Growth, yield, fruit quality and leaf nutrient status of grapefruit (Citrus paradisi Macf.): Variation from rootstocks

Present studies were made on 'Marsh Seedless' and 'Redblush' cultivars of grapefruit, budded on nine different rootstocks under the typical sub-tropical growing conditions of North India. Significant variations in tree vigour, fruit yield and quality and leaf nutrient concentrations were observed due to rootstock effects. For 'Marsh Seedless', 'sour orange' proved to be the most vigorous rootstock (45.88 m(3) canopy volume). Marsh Seedless budded on 'Attani-2' yielded best (29.15 kg tree(-1)) with the fruits having high TSS (10.72 degrees B), and highest contents of ascorbic acid (157.90 mg 100 g(-1)), phenol (128.43 mg GAE(-1) 100 g(-1)) and the activity of antioxidant (3.25 mu mol trolox g(-1)) with lowest acid content (0.92%). However, 'Redblush' cultivar while grown on 'rough lemon' showed vigorous growth (54.10 m(3) canopy volume). Rough lemon and 'Attani-2' proved high yielding rootstocks for 'Redblush' (25.80-28.92 kg tree(-1)), and produced the fruits with highest ascorbic acid (105.17 mg 100ml(-1) juice) and lowest acid (1.01%) contents. The budding of 'Redblush' on 'Billikhichli' yielded the fruits with highest TSS (12.65 degrees B) and phenol (92.80 mg GAE(-1) 100 g(-1)) contents and the highest antioxidant activity (3.70 mu mol trolox g(-1)). Besides, 'Attani-2' also enhanced the nutrients accumulation in 'Marsh Seedless' (P, K, Cu and Fe) and 'Redblush' (N, P, Ca, Mn and Fe). 'Rough lemon' as a rootstock also improved the nutrient accumulation in 'Redblush' (P, K, Mg and Mn). Yield showed the significant correlations with peel thickness (r = 0.582) and titratable acidity (r = -0.706). Growth, yield and fruit quality (TSS and Titratable acidity) of grapefruits were significantly influenced by seasonal variation. Overall, 'sour orange' for 'Marsh Seedless' and 'rough lemon' for 'Redblush' proved most vigorous. 'Attani-2' proved promising to achieve high yield of best quality fruits of 'Marsh Seedless', while high yield of 'Redblush' was obtained on either 'Attani-1' or 'rough lemon', with 'Billikhichli' being best for producing high quality fruits. Attani-2' proved a good Na excluder rootstock for both the cultivars too. (C) 2016 Elsevier B.V. All rights reserved.