Abstract
To identify factors involved in seed development of parthenocarpic tomato, the effects of combinations of crossing parents and crossing stage on seed development of parthenocarpic tomato were examined. And the ovary size of parthenocarpic tomato before and after the flowering stage was compared with that of non-parthenocarpic tomato. When the seed parent was the non-parthenocarpic tomato cultivar ‘Momotaro york’, the seeded fruit rate was 100% irrespective of the pollen parent, there were about two hundred seeds per fruit. When the seed parent was the parthenocarpic tomato pure bred strain ‘PASK-1’ or ‘PF-811K’, the seeded fruit rate was 72~94% irrespective of the pollen parent, there were 7.6~29.9 seeds per fruit. Therfore, it was suggested that seed development of parthenocarpic tomato was affected by the seed parent irrespective of the pollen parent, and seeds were apt to remain undeveloped when the seed parent was parthenocarpic. Concerning artificial crossing stage on seed development of parthenocarpic tomato, the seeded fruit rate of non-parthenocarpic tomato cultivar ‘Momotaro york’ was 100% irrespective of artificial crossing stage, and the numbers of seeds per fruit of ‘Momotaro york’ remained standard. The seeded fruit rate of ‘Renaissance’ two days after flowering was 8% in spring and 33% in autumn. Those values were very low compared with 96% in spring and 87% in autumn on flowering. And the numbers of seeds per fruit of ‘Renaissance’ were as few as 0.8 in spring and 4.0 in autumn. Furthermore, the ovary of ‘Renaissance’ from bud stage to two days after flowering enlarged successively in length and breadth. Accordingly it was suggested that the decline of seed development faculty of the parthenocarpic tomato cultivar ‘Renaissance’ by two days after flowering was not influenced by the decline of fertilization faculty of pistil, but the expression of parthenocarpy before flowering.
