What are the effects of Kaolin on olive trees and olive oil?
Kaolin efficacy depends on environmental conditions and morphological characteristics of the cultivar. Kaolin changed fatty acid composition and improved oil oxidative stability. The peroxide and iodine values were decreased
The aim of the study was to investigate the effects of exogenous application of kaolin clay particles, glycine betaine and Ambiol on olive (Olea europaea L.) plants subjected to drought stress. Two years old self-rooted cv. Chondrolia Chalkidikis olive trees were subjected to two irrigation regimes, i.e. the fully irrigated and the water stressed trees, while they were treated with the three pre-mentioned products. Drought decreased the relative water content, the actual water content and the succulence of leaves significantly, while leaf tissue density was increased. Carbon assimilation rate, stomatal conductance and intrinsic water use efficiency were significantly reduced under drought stress conditions, while intercellular CO2 increased. Among the alleviating products tested, kaolin clay particles had a significant positive effect on leaf water content, succulence, leaf tissue density and leaf temperature under both drought and well irrigated conditions. Glycine betaine and kaolin clay particles when applied to drought stressed trees, resulted in increased CO2 assimilation rates compared to control. Furthermore, kaolin clay particles treated leaves exhibited high diurnal CO2 assimilation rates under drought conditions. Based on the results of the present study, kaolin clay particles and glycine betaine proved to be the most effective, among the applied products, on alleviating the negative effects of drought stress.
Kaolin particle film (0, 3 and 6%; w/v), as an antitranspirant treatment, was applied to mature ‘Zard’ olive trees (Olea europaea L.). Olive oil was extracted from harvested fruit and fatty acid composition and other oil quality indices of the fruit assessed over crop seasons. Kaolin increased chlorophyll and carotenoid contents, but decreased peroxide and iodine values, and UV absorbance extinction coefficients, of the oil. The highest palmitic acid was observed in the oil obtained from untreated trees (17%). Kaolin increased oleic acid up to 65 and 64% in the first and second crop seasons, respectively, but decreased linoleic and linolenic acid contents. Monounsaturated acids (65%) and oleic acid/linoleic acid ratios (4) were higher in oil obtained from kaolin treated than untreated trees. Therefore it can be expected that extracted olive oil from kaolin treated trees has a higher oxidative stability and shelf life than untreated trees.
Esmaeil Khaleghi, Kazem Arzani, Norollah Moallemi, Mohsen Barzegar, The efficacy of Kaolin particle film on oil quality indices of olive trees (Olea europaea L.) cv ‘Zard’ grown under warm and semi-arid region of Iran, Food Chemistry, Available online 11 June 2014
Nikoleta-Kleio Denaxa, Peter A. Roussos, Theodoros Damvakaris, Vassilios Stournaras, Comparative effects of exogenous glycine betaine, kaolin clay particles and Ambiol on photosynthesis, leaf sclerophylly indexes and heat load of olive cv. Chondrolia Chalkidikis under drought, Scientia Horticulturae, Volume 137, 1 April 2012, Pages 87-94