Agricultural Systems ( IF 6.1 ) Pub Date : 2022-02-21 , DOI: 10.1016/j.agsy.2022.103387 Israel Navarrete 1, 2, 3, 4 , Victoria López 5 , Ross Borja 6 , Pedro Oyarzún 6 , Karen A. Garrett 7, 8, 9 , Conny J.M. Almekinders 3, 4 , Yanru Xing 7, 8, 9 , Paul C. Struik 2 , Jorge L. Andrade-Piedra 4, 10
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CONTEXT
Studies in the Andes have demonstrated that seed degeneration of potato occurred in experimental conditions, but was negligible in farmers' conditions. There are two hypotheses for this difference: (1) farmers cultivate resistant varieties, or (2) they use on-farm practices that can manage seed degeneration. Farmers may replace some of the seed saved from their fields with outside seed, but it is an open question what level of benefit farmers experience from partial replacement.
OBJECTIVES
The objective of this study was to investigate the role of the cultivated varieties, the on-farm seed management practices, and seed replacement in potato seed degeneration. Moreover, this study evaluated the potential effect of partial replacement of the farmers' seed lot each season with healthy seed, compared to less frequent nearly full replacement, in simulations.
METHODS
We surveyed farmers in the Cotopaxi province, Ecuador, in 2008, 2010, and 2018, and performed a study on the incidence of pathogens and pests in farmers' seed lots in 2018. We also evaluated the potential effects of the timing of replacement of farmers' seed lots by healthy seed to manage degeneration, applying the seedHealth model.
RESULTS AND CONCLUSIONS
We found that farmers experience no or only slow degeneration in their varieties. Analysing yield data reported by farmers to detect degeneration, we did not detect yield declines. The type of variety and year of data collection explained the variation in yield. These results seem to confirm the hypothesis that varieties cultivated in the Andes are resistant to the impact of seed degeneration on yield, and that seed degeneration depends on the agroecological conditions present within a cropping season or year. Because we did not find an impact on yield, we hypothesized that on-farm practices affect seed-borne pathogens and pests causing seed degeneration. We identified multiple on-farm practices playing a role in the process of seed degeneration: they either slowed down or accelerated this process depending on the seed-borne pathogen and pest causing seed degeneration. Our scenario analyses using the seedHealth model showed how replacing farmers' seed lots by healthy seed could usefully reduce seed degeneration compared to using the same amount of seed to periodically replace nearly all seed in a season. Our results showed that on-farm practices are also critical drivers in the process of seed degeneration.
SIGNIFICANCE
This study demonstrated the importance of considering on-farm seed management practices (i.e., use of cultivated varieties) to strengthen seed systems interventions aiming to manage potato seed degeneration. Additionally, this study showed the potential of partially replacing farmers' seed with healthy seed as an alternative when complete seed replacement is not an option.
中文翻译：
品种和农场种子管理实践影响厄瓜多尔热带高地马铃薯种子退化
语境
安第斯山脉的研究表明，马铃薯的种子退化发生在实验条件下，但在农民条件下可以忽略不计。这种差异有两个假设：（1）农民种植抗性品种，或（2）他们使用可以管理种子退化的农场实践。农民可能会用外来种子替换一些从他们的田地中保存下来的种子，但农民从部分替换中获得的收益水平是一个悬而未决的问题。
目标
本研究的目的是调查栽培品种、农场种子管理实践和种子替换在马铃薯种子退化中的作用。此外，本研究在模拟中评估了每个季节用健康种子部分替换农民种子批次的潜在影响，与不太频繁的几乎完全替换相比。
方法
我们分别于 2008 年、2010 年和 2018 年对厄瓜多尔科托帕希省的农民进行了调查，并在 2018 年对农民种子地块的病原体和害虫发生率进行了研究。我们还评估了农民更换时机的潜在影响' 种子批次由健康种子管理退化，应用 seedHealth 模型。
结果和结论
我们发现农民的品种没有或只有缓慢的退化。分析农民报告的产量数据以检测退化，我们没有发现产量下降。数据收集的品种类型和年份解释了产量的变化。这些结果似乎证实了这样的假设，即在安第斯山脉种植的品种能够抵抗种子退化对产量的影响，并且种子退化取决于种植季节或一年内的农业生态条件。因为我们没有发现对产量的影响，我们假设农场实践会影响种子传播的病原体和导致种子退化的害虫。我们确定了多种在种子退化过程中起作用的农场实践：根据导致种子退化的种子传播病原体和害虫，他们要么减慢要么加速这一过程。我们使用 seedHealth 模型进行的情景分析表明，与使用相同数量的种子在一个季节定期更换几乎所有种子相比，用健康种子代替农民的种子批次可以有效地减少种子退化。我们的研究结果表明，农场实践也是种子退化过程中的关键驱动因素。
意义
这项研究证明了考虑农场种子管理实践（即使用栽培品种）以加强旨在管理马铃薯种子退化的种子系统干预措施的重要性。此外，这项研究表明，当不能完全更换种子时，用健康种子部分替代农民种子作为替代方案的潜力。
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