Enhancement yield and fruit quality of Washington Navel orange by application of spraying potassium microencapsulated biodegradable polylactic acid

Abstract

This research seeks to improve the fertilizer use efficiency, particularly potassium nutrient, and to minimize any possible dose losses. The improvement was applied by the use of foliar sprays by encapsulated potassium element into biodegradable polymer. The potassium polylactic acid microspheres (K-PLA) were characterized by Gel Permeation Chromatography (GPC) and Scanning Electron Microscope (SEM).  Piratical size and zeta potential measurements were investigated. Thermal behavior (TGA and DTA) was studied. In capsulation percentage of potassium into PLA microspheres was 4.5 W %. Cumulative release was estimated by inductive coupled plasma-atomic emission spectrometry (ICP-AES), the maximum cumulative release was 3.74 % after 12 hours. Washington Navel orange trees treated with uploaded potassium (K₂O) and loaded potassium (K-PLA) or in their mixture (three times in the year) during two successive seasons 2015 and 2016 in private orchard located at El-Kalubia Governorate to evaluate the dual benefit (yield and fruit quality).  The results showed that, the sole treatments significantly increase yield and fruit quality than control (zero % K formulation). However, K-PLA can stabilize K and can significant improve yield and coloring percentage than uploaded K. Both treatments decrease juice acidity %. Whereas, increase content of total soluble solids and vitamin C especially K-PLA (100 %) and ascending order with applying formulations (75% K₂O+ 25% K-PLA), (50% K₂O+ 50% K-PLA) and (25% K₂O+ 75% K-PLA). It can be recommendation, foliar spray of Washington Navel orange orchards by loaded potassium formulation is promising to improve the dual benefit, providing fertilizers and environmentally safe.