Impact of soil application with humic acid and foliar spray of milagro bio-stimulant on vegetative growth and mineral nutrient uptake of Nonpareil almond young trees under Nubaria conditions

Abstract

Abstract Background At present, agricultural production management techniques focus on greater commitment to environmental sustainability. As such, this study was carried out during two successive seasons (2018 and 2019) to investigate the impact of two natural bio-stimulant substances: humic acid (H) and milagro (M) on vegetative growth and nutritional status of Nonpareil almond young trees grown in Experimental Research Station of National Research Centre, Nubaria, El Behera governorate, Egypt. Three-year-old uniform trees were treated at the beginning of growth season by soil application of humic acid (H) and foliar spray of milagro (M) bio-stimulant. There were ten treatments as follows: control (untreated seedlings),10 g humic acid plus 10 ml/l milagro, 20 g humic acid plus 10 ml/l milagro, 30 g humic acid plus 10 ml/l milagro,10 g humic acid plus 20 ml/l milagro, 20 g humic acid plus 20 ml/l milagro, 30 g humic acid plus 20 ml/l milagro, 10 g humic acid plus 30 ml/l milagro, 20 g humic acid plus 30 ml/l milagro, and 30 g humic acid plus 30 ml/l milagro. Results The results showed that different treatments improved the vegetative growth of seedlings, stem length, diameter, number of branches and leaves, leaf area, leaf fresh and dry weight, and specific leaf dry weight as well as leaf chlorophylls and minerals content comparing with untreated young trees. Conclusions Soil application of 30 g humic acid along with 30 ml/l milagro per young tree as foliar spray was the promising treatment as a new fertilization technique that is non-chemical, low-cost, and environmentally safe for improving growth and nutritional status of Nonpareil almond young trees under Nubaria conditions.