Effect of fertilization with bioproducts on the nutritional and physiological status of Glohaven peach cultivar

The study was carried out during the period 2020 – 2022 in a young peach plantation at the territory of the Fruit-Growing Institute of Plovdiv, Bulgaria. Glohaven cultivar, grafted on the vegetative rootstock GF677, was the object of the investigation. The following fertilization treatments were studied: soil application of Agriful at rates of 670 ml/da, 1.0 L/da and 1.3 L/da; foliar application of Humustim at rates of 120 ml/da, 140 ml/da and 180 ml/da; and Lumbreco applied as a foliar treatment (450 ml/da), soil treatment (1.7 L/da) or combined foliar (450 ml/da) and soil (1.7 L/da) treatment, as well as an untreated control. The aim of the present study was to follow the effect of the selected bioproducts on: the concentration of N, P, K, Mg and Fe in the leaves, the content of leaf pigments (chlorophyll a, b, a+b and carotenoids), and the biochemical composition of the fruits. The applied fertilization successfully maintained the nutrient reserves in the peach leaves and favoured the accumulation of larger amounts of N, Ca, Mg and Fe. The variants with Lumbreco 450 ml/da + 1.7 L/da, Agriful 1.0 L/da and Humustim 120 ml/da had the best effect on the formation of photosynthetic pigments. An increase of up to 62% in the content of chlorophyll a+b was reported at the end of the study period compared with the untreated control. All fertilized treatments had higher TSS (°Brix) values than the control. Sucrose concentrations were 1.4–2.0 times higher than those of invert sugars.