6-benzylaminopurine modulated the morphophysiological response of sweet potato (Ipomoea batatas L.) to drought stress

Sweet potato [Ipomoea batatas (L.) Lam.] is an important staple crop valued for its nutritional and economic contributions, particularly in regions vulnerable to climate change. Although relatively tolerant, prolonged drought stress substantially impairs its growth, physiology, and yield. This study evaluated whether exogenous application of 6-benzylaminopurine (BAP), a synthetic cytokinin, could mitigate drought-induced stress in sweet potatoes and enhance post-stress recovery. A factorial pot experiment was conducted using the Hungarian cultivar Ásotthalmi 12 under two water regimes (well-watered and water-stressed) and two BAP treatments (0 and 5 mg L⁻1). Morphophysiological traits, including vine length, node number, leaf number, chlorophyll content, and chlorophyll fluorescence, were measured at three stages: pre-stress, post-stress, and post-recovery. Analysis of variance revealed significant (p < 0.05) main effects and interactions among BAP application, water regime, and sampling stage. Water stress notably reduced the node formation, plant height, leaf number, and chlorophyll content. In contrast, BAP mitigated the effects of drought stress by notably increasing leaf number, chlorophyll concentration, and chlorophyll fluorescence under both water regimes. During recovery, BAP-treated plants exhibited superior regrowth compared to untreated controls. These findings demonstrate that BAP modulates key morphophysiological processes, counteracts drought stress, and promotes recovery after a water deficit. These results highlight the potential of exogenous cytokinin application as an agronomic intervention to enhance climate resilience.