Contrasting temporal responses of growth, photosynthesis and antioxidant defence to nitrogen supply in two table grape cultivars.

Red Globe maintains stable growth, photosynthesis, and antioxidant defenses across nitrogen levels, while Crimson Seedless shows stress responses and growth suppression at high nitrogen.

• Why it matters: Understanding cultivar-specific nitrogen responses is essential for optimizing grapevine nutrition and preventing stress-related damage, yet detailed temporal dynamics remain unclear.
• What they did: The study compared growth, photosynthesis, and biochemical responses of 'Red Globe' and 'Crimson Seedless' under four nitrogen levels over 75 days, using heatmaps and PCA to analyze physiological traits.
• The result: Findings reveal that Red Globe exhibits broader nitrogen tolerance with stable physiological traits, whereas Crimson Seedless is more sensitive, showing early antioxidant decline and stress indicators, guiding cultivar-specific nitrogen management strategies.