Phenological documentation of two seasonal cytotypic populations of Chenopodium album L. using extended BBCH scale

Abstract Chenopodium album L. is a globally important plant species recognized for its ethnobotanical value, ecological adaptability, and agricultural significance. Its young shoots are widely consumed as a nutrient-rich leafy vegetable, while the species also functions as one of the most persistent annual weeds in temperate and subtropical agroecosystems. A notable adaptive characteristic of C. album is the occurrence of ecologically differentiated seasonal cytotypic populations that differ in growth behaviour and phenology. Despite its widespread distribution, a standardized phenological framework for this species has remained unavailable. In the present study, the extended BBCH (Biologische Bundesanstalt, Bundessortenamt and CHemische Industrie) scale was applied to document the complete phenological development of winter (hexaploid) and summer (tetraploid) populations of C. album under natural field conditions. Phenological development was classified into nine principal growth stages (BBCH 0–9), from germination to senescence, and developmental progression was evaluated using days after sowing (DAS), accumulated growing degree days (∑GDD), and plant height. Comparative statistical analyses revealed significant differences ( P < 0.05) between the two seasonal populations for most corresponding BBCH growth stages and plant height, demonstrating pronounced seasonal phenological plasticity. The summer population exhibited more rapid vegetative development, whereas reproductive development and senescence occurred earlier in the winter population. The resulting BBCH framework provides standardized developmental reference points for C. album and demonstrates the potential application of standardized phenological staging for ecological interpretation and stage-specific weed and crop protection management, while establishing a basis for future phenological, ecological, and comparative studies.