Iron deficiency stress impairs iron absorption and accumulation, compromising photosynthetic performance and antioxidant defense to limit grapevine growth.

Iron (Fe) deficiency is a common nutritional disorder that causes iron chlorosis in crop production, affecting plant growth, development, yield, and quality. To elucidate the growth-physiological characteristics, iron accumulation dynamics, and allocation patterns of grapevines under long-term gradient iron deficiency stress, this experiment was conducted. Using 'Red Globe' grapevines as the experimental subject, four gradient Fe-deficiency treatments (1/5, 2/5, 3/5, and 4/5 of normal iron supply) were established under tissue culture conditions, with a control (CK) group maintained at normal iron supply. After 40 days of cultivation, key growth indicators (e.g., plant height, leaf area), photosynthetic pigment contents (chlorophyll a, b), chlorophyll fluorescence parameters (e.g., Fv/Fm, Y(II)), antioxidant enzyme activities (e.g., SOD, POD), and other physiological-biochemical attributes were systematically measured. Additionally, iron accumulation levels in root and leaf tissues were quantified. Comprehensive statistical analysis was performed to evaluate grapevine responses to varying iron deficiency severities. Results demonstrated that as iron deficiency intensified, both aboveground shoot and root system development in grapes were progressively suppressed, characterized by stunted growth, reduced leaf area, impaired root expansion, decreased chlorophyll content, and suppressed photosynthesis. Under prolonged iron deficiency stress, declines in key antioxidant enzyme activities, elevated proline (Pro) levels, disruption of the enzymatic defense system, and reduced antioxidant capacity collectively exacerbated membrane lipid peroxidation. These cumulative physiological perturbations were the primary drivers of growth retardation and compromised metabolic functionality in grapevines. Iron accumulation patterns in leaves and roots further confirmed the multi-stage regulatory cascade from Fe supply to uptake-translocation dynamics and subsequent involvement in grape physiological metabolism. These mechanistic insights provide a theoretical framework for optimizing Fe nutrition management in grape production.