Effects of saline stress and temperature on germination and seed vigor of Luffa operculata L. Cogn

Luffa operculata (L.) is a native Brazilian biome plant used for the treatment of respiratory diseases. Although Brazil’s flora comprises 67% of the world’s plants, only 8% of Brazilian plant species are studied each year. The studies indicate that climate change in tropical biomes intensifies the increase in salinized areas by about 10% per year for several reasons, including high temperatures, low rainfall and high evapotranspiration rates, due to surface water scarcity. Therefore, the aim of the present study was to evaluate the germination behavior and vigor of L. operculata seeds submitted to saline stress at different temperatures. To simulate salt stress conditions, sodium chloride was applied at 0.0; 3.0; 6.0; 9.0 and 12.0 dS m-1, at 25, 30, 35, 20-30 °C, with treatments distributed in a 5 x 4 factorial scheme (five levels of osmotic potential and four temperatures), using four replications. The seeds were then evaluated concerning water content, germination tests, first counts, germination speed index and seedling root and shoot lengths. At 30 and 35 °C, the seed germination and vigor of L. operculata were less affected up to an osmotic potential of 9.0 dS m-1, where it is considered a moderate salinity tolerance. At 35 ºC, the germination uniformity was reduced to 98 and 93% by applying the 6 and 9 dS m-1 solutions, respectively. For the same temperature, the germination velocity remained 6.09 (IVG) until the saline potential of 9.0 dS m-1