Responses of Solanum lycocarpum A.St.-Hil. seed germination to the combined effects of seed pretreatment and physiological conditioning

Solanum lycocarpum is a species native to the Brazilian Cerrado with great ecological importance, but the slow and irregular germination of its seeds hinders propagation. Thus, this study evaluated the effects of ultrasonic bathing and physiological conditioning on the germination and development of seedlings of this species. The seeds underwent dormancy breaking and were subjected to germination and vigor tests. After treatment, they were germinated in a controlled chamber (20–30 °C) and analyzed for their germination speed index (GSI), mean germination time (MGT), and root and shoot development. Biochemical analyses of antioxidant enzymes (SOD, CAT, APX), hydrogen peroxide (H₂O₂), and malondialdehyde (MDA) were performed. Compared with the control (33%), all the treatments increased the germination rate (82–89%). The ultrasonic bath promoted more vigorous seedlings, especially when combined with indoleacetic acid (IAA), which presented a greater GSI and lower MGT. The use of sodium nitroprusside (SNP) and hydrogen peroxide (HP) also improved germination, whereas the use of chitosan (CHI) favored the formation of secondary roots. Principal component analysis confirmed the effectiveness of the treatments in improving the physiological characteristics of seeds and seedlings. In addition, seeds subjected to ultrasonic bathing presented greater resistance to oxidative stress. Thus, pretreatment with ultrasonic bathing and conditioning agents has proven to be an effective strategy for overcoming limitations in the germination of S. lycocarpum seeds, contributing to their conservation and sustainable management in the Cerrado.