Germinación y crecimiento ex vitro e in vitro de cinco especies de cactáceas del género mammillaria

ABSTRACT: The germination and growth rate (RGR) of M. albilanata, M. bocasana, M. columbiana, M. rhodantha and M. spinosissima were compared under ex vitro and in vitro conditions. In the first case, the germination percentages (PG), germination speed (VG) and medium germination (G50) were evaluated. In the second, the RGR was determined after 40 weeks of culture. The in vitro treatment consisted of 25% Murashigue-Skoog (MS) medium for germination, and 50% MS with sucrose dose (3, 6 and 9%) for growth, while the ex vitro treatment was from a mixture of leaf soil and tezontle (1: 1). The analysis of variance and the Tukey tests showed significant differences between the responses generated in the level of treatments and species (p < 0.05), obtaining better results in the in vitro treatment. On the other hand, sucrose supplementation at 6% and 9% generated a higher growth rate in the aerial part, while in the 3% there was a higher growth rate in roots, in both cases superior to the ex vitro treatment. The survival rate of plants obtained in both conditions was 100%.RESUMEN: Se comparó la germinación y ritmo de crecimiento (RGR) de M. albilanata, M. bocasana, M. columbiana, M. rhodantha y M. spinosissima bajo condiciones ex vitro e in vitro. En el primer caso se evaluaron los porcentajes de germinación (PG), velocidad de germinación (VG) y germinación media (G50). En el segundo, se determinó el RGR luego de 40 semanas de cultivo. El tratamiento in vitro consistió de medio Murashigue-Skoog (MS) al 25% para germinación, y MS al 50% con dosis de sacarosa (3, 6 y 9%) para crecimiento, mientras que el tratamiento ex vitro fue a partir de una mezcla de tierra de hoja y tezontle (1:1). El análisis de varianza y las pruebas de Tukey evidenciaron diferencias significativas entre las respuestas generadas a nivel de tratamientos y especies (p < 0.05), obteniéndose mejores resultados en el tratamiento in vitro. Por otro lado, la suplementación de sacarosa al 6% y 9% generó un mayor ritmo de crecimiento en la parte aérea, mientras que en la de 3% se presentó un ritmo de crecimiento mayor en raíces, en ambos casos superiores al tratamiento ex vitro. La tasa de sobrevivencia de plantas obtenidas en ambas condiciones fue del 100%

Allelopathic potential of Petiveria alliacea L.

Petiveria alliacea (Phytolaccacea) is a herbaceous plant of great importance in traditional medicine. It has been reported to be effective as an insecticide and acaricide; however, its allelopathic activity is unknown. The objective of this study was to evaluate its allelopathic activity in seeds of Triticum aestivum, Oriza sativa, Lactuca sativa and Amaranthus hypochondriacus. Tests were performed with different concentrations of the aqueous, methanolic and dichloromethanic leaf extracts. Total germination (Gt), accumulated germination velocity (AGV), length of the aerial portion (LAP) and radicular length (RL) were evaluated. It is demonstrated that the the organic extracts were more phytotoxic than the aqueous extract, producing a significant effect on lettuce and amaranth. However, in the evaluation carried out in the soil, no phytotoxic effect was observed in the germination of lettuce seeds. Therefore, the tested extracts of Petiveria alliacea were moderately phytotoxic

Influence of dry handling at two temperatures and stem length in vase life of rose ‘Polo’

The effect of room and refrigeration temperature and the length of the flower stem in vase life of rose ‘Polo’ was evaluated. Floral stems of 60 cm length were harvested and stored at 4 and 23 °C during 72 h in dry conditions. During storage, three stems were taken daily to determine the damage of the cell membrane. After storage, eight stems of each temperature were trimmed at 33, 41 and 54 cm in length and were placed in vases with 250 mL of tap water and randomized into an area with illumination of 10 μmol m-2 s-1, photoperiod of 12 h, average temperature of 23 ± 3 °C and 40 % of relative humidity (RH) to evaluate vase life (VL). The results indicated a direct relationship (R2 = 0.9835) between the number of vessels and stem length between 33 and 54 cm. The membrane cell damage was higher at 23° than at 4 °C. Stems stored at 23 °C decreased their fresh weight in the fourth day and their water absorption on day seven, they also had less flower opening and vase life compared to the stems stored at 4 °C. Dry storage at room temperature for 72 h only decreases from 11.5 to 9.4 days the VL of rose ‘Polo’, resulting in a good choice in places where the cold rooms do not exist; the short stems had higher water absorption but did not improve the VL