Chile pepper (Capsicum annuum) is an important crop worldwide, with an estimated 25% of people consuming some form (vegetable, spice, or food colorant) of pepper every day (Halikowski-Smith 2015). In 2017, global harvested area of chile peppers was ≈3.8 million ha, with the vast majority (≈65%) of production occurring in Asia [Food and Agriculture Organization of the United Nations (FAO), 2017]. Chile peppers are a high-value crop (DeWitt and Bosland, 1993) and can have economic benefits for smallholder farmers (Kahane et al., 2013; Weinberger and Lumpkin, 2007).
Chile pepper production occurs across a broad range of agroecological conditions, including the humid tropics, deserts, and cool, temperate climates (Bosland and Votava, 2012); and different systems ranging from open field to protected cultivation. Productivity of chile peppers is often reduced by both biotic and abiotic stresses, the types of which can vary among regions (Barchenger and Bosland, 2019). Although no cultivar of a given crop is adapted everywhere, cultivars differ in the extent of their adaptations (Barchenger et al., 2018). Plant breeders must examine whether a given cultivar is better adapted to a specific type of environment and whether its performance is stable relative to that of other cultivars. Consumer preference of chile peppers is region specific and can vary greatly within a country (Bosland and Votava, 2012). Although studies in this area are limited, it has been observed that regional-specific preferences for chile pepper fruit shape, size, color, and capsaicinoid content, as well as yield, are major driving forces for farmer cultivar selection (Barchenger et al., 2018). Adaptation to warm, humid climates; high yield potential; yield stability; and multiple disease resistance are the key breeding goals in tropical and subtropical Asia (Barchenger et al., 2018).
Agriculture is an important component of the Myanmar economy, and horticultural production provides an opportunity for fostering development and economic growth with potential that is yet to be fully reached (Beed and Bahala, 2017). The agriculture sector contributes 38% of gross domestic product and employs more than 60% of the workforce in Myanmar (World Bank, 2016). However, yields of the majority of vegetable crops grown in Myanmar are well below global averages (Davis et al., 2017). It is estimated that ≈50% of people in Vietnam are actively involved in production agriculture (≈48 million people). According to the World Bank (2016), agriculture, forestry, and fishing contributed 15% of the total gross domestic product of Vietnam in 2016 (≈$33 billion). In 2008, there were ≈11.5 million smallholder farms (≤1.4 ha) in Vietnam, which account for more than 70% of domestic food production (Margherita, 2017). The poverty rate in remote areas of Vietnam is closely associated with low agricultural development potential and lack of access to markets (Minot et al., 2006). Vegetable production has the potential to contribute substantially to an increase in rural household income in Vietnam (Huong et al., 2013). A major component of increased productivity and quality of vegetables in a sustainable, safe, and environmentally friendly manner is the development of disease-resistant, locally adapted, and consumer-preferred cultivars.
In 2017, Myanmar produced 130,588 t of chile peppers on 109,222 ha and Vietnam produced 65,925 t of chile peppers on 95,844 ha (FAO, 2017). Chile peppers in Myanmar are produced largely for the domestic market. While widely consumed domestically, ≈75% of chile peppers produced in Vietnam are for export. A recent scoping study in the Ayeyarwady Delta of Myanmar conducted by Luther et al. (2017) indicated that abiotic and biotic stresses are major constraints for vegetable production. These stresses are likely a cause of lower yields of many vegetable crops, compared with global averages (Davis et al., 2017). Although comprehensive surveys of the biotic disease in Myanmar are lacking, initial surveys have identified Geminivirus, Polerovirus, Cucumber mosaic virus, Chilli veinal mottle virus (ChiVMV), Tomato mosaic virus, and anthracnose (Colletotrichum truncatum) in chile pepper samples (L. Kenyon, unpublished data). In Vietnam, the major chile pepper diseases include ChiVMV, phytophthora root rot (Phytophthora capsici), bacterial wilt (Ralstonia solanacearum), bacterial spot (Xanthomonas campestris pv. vesicatoria), and anthracnose (C. scovillei and C. truncatum) (Tran and Kim, 2007). Resistant cultivars are the cheapest, simplest, and most environmentally friendly approach for disease management.
Although there are major differences in the chile pepper industries in Myanmar and Vietnam, one important similarity is that the majority of chile pepper seeds are imported and distributed by foreign seed companies, despite both countries being major chile pepper producers. In other crops, such as mungbean (Vigna radiata), the collaborative breeding and cultivar trials between international agriculture research organizations and national or governmental organizations in underdeveloped countries has resulted in significant increases in yield and widespread adoption of improved cultivars (Schreinemachers et al., 2019). In this project, our aim was to identify high-performing, locally adapted chile pepper entries that could be used by domestic breeding programs as parental lines or as direct release as cultivars.
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