単為結果性トマトの種子形成に及ぼす交配親および交配時期の影響(発育制御)  [in Japanese] Effects of Crossing Parents and Artificial Crossing Stage on Seed Development of Parthenocarpic Tomato(Growth Regulation)  [in Japanese]

単為結果性トマトの種子形成に関与する要因を明らかにするため,交配親の組み合わせおよび交配時期が単為結果性トマトの種子形成に及ぼす影響について検討した.また,開花の前後における子房の大きさの変化について,単為結果性トマトと非単為結果性トマトの品種比較を行った.種子親を非単為結果性品種の'桃太郎ヨーク'とした場合,花粉親の種類にかかわらず有種子果率は100%で,1果当たりの種子数は200粒前後であった.種子親を単為結果性固定系統の'PASK-1'および'PF8HK'とした場合,花粉親の種類にかかわらず,有種子果率は72〜94%とやや低く,1果当たりの種子数は7.6〜29.9粒であった.従って,単為結果性トマトの種子形成には,花粉親の種類は関係がなく,種子親の種類が大きく関与し種子親が単為結果性の場合に種子は形成されにくくなると推察された.交配時期が単為結果性トマトの種子形成に及ぼす影響については,非単為結果性品種の'桃大節ヨーク'は,交配時期にかかわらず有種子果率はいずれも100%であり,1果当たりの種子数も標準的であった.一方,単為結果性品種の'ルネッサンス'の有種子果率は,開花2日後では春季が8%,秋季が33%と,開花時での春季96%,秋季87%に比べて大きく低下し1果当たりの種子数も開花2日後では春季が0.8粒,秋季が4.0粒と極端に少なかった.また,蕾時から開花2日後にかけて'ルネッサンス'の子房は,横径および縦径とも順次増加した.従って,'ルネッサンス'の開花2日後における種子形成能力の低下は,雌ずいの受精能力低下ではなく,開花前からの単為結果性の発現による影響と推察された.

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 TASK-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.