Stionic effects on leaf mineral nutrient contents in Pummelo (Citrus maxima Merr.) grafted on different rootstocks

A study was conducted to determine the mineral nutrients concentration in the index leaf of pummelo accessions. Index leaf samples from 25 pummelo accessions grafted on pummelo and 12 pummelo clones grafted on Rangpur lime rootstocks were collected for assessing leaf mineral nutrient status. The results revealed that pummelo plants grafted on pummelo, the concentration of leaf N (1.43-2.49 %), P (0.17-0.22 %), K (0.75-4.45 %), Ca (2.37-6.29 %), Mg (0.60-1.04 %), S (0.06-0.22 %), Fe (124-245.45 mg kg-1), Mn (9.85-50.05 mg kg-1), Zn (17-69 mg kg-1) and Cu (8.8-25.15 mg kg-1) showed significant variation with different accessions. Out of 25 pummelo accessions, twenty-four accessions were deficient in N and S, fourteen were deficient in K, four were deficient in Mn and five were deficient in Zn and all accessions were sufficient in P, Ca, Mg, Fe and Cu. The observed trends in the leaf nutrient concentration of pummelo accessions clearly indicated the significance of the genotypic variation when chemical analysis is used for diagnosing the leaf nutrient status of pummelo trees. Similarly, leaf N, P, K, Ca, Mn, Cu and Zn varied significantly among twelve pummelo clones grafted on Rangpur lime. Among the clones grafted on Rangpur lime, 18-3 and 18-5 found to have higher and lower leaf nutrient content in most of the mineral nutrients, respectively. The leaf nutrient content of pummelo varies among genotypes, but there is no genotype that stands out in all macro and micronutrients evaluated. The N, P, K, Ca, S, Fe, Mn and Cu leaf contents in pummelo were always higher in plants grafted on Rangpur lime. However, the foliar Mg and Zn contents were continually higher in plants grafted on ‘pummelo’ compared to Rangpur lime which eventually reduces leaf yellowing/chlorosis in pummelo. Pummelo rootstocks were found to respond well in terms of Mg and Zn nutrient uptake and tolerance to Phytophthora as compared to Rangpur lime. Therefore, it is concluded that pummelo can be an ideal rootstock for commercial pummelo cultivation