Varieties tolerant to stress: initial performance in Costa Rican highlands
A permanent line of research in the ASD oil palm breeding program is the concentration of genes in 'guineensis' varieties, which confer tolerance to abiotic stress (e.g. low temperatures and water deficits).
In 2006, four varieties of oil palm (Deli x Ghana, Deli x Nigeria, Bamenda x Ekona and Tanzania x Ekona) were planted in an area with low temperatures (highlands: minimum: 16, maximum: 28o C) and moderate to severe water deficits (up to four months with monthly precipitation below 100 mm). The Bamenda and Tanzania lines come from the highlands of west and central Africa and the Ghana origin has shown good tolerance to water deficits and low temperatures in several African countries.
Two plots were planted at the San Vito locality (Site 1: 730 masl and Site 2: 920 masl) as was a control in the lowlands of Coto. The highlands of San Vito have lower fertility than the Coto region and Site 1 was previously used for pasture and presents surface compaction. Site 2 is of volcanic origin.
Due to their remoteness, some logistics problems had a negative impact on fruit harvesting and did not allow offering the best agronomic management. Notwithstanding the foregoing and the remoteness of the commercial oil palm plantations (pollen sources), most of the plants presented a good bunch loads at 36 months of age, a high pollinating insect population was found (E. kamerunicus), and bunch conformation was good.
The Deli x Nigeria variety has so far been the one with the best production in the three sites, but at Site 1 it has shown greater variability in the bunch load per plant, and some nutritional deficiencies, possibly associated with the management and the poorest soil conditions. The Tanzania x Ekona variety has shown slow vegetative growth, high bunch production (second to Nigeria in the three sites) and higher oil content in the fruit. Ghana has been second in oil content, less vegetative development and also shows good bunch loads. In spite of the climatic and soil limitations, bunch production is 17 t/ha/year, which could undoubtedly be improved with good agronomic management.