Brassinolide Maximized the Fruit and Oil Yield, Induced the Secondary Metabolites, and Stimulated Linoleic Acid Synthesis of Opuntia ficus-indica Oil

Prickly pear plant is widely cultivated in arid and semi-arid climates. Its fruits are rich in polyphenols, proteins, vitamin C, minerals, fatty acids, and amino acids. The oil extracted from the seeds also has a significant proportion of linoleic acid (ω6) and might be employed as a therapeutic raw material. The potential of enhancing fruit yield, increasing bioactive compounds of the fruit pulp, and improving the unsaturated fatty acid content of prickly pear oilseed by using the foliar application of brassinolide as a plant growth regulator was the main goal of this study. Prickly pear plants were foliar sprayed with a brassinolide solution at concentrations of 0, 1, 3, and 5 mg L−1. The plant performance was significantly improved following brassinolide applications, as compared with untreated plants. The plants subjected to 5 mg L−1 application exhibited 183 and 188% stimulation in the fruit yield, and 167 and 172% in the seed yield for the first and second seasons, respectively. The highest concentration of phenolic, flavonoid, protein, vitamin C, and maximum antioxidant activity in the fruit pulp was observed following 5 mg L−1 brassinolide treatment. The oil yield has been increased by 366 and 353% following brassinolide at a 5 mg L−1 level over control plants. Linoleic, oleic, and palmitic acids are the major components in prickly pear seed oil. Brassinolide foliar spraying induced an alternation in the fatty acid profile, as linoleic and oleic acids exhibited 5 and 4% higher following 5 mg L−1 application as compared with untreated plants. In conclusion, the treatment of 5 mg L−1 brassinolide improved the growth and quality of prickly pear plants by boosting fruit and seed yields, increasing active component content in the fruit pulp, improving mineral content, and increasing oil production and linoleic acid proportion.