LAUSR

BACKGROUND The kinetic parameters of peach rootstock are a major contributing factor for nitrogen (N) uptake efficiency that directly affects the yield and quality parameters. However, the impact of grafting on N kinetic parameters is not sufficiently known in the literature as rootstocks are grafted with other scion cultivars before being transplanted to the field. Therefore, the objective of this study was to evaluate if the grafting of Okinawa rootstock with the scion cultivar Chimarrita can alter the kinetic parameters related to N uptake. RESULTS The plants were acclimatized in a 50% strength Hoagland solution and, at 15 and 30 days, assessed the depletion of the internal reserves in CaSO4 solution, evaluating the depletion period during 65 hours. In addition, morphological and physiological parameters were evaluated and kinetic parameters were calculated. The Nitrogen internal reserve depletion period to reach the Cmin was 62 hours for NO3- and 56 hours for NH4+, being 30 days the optimal time for internal reserve depletion for 'Okinawa' rootstock with and without 'Chimarrita' scion. CONCLUSION 'Okinawa' rootstock grafted with 'Chimarrita' scion cultivar was more efficient in NO3 - and NH4 + uptake, as it presented the lowest Km and Cmin values for NO3 - and the highest Vmax values for NH4 + . This article is protected by copyright. All rights reserved.