Germination response of Paspalum dilatatum from the Flooding Pampa of Argentina to different incubation and pre-incubation conditions

摘要

We analysed the germination behaviour of seeds of Paspalum dilatatum Poir. from populations located in areas with different topographic positions (midland and lowland), and history (exclosure and continuous grazing). Incubation conditions were alternate light and temperature (16 hs at 20oC and darkness - 8 hs at 35oC and light) and darkness at constant temperature (25oC). They were expected to simulate grazing and exclosure environments. Previously, one half of the seeds was placed in water immersion, to simulate natural events of flooding. Total germination was estimated by germination percent at the 30th day and by Maguire's index rate of initial germination. Both water immersion and alternate light and temperature conditions significantly increased total and initial germination. The interaction between topographic site and incubation condition and between the latter and use history was significant for initial germination. Differences in initial germination between incubation conditions were greater in midland populations than in lowland populations and in populations from grazed plots than in exclosure populations. This may be explained by seed size differences between grazed and exclosure environments