Effects of Deep Shading on Agronomic Traits, Coloration, and Antioxidant Properties in Sweetpotato Leaves

TL;DR

This study explores how deep shading affects the growth, color, and nutritional value of sweetpotato leaves, offering insights for cultivating them in low-light conditions.

Contribution

The study reveals how sweetpotato adapts to deep shading through changes in leaf morphology, pigmentation, and antioxidant properties.

Findings

Shading increased leaf size and plant height but decreased stem thickness and dry-matter content.

Shading caused darker green and lighter red foliage due to higher chlorophyll and lower anthocyanin levels.

Antioxidant capacity was most strongly linked to soluble sugar and dry-matter content.

Abstract

The vegetable sweetpotato (Ipomoea batatas L.) is a novel, specialized type, cultivated for its tender stems and leaves, which are rich in nutrients and bioactive compounds. To clarify its growth adaptation to weak light conditions often encountered during cultivation, this study examined the impact of 70% shading on 12 representative cultivars from 4 leaf color types. Agronomic traits, color, and nutritional and antioxidant properties were assessed in both young and mature leaves. Shading promoted leaf expansion, plant height, and vine length, but reduced stem thickness and dry-matter content. Leaf shape shifted from lobed to more cordate, with the foliage becoming darker green and lighter red due to elevated chlorophylls and reduced anthocyanins. Shading generally reduced soluble protein, sugar, cellulose, total phenols, flavonoids, and total antioxidant capacity. Antioxidant capacity correlated most strongly with soluble sugar and dry-matter content, followed by total phenols and flavonoids. Gene expression analysis of key light- and leaf color-related genes revealed up-regulation of chlorophyll genes and down-regulation of anthocyanin genes under shading, with light-responsive genes potentially affected by pigment feedback. These results elucidate the sweetpotato’s adaptive responses to deep shading and provide valuable guidance for optimized cultivation and breeding of vegetable sweetpotato in light-limited environments.

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