:: Fincas de Ambato :: Polinización Artificial / Introdución, Referencias, Figuras

One of the most recurring issues faced during the jojoba domestication process is its inconsistent and/or poor yield levels (Coates et al., 2003). Certain studies have identified the low number of male plants and/or the distance between male and female plants as the main causes. In other cases, this problem relates to climatological phenomena such as high temperatures, strong winds or rainfall during the pollination stage.

After proving its yield-improving ability, artificial pollination (also referred to as assisted pollination) is now becoming an increasingly regular practice for many crops, such as olive plantations.

For several species, the increased yields obtained through artificial pollination in regions featuring high temperatures and strong winds during the flowering season are basically due to the possibility to apply pollen under optimal weather conditions for effective pollination (Ayerza and Coates, 2004).

As explained in the “Jojoba Pollination in Catamarca: a comparison :between 2002 and 2003” section, strong, hot winds have serious effects on the reproduction of jojoba and other species in the Central Valley of Catamarca. The pollination stage of jojoba, which in this ecosystem may last 30 to 45 days, usually takes place between August 15 and October 15, a period usually featuring a high number of days with very strong winds (Table 1-PA).

Between 1994 and 2003, the maximum flowering period (PMF) for jojoba in the Arid Chaco area averaged 30 days with maximum sustained winds above 25 km/hour, thus affecting one of every two days of the PMF. In addition to causing effects that are per se negative, winds above 20-25 km/h cause a significant reduction in pollen release for periods of up to 5 subsequent days. Artificial pollination allows pollen to be applied on the quieter days following windy days, when lack of pollen is a regular feature.

Rainy days are also negative as a far as pollination is concerned. After rainfall, jojoba airborne pollen concentration decreases to and remains at insignificant levels for at least one day (Buchmann, 1987). Even though the average number of rainy days (3.4 days) in the Arid Chaco area is not high during the jojoba pollination period, there may be up to 5 to 8 rainy days in 40% of all years (Table 2-PA); this means that, many years will feature extremely low pollen availability levels over no less than 10-16 days, which represents 17% to 27% of the PMF. Artificial pollination, if carried out on days following rainfall, will allow an instant increase in the low concentration of airborne pollen.

Given that pollen viability in the same lot and the same year fluctuates during the flowering period, showing a downward trend as the period nears its end (Table 3-PA), by allowing to gain knowledge of stored pollen viability, artificial pollination allows application of top-quality pollen at different times during the flowering period.

Artificial pollination makes it possible to improve the low yields resulting from low male density without resorting to an increase in the number of male plants and the resulting reduction in the number of female plants, and without creating the need to wait between 4 and 5 years after rooting cuttings until they are sufficiently developed to produce the required amounts of pollen. Upon seeding to increase male plant density, in addition to having to wait for the plants to become adult even longer than was the case for cuttings, there is no telling whether the resulting genotypes will flower at the same time as female clones, or anticipating the potential incompatibility between them.

Based on this information and experience, a program was created with a view to developing and implementing the mechanical application of supplementary pollen. The program was launched in 2002; it is run by the University of Arizona and co-funded by Fincas de Ambato and the State of Arizona. Scientific leadership of the project lies with Dr. Wayne Coates, Office of Arid Lands Studies, University of Arizona; Ing. Ricardo Ayerza (h) (University of Arizona) and Dr. David Palzkill (Desert Plants, Tucson, Arizona) are also involved. The program has developed the machinery required for collecting (Photo 1-P) and applying (Photo 2-P) pollen, the pollen handling and preservation techniques (Photo 3-P), application dosage, etc. Due to the possibility to work both in Arizona and Catamarca, a 6-month reduction has been achieved in the gap between pollen collection and application (Coates et al., 2034).

Fincas de Ambato is currently involved in a new project which is being implemented under the joint efforts of the University of Arizona and Israel’s Volcani Center; this project is intended to render the pollen collection, storing and application techniques more efficient.