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Characterization of germination in the commercial seed of eight cultivars of tropical forage grasses

Abstract:

Seed germination is a critical phase for the establishment of pastures. This study was carried out to characterize seed germination in Mulato II hybrid and seven other cultivars of the species Brachiaria brizantha, B. decumbens, B. humidicola and Panicum maximum. Three germination indices were used: germinability (G), germination value (GV), and cumulative speed of germination (SG). Daily germination data was adjusted with two growth models of four parameters: Gompertz and Weibull. Significant differences were observed among cultivars; Mombaza, Tanzania, Basilisk and Paiaguás showing greater (P≤0.05) G values (between 58 and 69%) than Xaraés and Marandú (23-36%), and Tully and Mulato II (7-8%). The other indices allowed differentiating between cultivars even with similar G values, the temporal pattern of germination increment. Such differences were mostly associated with variations in the maximum daily germination percentage and/or SG. A better adjustment was found by using the Gompertz function. Finally, the biological and agronomical significance of the introduced parameters and the germination indices is discussed as tools to characterize seed quality in forage grasses.