Physiological Characteristics of Flooding Tolerance in Wild and Domesticated Species of Capsicum

Flooding stress severely impacts plant growth and productivity by reducing oxygen availability, disrupting photosynthesis, and inducing oxidative stress. Although extensive studies have been conducted to examine drought and heat stress in Capsicum species, relatively little is known about response to flooding. In this study, we evaluated 17 entries from five Capsicum species ( Capsicum annuum , Capsicum baccatum , Capsicum chacoense , Capsicum chinense , and Capsicum frutescens ) under controlled flooding conditions to assess physiological and morphological response. Plant height, width, pollen activity, wilt index, chlorophyll content (SPAD), and leaf temperature (T leaf ) were measured to determine flooding tolerance. Principal component analysis revealed distinct flooding responses, with members of C. annuum and C. chinense exhibiting greater sensitivity, whereas members of C. frutescens and C. baccatum demonstrated higher tolerance to flooding stress for 5 days. Plant height and width were generally reduced under flooding stress, although responses varied by species and season. Pollen activity remained largely unaffected, suggesting that reproductive structures may be less sensitive to short-term flooding. Seasonal differences influenced flooding responses, with greater physiological stress observed in the summer, likely due to elevated temperatures. Wilt index was the most responsive indicator, showing significant interspecific variation. T leaf increased under flooding stress, correlating with reductions in chlorophyll content and growth parameters. Proline accumulation increased significantly but was more closely associated with heat stress than flooding stress. These findings provide insights into species-specific flooding responses in Capsicum and highlight key traits for breeding flood-tolerant pepper varieties to improve climate resilience in pepper production.