砂糖橘夏梢生长对幼果内源激素动态的影响

Effects of summer shoots growth on endogenous hormones of fruitlet in ‘Shatangju' Mandarin

以8年生砂糖橘（Citrus reticulata Blanco）为试材,研究夏梢生长对幼果及离区中内源激素含量的影响。结果表明,夏梢生长明显促进了果实、离区中脱落酸（ABA）和乙烯含量的提高,相关性分析表明离区中ABA含量与累积落果率（AAR）,以及果实中乙烯释放量与相对落果率（RAR）、AAR均达极显著正相关。果实、离区中的赤霉素（GAs）、玉米素核苷（ZR）不受夏梢生长所影响,其与落果率的相关性亦不显著。总体上生长素（IAA）含量与落果率呈负相关,但在夏梢生长的9-15 d,果实及离区的IAA含量与落果率表现为极显著正相关,表明IAA与落果的关系较复杂。对激素平衡进行分析,发现夏梢生长6 d和15-18 d,果实及离区中的ABA/（IAA＋GAs＋ZR）比值有突然升高之势。综合认为夏梢生长过程中,果实或离区ABA、乙烯含量的升高,以及内源激素的相对平衡被打破是导致幼果脱落的原因之一。

The objective of this work was to investigate the effects of shoot-growth on contents of endogenous hormones and abscission of fruitlets in Citrus. 8-year old trees of ‘Shatangju＇ mandarin（Citrus reticulata Blanco） were used as materials. The results showed that the contents of abscisic acid（ABA） and ethylene significantly increased by the summer shoots. Correlation analysis indicated that there was significantly positive correlationship between ABA and the accumulative abscission rate（AAR） in abscission zone（AZ）,as well ethylene with the relative abscission rate（RAR） and AAR. While the shoot-growth did not affect the contents of gibberellins（GAs） and zeatin riboside（ZR）,and the content of GAs or ZR didn＇t show a significantly positive correlationship with fruitlet abscission rate. Indole acetic acid（IAA） had negative correlationship with fruitlet abscission rate,indicating that IAA would inhibit the fruitlet abscission. But at the 9-15 th day after summer shoot growth,the IAA content in fruitlet and AZ suddenly increased,and had significantly positive correlationship with fruitlet abscission rate,indicating the complexity of IAA and abscission. The hormonal balance was analyzed,it was found that there was break of ABA/（IAA＋GAs＋ZR） at the 6th day or the 15-18 th day of summer shoots growth,indicating that the increase of ABA and ethylene contents,as the break of hormonal balance were factors causing fruitlet abscission.