No abstract

Low yields have been observed in annual production systems in raspberry (Rubus idaeus L.) compared with annual yields in perennial systems. This yield reduction could be related to a depletion of root carbohydrates and its consequent detrimental effect on fruit number or size. Additionally, primocanes could play an important role in the carbohydrate dynamics in an annual system and may also affect yield. Two experiments were carried out in 2003 and 2004 to determine the importance of root carbohydrates and primocanes in fruiting and yield components of ‘Tulameen’ red raspberry in an annual production system. In the 2003 experiment, girdled floricanes were compared with nongirdled controls. Girdling before bloom decreased fruits per cane and consequently yield per cane compared with controls, whereas girdling at the end of bloom had no effect. Root dry weight accumulation at the end of the fruiting season was significantly less in both early and late girdled compared with nongirdled plants. In 2004, floricanes were completely girdled or nongirdled at midflowering. Additionally, three primocanes were permitted to grow in one-half of the nongirdled and girdled plants, whereas primocanes were completely removed from the other half. Girdling and removal of all primocanes resulted in 100% plant mortality. In the presence of primocanes, floricane girdling had no effect on yield compared with the nongirdled treatments. There was a reduction in root dry weight in the nongirdled + primocane removal treatment compared with the treatments in which three primocanes were present. In the presence of primocanes, however, root dry weights were similar in both girdled and nongirdled plants. These results suggest that root carbohydrates are important in determining fruit number and yield in the annual system, and reductions in root carbohydrate during early flowering results in decreased yield. However, roots appear to quickly convert from source to sink status, and as the season progresses, both floricanes and primocanes act as sources to replenish root carbohydrate reserves. Carbohydrate dynamics appear to be similar between the annual production system and the traditional perennial system; however, because the annual system begins with limited carbohydrate reserves resulting from root pruning that occurs during removal from the nursery, yields are lower than those seen in perennial systems.

Due to their correlation with temperature, growing degree days (GDD) allow to analyze the effect of climate change on plant phenology, while being also useful for scheduling activities in a cultivation system. Fruit cropping systems in general lack enough information in this regard. This research aimed to determine GDD during the phenology of Festival strawberry (Fragaria × ananassa Duch.) grown on two substrates at two plant densities under a macro-tunnel. Previously chilled (4 o C/720 h), one-leaf plants were grown from August 2016 to March 2017 either in hydroponics on red volcanic rock or in soil with fertigation at 10 or 15 plants m-2. A Steiner nutrient solution reduced to 50% of its original concentration was used. GDD were counted daily after planting using the single sine curve method with a base temperature of 3 o C. A high correlation coefficient (r > 0.964) was found between GDD and days after planting (DAP) for the phenological stages studied. The phyllochron was not affected by treatments, and 597 GDD were required as an average for the onset of leafing and a high correlation between air temperature and the emission of leaves number 2 to 10 (r = 0.9754; P ≤ 0.0001). The substrate did not affect the chronology of the reproductive phenological stages. The onset of anthesis was delayed by 17 days in plants grown at 15 plants m-2 (2039.4 GDD) compared to those grown at 10 plants m-2 (1829.7 GDD), but there was no effect of plant density for the sequent phenological stages. It is concluded that GDD have a high predictive value in Festival strawberry for DAP of the phenological stages studied; likewise, the phyllochron and reproductive phenology were not affected by substrate cultivation; however, planting at high densities could delay the onset of anthesis.

La demanda de higo (Ficus carica L.) fresco crece anualmente en el mercado nacional e internacional, y México tiene potencial para convertirse en importante productor mundial. Para lograrlo, es necesario incrementar el rendimiento, adelantar las cosechas y obtener frutos de calidad. La maduración escalonada de los siconos en la planta representa una desventaja económica, por lo que es importante concentrar la producción de higos maduros para reducir la frecuencia de cosechas. Se ha demostrado que los biorreguladores aceleran el desarrollo de los frutos y mejoran su rendimiento y calidad. El objetivo de esta investigación fue analizar el efecto de la aplicación de cinco combinaciones de biorreguladores (thidiazurón, ácido giberélico, ácido glutámico, triptófano y tiamina) sobre la brotación de yemas axilares secundarias, el crecimiento, rendimiento y calidad de frutos de yemas primarias. Como material genético se utilizaron higueras cv. Netzahualcóyotl cultivadas en invernadero. Los tratamientos se aplicaron por aspersión dirigida a las yemas axilares secundarias en reposo. Las variables evaluadas fueron brotación de yemas axilares secundarias, crecimiento y rendimiento del fruto de la yema principal. Al momento de cosecha se evaluó la longitud, diámetro y peso del fruto, color de la epidermis, firmeza, sólidos solubles totales y acidez titulable. Los biorreguladores adelantaron en 15 d el tiempo a la cosecha, excepto la combinación de ácido glutámico y tiamina. En los frutos se incrementó el contenido de sólidos solubles totales (5 a 10 ºBrix), la longitud (≈ 1 cm), el diámetro (≈ 0.5 cm) y el peso individual (5 a 20 g) con respecto al testigo. El color se afectó por los biorreguladores en forma negativa; los higos tuvieron zonas verdes e inmaduras cercanas al pedúnculo. El rendimiento de fruto no presentó diferencias signifiativas. Aunque los tratamientos con biorreguladores mejoraron algunas variables de calidad, ninguna combinación fue consistente para incrementar el rendimiento y la calidad de frutos de higo.

El presente artículo analiza aspectos referentes al cultivo de nopal en la Delegación Milpa Alta de la Ciudad de México. En primera instancia se efectúa un estudio comparativo de tipos de tratamiento para la fertilización del nopal, el cual se realizó mediante un proceso experimental donde se analizaron rendimientos y características con diferentes fertilizantes, que permitió identificar un sistema a base de lixiviados como una alternativa con mayor eficiencia. Por otro lado, se estableció una metodología para la extracción del mucílago de nopal a través de la selección, secado y molienda para elaborar un aditivo que permitió estimar el contenido de azucares y nivel de acidez en laboratorio. En una parcela experimental se llevo a cabo el proceso de muestreo que permitió cultivar el nopal con las condiciones climatológicas y propiedades del suelo de la región, así como en diferentes modalidades de fertilización para evaluar rendimientos y calidad.