UNLOCKING SEED DORMANCY IN NUTRI-CEREALS: PHYSIOLOGICAL CHARACTERISATION AND EFFECTIVE DORMANCY-BREAKING TREATMENTS FOR CUMBU, RAGI AND SORGHUM

Abstract

Seed dormancy is a major challenge in the seed supply chain as freshly harvested, viable seeds often fail to germinate under favourable conditions, delaying seed testing, certification, multiplication and timely sowing. This study investigated the dormancy behaviour of freshly harvested cumbu (pearl millet), ragi (finger millet) and sorghum varieties through germination, tetrazolium (TZ) viability, fresh ungerminated seeds (FUS), total phenolic content and evaluation of dormancy-breaking treatments. Nine varieties comprising two cumbu, three ragi and four sorghum genotypes were assessed under laboratory conditions. Sorghum varieties exhibited high germination (82–94%), indicating negligible dormancy, whereas cumbu (8–18%) and ragi (0–4%) showed severe dormancy despite high seed viability (96–100%). High FUS percentages in cumbu and ragi further confirmed that poor germination resulted from dormancy rather than loss of viability. Ragi varieties recorded the highest total phenolic content (5.98–6.39 mg g⁻¹), suggesting a strong association between phenolic accumulation and physiological dormancy. Dormant cumbu and ragi varieties were subsequently subjected to six dormancy-breaking treatments. Dry heat treatment at 40°C for 30 min proved to be the most effective treatment, producing the highest overall mean germination (65.2%) across both crops. Potassium nitrate (0.2%) was particularly effective in ragi, while dry heat treatment for 15 min also performed well in cumbu. The findings demonstrate that dormancy in freshly harvested millets is predominantly physiological but differs between crops, necessitating crop-specific dormancy breaking strategies. These results provide practical recommendations for seed testing laboratories, breeders and seed producers to improve germination, accelerate seed certification and enhance the efficiency of the seed supply chain.