Seed polyembryony is an important trait for breeding and commercial multiplication of citrus rootstocks. This study evaluated relationships of polyembryony with different morphological seed traits of 12 citrus genotypes selected as rootstocks. The following traits were evaluated individually on 50 seeds per genotype: seed mass, height, width and embryo number, polyembryony level, difficulty for seed coat extraction, and seed color, which was estimated by a two-grade scale representing predominant colors on the endosperm. Data was submitted to variance analyses and the means were compared by the Scott-Knott Test (P < 0.05). Pearson's Correlation Coefficients were determined among all variables for all genotypes and individually. Citrus rootstocks had significantly distinct seed traits and could be classified in three polyembryony groups, with three Rangpur lime selections presenting polyembryony lower than 50% and the citrandarins as totally polyembryonic. Other trifoliate hybrids showed low to intermediate polyembryony. Seed coat extraction was more difficult in smaller seeds. For majority of genotypes, the number of embryos in the seed had positive correlation to the seed mass, height and width and negative correlation to the color ratio, which was calculated by the division of the lowest and highest color grades. This result suggests that the whole seed color analysis may be an alternative method for a rapid visual evaluation of polyembryony manifestation.
Citrus spp.; genetic breeding; polyembriony; propagation; seed color analysis; seed morphology
