Effects of heat stress and seaweed-derived biostimulants on the germination of Comanthera mucugensis, an endemic plant of fire-prone Campos rupestres of Chapada Diamantina (Brazil)

Abstract

Fires are common in Chapada Diamantina and reach large extensions of Campos rupestres, where there is a high number of endemic species, among which Comanthera mucugensis stands out. However, the effect of high temperatures on the seeds of this species is unknown (or alternatives to mitigate thermal stress). The present study evaluated the effects of heat stress and the effect of aqueous and polysaccharide extracts from seaweeds Agardhiella subulata and Hypnea pseudomusciformis, and κ-carrageenan on germination and post-seminal development of C. mucugensis seeds. The seeds were exposed to four high-temperature levels: 40, 45, 50, and 55 °C. Subsequently, they were germinated in germitest paper moistened with distilled water, aqueous and polysaccharide extracts from seaweeds and κ-carrageenan in different concentrations: 10, 1 and 0.1 mg ml−1. The seeds of C. mucugensis were heat tolerant up to 50 °C. The high concentration of aqueous and polysaccharide extracts was efficient in mitigating the thermal stress on seeds stressed at 45 and 50 °C. In a condition of non-stress and low thermal stress (40 °C), the low concentration of extracts and κ-carrageenan improved the frequency of germination and post-seminal development of the seeds. It is the first report on the effects of heat on seeds of Eriocaulaceae species from Chapada Diamantina.