Responses of semi-vigorous apple rootstocks (MM106 and MM111) to different nitrate and ammonium ratios under soilless culture

In this study, the effects of nitrate (NO3−) to ammonium (NH4+) ratios on vegetative growth parameters, mineral uptake, physiological and biochemical responses of two semi-vigorous apple rootstocks (MM106 and MM111) in hydroponically grown under greenhouse conditions were evaluated. Treatments were five nutrient solutions of differing NO3−:NH4+ ratios as follows (100:0, 80:20, 60:40, 40:60, 20:80) and two apple rootstocks. After 120 days of treatment, parameters were determined. The NO3−:NH4+ ratios significantly affected the vegetative growth of MM106 and MM111 rootstocks. Rootstocks fertilized with a high NH4+ ratio produced larger leaves, longer roots, stems, and diameter, while the plants under NO3− treatment alone had smaller and shorter roots. N-form significantly influenced the uptake and utilization of essential plant nutrients in both rootstocks. Leaf concentrations of nitrogen (N), potassium (K), and calcium (Ca) were highest with NO3−. Leaf concentrations of phosphorous (P), magnesium (Mg), copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn) increased as NH4+ supplied more of the N-ratio. The highest chlorophyll a and b and total chlorophyll were observed at the 20:80 NO3−:NH4+ ratio. In comparison, the lowest content was at the highest dose of NO3− (100:0) treatment. The highest soluble sugars were obtained in the leaves of MM106 and MM111 at the ratio of 80:20. Soluble sugars in the root of both rootstocks decreased by increasing the NH4+ ratios in the nutrient solution. Our results show that supplying rootstocks with high NO3− as N form can affect vegetative growth and mineral uptake at this stage of growth.12 month embargo; published online: 09 May 2022This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu