ABSTRACT
Polyembryony and nucellar apomixis are important traits for citrus rootstocks breeding and selection and for commercial multiplication. This study evaluated the polyembryony and estimated the optimal sample size of citrus rootstocks fruits and seeds for fruit seed number, seed embryo number and polyembryony rate, respectively. Fruits and seeds were collected from mother plants in the experimental field of Embrapa Manioc and Fruitculture, in Cruz das Almas, state of Bahia, Brazil. Rootstock species evaluated were: ‘Sunki Tropical’, ‘Sunki Maravilha’,‘Sunki da Florida’, ‘Sunki Comum’, ‘Dancy’ and ‘Cleopatra’ mandarins; ‘Rugoso Jambhiri’, ‘Rugoso da Florida’, ‘Rugoso Comum’ and ‘Volkameriano Lagoa Grande’ lemons; ‘Santa Cruz’ Rangpur lime; and the hybrids ‘Rangpur’ lime x ‘Sunki Maravilha’ mandarin, ‘Sunki da Florida’ mandarin x citrangequat ‘Thomasville’ and an open pollinated hybrid of ‘Tahiti’ lime. Data was submitted to descriptive analysis and equations of maximum curvature were estimated for determination of fruit and seed sample optimal size using 20 or 100 fruits and 156 seeds per genotype, respectively. Seed production and polyembryony varied significantly among the genotypes, which could be grouped by seed production and by polyembryony rate in five classes, respectively comprising intervals of 2 to 28 seeds and 12 to 100%. Optimal size sample was respectively of nine uniform fruits, ten and 23 seeds to determine fruit seed mean number, seed embryo mean number and polyembryony rate by direct counting, because these sample levels were sufficient for all genotypes evaluated.
Citrus spp.; apomixis; biostatistics; breeding
