Identification of reciprocal hybrids in citrus by the broadness of the leaf petiole wing

Broadness of leaf petiole wing (WB) was investigated as a morphological marker for screening hybrids of the very narrow-winged species Citrus limonia and C. sunki with broad-winged species C. aurantium and C. sinensis. Controlled polinizations produced over 500 reciprocal hybrids with potential in the ongoing rootstock breeding program identified by the Pgi-1 and Prxa-1 isozyme loci. Measurement ratios WB/leaf length, WB/leaf broadness and WB/petiole length identified 86 to 91% of the reciprocal hybrids produced. However, visual classification of WB was an equally efficient but much easier and faster method. It can be very useful in breeding programs when large number of plants have to be screened or when isozyme, RFLP or RAPD laboratories are not available.