Agricultural systems are facing the threat of anthropogenic climate change. As one important aspect in climate change, warming not only alters crop physiology, phenology, and growth, but also changes the activities of pests including diseases, insect pests, and weeds. There are still a lot of uncertainties on how an agricultural system as a whole will respond to warming, and how different crop systems will respond differently. For better planning for the future, it is crucial to identify both the positive and negative effects of warming on the agricultural system. Here, we aimed to identify the positive and negative effects of warming on a temperate native North American crop, the wild blueberry (Vaccinium angustifolium). Wild blueberry farms are a semi-natural agricultural system with naturally growing blueberry plants managed to form berry-producing fields. We used both passive and active heating open-top chambers (OTCs) to manipulate warming for six wild blueberry genotypes at a blueberry farm in Maine, USA, and studied warming effects on crop phenology, physiology, and yield, as well as pest pressures.
Results/Conclusions
Passive OTCs elevated mean air temperatures by 1.2 oC, while active OTCs elevated by 3.3 oC. Overall, both passive and active warming resulted in significantly higher yields, compared to the ambient control. The increase in yield could be related to the positive effects of warming including an extended growing season and significantly lower infections of leaf spot diseases under warming. Meantime, we found negative effects of warming including increased transpiration and water stress, lower photosynthetic rates in dry years (but not in wet years), and increased insect pest activity. Therefore, climate warming brings both challenges and benefits to the production system of this temperate crop. New management practices could be developed to use the positive effects of warming while mitigating the negative effects to sustain the production of this crop.
