Cherimoya (Annona cherimola Mill.) investigation in Southern Ecuador

Xavier Scheldeman, Vicente Ureña, José Romero & Patrick Van Damme

Introduction

Loja Province, situated in the southern Andean part of Ecuador (latitude 3°19’-4°45’ S, longitude 79°05’-80°29’ W), is generally considered as the botanical garden of Ecuador (Organización de los Estados Americanos, 1994). Due to its unique position between the humid Amazon basin and the coastal Sechura desert in Peru, and marked by a characteristic relief (ranging 150-3,761 masl), Loja Province shows a huge variety of microclimates, resulting in numerous ecological zones, each characterised by its typical vegetation. Loja Province alone, covering 10,790 km², possesses 11 of the 38 life zones described worldwide by Holdridge (PREDESUR, 1998). 

During a first intensive ethnobotanical study realised in Southern Ecuador from 1994 till 1997, Loja Province was shown to comprise 109 native edible plant species, with the majority of these plant species being used only for autoconsumption (Van den Eynden, 1997). Based on local preferences as well as cultivation and commercialisation parameters, cherimoya and the complex of highland papayas were selected as the most promising fruit species for future cultivation in this area.

Cherimoya (Annona cherimola Mill.) is a delicious syncarpous fruit, often called the “queen of subtropical fruits” (National Research Council, 1989). It occurs commonly between 1,500 and 2,000 masl in the wild or is tolerated in backyard gardens. Loja Province is undoubtedly a primary centre of Annona plant diversity and probably the centre of origin of the species (Scheldeman et al., 1999a). Nevertheless, neither Loja Province nor Ecuador possesses commercial cherimoya plantations nor are they exporting cherimoya fruits. Main cherimoya exporters at world level are Spain, Chile, Australia and United States (Gardiazabal & Rosenberg, 1993).

The project “Conocimientos y Prácticas Culturales sobre los Recursos Fitogenéticos Nativos en el Austro Ecuatoriano” aimed at extending and conserving the knowledge on local native fruit species in Southern Ecuador. Cherimoya was one of the main targeted native fruit species. On the one hand it shows a lot of potential but on the other hand germplasm is under increasing threat of genetic erosion due to the growing pressure on fallow and forest land. The present work recapitulates the main research topics and their general results.

Metodology

Initially, an ethnobotanical survey was realised in order to fully understand the actual situation and problems related to the selected fruit species. For cherimoya, a survey in 13 villages, selected for their abundance of wild and semi-cultivated cherimoya trees, was realised by interviewing l62 farmers about their plants, cultivation practices, plant uses, commercialisation and crop related problems.  

Crop ecology was determined by examining the edaphoclimatological conditions in which each fruits species occurs. Climatic characteristics were defined using existing temperature and precipitation maps, whereas soil characteristics were determined by combining elementary soil maps with soil analyses (texture, pH, organic matter content, CEC, N, P₂O₅, K₂O). In case of cherimoya, ecology was determined from wild cherimoya stands at 20 locations, combined with 52 soil analyses. Climate, soil and overall suitability maps for each species were created by way of a Geographical Information System (IDRISI) using an adaptation of the “Simple Limitation Method” developed by FAO (Sys et al., 1991), in order to get an idea about potential cultivation zones.

Morphological variability and consequent phenotypical selection was based on characterisation data obtained during intensive germplasm collections. Pomological characteristics (e.g. fruit measurements and weights, seed content, colour, form, soluble solids) were particularly targeted as these characteristics can quickly be assessed and can form the basis for a first selection. In case of cherimoya, a total of 137 accessions in 32 sites were collected and characterised. For cherimoya the best accessions of the collection were selected and, because some pomological research has already been realised in exporting countries, their characteristics compared to commercial cultivars of cherimoya exporting countries.

Adequate knowledge on germination characteristics is another important factor in the preparation of future cultivation programmes. Seed morphology of the ungerminated and germinating seed were described and different germination enhancing methods were examined in order to increase and homogenize germination. Germination of cherimoya seeds, very irregular and slow, was investigated during 900 days using 11 pre-applied treatments including gibberellic acid (GA₃) and water soaking. Germination tests took place in rolls of filter paper (4 repetitions of 50 seeds) placed in a darkened glass chamber within a greenhouse with a stable temperature of 25 °C.  

Results

The actual situation of cherimoya cultivation in Loja Province can only be described as a low level cultivation, approaching gathering. These low level cultivation techniques result in qualitatively and quantitatively low yields with severe phytopathological problems (Anastrepha spp., fruit fly), keeping fruit quality and thus market prices very low and generating low income to the farmer. This vicious circle of low input and consequent low output, combined with limited commercialisation channels, due to the lack of well-developed infrastructure, such as roads, is seriously impeding the development of  commercial cherimoya cultivation (Scheldeman et al., 1999b).

However, Loja Province possesses some ideal cherimoya cultivation zones, illustrated by the presence of abundant wild cherimoya stands. 24 % of Loja Province is considered to possess good edaphoclimatological conditions for cherimoya cultivation. Potential cultivation zones can be defined using the obtained suitable soil and climate characteristics (Bydekerke et al., 1999).  

Cherimoya shows a huge diversity in pomological characteristics, which is typical for a species in its centre of origin (Scheldeman et al., 1999a), with some selected accessions that can easily withstand the preliminary comparison with commercial cultivars of cherimoya cultivars (Scheldeman & Van Damme, 1999).  

Comparison between number of seeds/100 g fruits of selected accessions and commercial cultivars	Comparison between fruit weight of selected accessions and commercial cultivars

Germination can be considerably increased and homogenised by pre-applying during 24 h a concentration of 1,000 ppm gibberellic acid (GA₃), although resource-poor growers can already obtain significant results applying pre-soaking for 48-72 h in water (De Smet et al., 1999).  

More Pictures

References

Bydekercke, L., Scheldeman, X., Van Ranst, E. & Van Damme, P. (1999). Edaphoclimatological Study of Cherimoya (Annona cherimola Mill.) in Loja Province, South Ecuador. Acta Horticulturae, 497, 71 - 80.

De Smet, S., Scheldeman, X., Romero, J. & Van Damme, P. (1999). Seed Structure and Germination of Cherimoya (Annona cherimola Mill.). Acta Horticulturae, 497, 269 - 279.

Gardiazabal, F. & Rosenberg, G. (1993). El Cultivo del Chirimoyo. Universidad Católica de Valparaíso. Facultad de Agronomía. Valparaíso, Chile. 145 pp.

National Research Council (1989). Lost Crops of the Incas. Little-Known Plants of the Andes with Promise for Worldwide Cultivation. National Academy Press. Washington D.C., USA. 415 pp.

Organización de los Estados Americanos (1994). Plan Integral de Desarrollo de los Recursos Hídricos de la Provincia de Loja. Secretaria General de la Organización de los Estados Americanos. Washington DC, USA. 140 p.

PREDESUR (1998). Plan de Desarrollo Regional del Sur 1998-2003. Tomo 1. Diagnostico Regional – Diagnostico Sectorial. Subcomisión Ecuatoriana PREDESUR. Cuenca, Ecuador. 740 p.

Scheldeman, X., Ureña, V. & Van Damme, P. (1999a). Collection and Characterization of Cherimoya (Annona cherimola Mill.) in Loja Province, South Ecuador. Acta Horticulturae, 497, 153 - 162.

Scheldeman, X., Ureña, V., Romero, J. And Van Damme, V. & Van Damme, P. (1999b). Potencial del Cultivo de Chirimoya (Annona cherimola Mill.) en la Provincia de Loja, Ecuador. Memorias del II Congreso Internacional de Anonáceas. Adenda, 11-20.

Scheldeman, X. & Van Damme, P. (1999). Promising Cherimoya (Annona cherimola Mill.) Accessions in Loja Province, South Ecuador. Acta Horticulturae, 497, 173 - 183.

Sys, C., Van Ranst, E. & Debaveye, J. (1991). Land Evaluation. Principles in Land Evaluation and Crop Production Calculations. Agricultural Publications n° 7. Brussels, Belgium, 274 pp.

Van den Eynden, V. (1997). Plantas Comestibles en la Provincia de Loja. In: Pedersen, H.B. & Rios, M. (Eds.). Uso y Manejo de Recursos Vegetales. Ediciones Abya-Yala, Quito, Ecuador. p. 203-221.

Van den Eynden, V., Cueva, E. & Cabrera, O. (1999). Plantas Silvestres Comestibles del Sur del Ecuador – Wild Edible Plants of Southern Ecuador. Ediciones Abya-Yala, Quito, Ecuador. 221 pp.   

[ Home ] [ Cherimoya ] [ Highland papayas ]