The Central Andean Highlands are the center of origin of the potato (Solanum spp.) and one of the centers of diversity with more than 3800 different native potato varieties grown by farmers (CIP, 2007). For centuries, indigenous subsistence farmers have selected landraces adapted to harsh and variable agro-ecological conditions and managed the land with minimal inputs to achieve sustainable yields. Nowadays farmers employ a wide range of cropping systems, comprising high input systems with fertilizer applications of up to 500 kg NPK ha-1 and frequent pesticide use to low-input subsistence systems with limited organic manure application and almost no pesticides. Yield levels are medium to low, ranging between 15 and 20 t ha-1 for high input and 5 to 8 t ha-1 for low input systems (Davies Jr. et al., 2005; MINAG, 2007).
Soil fertility management has a prominent role for crop production in these conditions. An appropriate soil fertility management guarantees a certain level of yield stability even in difficult agro-ecological conditions and increases the overall resilience of the cropping system to adverse biotic and/or abiotic stresses (Fliessbach et al., 2007, Karlen et al., 1997, Mallory and Porter, 2007). Furthermore the enhancement of food production that is required to feed the growing population would have to come from “land saving” technologies oriented to intensify the production of the system, converting marginal lands into productive areas and restoration of degraded areas (Lal, 2000).
The supply of new, improved varieties, accessible through the genetic resources contained in the totality of potato landraces in the Andean area may, in this context, represent convenient options to produce yield surpluses to generate income that enables farming community to move out of - and stay out of - poverty. In support of this objective, small-scale farmers need yield sustainable improving and input-saving technologies.
Soil microbes are key-components of any agricultural system and exert multiple functions, from detrimental (as pathogens) to beneficial (in particular in low input systems, e.g. plant growth promoters and pathogen antagonists), impacting yield and quality of food. Nowadays, increasing attention is devoted to rhizosphere and endophytic microbes which play a central role in promoting plant growth and health
It has been stated that “the ultimate agricultural goal in studies of the biology of the soil-root interface, must be the manipulation of microorganisms in this zone to increase plant health and growth” (Rovira, 1979). Research should aim at improving our knowledge of the interactions between plants and microbes and of sustained management of these microbes to benefit the plant-food-consumer chain. This knowledge could help to reduce excessive use of agrochemicals alleviating hazardous effects of agricultural production on the environment.
The approach combining suited potato ‘genotypes’, proper land management and inoculation with appropriate beneficial microbes (e.g. arbuscular mycorrhizal fungi (AMF), plant growth promoting rhizobacteria (PGPR), pathogen antagonists) a major challenge for the sustainable intensification of potato-based farming systems in the Andean area. This combines improving soil fertility, plant resistance, and plant nutrition. This approach is in agreement with UNESCO, (2008) policy that potato-based agricultural systems need a continual supply of new, improved varieties, albeit at the same time potato diversity should be protected, conserved and exploited, and with the EU Code for “Good Agricultural Practices” that seeks to minimize environmental damage associated with agricultural practices through the reformed common agricultural policy (CAP) and various EC directives. Within this project, we strongly support the sustainable intensification of potato based cropping systems focusing attention on solutions that will stop or reverse the loss of natural resources (UNESCO, 2008).
CIP – International Potato Center (2007). Facts and figures: improvement and conservation. http://www.cipotato.org/pressroom/facts_figures/improvement_conservation.asp
Davies Jr FT, Calderon CM, Huaman Z and Gomez R (2005). Influence of a flavonoid on mycorrhizal acitivity in the highlands of Peru. Sci. Hort. 106:318-329.
Fliessbach A, Oberholzer HR, Lucie G and Maeder P (2007). Soil organic matter and biological soil quality indicators after 21 years of organic and conventional farming. Agricult. Ecosys. Environ. 118:273-284.
Karlen DL, Mausbach M, Doran J, Cline R, Harris R and Schuman G (1997). Soil quality: a concept, definition and framework for evaluation. Soil Sci. Soc. Am. J.61: 4-10.
Lal R (2000). Soil management in the developing countries. Soil Sci. 165:57-72.
Mallory E B and Porter G A (2007). Potato yield stability under contrasting soil management strategies. Agron. J. 99:501-510.
MINAG - Ministerio de Agricultura de Peru (2007). Importancia de las papas nativas. http://www.portalagrario.gob.pe/
Rovira AD (1979). Biology of the soil root interface. In: Harley J.L., Russell R.S. (Eds). The soil root interface. Academic Press London, pp. 145-160.
UNESCO (2008). International Year of the Potato.http://www.potato2008.org/en/