The use of female monoembryonic parents to obtain citrus rootstocks hybrids

Seeking to avoid the effects of polyembryony, that difficult the identification of hybrids and individuals of maternal origin (nucellar), the Citrus Breeding Program of Embrapa Cassava & Tropical Fruits selected monoembryonic hybrids with potential of generating new rootstocks. Thus, the trifoliate hybrids HTR-001, HTR-002, HTR-005, HTR-037, HTR-073 and HTR-135, besides LCR ('Rangpur' lime Citrus limonia) x LRF ('Florida' rough lemon C. jambhiri) - 005 were used as female parents in open pollinations design. The half-sibling progenies obtained were, respectively, 364; 55; 12; 58; 51; 551 and 59 zygotic seedlings. The hybrids inside progenies were extremely variable as regards the height of the plant and diameter of the stem, also showing differences in the presence of ramifications, format, color and texture of the limb of leaves and size of the thorns. The most vigorous progeny was derived from HTR-073 parent, the opposite being observed with the hybrid progeny related to the parent LCR x LRF-005. This work indicates that, in citrus, the use of female monoembryonic parents in open pollinated crossings constitutes a simple and easy method of obtaining hybrids.