اثر محلول‌پاشی برگی نانوذرات سیلیسیم و پتاسیم بر ترکیب اسیدهای چرب روغن زیتون رقم زرد

با توجه به تاثیر تغذیه بهینه و نوع کود استفاده شده بر کمیت و کیفیت اسیدهای چرب زیتون، در این پژوهش اثر محلول پاشی پتاسیم و سیلیسیم به شکل نانوذرات بر ترکیبات اسیدهای چرب روغن زیتون رقم زرد بررسی شد. آزمایش به صورت فاکتوریل در قالب طرح بلوک های کامل تصادفی با سه تکرار در بهار و تابستان سال 1400 طراحی و در دره شهر استان ایلام اجرا شد. نانوذرات پتاسیم در سه سطح (صفر، 400 و 800 میلی گرم در لیتر) و نانوذرات سیلیسیم نیز در سه سطح (صفر، 30 و 60 میلی گرم در لیتر) بصورت محلول پاشی استفاده گردید. نتایج محلول پاشی با این ترکیبات اثر معنی داری بر ترکیب روغن زیتون داشت و میزان اسیدهای چرب اشباع و غیر اشباع در تیمارهای آزمایشی افزایش یافت، به‌طوری‌که بیشترین میزان اسیدهای چرب اشباع (19/24درصد) و اسید پالمیتیک (15/47درصد) در تیمار ترکیبی 800 میلی گرم بر لیتر پتاسیم و 60 میلی گرم بر لیتر سیلیسیم به دست آمد. در حالیکه اسید آراشیدیک (0/94درصد) در تیمار 400 میلی گرم بر لیتر پتاسیم و 30 میلی گرم بر لیتر سیلیسیم و اسید استئاریک (3/37 درصد) در تیمار 400 میلی گرم بر لیتر پتاسیم بیشترین میزان را داشتند. حداکثر اسیدهای چرب چند غیر اشباعی اسید لینولنیک (1/24درصد) و لینولئیک (12/12 درصد) در تیمار 800 میلی گرم بر لیتر پتاسیم و 30 میلی گرم بر لیتر سیلیسیم حاصل شد. تیمارهای غیرترکیبی 800 میلی گرم بر لیتر پتاسیم و یا 60 میلی گرم بر لیتر سیلیسیم منجر به تشکیل حداکثر اسید اولئیک، پالمیتولئیک، اسیدهای چرب غیر اشباع و اسید های چرب تک غیر اشباعی شدند. بر اساس نتایج این پژوهش نشان داد که غلظت متوسط پتاسیم برای بهبود اسیدهای چرب اشباع و غلظت بالاتر آن برای اسیدهای چرب غیراشباع مناسب تر باشد. همچنین محلول پاشی هر کدام از عناصر مغذی نانوپتاسیم و نانوسیلیسیم برای بهبود اسیدهای چرب تک غیراشباعی مفید بوده و استفاده توام از این دو نانو ذره برای بهبود اسیدهای چرب چند غیراشباعی و اسیدهای چرب اشباع مناسب تر باشد.

effect of foliar application of silicon and potassium nanoparticles on the fatty acid composition of olive oil cv. zard

due to the role of optimal nutrition and fertilizer types applied on olive fatty acids, in this study the effect of foliar application of nano-potassium (k) and nano-silicon (si) fertilizers on the fatty acid composition of olive fruit cv. zard were investigated in spring and summer of 2021 in darreh shahr, ilam province, iran. the k nanoparticles at three levels; 0, 400, and 800 mg l-1 and si nanoparticles at three levels; 0, 30, and 60 mg l-l nanoparticles were foliar applied on olive tree canopies using factorial arrangements in complete randomized block design with three replications. the results showed that the content of majority of fatty acids in the oil olive fruit were affected by treatments and the content of both saturated and unsaturated fatty acids were increased in fruits of treated plants. the highest saturated fatty acids content (19.24%) and palmitic acid (15.47%) was recorded in 800 mg 1-1 potassium and 60 mg l-1 silicon, respectively, while arachidic acid was highest (0.94%) in 400 mg l-1 potassium and 30 mg l-1 silicon. the maximum stearic acid (3.37%) was attained in 400 mg l-1 potassium. the highest level of linolenic acid (1.24%) and linoleic acid (12.12%) was recorded in the simultaneous application of 800 mg l-1 potassium and 30 mg l-1 silicon, while application of 800 mg l-1 potassium and or 60 mg l-1 silicon led to the highest content of oleic, palmitoleic, unsaturated and mono unsaturated fatty acids. it is concluded that intermediate levels of potassium is more efficient for enhancement of saturated fatty acid while unsaturated fatty acids were highest in 800 mg l-1. moreover, application of each fertilizer at high concentrations led to the highest monounsaturated fatty acids content, while a combination of lower levels of potassium and silicon was more efficient for increasing the content of saturated and polyunsaturated fatty acids. keywords: olive, nano-fertilizer, foliar spraying, oil composition, unsaturated fatty acids.introductionolive (olea europaea l.) is one of the most important fruit crops widely grown worldwide and has been praised for its high quality oil in the mesocarp of its fruits. the mono-unsaturated fatty acids (mufa) of oleic acid (c18:1) is the major component of olive oil that along with other unsaturated fatty acids such as linoleic acid (c18:2) and linolenic acid (c18:3) constitute high-quality oil that its regular inclusion into the human diet is strongly suggested mainly due its health promoting properties (revelou et al., 2021; razeghi-jahromi et al., 2022b). the oil content and composition of olive oil is influenced by different factors including genotype, environmental conditions as well as orchard management practices. proper orchard fertilization is among the important factors that affects productivity of olive trees and oil composition of its fruit (zipori et al., 2023). application of new fertilizer such as nanoparticle-sized nutrient has opened up new opportunities for delivering nutrient to the plant in a way that is more efficient and sustainable than common synthetic fertilizers, due to their higher uptake rate by plants and lower residue in the soil and impact on the environment (seleiman et al., 2021). the aim of the present study was to evaluate the effects of foliar application of potassium (k) and silicon (si) nano-fertilizers on the composition and quality of olive oil. materials and methodsthe effect of foliar application of nano-potassium (k) and nano-silicon (si) fertilizers were investigated on the fatty acid composition of olive fruit cv. zard in spring and summer of 2021 in darreh shahr, ilam province, iran. for this purpose, the k nanoparticles at three levels; 0, 400, and 800 mg l-1 and si nanoparticles at three levels; 0, 30, and 60 mg l-l nanoparticles were foliar applied, twice during the growing season, on olive tree canopies using factorial arrangements in complete randomized block design with three replications. the fruits were harvested at ripening stage and their oil composition were determined using gas chromatography method. data were subjected to the analysis of variance with sas software (ver. 9.4) and the means were compared using least significant differences (lsd) test. results and discussionthe results showed that the content of majority of fatty acids in the oil olive fruit were affected by treatments and the content of both saturated and unsaturated fatty acids were increased in fruits of treated plants. the highest saturated fatty acids content (19.24%) and palmitic acid (15.47%) was recorded in 800 mg 1-1 potassium and 60 mg l-1 silicon, respectively, while arachidic acid was highest (0.94%) in 400 mg l-1 potassium and 30 mg l-1 silicon. the maximum stearic acid (3.37%) was attained in 400 mg l-1 potassium. the highest level of linolenic acid (1.24%) and linoleic acid (12.12%) was recorded in the simultaneous application of 800 mg l-1 potassium and 30 mg l-1 silicon, while application of 800 mg l-1 potassium and or 60 mg l-1 silicon led to the highest content of oleic, palmitoleic, unsaturated and mono unsaturated fatty acids. it is concluded that intermediate levels of potassium are more efficient for enhancement of saturated fatty acid while unsaturated fatty acids were highest in 800 mg l-1. moreover, application of each fertilizer at high concentrations led to the highest monounsaturated fatty acids content, while a combination of lower levels of potassium and silicon was more efficient for increasing the content of saturated and polyunsaturated fatty acids.in general, foliar application of potassium and silicon nano-fertilizers positively affected the content and composition of olive oil (sleiman et al., 2021). results of this study revealed that nanoparticle-sized nutrients might be a good choice for improving productivity of fruit crop (zipori et al., 2023). in addition to potassium that is an essential nutrient for plant, silicon foliar application also significantly affected the composition and quality properties of olive oil. the results also showed the synergistic effects of potassium and silicon. therefore, it is suggested that simultaneous foliar application of potassium and silicon nono-fertilizes be included in the olive orchard nutrition management practices. referencesrazeghi-jahromi, f., zarei, a., parvini, f. and hosseini-mazinani, m. 2022b. change in oil composition and the major fatty acids and triacylglycerol biosynthesis genes in drupe of selected olive cultivars during growing season; a two years study. european journal of lipid science and technology, 124(12), 2200079. doi: 10. 1002/ejlt.202200079revelou, p.k., xagoraris, m., alexandropoulou, a., kanakis, c.d., papadopoulos, g.k., pappas, c.s. and tarantilis, p.a. 2021. chemometric study of fatty acid composition of virgin olive oil from four widespread greek cultivars. molecules, 26(14), 4151. doi: 10.3390/molecules26144151seleiman, m.f., almutairi, k.f., alotaibi, m., shami, a., alhammad, b.a. and battaglia, m.l. 2021. nano-fertilization as an emerging fertilization technique: why can modern agriculture benefit from its use? plants, 10(1), pp.1-27. doi: 10.3390/plants10010002zipori, i., yermiyahu, u., dag, a., erel, r., ben-gal, a., quan, l. and kerem, z. 2023. effect of macronutrient fertilization on olive oil composition and quality under irrigated, intensive cultivation management. journal of the science of food and agriculture, 103(1), pp.48–56, doi: 10.1002/jsfa.12110