundo año. "Gialla" superó a las restantes variedades en crecimiento vegetativo y producción. Las variedades nacionales no se diferenciaron en su comportamiento productivo y vegetativo. El efecto del sistema cladodio doble sobre la producción y el crecimiento vegetativo fue significativamente superior en la variedad italiana. La mayor parte de la producción (>80%) se concentró en las categorías mediana (96 a 140 g) y grande (>140 g) en las variedades nacionales, y en las categorías mediana y chica (<96 g) en "Gialla"

Intercambio gaseoso y eficiencia en el uso del agua de cultivos de cobertura con especies nativas (Mendoza, Argentina), exóticas cultivadas y malezas

Cover crops have been largely used in the soil management of vineyards as an environmentally sustainable tool for diverse purposes. A major limitation for cover crop use is the additional water consumption. Native grasses adapted to low water availability may be a feasible alternative under drip irrigation. The aim of the study was to evaluate water use efficiency and carbon dioxide fixation of three introduced cover crops, two weeds and six native grasses selected from three viticultural regions of Mendoza, Argentina. The experiment was conducted in Lujan de Cuyo, Mendoza, with experimental units (pots) distributed in a completely randomized design with 12 treatments and five replicates. Water consumption following the gravimetric method and gas exchange in whole plant were measured. Native C4 grasses presented the lowest annual water consumption and high water use efficiency under elevated temperature and limited water availability, since evapotranspiration decreased proportionally more than the carbon dioxide fixation. Results obtained under controlled conditions suggest that these native grasses can succeed as interrow cover crops in vineyards under drip irrigation.Los cultivos de cobertura son utilizados como una herramienta ambientalmente sostenible con diversos propósitos. Una de las mayores limitantes para el uso de una cobertura vegetal es el consumo adicional de agua. Las especies herbáceas nativas adaptadas a baja disponibilidad hídrica pueden ser una alternativa factible en cultivos bajo riego localizado. El objetivo del estudio fue evaluar la eficiencia en el uso de agua y la fijación de dióxido de C de tres especies exóticas cultivadas, dos malezas y seis gramíneas nativas seleccionadas en tres regiones vitivinícolas de Mendoza, Argentina. La experimentación se efectuó en Luján de Cuyo, Mendoza, con unidades experimentales (macetas) distribuidas en diseño completamente aleatorizado con 12 tratamientos y 5 repeticiones. Se determinó consumo hídrico por el método gravimétrico e intercambio gaseoso en la planta entera. Las especies nativas tipo C4 su presentaron el menor consumo hídrico anual y elevada eficiencia en el uso del agua en condiciones de restricción hídrica y temperatura elevada, debido a que su evapotranspiración se redujo proporcionalmente más que la fijación de dióxido de C. Los resultados obtenidos bajo condiciones controladas sugieren que estas gramíneas nativas pueden tener éxito como cultivos de cobertura en el sitio interfilar de viñedos bajo riego por goteo

Potencial alelopático de lixiviados de cultivos de cobertura y malezas sobre plantas jóvenes de vid

Interactions between vines and herbaceous species may involve competition for resources and allelopathy. It is presumed that certain cover crops and weeds have allelopathic effects on the growth of grapevines. The objectives were: a) to evaluate the effect of leachate from irrigation of different cover crops on vines and b) to determine its inhibitory effect on seed germination. Greenhouse and field experiments were conducted with cover crops and potted vines. Eleven leachates from different green covers and a bare soil control were tested with a randomized design and five replicates. The vegetative and productive expression of the vines was evaluated. Seed germination tests were conducted using leachate from irrigation and different concentrations of the aqueous solution. Adverse effects were not detected in the vegetative growth, the grape production in young vines or the germination of other plant species. The pot trial showed that there is an interaction between cover crops and soil, whereby the balance of nutrients is altered depending on the species. This balance can positively or negatively affect the growth of the vines.Las interacciones entre la vid y especies herbáceas pueden involucrar competencia por recursos y alelopatía. Se presume que determinados cultivos de cobertura y malezas poseen efectos alelopáticos sobre el crecimiento de las cepas. Los objetivos del trabajo fueron: a) evaluar el efecto de los lixiviados de riego de diversas coberturas vegetales sobre plantas de vid y b) determinar su efecto inhibitorio sobre la germinación de semillas. Se efectuaron experimentaciones de campo e invernadero, con cultivos de cobertura y vides en macetas. Se utilizaron 11 lixiviados de diferentes cubiertas vegetales y un testigo con suelo descubierto, con un diseño completamente al azar y cinco repeticiones. Se evaluó expresión vegetativa y productiva de las vides. Se realizaron pruebas de germinación sobre semillas, utilizando lixiviados del riego y diferentes concentraciones de la solución acuosa. No se detectó efecto negativo en el crecimiento vegetativo ni en la producción de uva en plantas jóvenes de vid, ni tampoco en la germinación de otras especies vegetales. El ensayo en macetas evidenció que existe una interacción entre las coberturas y el suelo, mediante la cual el balance de nutrientes es alterado según la especie, y puede afectar positiva o negativamente el crecimiento de las vides

Muskmelon seed priming in relation to seed vigor

A number of important factors may affect seed priming response, including seed quality. Effects of seed vigor on seed priming response were investigated using seed lots of two muskmelon (Cucumis melo L.) cultivars. Seeds of muskmelon, cvs. Mission and Top Net SR were artificially aged at 43°C for 0, 20 and 40 hours. Seeds were primed for six days in darkness at 25°C in KNO3 (0.35 mol L-1) aerated solution. Aged seeds germinated poorly at 17°C. Priming increased germination rate at 17 and 25°C and germination percentage at 17°C. An interaction effect on germination performance between vigor and priming was observed, especially at low temperature. Priming increased germination performance in seeds of low vigor, and the response was cultivar dependent

Seed conditioning of red oak: a recalcitrant North American seed Condicionamento de sementes de carvalho vermelho: semente recalcitrante da América do Norte

A ten day aerated water soak was developed as a seed conditioning treatment for red oak (Quercus rubra L.). Conditioned seeds had higher germination completeness, uniformity and speed compared to control seeds. Seeds could be conditioned under a wide range of temperatures and durations. Conditioned seeds were maintained at 7(0)C for 30 days without loss of seed quality. During conditioning, pericarps split in response to seed hydration. Split pericarps could be used as a pre-sowing indicator for high quality seeds. Seed conditioning was ineffective on dormant seeds. Increased crop uniformity and higher stand establishment can be realized by subjecting red oak acorns to an aerated water soak treatment followed by selecting seeds with split pericarps. These results are especially important in container production systems where limited numbers of value seeds are available.<br>Sementes de carvalho vermelho (Quercus rubra L.) foram condicionadas diretamente em água, sob aeração, durante 10 dias. As sementes condicionadas fisiologicamente apresentaram maior percentagem, velocidade e uniformidade de germinação, quando comparadas com a testemunha. O condicionamento das sementes pode ser efetuado sob ampla variação de temperaturas e períodos de exposição. Sementes condicionadas podem ser mantidas a 7ºC/30 dias, sem perda de qualidade. Durante o condicionamento ocorre ruptura do pericarpo, em resposta à hidratação da semente; essa ocorrência pode ser utilizada para estimar a qualidade da semente. O condicionamento não apresentou efeitos em sementes dormentes. O condicionamento das sementes de carvalho vermelho em água, com aeração, seguido pela seleção de sementes com ruptura do pericarpo, proporciona o rápido estabelecimento e uniformidade das plântulas