Nitrogen forms and Iron deficiency: how do Grapevine rootstocks responses change?

Abstract

Grapevine rootstocks provide protection against environmental biotic and abiotic stresses. Nitrogen (N) and iron (Fe) are growth-limiting factors in many crop plants due to their effects on the chlorophyll and photosynthetic characteristics. Iron nutrition of plants can be significantly affected by different nitrogen forms through altering the uptake ratio of cations and anions, and changing rhizosphere pH. The aim of this study was to investigate the response mechanisms of grapevine rootstocks due to the interaction between different nitrogen forms and iron uptake. Rooted woody cuttings of the rootstocks Fercal (V. berlandieri x V. vinifera) and Couderc 3309 (V. riparia x V. rupestris) were grown within a hydroponic system (Kick-Brauckmann, 7.5 L pots) filled with modified half-strength Hoagland solution under semi-controlled climatic glasshouse conditions in 2021. Plants were grown with or without FeNa(III)- EDTA, and with two  NO₃^– /NH₄⁺ ratios (100:0; 50:50). The results could differentiate iron deficiency effects, nitrogen form effects and rootstock effects. Interveinal chlorosis of young leaves appeared earlier on 3309C from the second week of treatment with NO₃^–/NH₄⁺ (100:0)/-Fe, while Fercal leaves showed less severe symptoms after four weeks of treatment, corresponding with chlorophyll concentrations lower by 75% for 3309C and 57% for Fercal. The treatment NO₃^–/NH₄⁺(50:50)/+Fe had significantly higher biomass compared with NO₃^–/NH₄⁺(100:0)/+Fe in both rootstocks while results with NO₃^–/NH₄⁺(100:0)/-Fe were lowest. Ferric chelate reductase (FCR) activity was specifically increased under iron deficiency in Fercal with both N combinations, whereas 3309C showed an increase in FCR activity just with NO₃^–/NH₄⁺ (50:50). These first results indicate that rootstocks differ in their preference on both the physiological and molecular level depending on the nitrogen form and in interaction with iron deficiency stress.

References:

1) Nasar, J. et al. (2022). Nitrogen fertilization coupled with iron foliar application improves the photosynthetic characteristics, photosynthetic nitrogen use efficiency, and the related enzymes of maize crops under different planting patterns. Front. Plant Sci. 13, 988055.
2) Yin, H. et al. (2020). Effect of ammonium and nitrate supplies on nitrogen and sucrose metabolism of cabernet sauvignon (Vitis vinifera cv.). J. Sci. Food Agric.100(14), 5239–5250. doi: 10.1002/jsfa.10574.