The effect of amino acids and fulvic acids on the growth, yield, and quality of apple varieties in the conditions of the Republic of Armenia

Abstract

Background: Apples are widely recognized as a source of bioactive compounds, including polyphenols, flavonoids, dietary fiber, and antioxidant constituents that support cardiometabolic and metabolic health. Agricultural practices, environmental conditions, and nutrient management strategies can significantly influence the accumulation of these health-promoting compounds. Intensive orchard systems, particularly in foothill zones, offer a promising opportunity to enhance both yield and the functional quality of fruit.

Objective: This study aimed to evaluate how high-intensity orchard management practices—including foliar nutrition with macro- and microelements, phytohormones, and fruit load normalization—affect the growth, yield, and functional quality indicators of Gala Schnico Red and Red Velox apple varieties cultivated in the foothill zone of Armenia. A secondary objective was to assess how these practices contribute to the nutritional and bioactive compound profile of apples within a functional food framework.

Methods: Tree growth, phenological stages, yield, and fruiting capacity were assessed according to I.V. Michurin’s methodology. Experiments were conducted in three replications, with 5–10 trees per replication. Standard entomological and phytopathological methods were used for pest and disease monitoring. Fruit samples were analyzed for dry matter, total carbohydrate content (Bertrand method), and quality grading. Orchard treatments included foliar applications of Promalin + Tekamin Max, macro- and micronutrient sprays, pruning, flower and fruit normalization, soil mulching, and application of organic and mineral fertilizers. Data were statistically evaluated using dispersion analysis.

Results: Foliar nutrition combined with fruit load regulation significantly improved yield structure, fruit size uniformity, and biochemical markers relevant to nutritional and functional quality, including increased dry matter and carbohydrate accumulation. Orchard management practices also contributed to improved classification of harvested fruit into higher product grades, with only 1.5% falling outside regulatory standards. These findings suggest that intensification practices may positively influence factors associated with bioactive compound concentration and functional value.

Novelty: This study is the first to evaluate the growth dynamics, yield performance, and functional-quality indicators of Gala Schnico Red and Red Velox apple varieties cultivated under intensive orchard conditions in the foothill zone of Armenia (1000–1600 m). The work integrates modern horticultural intensification practices with functional food science by linking orchard management strategies to nutritional and bioactive-related quality parameters. These findings provide region-specific evidence supporting the development of apples as functionally enhanced agricultural products. 

Conclusions: In intensive two-year orchards, high-quality and selective apple harvests can be achieved through foliar feeding with macro- and microelements, application of Promalin + Tekamin Max, and precise fruit load normalization (two flowers per fruiting branch; 15–20 fruits per two-year-old tree). These optimized horticultural practices not only enhance yield and quality but may also support the development of apples with improved nutritional and functional properties, contributing to their positioning as evidence-based functional foods.

Keywords: intensive orchard system, bioactive compounds, nutritional quality, foliar nutrition, phytohormones, fruit load normalization, functional food potential