In recent years, the juvenile period of olive seedlings has been reduced by diverse forcing and pruning-formation techniques, but it is still a major drawback for breeding. Plant height at the time when seedlings are transplanted to the field has been found effective for obtaining earlier flowering, but the value of this parameter varies widely among olive breeding programs. We evaluated different transplant dates, taking into account mean plant height and age, with the aim of determining the optimum parameters for achieving early flowering and easy plant management and, at the same time, for the early elimination of genotypes with a long juvenile period. A mean seedling height of ≈100 cm at the time of planting in the field provided the best results in terms of shortening the juvenile period and facilitating handling of the seedlings. For all dates tested, seedling height at transplanting was effective as a pre-selection criterion for the early elimination of genotypes with long juvenile periods, with slight improvement in effectiveness with advancing transplant date.
Inmaculada Moreno-Alías, Hava F. Rapoport, Rafael López, Lorenzo León and Raúl de la Rosa
Roberto López-Pozos, Gabino Alberto Martínez-Gutiérrez, Rafael Pérez-Pacheco and Miguel Urrestarazu
Inadequate oxygenation of the nutrient solution (NS) in recirculating hydroponic systems leads to root hypoxia in several plants as a result of low oxygen solubility, and this is most notable in warm climates. Hypoxia affects crop nutrient and water absorption and results in reduced crop yield. However, increased air supply to the NS serves as a source of oxygen for the roots. To evaluate the incorporation of oxygen into the system, we varied the slope of 14-m long containers from 2% to 4% and applied zero, one, two, or three gaps of NS. The channel width measured 10 cm and was equidistant from the end points. The effect of the dissolved oxygen in the NS was measured by the production of a tomato cultivar. The oxygen dissolved in the NS was 5% greater in the channels with a 4% slope compared with those with a 2% slope. The channels that included the gaps incorporated a higher quantity of dissolved oxygen during cultivation. In the middle of the day, the available oxygen was the limiting factor for the yield. The best results were obtained with a steeper slope, and gaps also improved the tomato yield. More rapid changes in NS were associated with a higher quantity of dissolved oxygen.
Rafael Urrea-López, Rocío I. Díaz de la Garza and Juan I. Valiente-Banuet
Although habanero peppers (Capsicum chinense, Jacq.) are highly appreciated as a result of their organoleptic and pungency properties, the crop faces edaphic stresses throughout Mexico. A study was conducted to determine how the photosynthetic parameters, vegetative growth, yield, and fruit quality of the plant change in response to suboptimal conditions in the substrate. Habanero plants were grown in an inert substrate (perlite) and exposed to increased salinity levels (4 and 7 dS·m−1) and reduced nitrogen and phosphorus conditions. Plants grown with a Hoagland-based solution were used as controls. High salinity conditions reduced the light-saturated photosynthetic rates (64% of the control) but did not compromise yield or fruit quality. This effect was possibly the result of the addition of Ca2+, which reduced salinity-induced calcium deficiency. Although comparable low nitrogen levels in previous studies were shown to cause a severe reduction in plant viability, in our study, low nitrogen reduced the light-saturated photosynthetic rates (47% of the control) and shoot:root ratio (67% of the control) but did not significantly affect yield or fruit quality. Low nitrogen and 7-dS·m−1 treatments increased fructose and glucose content (increases of 27% and 21%, respectively). Low phosphorus significantly affected plant growth and yield and reduced fructose content (73% of the control). Plants were not sensitive to low nitrogen and high salinity, possibly as a result of the use of nitrate-based fertilizers and the addition of calcium, respectively. These results provide guidelines for habanero pepper production under suboptimal edaphic conditions.
José M. López-Aranda, Carmen Soria, José F. Sánchez-Sevilla, Josefa Gálvez, Juan J. Medina, Antonio Arjona, José I. Marsal and Rafael Bartual
Public and private institutions in Spain are increasing strawberry (Fragaria ×ananassa Duch.) breeding efforts to obtain new strawberry cultivars well-adapted to growing conditions in Huelva and other Spanish areas, such as Valencia on the eastern Spanish coast. The new `Medina' is a short-day cultivar that is remarkable for its high production of first quality fruits, and large fruits. `Medina' has also an appropriate harvest calendar for the economic interest of the Huelva area.
José M. López-Aranda, Carmen Soria, José F. Sanchez-Sevilla, Josefa Gálvez, Juan J. Medina, Antonio Arjona, José I. Marsal and Rafael Bartual
Carmen Soria, Juan J. Medina, Pedro Domínguez, María T. Ariza, Luis Miranda, Rosalía Villalba, Josefa Gálvez, José F. Sánchez-Sevilla, Iraida Amaya, Rafael Sesmero and José M. López-Aranda
Carmen Soria, José F. Sánchez-Sevilla, María T. Ariza, Josefa Gálvez, José M. López-Aranda, Juan J. Medina, Luis Miranda, Antonio Arjona and Rafael Bartual
Yolanda Godínez-Hernández, José Luis Anaya-López, Raúl Díaz-Plaza, Mario González-Chavira, Irineo Torres-Pacheco, Rafael F. Rivera-Bustamante and Ramón G. Guevara-González
Seven pepper (Capsicum chinense Jacq.) populations from the Yucatán Peninsula, México, that were selected from a field screening for viral diseases were tested for pepper huasteco geminivirus (PHV) resistance. Two populations (UX-SMH-1 and UX-SMH-24) displayed <50% of infection with PHV. Four plants did not show viral symptoms 3 months postinoculation using biolistic and grafting methods. When leaf tissue from these individuals was analyzed for PHV using quantitative PCR, it supported PHV replication, thus, the ineffective PHV infection in these symptomless individuals may be a result of restricted viral movement.
José M. López-Aranda, Carmen Soria, Luis Miranda, José F. Sánchez-Sevilla, Josefa Gálvez, Rosalía Villalba, Fernando Romero, Berta De Los Santos, Juan J. Medina, Javier Palacios, Emilio Bardón, Antonio Arjona, Antonio Refoyo, Anselmo Martínez-Treceño, Antoñeta De Cal, Paloma Melgarejo and Rafael Bartual
Aguedilla is a short-day strawberry (Fragaria ×ananassa Duch.) cultivar obtained by the Spanish public breeding program (Agreement CC01-0008-F1). 'Aguedilla' produces excellent extra-early, early, mid-season, and late-season large-sized, wedge-shaped fruit, and a low percentage of second quality fruit. An agronomic and sensorial characterization of this new cultivar, in comparison with the well-adapted cultivars 'Camarosa', 'Medina', and 'Ventana', was undertaken during the 2002–03 and 2003–04 crop seasons.