Published in Scientific Papers. Series B, Horticulture, Vol. LXV, Issue 1
Written by Stoyan FILIPOV, Kostadin KOSTADINOV, Neli KERANOVA
In an experiment with a greenhouse lettuce in the period 2018-2020, the influence of biological fertilization on the visual characteristics, taste indicators and nitrate content were studied. The biological fertilizers were tested: Arcobaleno, Italpolina, Lumbrical and the microbiological fertilizer Ecoprop NX with control of non-fertilized and mineral fertilization (MF) - NPK. The study was conducted with three varieties of salads: ʻMaritimaʼ - ʻBataviaʼ type, ʻTuskaʼ variety - ʻLolo rosaʼ type and ʻWinter Butterheadʼ - ʻButterheadʼ type. An organoleptic assessment was performed on a five-point scale. A differentiated variety reaction was established. The ʻMaritimaʼ variety is the most responsive to the applied organic fertilizer. The variants with organic fertilization have a complex score from 3.52 for Ecoprop NX to 3.62 for Arcobaleno compared to 3.30 for the control of non-fertilized and 3.49 for the control of mineral fertilization. For the variety ʻTuskaʼ only the variant fertilized with Italpolina exceeds the control and has the highest complex score of 3.82. Biological fertilization has improved the quality of the ʻWinter ButterHeadʼ variety and the complex assessment is from 3.14 in Italpolina to 3.41 in Lumbrical compared to the control variants non-fertilized 3.07 and MF 3.10. Fertilization with the tested biological fertilizers does not increase the amount of nitrates in lettuce leaves above the maximum permissible amounts set by the European Commission.
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