Tracking lipid profiles of Jatropha curcas L. seeds under different pruning types and water managements by low-field and HR-MAS NMR spectroscopy

Jatropha corms L. seeds have been used as a promising source of oil for biodiesel production. In the present work, the impacts of different pruning procedures and water management on the content and lipid profile of the Jatropha seed oils were evaluated via nuclear magnetic resonance (NMR). The experiment was conducted at Research Station of ESALQ/USP, located in Piracicaba (Sao Paulo), Brazil. Jatropha plants were cultivated over four years under two different water conditions (irrigation - I and rainfed - R) and three pruning types (without pruning - P0, with removal of twigs at a height of 1.5 m from the ground and 0.75 m from the central stem - P1, and with the pruning performed at a height of 2.0 m from the ground and 0.75 m from the central stem - P2). The evaluation of seed oil contents was performed via low-field NMR, while the fatty acid composition was assessed by HR-MAS NMR. Low-field NMR results showed no changes in the oil content of Jatropha seeds regardless the treatment employed. H-1 HR-MAS NMR spectral profile of seeds revealed the presence of well-known signals of triacylglycerols, with the predominance of signals coming from oleic acid (C18:1) and linoleic acid (C18:2). Quantitative analyses of J. curcas seeds showed that the combination of irrigation and pruning managements influenced statistically the contents of unsaturated fatty acids. Among the evaluated conditions, the lipid profile achieved with pruning at 2.0 m height and 1.5 m canopy diameter (named P2) under irrigation (I) conditions might be considered the most effective for biodiesel production.