The Effect of Nitrogen Fertilization on the Yield, Quality and Fatty Acid Composition of Opuntia ficus-indica Seed Oil

Cactus pears are nutritious, drought-tolerant plants that flourish in hot and arid regions. All its plant parts can be consumed by humans and animals. Fruit seed oil production is an important emerging industry in South Africa. As part of an initiative to promote cactus pears as multi-functional crops, dual-purpose cultivars should be identified, and their production increased. The aim of this study was to investigate the role of nitrogen (N) fertilizer on the seed oil yield and quality of Opuntia ficus-indica . The project encompassed a trial using N fertilization from three N sources (limestone ammonium nitrate, ammonium sulfate, urea) and four N application levels (0, 60, 120, 240 kg ha −1 ). Oil was quantitatively extracted from the seed using the Folch method; fatty acids were quantified using a Varian 430-GC. Seed oil content significantly increased ( p = 0.035) with increased N fertilization rates; the oil yield ranged between 7.96 and 9.54%. The composition of the main fatty acids (oleic, palmitic, cis -vaccenic and stearic acid) was significantly influenced; oleic and stearic acid were significantly increased by higher fertilization levels whereas a reducing trend was observed in palmitic and cis -vaccenic acid levels. The highest content fatty acid, linoleic acid, was not significantly influenced.