Boron efficiency in increasing olive (cv. Frantoio) fruit productivity and oil yield and quality
R. A. El-Motaium, M. E. Hashim
Abstract
This study was conducted for two successive seasons, 2017 and 2018, using 20-yr old olive trees (cv. Frantio). The trees are grown in sandy soil under drip irrigation system at the Nuclear Research Center Experimental Farm, Inshas, El-Qaliubiya Governorate, Egypt. Treatments included six pure boron concentrations (0.0, 100, 200, 300, 400, 500 mg.L−1) applied on 1st January (before bloom). Boron was applied as foliar spray boric acid. The objective of this study was to investigate the effect of boron foliar application on olive (OleaeuropeaL.) fruit productivity, oil yield and quality. Boron treatments increased olive fruit productivity and oil yield relative to the control. The maximum fruit yield and oil yield was observed at 200 mg.L−1 boron treatment. This treatment has increased fruit yield by 275% and oil yield by 318% (average of two seasons). The acid value range was from 1.173 to 1.667 (mg KOH/g oil) in the first season and from 1.323 to 1.800 (mg KOH/g oil) in the second season. The acid value significantly decreased as the boron application rate increased. The peroxide value range was from 0.0026 to 0.0067 in the first season and from 0.0032 to 0.0078 in the second season. The peroxide value decreased as the boron application rate increased. A non-significant reduction in the iodine values was observed as the boron application rate increased. The iodine value range was (from 77.20 to 77.40 g/100 g of oil) for the first season and (from 77.67 to 78.23 g/100 g of oil) for the second season. The saponification value range is (from 191.4 to 193.3 mg KOH/g oil) for the first season and (from 192.5 to 193.8 mg KOH/g oil) for the second season. The saponification value significantly decreased as the boron application rate increased. Boron has improved oil quality by decreasing the acid value, the peroxide value and the saponification value, while maintained the iodine value almost similar to the control. Boron treatment has increased olive fruit productivity and oil yield and it improved oil quality characteristics.