Precocious flowering of Citrus seedlings and its use for determination of cultivars generating male sterile progenies

• Precocious flowering was highly found in progenies of pummelos, yuzu and oranges.
• Male sterility was observed among the precocious-flowering seedlings.
• Pummelos and pummelo relatives have fertile cytoplasm for male sterility.
• Mandarin and yuzu have sterile cytoplasm for male sterility.
• Almost all Citrus accessions are heterozygous for the fertility restorer genes.

Precocious flowering in several-month-old to one-year-old seedlings is known in many Citrus cultivars with very long juvenile phase of around ten years. The Citrus accessions generating precocious flowering seedlings are interesting materials for rapid genetic analysis. Precocious flowering was observed in the zygotic seedlings obtained from the most pummelo and pummelo-relative accessions used, and many of yuzu, mandarin and their relative accessions with the range between less than 1% and about 20%. The rates indicated that some pummelo and orange cultivars have high ability to generate precocious-flowering seedlings. Male sterility in the seedlings showed stability in the flowers of first, second, and third years after seed germination. Male sterile seedlings did not segregate in the progenies of pummelo and pummelo-relative accessions used as pistillate parents, whereas they segregated in those of accessions related to ‘Yuzu’ (C. junos) and mandarin, indicating pummelo cytoplasm is fertile for male fertility, whereas ‘Yuzu’ and mandarin cytoplasm was sterile. The segregation of sterility in the progenies also indicated that most Citrus accessions are heterozygous for male fertility restoration genes.