Stanislav Magnitskiy

Influence of mycorrhizal fungi on the rooting of stem and stolon cuttings of the Colombian blueberry (Vaccinium meridionale Swartz).

The Colombian blueberry (Vaccinium meridionale Swartz) is a promissory crop for the Andean Region of South America, and the absence of a suitable propagation protocol presents a difficulty introducing it into commercial production. This research was undertaken in order to evaluate the effect of mycorrhizal fungi on rhizogenesis of stem and stolon cuttings of the Colombian blueberry. The highest rooting percentages (up to 73.3%) were observed at day 60 on stem cuttings treated with 200 mg −1 4-indole-3yl-butyric acid or napthtalene-acetic acid in mycorrhiza-free substrate. The presence of mycorrhizas in substrate increased cutting viability up to 95%, but reduced percentage rooting, root number, and root length on stem cuttings of the Colombian blueberry. Treating stem cuttings with 200–400 mg −1 4-indole-3yl-butyric acid or napthtalene-acetic acid diminished the effects of fungi on root formation. The use of stolon cuttings for vegetative propagation of the Colombian blueberry had low practical applicability. The results of the study might further serve to establish the optimal substrate conditions and cutting source for vegetative propagation of the Colombian blueberry in commercial culture.

Rooting Ability of Stem Cuttings of Macleania rupestris Kunth A.C. Sm., a South American Fruit Species

Macleania rupestris Kunth A.C. Sm. (Ericaceae) is a wild shrub native to the Andean montane forests and regions of páramo that possesses edible berries. The lack of a propagation protocol for this species further limits its use in commercial cultivation. The rooting ability of leafy stem cuttings of Macleania rupestris was evaluated as affected by cutting position on the mother plant and application of growth regulators, indolebutyric acid (IBA) or naphthaleneacetic acid (NAA), at 0, 100, 500, or 1000 mg L−1. Semi-hardwood cuttings collected from the central parts of the stems presented the highest rooting, 75.5% on average, compared to softwood (71.7%) and hardwood (49.8%) cuttings. Hardwood basal cuttings produced more callus and shoot mass and fewer adventitious roots than softwood apical cuttings. Softwood and semi-hardwood cuttings of Macleania rupestris treated with IBA or NAA at the concentrations close to 500 mg L−1 produced the highest number (up to 14.0 per cutting) of adventitious roots at day 120. For propagation of Macleania rupestris through stem cuttings, selection of cuttings from the apical and middle parts of the stem and applying IBA or NAA at 500 mg L−1 to stimulate rooting is recommended.

Germination, protein contents and soluble carbohydrates during storage of sugar apple seeds ( Annona squamosa L.)

The aim of this study was to evaluate changes in the germination potential, protein contents and soluble carbohydrates in sugar apple ( Annona squamosa L.) seeds from Castilla-Tolima and Apulo-Cundinamarca, Colombia during storage for 30, 60 and 120 days in a cool room, refrigeration, and ambient conditions. In each period, the seed moisture contents, germination percentage (GP), mean germination time (MGT), mean germination rate (MGR), soluble protein content, and contents of sucrose, glucose and fructose were evaluated. The highest GP (> 80%) and MGR (0.15 germinated seeds / day) and the lowest MGT (<7 days) were reached after 60 and 120 days of storage under ambient conditions. In the three storage conditions, the protein contents declined at 60 days and 120 days in seeds from Castilla and Apulo, respectively. Under the ambient conditions (AC), there was an increase of 72.3% in the sucrose content, 61% increase in the fructose content and 70% decrease in the glucose content. The results show that this environment temperature for 60 and 120 days was best suited for maintaining short term germination. The high GP and MGT values and low MGR value indicated a possible dormancy release that occurred naturally.

Temperatura de germinación de semillas de anón (Annona squamosa L.)

La propagacion sexual del anon es el metodo mas utilizado por los productores en Colombia, sin embargo uno de los problemas del cultivo es la baja e irregular germinacion de las semillas. En esta investigacion se busco establecer la temperatura optima de germinacion de semillas de A. squamosa L. Esta se realizo en el laboratorio de Fisiologia Vegetal, Facultad de Agronomia, Universidad Nacional de Colombia, semillas de accesiones de Apulo (Cundinamarca) y Castilla (Tolima) fueron puestas a germinar en turba rubia humeda sin nutrientes en un fitotron (humedad relativa de 60%, sin luz) durante 30 dias, en dos regimenes de temperatura constante: 30 y 35°C y dos regimenes de temperatura alterna: 30/20°C y temperatura ambiente (media: 18,7°C; maxima: 22,9°C; minima: 17,3°C). Se evaluo la respuesta de las variables porcentaje de germinacion (PG) cada 5 dias durante 1 mes y los indices sincronia de germinacion (E), tiempo medio de germinacion (TMG) y velocidad media de germinacion (VMG) al finalizar el ensayo. El maximo porcentaje de germinacion se obtuvo a una temperatura constante de 35°C para las semillas provenientes de Cundinamarca como del Tolima (58% y 57%, respectivamente), igualmente a esta temperatura se observo un menor TMG (18,41 dias para Cundinamarca y 17,09 dias para Tolima), una mayor VMG (0,035 y 0,040 semillas germinadas/dia para Cundinamarca y Tolima, respectivamente) y un indice de sincronizacion mas bajo (0,29 y 0,33 para Cundinamarca y Tolima, respectivamente), lo que sugiere como temperatura optima 35°C para la germinacion de las semillas de A. squamosa. Temperatura de germinacion de semillas de anon (Annona squamosa L.)

Effect of GA3, KNO3, and removing of basal point of seeds on germination of sweet granadilla (Passiflora ligularis Juss) and yellow passion fruit (Passiflora edulis f. flavicarpa)

Passiflora seeds germinate erratically presenting difficulties for their handling in a greenhouse. The effect of removing of basal point of seeds (RB) and pre-imbibition of seeds of sweet granadilla and yellow passion fruit in 50, 100, 200, and 400 mg mL -1 solutions of gibberellic acid (GA 3 ) or 0.1% KNO 3 solution was studied. The experiment was conducted in greenhouses in La Plata, Colombia. Two accessions PrJ1 and PrJ2 of sweet granadilla were evaluated. There were calculated the final percentage of germination (PG), mean germination time (MGT), and the mean germination rate (MGR). The leaf area and dry mass of seedlings were measured 22 days after sowing (das); with this data, specific leaf area and relation root/ shoot were calculated. In all cases, the highest germination percentages were achieved treating seeds with KNO 3 (89, 92, and 87% for yellow passion fruit, PrJ2, and PrJ1, respectively), but the increase in MGR (3.3 germinated seeds per day) and the decrease in MGT (16 days) were only significant for PrJ1. RB had a significant reduction of PG in all cases (28, 12, and 33% for passion fruit, PrJ2 and PrJ1, respectively). With the increase in the concentration of GA 3 , PG was reduced for two accessions of sweet granadilla, for yellow passion fruit this trend was not clear, no treatment with GA 3 showed significant differences with the control. Leaf area (24.07 cm2) and dry mass of seedlings (135 mg) were significantly higher than seeds previously treated with KNO 3 only for PrJ1.The solution of KNO 3 0,1% is recommended to improve the germination and initial growth of granadilla seedlings. Index terms: Pre-imbibition, final percentage of germination, mean germination time, mean germination rate, leaf area.