Sawe Thomas, Eldegard Katrine, Totland Ørjan, Macrice Samora, Nielsen Anders
Faculty of Environmental Sciences and Natural Resource Management Norwegian University of Life Sciences Ås Norway.
Department of Biological Sciences University of Bergen Bergen Norway.
Ecol Evol. 2020 Apr 23;10(12):5343-5353. doi: 10.1002/ece3.6278. eCollection 2020 Jun.
Agricultural practices to improve yields in small-scale farms in Africa usually focus on improving growing conditions for the crops by applying fertilizers, irrigation, and/or pesticides. This may, however, have limited effect on yield if the availability of effective pollinators is too low. In this study, we established an experiment to test whether soil fertility, soil moisture, and/or pollination was limiting watermelon () yields in Northern Tanzania. We subjected the experimental field to common farming practices while we treated selected plants with extrafertilizer applications, increased irrigation and/or extra pollination in a three-way factorial experiment. One week before harvest, we assessed yield from each plant, quantified as the number of mature fruits and their weights. We also assessed fruit shape since this may affect the market price. For the first fruit ripening on each plant, we also assessed sugar content (brix) and flesh color as measures of fruit quality for human consumption. Extra pollination significantly increased the probability of a plant producing a second fruit of a size the farmer could sell at the market, and also the fruit sugar content, whereas additional fertilizer applications or increased irrigation did not improve yields. In addition, we did not find significant effects of increased fertilizer or watering on fruit sugar, weight, or color. We concluded that, insufficient pollination is limiting watermelon yields in our experiment and we suggest that this may be a common situation in sub-Saharan Africa. It is therefore critically important that small-scale farmers understand the role of pollinators and understand their importance for agricultural production. Agricultural policies to improve yields in developing countries should therefore also include measures to improve pollination services by giving education and advisory services to farmers on how to develop pollinator-friendly habitats in agricultural landscapes.
非洲小规模农场提高产量的农业实践通常侧重于通过施用化肥、灌溉和/或杀虫剂来改善作物的生长条件。然而，如果有效传粉者的数量过低，这对产量的影响可能有限。在本研究中，我们开展了一项实验，以测试土壤肥力、土壤湿度和/或授粉是否限制了坦桑尼亚北部西瓜（）的产量。我们在试验田采用常规耕作方式，同时在一个三因素析因实验中对选定的植株进行额外施肥、增加灌溉和/或额外授粉处理。收获前一周，我们评估了每株植物的产量，以成熟果实的数量及其重量来量化。我们还评估了果实形状，因为这可能会影响市场价格。对于每株植物上第一个成熟的果实，我们还评估了糖分含量（糖度）和果肉颜色，作为供人类食用的果实品质指标。额外授粉显著提高了植株结出第二个可供农民在市场上出售大小果实的概率，同时也提高了果实的糖分含量，而额外施肥或增加灌溉并没有提高产量。此外，我们没有发现增加肥料或浇水对果实的糖分、重量或颜色有显著影响。我们得出结论，在我们的实验中，授粉不足限制了西瓜产量，我们认为这在撒哈拉以南非洲可能是一种常见情况。因此，小规模农民了解传粉者的作用及其对农业生产的重要性至关重要。因此，发展中国家提高产量的农业政策还应包括通过向农民提供教育和咨询服务，指导他们如何在农业景观中营造有利于传粉者的栖息地，从而改善授粉服务的措施。
