Resposta germinativa de Solanum americanum Mill. E Solanum crinitum Lam. (SOLANACEAE) a diferentes condições de temperatura e giberel

Abstract

The species Solanum americanum Mill. is a fast-growing annual herbaceous shrub, while Solanum crinitum Lam. is a shrubby tree species, both considered pioneer species. Because they favor the initial regeneration of degraded areas, it is important to understand the ecophysiological aspects of their germination. Considering their different habits, it is expected that S. americanum germinates faster than S. crinitum. In addition to being present in regions with hot climates, we hypothesize that germination parameters are accelerated under high temperature conditions. Therefore, this study aims to investigate the effects of temperature and gibberellin on the germination of S. americanum and S. crinitum. Fruits collected from five individual matrices had their seeds processed and subjected to tests within 10 days after processing. The experiment was conducted in a 2x2 factorial design in air-conditioned incubators with two temperature ranges (25/15ºC and 30/20ºC day/night 12h/12h) and gibberellin concentrations (0 and 500 mg/L). The experiment was monitored daily, considering seeds with root protrusion > 2 mm as germinated. The results obtained showed that alternating temperatures between 30/20°C decreased the mean germination time, accelerating the parameters of mean germination rate and germination speed for S. americanum. In contrast, for S. crinitum, the application of gibberellin increased germinability, reduced the mean germination time and increased the germination speed. However, the presence of gibberellin also provided greater non-uniformity in the germination frequency of S. crinitum. Despite the differences observed, for both species, the alternating temperature between 30/20°C was shown to favor germination.