Sweet potato (Ipomoea batatas) growth faces two critical problems: variability in storage root (SR) number and size among individual plants, and skinning injuries that render the SR susceptible to pathogen infections during storage. We hypothesized that application of potassium (K) fertilizer, an essential mineral for sweet potato, would contribute to increased yield, uniformity, and skin quality of SRs. Sweet potatoes were grown in sandy soil, which is poor in K, and in loess soil. The fertilizers potassium chloride (KCl) and polyhalite were applied before planting. Polyhalite is a hydrated sulfate of K, calcium, and magnesium that has been shown to improve potato skin appearance. Soil type was the major factor affecting SR yield—higher in sandy vs. loess soil. The K fertilizers did not affect yield in either soil type, or improve SR uniformity. However, the skin of the SRs from loess soil had more phellem layers and larger phellem cells following fertilization, mainly with KCl. Accordingly, the expression of suberin marker genes was significantly higher in mature vs. immature skin of SRs fertilized with KCl. Overall, soil type was the major factor affecting sweet potato yield, and addition of K positively affected skin morphology and related gene expression.

中文翻译：

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钾积极影响甘薯贮藏根的皮肤特性

甘薯（番薯））生长面临两个关键问题：单个植物之间的贮藏根（SR）数量和大小的变异，以及使SR在贮藏期间易受病原体感染的剥皮伤害。我们假设使用钾（钾）肥料（甘薯的一种必需矿物质）将有助于提高SR的产量，均匀性和皮肤品质。甘薯生长在钾含量低的沙土和黄土土壤中。播种前先施用氯化钾（KCl）和多卤石肥料。多卤石是钾，钙和镁的水合硫酸盐，已显示可改善马铃薯的皮肤外观。土壤类型是影响SR产量的主要因素-沙土相对于黄土更高。钾肥在两种土壤类型中均不会影响产量，也不会提高SR均匀度。然而，施肥后，黄土土壤SRs的皮层有更多的叶层和较大的叶细胞，主要是用氯化钾。因此，用KCl受精的SR的成熟皮肤与未成熟皮肤相比，Suberin标记基因的表达明显更高。总体而言，土壤类型是影响甘薯产量的主要因素，钾的添加对皮肤形态和相关基因表达有积极影响。