Germinação de Solanum americanum Mill. (SOLANACEAE) e Solanum crinitum Lam. (SOLANACEAE) sob condições de salinidade

Abstract

Germination is a fundamental phase in the plant life cycle, and medium salinity affects this process, potentially inhibiting germination through physicochemical or physiological mechanisms. Different species exhibit distinct sensitivities to salinity and may display tolerance responses. The genus Solanum is the most diverse within the Solanaceae family, occurring across a wide range of biomes, from arid to humid climates. Solanum americanum Mill. is a pan-American species with a herbaceous-shrubby habit, considered a pioneer, occurring in areas with sparse vegetation, such as coastal sandbanks, forest edges, and degraded or anthropogenic environments, whereas Solanum crinitum Lam. is a xerophytic tree species occurring mainly in semiarid regions. Therefore, it is hypothesized that S. americanum and S. crinitum exhibit different responses to salinity due to their distinct occurrence areas. The present study aimed to evaluate the potential effects of salinity on the germination of S. americanum and S. crinitum. Fruits collected from 10 mother plants were processed, and their seeds tested within 10 days after collection. The experiment was conducted in a climate-controlled incubator (30/20 °C, day/night; 12/12 h photoperiod) under different NaCl concentrations (0, 5, 10, 25, and 50 mM). Four replicates of 25 seeds per treatment were used, and germination was monitored daily for 21 days, considering seeds germinated when the radicle protrusion exceeded 2 mm. The following germination parameters were evaluated: total germination percentage (GRP), mean germination time (MGT), synchronization (SYN), and uncertainty index (UNC). S. americanum exhibited high germinability, reaching 98% in the control treatment with no reduction in the other treatments. In the control treatment, MGT was 6.01 days, increasing to 12.81 days under 50 mM NaCl (p = 0.0081). UNC increased starting at 25 mM NaCl, whereas SYN was the most sensitive parameter to NaCl concentration, showing a significant reduction from 10 mM onwards (p = 0.014). S. crinitum showed no changes in the evaluated germination parameters in response to salinity. These differences between species may have phylogenetic and ecophysiological bases.