East African highland bananas and climbing beans are important crops for food and income in the highlands of Uganda. Intercropping of banana with legume crops is a common practice, yet climbing bean intercropping with perennials has rarely been studied in Uganda. To understand how best to improve the production system, we assessed the effects of pruning of banana leaves on light availability for climbing beans, resulting effects on bean yields and potential differences in shade tolerance between two climbing bean varieties in the eastern and southwestern highlands of Uganda. Measurements of the transmission of photosynthetically active radiation (PAR) through the banana canopy were combined with yield measurements of a local and improved climbing bean variety and with banana pseudostem girth in two seasons (2016A and 2016B). We also compared yields of intercropped with sole-cropped climbing beans. The mean fractions of PAR transmitted through the banana canopy – hence available for beans – were 0.43 on pruned and 0.38 on non-pruned subplots, a significant 15% difference. The improved light availability did not increase climbing bean yield. Although no direct relationship between light interception and bean yields was found, bean yields on the most and least shaded parts of the intercropped fields differed significantly, suggesting that beans do benefit from improved light availability in intercropping. Generally, yields of sole-cropped beans were significantly larger than of intercropped beans, but we could not single out the effects of competition for light, water, and/or nutrients. The bean varieties responded similarly to the pruning treatments. The local variety tended to perform relatively better in intercropping, the improved variety in sole cropping, though differences were not significant overall. Pruning and retention of eight banana leaves over the course of a season did not affect banana pseudostem girths in the mature banana plantations. Although light availability improved, farmers may not expect a major effect on bean yield. Future research may focus on the effects of a lower number of leaves retained, comparing a number of bean varieties for suitability in sole or intercropping, or on other factors influencing the relation between the two crops such as relative plant densities of beans and bananas.

中文翻译：

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乌干达高地攀缘豆 (Phaseolus vulgaris, L.) 和东非高地香蕉 (Musa spp.) 间作

东非高地香蕉和攀缘豆是乌干达高地粮食和收入的重要作物。香蕉与豆类作物间作是一种常见做法，但在乌干达很少研究攀缘豆与多年生植物间作。为了了解如何最好地改进生产系统，我们评估了香蕉叶修剪对攀缘豆光照可用性的影响，从而对豆类产量的影响以及乌干达东部和西南部高地两个攀缘豆品种之间耐荫性的潜在差异. 在两个季节（2016A 和 2016B），将通过香蕉树冠的光合有效辐射 (PAR) 传输的测量与本地和改良攀援豆品种以及香蕉假茎周长的产量测量相结合。我们还比较了间作和单作攀缘豆的产量。通过香蕉树冠传播的 PAR 的平均分数（因此可用于豆类）在修剪的子地块上为 0.43，在未修剪的子地块上为 0.38，差异显着 15%。改善的光照利用率并未增加攀缘豆产量。虽然没有发现光截获与豆类产量之间存在直接关系，但间作田地中阴影最多和最不明显部分的豆类产量差异显着，这表明豆类确实受益于间作中光照利用率的提高。一般来说，单作豆​​类的产量明显高于间作豆类，但我们无法单独列出竞争光、水和/或养分的影响。豆类品种对修剪处理的反应相似。地方品种在间作方面表现相对较好，改良品种在单作方面表现较好，但总体差异不显着。在一个季节中修剪和保留八片香蕉叶不会影响成熟香蕉种植园中的香蕉假茎周长。尽管光照利用率有所提高，但农民可能不会期望对豆类产量产生重大影响。未来的研究可能集中在保留叶子数量较少的影响，比较一些豆类品种是否适合单作或间作，或关注影响两种作物之间关系的其他因素，例如豆类和香蕉的相对植物密度。在一个季节中修剪和保留八片香蕉叶不会影响成熟香蕉种植园中的香蕉假茎周长。尽管光照利用率有所提高，但农民可能不会期望对豆类产量产生重大影响。未来的研究可能集中在保留叶子数量较少的影响，比较一些豆类品种是否适合单作或间作，或关注影响两种作物之间关系的其他因素，例如豆类和香蕉的相对植物密度。在一个季节中修剪和保留八片香蕉叶不会影响成熟香蕉种植园中的香蕉假茎周长。尽管光照利用率有所提高，但农民可能不会期望对豆类产量产生重大影响。未来的研究可能集中在保留叶子数量较少的影响，比较一些豆类品种是否适合单作或间作，或关注影响两种作物之间关系的其他因素，例如豆类和香蕉的相对植物密度。