RESEARCH ON EARLY IDENTIFICATION OF NUTRITIONAL STATUS IN HIGH DENSITY FERTIGATED CHERRY ORCHARDS THROUGH ION SELECTIVE ELECTRODE DETERMINATION VALIDATED BY FOLIAR DIAGNOSIS

The aim of the present research was to assess a specialized methodology of nutritional status determination of three sweet cherry cultivars (‘Lapins’, ‘Tamara’, ‘Kordia’) grafted on ‘GiSelA 3’ and ‘GiSelA 5’ rootstocks, in a drip fertigated high density field trial at Fruit Research and Development Station Bistrita in Northern Transylvania, Romania. The research was carried out between 2020 and 2022 on the background of mineral fertigation using Solfert (10 kg/ha) and Cropmax (0.2%) foliar fertilizer, in a molic eutricambosoil. The trees were trained as spindle bush with 1,250 trees/hectare. It was implemented a parallel determination of main nutritional elements via foliar diagnosis (N, P, K, Ca, Na) performed in an accredited chemical laboratory for plant and soil analysis, respectively via the L`aqua Horiba ion selective electrode determination of NO3_, K+, Ca2+, Na+ ions. The results from foliar diagnosis indicated that the level of mineral elements N, P, K, Ca, Na were within the established normal limits for cherry leaves in 2021. The study evaluated also the impact of meteorological conditions on reference evapotranspiration (Etr) which has a direct influence on the water deficit and tree physiology. The calculated water deficit in 2021 was - 128 mm, respectively in comparison the water deficit calculated in 2022, when it was - 283.7 mm, thus in 2022 it was needed to fertigate more to compensate the difference of 155.78 mm. As a result of increased fertigation a significantly higher content of nitrogen was registered at foliar level in 2022 and a medium content of other chemical elements P, K, Ca, Na. Ion selective determinations using L`aqua meters showed values ranging 540-550 ppm for nitrate NO3- which correlated with the higher percent of nitrogen assessed by foliar diagnosis, 1,700-2,500 ppm potassium (K+), 64-96 ppm calcium (Ca2+)and 21-58 ppm sodium (Na+) content in both years.