Phenotypic stages of some improved varieties of groundnut (Arachis hypogaea L) in the humid South Western Nigeria

Background: Groundnut is an important legume crop of tropical and semiarid tropical countries, where it provides a major source of edible oil, vegetable protein and source of raw materials for agro-allied industries. To aid in groundnut research planning, varietal development, crop modeling and for extension workers in recommending time of cultural practices, standard descriptions of some improved (SAMNUT 10, SAMNUT 22 and SAMNUT 23) and local (kampala) varieties of groundnut were recorded. Methods: The descriptions were based on visually observable vegetative (V) and reproductive (R) events. The V stage recorded was V E (Emergence: Cotyledons near the soil surface with the seedling showing while some part of the plant visible). The R stages recorded are R 1 (beginning flowering), R 2 (beginning peg), R 3 (beginning pod), R 4 (full pod), R 5 (beginning seed), R 6 (full seed), R 7 (beginning maturity) and R 8 (harvest maturity). A growth stage is reached when 50% of the plants or seeds sampled have achieved or exhibiting the specified the specified trait. Results: V E of 7 days after sowing (DAS) was recorded for the improved varieties and 6 DAS for kampala. R 1 was 28 DAS for all the varieties, R 2 of 33 and 35 DAS was recorded for the improved varieties and kampala respectively. R 3 of 43 DAS, R 4 of 56 DAS, and R 5 of 63 DAS for the four varieties. R 6 (76, 74, 75 and 77 DAS for SAMNUT 10, SAMNUT 22, SAMNUT 23 and kampala respectively) and R 7 (93, 93, 92 and 94 DAS for SAMNUT 10, SAMNUT 22, SAMNUT 23 and kampala respectively) varies for the varieties. Harvest maturation, R 8 varies within the varieties; 135 DAS, 120 DAS, 100 DAS and 120 DAS for SAMNUT 10, SAMNUT 22, SAMNUT 23 and kampala respectively. Conclusions: The stages apply to both improved varieties and the local variety and could be used to schedule cultural practices including irrigation, herbicides, insecticides, fungicides, growth regulators, and harvest. Key Words : Groundnut, Growth stages, Vegetative events, Reproductive events, Standard descriptions.