Variability and selection potential of 396 hybrids of Rangpur lime 'Limeira', (Citrus limonia) (C), Sunki mandarin (C. sunki) (S), Sour orange 'São Paulo'(C. aurantium) (A) and Trifoliate orange 'Davis A'(Poncirus trifoliata) (T) tolerant to the tristeza disease were studied, comparatively to the genitors Rangpur lime, Sunki and Trifoliate orange. Hybrids TxA, TxS, SxT, CxS, SxC, CxA and SxA were investigated as to yield of first three crops, productivity and several vegetative and industrial characteristics of Valencia sweet orange onto them. Rangpur lime, Trifoliate orange and T x S, S x T, T x A, C x A hybrids initiated yielding before Sunki and S x C, C x S, S x A hybrids. This result indicates a dominance of the precocious yield of Trifoliate even in the hybrids with Sunki and conversely, the opposite trend of Sunki and its hybrids, except in the combination with Trifoliate orange. Yield per canopy area induced by Trifoliate orange was low, contrasting with Rangpur lime, Sunki mandarin and T x S, S x T hybrids. It was observed a close relationship between the diameter of scions, the diameter of rootstocks right after transplant to the field and the same parameters in the subsequent years. Height, canopy, rootstock and scion trunk diameters were highly correlated and useful for composing an index vigor. Trifoliate orange and Sunki mandarin are the most divergent genitors regarding vigor, and the hybrids between them the most variable group. Vigor and yield in 2000 were correlated with scion diameter in 1996, indicating the suitability of customary practice of choosing the most vigorous seedlings for transplanting to commercial fields. Such strategy would be most beneficial if applied for pre-selecting hybrids, before transplant to selection fields. Partial scion/rootstock incompatibility observed in Valencia/ Trifoliate orange was present in Trifoliate hybrids but was not correlated with early yield or industrial attributes of this rootstock. Juice ratio of Trifoliate orange and its hybrids was higher than the ones of Sunki mandarin and Rangpur lime. Yields of Rangpur lime were higher than those of Sunki mandarin and Trifoliate orange. The hybrids displayed considerable genetic variability provided 228 had significant higher yields than Trifoliate orange, 100 higher than Sunki mandarin, and 47 higher than Rangpur lime. The results indicate a good potential selection of such hybrids.
Citrus; Poncirus; breeding; selection; yield; vegetative and industrial characteristics
