Phenological growth stages of sweet potato (Ipomoea batatas (L.) Lam.) according to the extended BBCH scale

Abstract Sweet potato is grown for its starchy roots in many countries and is widely cultivated in India. This crop is widely acknowledged for its substantial economic and health benefits. However, a comprehensive description of its phenology has not been reported. The phenological growth stages of sweet potato are described here for the first time using the extended Biologische Bundesantalt, Bundessortenamt, and Chemische Industrie (BBCH) scale. Nine primary growth stages have been specifically defined, including germination (0), leaf development (1), main shoot development (2), side shoot development (3), tuber development (4), inflorescence emergence (5), flowering (6), fruit development (7), fruit maturation (8), and senescence (9). The sequential progression of key growth stages has been described according to the phenological development structure and environmental requirements of different phenophases. Because it covers all phenophases related to the vegetative and reproductive stages, the extended BBCH scale is extensively useful for sweet potato cultivation. The extended BBCH scale may also be a useful tool for assessing the potential effects of climate change on crop productivity and fruit quality.