Improving avocado pollination with bumblebees: 3 seasons summary.
Ish-Am, G.; Regev, Y.; Peterman, Y.; Lahav, E.; Degani, C.; Elbatzri, R.; Gazit, S.;
California Avocado Society Yearbook Year: 1998 Vol: 82 Pages: 119-135 Ref: 19 ref.
1998
บทคัดย่อ
Experiments in avocado pollination under field conditions using bumblebees were conducted at 8 Israeli sites during the 1995-96, 1996-97 and 1997-98 seasons. The experiment was terminated at 4 of these sites in 1998, and is continuing at the other sites. At the onset of avocado bloom honey-bee colonies were placed at equal densities in the treatment and in the control plots of each site, and 25 bumblebee hives (7 per ha) were added to the "bumblebee treatment" plot. At 3 sites, which were established in 1997, a "honey-bee treatment" plot was also included, in which the honey-bee hive density was doubled. The experiment plots of each replication were located 1-4 km apart. A row of cv. Ettinger was selected in each plot, as well as a row of cv. Hass adjacent to Ettinger ("near Hass"), and a row of Hass at a distance of 3-4 rows away from the Ettinger ("far Hass"). Bee density, flower density and initial fruit set of each cultivar was monitored throughout the flowering season. Yield data was collec
ted prior to harvest from 20 sample trees per cultivar, and later postharvest data for entire plots were recorded. Pollination rates were examined at 2 sites, and the percentage of Hass fruits resulting from cross-pollination was determined at one site. Each replication was run for 2 consecutive years. No significant differences in honey-bee activity were observed between the bumblebee treatment and the control, while in the honey-bee treatment the honey-bee activity increased. The correlation between honey bee-activity and avocado flowering was low or negative, whereas the same correlation of bumblebee activity was positive. The pollination efficiency of the honey bees was low in the first 2 seasons, and higher during the 1997 season. Pollination rates were higher in the bumblebee treatment plots than in the honey-bee treatment and in the control plots. In the first two experimental years higher rates of surviving Hass initial fruits were found in the bumblebee treatment, in comparison to the control, howev
er no clear trend was observed in 1997. In the four replications that ended in 1998 the average yield of Ettinger increased by 66% in the bumblebee treatment plots as compared to the control. The average Hass yield increased by only 14%, which was mainly due to the 34% increase in the "far Hass" yield. A significant increase in Hass yield in the bumblebee treatment (+51%) was found in the organic orchard in Yodfat. At this stage, a limited use of bumblebees for Ettinger pollination is recommended.