Estimation of genetic erosion on Ethiopian tetraploid wheat landraces using different approaches

Abstract

The demand and use of improved crop varieties by farmers has increased in the central highlands of Ethiopia, where continuous loss of local traditional varieties has been occurring in the last two to three decades. The objectives of the study were to assess the extent of genetic erosion and perception of farmers and associated causes for the reduction of traditional farmers' varieties. Direct field assessment covering 56 wheat farms and a survey in which 149 farmers participated were carried out in three districts of central Ethiopia. Based on data collected during direct farm assessment, the loss of genotypes was found to be 88% in Ada followed by 80% and 60% in Lume and Gimbichu districts, respectively. The farmer survey indicated an even greater loss of diversity of100% in Ada followed by Lume (93%) and Gimbichu (67%). Diseases and pests as well as shorter growing seasons associated with climate change were identified as main causes for farmers to switch to modern varieties. The expansion of high yielding improved bread and durum wheat varieties also contributed to gradually replace local durum wheat varieties by local farmers of these districts. Overall, genetic erosion of tetraploid wheat varied among the three districts of central Ethiopia. Reductions in the number of farmers and area coverage in the study districts could be used as good indicators for the existence of genetic erosion.

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“…The number of farmers cultivating landraces and their relative area coverage were determined. The number of landraces cultivated recently as compared to the previous number was the basis for the calculation of genetic erosion [ 15 , 47 , 48 ]. A reduction in richness (that is a reduction in the total number of crops, varieties or alleles) is a better indicator for genetic erosion, as it does recognize the dynamics in the system [ 12 ].…”

“…Direct field observations provided the first lines of evidence for genetic erosion. Local knowledge, gathered through interviews with farmers and their families, community meetings, and surveys, have been widely used to assess change and document farmers’ perspectives [ 10 , 11 , 12 , 13 , 14 , 15 , 16 ].…”

“…In spite of the evident declines in crop diversity that have been raised, the magnitude, trajectory, drivers and significance of these losses remain insufficiently understood [ 15 ].…”

“…In 2002–2003, a survey on traditional ecological knowledge was carried out to assess the causes of genetic erosion of the studied taxa—coriander ( Coriandrum sativum L.), hart’s pennyroyal ( Mentha cervina L.) and pennyroyal ( Mentha pulegium L.). The concept of crop genetic erosion, as applied in this research, is the loss of crop diversity in a defined area over a period of time, typically measured by the decline of species, varieties and/or within varieties [ 15 , 32 ]. In 2011, the same wild ( n = 28) and cultivated ( n = 111) populations were studied, using indirect data (loss of accessions) and field observations to estimate the risk of genetic erosion and its causes.…”

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“…This has led to an alarming rate of genetic erosion. Alemayehu et al (2021) reported that, on average, 75.8% genetic erosion was observed in tetraploid wheat after 25 years based on direct farm assessments and survey studies in Lume, Adaa, and Chefe, respectively. The lowest genetic erosion was observed at Chefedonsa, which is found in the highlands of Shoa.…”