Unravelling the impact of seed fatty acid profiles on spinach seed germination under temperature stress

Limited knowledge exists regarding the fatty acid profiles of spinach (Spinacia oleracea L.) seeds and their correlation with germination. This study aims to address this gap by thoroughly investigating these profiles and their relationship with seed germination. Therefore, the objectives include assessing the impact of different temperatures on seed germination in spinach cultivars, identifying cultivar(s) tolerant to temperature stress during germination, and exploring the relationship between fatty acid profiles and seed germination under varying temperature conditions. Nine spinach cultivars (‘Matador-1, 2, and 3’, ‘Ranchero F1’, ‘Aras F1’, ‘El Tajin’, ‘Alreal F1’, ‘Catrina F1’, and ‘Poyraz F1’) were used as seed material. The study employed simple correlation tests, stepwise multiple regression tests, and principal component analyses (PCA) to determine these relationships. The fatty acid contents significantly varied among cultivar seed samples. C18:2n-6, C18:1n-9, C16:0, and C18:0 exhibited the highest concentrations, followed by C20:1n9 at less than 3%, with other fatty acids at even lower contents (<1%) in spinach cultivars. These analyses revealed that the optimal temperature for spinach seed germination is 20 °C. Above 20 °C, germination percentages decreased, with a sharp decline at 35 °C. ‘Catrina F1’ demonstrated notable heat tolerance, with a 62.04% germination rate at 32 °C and 9.10% at 35 °C, indicating its potential as a valuable heat-tolerant cultivar for spinach breeding programs. C17:1, C18:1n9, and monounsaturated fatty acids (MUFA) displayed negative correlations with germination percentage, while positive correlations were observed between C18:3n-6, C20:1n9, and germination percentage at 30 °C and 32 °C. Based on the results of simple correlation tests, stepwise multiple regression tests, and PCA, it has been revealed that C16:1n7, C17:1, C18:1n9, C18:2n6, C18:3n-6, C20:1n9, C22:0, MUFA, and n-6 PUFA have great potential to predict the germination capacity of spinach seeds under stress temperatures.