Fertilization impact on chemical composition of Asparagus (Asparagus officinalis L.) spears

Abstract

Urea application significantly reduced the amount of nitrates in asparagus spears. The morphological characteristics and productivity parameters of asparagus spears are determined by the properties of the species or variety and the growing conditions as well. Nitrogen fertilizers are applied widely for the plants to provide the necessary nutrients. The influence of humic acids on the growth of asparagus shoots has been studied in Spain. It has been determined that humic acids in asparagus improve water usage and accelerate the transfer of nutrients in the synthesis sites of the plant. The application of fertilizers with humic acids stimulates the absorption of nutrients and thus improve plant growth increasing the yield. Experiment has been carried out in 2015-2016 in the Pomological Nursery of Aleksandras Stulginskis University. Experiment of two factors has been conducted: factor A - variety (‘Gijnlim’ and ‘Avalim’) and factor B - fertilization. Fertilization variants: Variant I - Control (background - N5P10 K25) Variant II - background + Ammonium nitrate + Humistar Variant III - background + Ammonium nitrate Variant IV - background + Urea + Humistar Variant - background + Urea. The background fertilization of the control variant has been carried out on 24th of September in 2015. Fertilizers N5P10K25 (550 kg ha-1) has been applied. Ammonium nitrate ((N) - 34.4%) (270 kg ha-1), Urea ((N-NH2) - 46.5%) (200 kg ha-1) and Humistar (50 l-1) has been used on 26th of March in 2016. The aim of the research: to determine the influence of fertilizers on the chemical composition of the asparagus spears. Results of the research: The highest dry matter content (10.9 %) was accumulated in asparagus spears of variety ‘Gijnlim’ fertilized with Urea and Humistar. The highest amount of vitamin C (202.3 mg kg-1) was determined in ‘Avalim’ asparagus spears fertilized with Urea. Maximum potassium content (1716.9 mg kg-1) was determined in ‘Gijnlim’ asparagus spears when Urea for plant fertilization has been used.