Biostimulant-induced enhancement of germination and early seedling growth in creole and hybrid purple maize (Zea mays L.)

Purple maize native to the Peruvian Andes, is a key source of anthocyanins with notable antioxidant properties. In field cultivation, seed germination and early seedling development are critical stages influencing crop establishment and yield. This study evaluated the effects of three stimulants, namely seaweed extract, sulfur dioxide, and milk whey, on the germination and early development of creole and hybrid purple maize varieties under controlled laboratory and greenhouse conditions. Seeds of each variety were subjected to seven pre-sowing treatments in a completely randomised design with three replications. Germination indices (imbibition rate, germination percentage, speed, and index) were assessed, followed by evaluation of eleven biometric traits at 15 days after emergence. Seaweed extract significantly enhanced plant height, shoot dry weight, and leaf dimensions in both varieties, particularly at 1.5 L/200 L. Sulfur dioxide improved root biomass and length, while low-dose milk whey treatments favoured moderate root growth. Creole seeds showed higher vigour in early germination, while hybrids responded better to stimulant application during early development. These findings demonstrate that biostimulants, particularly seaweed extract, can effectively enhance early growth traits in purple maize, offering potential for improving seedling establishment in sustainable production systems.