Genetic Evaluation Of Selections And Hybrids Of Rangpur Lime, Volkamer And Rough Lemons Rootstocks For Valencia Orange Trees In The Presence Of The Citrus Sudden Death

This study aimed to perform the genetic evaluation of fruit production, productive efficiency and growth of Valencia orange (Citrus sinensis) trees scions grafted on selections and hybrids of Rangpur lime (C. limonia), Volkamer (C. volkameriana) and Rough (C. jambhiri) lemons rootstocks grown in the presence of the Citrus Sudden Death (CSD). In an affected endemic area for CSD 36 genotypes of these rootstocks were evaluated, represented by five plants each one, measured in five harvests from the third to seventh years after planting. Seven of them showed symptoms of CSD: Rangpur Otaheite orange 12901 (859), Rangpur Red Lime D.33.30 (866), Limao Cravo EEL (871), Rangpur Borneo red (874), Citrus kokhai (1649), Rough lemon 58329 (1655) and Limao Cravo x Swingle B (1695). For selection and breeding purposes, genetic and phenotypic parameters were estimated and individual genotypic values were predicted for all traits by the REML/BLUP (restricted maximum likelihood/best linear unbiased prediction) procedure. The analysis of fruit production in five harvests showed selective accuracy of 84.59% revealing that a greater number of harvests is unnecessary. Selection of the best seven genotypes led to a genetic gain of 11.5% for fruit production while the selection of the very best genotype provided an estimated genetic gain of 16.3%. The higher predicted genetic means (>70.0 kg.pl(-1)) for fruit production were obtained for the genotypes Ipanema Rangpur Lime (1522), Santa Barbara Red Lime (884), Limeira Rangpur Lime (863), Taquaritinga Rangpur Lime (869), Do Cabo Rough Lemon (1643), Rangpur Rose Lime (868) and California Rangpur Lime (1467). The selective accuracy for the productive efficiency based on four harvests was 77.4%. For this trait the higher predicted genetic means (>8.0 kg.pl(-1)) were obtained for the genotypes Rangpur Lime x Trifoliata 3810 (1648), Rangpur Lime x Trifoliata 5320 (1644), Rangpur Lime x Citrange Carrizo (1524), Citrus pennivesiculata (880), Rangpur Lime x Trifoliata Swingle A (1707), Rangpur Rose Lemon 124684 (864), Rangpur Red Lime D33.47 (867) and Ipanema Rangpur Lime (1522). Among the best 10 genotypes for fruit production and for productive efficiency only three are coincident: Rangpur Rose Lime (868), Citrus pennivesiculata (880) and Ipanema Rangpur Lime (1522).