Effects of cultivation and landrace on germination in Mexican wild and cultivated chile pepper
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Date
2019-05
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The Ohio State University
Abstract
Throughout the world, the impacts of climate change on food production are far-reaching, potentially devastating and in many places already underway, bearing the greatest consequences for smallholder and subsistence farmers growing in rain-fed systems. For these farmers, increasingly frequent and extreme drought events and less reliable precipitation will necessitate the adoption of various climate-adaptive strategies, including the use of drought-tolerant crops. Locally-adapted crop varieties, also known as “landraces,” offer one important wellspring of adaptive genetic resources that could help farmers adapt to drought, and yet this genetic material continues to erode at an alarming rate due to continuous processes of globalization, industrialization in agriculture, and via climate change itself. To prevent the extinction of this genetic material, conservation programs must be grounded in understandings not simply of the biological responses of landraces to climate change, but also of the cultural, historical, and biogeographical factors that ultimately inform these responses, which will assist in the identification of new adaptive genotypes, as well as best-practices for their in-situ management. It is through this interdisciplinary the study that follows examines the drought responses of diverse Capsicum annuum sp landraces from Oaxaca, Mexico, a center of diversity for and the evolutionary home of chile peppers, analyzing the effects of each accession’s domestication level and cultivation type on different seed characteristics related to drought tolerance. Employing a Randomized Complete Block Design and using polyethylene-glycol (PEG) 8000 (PEG) to simulate water stress, we measured germination with and without PEG for 10 distinct landraces from across 6 domestication levels and 4 common cultivation systems (including plantations, milpas, backyard gardens, and forest growing environments). We observed several expected effects: Namely, water stress reduced germination across the board, and different landraces expressed variation in germination levels. Contrary to our expectations, we found that neither the domestication gradient nor the cultivation system had consistent or expected effects on seed germination, suggesting that other sources of variation such as environmental factors may play a larger role in shaping the germination behavior of chile pepper seeds.
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Keywords
Climate change, Biogeography, Peppers, Oaxaca, Mexico, Evolution, Biodiversity