Improving dryland seedling recruitment using fungicide seed coatings

The success of seed-based restoration in dryland regions of the world is often low or sporadic, with most mortality occurring between germination and emergence. Fungal pathogenesis is one process that may reduce seedling emergence and limit restoration success.

Our objective was to determine whether fungicide seed coatings constitute an economically viable strategy for increasing emergence by reducing fungal pathogenesis and mortality.

We performed an experiment across two sites and three years, using bluebunch wheatgrass (Pseudoroegneria spicata) as a model species. We found that fungicide coatings increased germination by 8.8% and emergence by 54.0% on average compared to the control. A cost analysis indicated that the fungicide coating was economically viable with an average estimated effective cost reduction of 18.8% under the study conditions.

There was a strong interaction (P < 0.001) between the effects of the fungicide coating, site, and year on emergence. The fungicide coating increased emergence compared to the control in five of the six sites and years, with the effect ranging from a 33.7% decrease (P = 0.042) to a 150.9% increase (P = 0.004).

The observed interaction was likely related to the effect of the hydrothermal microsite environment on disease severity. In the site and year that the fungicide coating performed worse than the control, prolonged periods of exceptionally low soil moisture may have reduced disease severity through a variety of individual and community scale mechanisms.

Overall, these results indicate that fungicide seed coatings have the potential to improve dryland restoration efforts.

全球旱地地区基于种子的植被修复成功率往往偏低且不稳定，多数植株死亡发生在种子萌发与幼苗出土之间的阶段。真菌致病作用是可能抑制幼苗出土、制约修复成效的关键过程之一。
本研究旨在明确：通过种子杀菌剂包衣抑制真菌致病作用与植株死亡，进而提升幼苗出土率，是否为一项经济可行的修复策略。
本研究设置两个试验点、开展三年试验，以蓝茎冰草（Pseudoroegneria spicata）作为模式物种。结果显示，相较于对照组，杀菌剂包衣可使种子萌发率平均提升8.8%，幼苗出土率平均提升54.0%。成本分析表明，在本研究条件下，种子杀菌剂包衣具备经济可行性，经估算平均有效成本可降低18.8%。
杀菌剂包衣、试验点与试验年份对幼苗出土率的影响存在显著交互作用（P < 0.001）。在6组试验点-年份组合中的5组里，杀菌剂包衣均较对照组提升了幼苗出土率，其作用效果从降低33.7%（P = 0.042）到提升150.9%（P = 0.004）不等。
上述交互作用可能与热湿微生境环境对病害严重程度的调控作用相关。在杀菌剂包衣效果劣于对照组的那组试验点-年份组合中，长时间的极端低土壤水分条件可能通过多种个体及群落尺度的机制降低了病害严重程度。
综上，本研究结果表明，种子杀菌剂包衣具备提升旱地植被修复成效的应用潜力。