The abandonment of maize landraces over the last 50 years in Morelos, Mexico: a tracing study using a multi-level perspective

Abstract

Understanding the causes of maize landrace loss in farmers' field is essential to design effective conservation strategies. These strategies are necessary to ensure that genetic resources are available in the future. Previous studies have shown that this loss is caused by multiple factors. In this longitudinal study, we used a collection of 93 maize landrace accessions from Morelos, Mexico, and stored at the International Maize and Wheat Improvement Center (CIMMYT) Maize Germplasm Bank, to trace back to the original 66 donor families after 50 years and explore the causes for why they abandoned or conserved their seed lots. We used an actor-centered approach, based on interviews and focus group discussions. We adopt a Multi-Level Perspective framework to examine loss as a process, accommodating multiple causes and the interactions among them. We found that the importance of maize landrace cultivation had diminished over the last 50 years in the study area. By 2017, 13 families had conserved a total of 14 seed lots directly descended from the 1967 collection. Focus group participants identified 60 accessions that could still be found in the surrounding municipalities. Our findings showed that multiple interconnected changes in maize cultivation technologies, as well as in maize markets, other crop markets, agricultural and land policies, cultural preferences, urbanization and climate change, have created an unfavorable environment for the conservation of maize landraces. Many of these processes were location-and landrace-specific, and often led to landrace abandonment during the shift from one farmer generation to the next.

Conservation and Use of Latin American Maize Diversity: Pillar of Nutrition Security and Cultural Heritage of Humanity

“…Dyer et al [13] estimated that the average number of maize varieties cultivated per farm in Mexico dropped from 1.43 to 1.22 in the recent 15 years. Consistently, a field survey in the Mexican state of Morelos, comparing seed collections made in 1967 and 2017 in the same study area, found that of the 66 farmer families originally cultivating 93 maize landraces, only 13 families still conserved a total of 14 landraces directly descended from the 1967 collection [60]. Likewise, while the maize race 'Jala' was historically the dominant maize grown in the valley of Jala in the state of Nayarit, Mexico, today it is grown by fewer than 20% of farmers and on only 5% of the maize cultivation area [61].…”

“…The reasons leading to maize landrace abandonment are often complex and include agronomical, ecological, economic and social factors. One of the major reasons for landrace abandonment is their substitution with modern cultivars, including improved OPVs and hybrids, introduced since the 1950s [60]. Farmers' preference for hybrids over landraces is mainly due to: (1) agronomy, e.g., higher yields or disease resistance; (2) market factors, e.g., uniformity of quality or processing properties; (3) policy, e.g., subsidies for hybrids coupled with agricultural extension; or (4) commercial seed systems that favor the provision of few improved varieties in large quantities, while landraces' seed exchange is based on relations among farmers, friends, families, communities, and markets [60,65,66].…”

“…While some authors demonstrated that those policies reduced the prevalence of small-holder farming, a great persistence and adaptability of small-holders in heterogeneous and regionally differentiated maize farming systems has also been reported [77]. Another reason for landraces' abandonment is to replace them with cash crops including flowers, fruits (avocado, blackberry, lime, mango, papaya), industrial crops (e.g., sugar cane), and vegetables (e.g., onion) [60,[78][79][80][81].…”

Genetic diversity and selection signatures in maize landraces compared across 50 years of in situ and ex situ conservation

“…Diverse culinary and cultural uses have been developed with this diversity (Fernández-Suárez et al 2013 ), and farmers can rely on it, especially in traditional settings, to retain their autonomy for seed production (Hoogendoorn et al 2018 ). However, the conservation of agrobiodiversity in the agricultural landscape is threatened by the expansion of modern agricultural production systems (including improved varieties), urbanization, climate change, environmental degradation, changes in consumers’ preferences, natural disasters and social conflicts (van de Wouw et al 2009 ; McLean-Rodríguez et al 2019 ).…”

Dynamic conservation of genetic resources: Rematriation of the maize landrace Jala

“…More importantly, the circular model is a dynamic strategy that ensures maintenance of genetic integrity. This model has been interpreted and followed by other researchers (Piergiovanni and Laghetti, 1999;Hawkes et al, 2000;Tin et al, 2001;Enjalbert et al, 2011;CIP, 2015;McLean-Rodríguez et al, 2019); we are incorporating the concept of rematriation in this model.…”