Abstract

BOLANOS, Víctor R. A; VECCHIO, Marí­a C  and  GOLLUSCIO, Rodolfo A. Germination temperatures of four native grasses of halophytic grassland of the Flooding Pampas, Argentina. Ecol. austral [online]. 2019, vol.29, n.2, pp.249-260. ISSN 1667-782X.

The germination of four grasses with fodder value and native from the halophytic steep of the grassland of the flooding Pampa, was evaluated under four temperatures regimens. Three have summer growth. Among them, Stapfochloa berroi Arech. and Sporobolus indicus Br. are perennials, while Leptochloa fusca ssp. uninervia N. Snow is annual and Polypogon elongatus Kunth is wintry and perennial. Nine months after harvested, fifty selected seeds by experiment unit were sown on filter paper. On incubator three constant temperatures were evaluated: 25 °C, 28 °C, 37 °C, and an alternant temperature regime: 12 hours at 20 °C and 12 hours at 35 °C (TA). Light and humidity remained constant. A CRD with factorial arrangement was used (species x temperature), with five repetitions. The number of germinated seeds was counted at days 5, 10, 18 and 25. The germination power in proportion to the viable seeds was calculated (PG) and, in addition, the germinative energy was evaluated using the curve of PG evolution and the calculus of the germination speed index. The maximum PG of the three summer species evidenced that, at the moment of the experiment, a big part of the dormancy had diminished, not so the wintry one. Both S. berroi and S. indicus only registered a maximum PG and more germinative energy under TA, while, in difference to the perennials, L. fusca ssp. uninervia showed maximum values both at TA and 37 °C. In difference to the summer ones, P. elongatus had a maximum PG at 25 °C and did not germinate in TA. Each species' requirements to germinate might be interpreted as examples of ecological adaptation to the environment; this knowledge can be used to test different ways of using natural grasslands that promote them.

Keywords : The halophytic steep; Fodder species; Thermic requirement of germination.

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