外源GA_3对高原夏季胡萝卜肉质根发育的影响

Exogenous GA_3 influence on the development of summer cultivated carrot fleshy root on plateau

为了揭示外源 GA3对胡萝卜肉质根发育的影响机理,并为高原夏季胡萝卜安全高效栽培技术研究提供参考理论,本试验以耐先期抽薹的胡萝卜品种为试材,采用酶联免疫吸附法（ELISA）,研究了外源 GA3对高原夏季胡萝卜肉质根膨大、木质化及其内源激素含量的影响。结果表明,在叶片旺盛生长期和肉质根迅速膨大期分别喷施5.78×10-4 mol·L-1外源GA31次,或在苗期、叶片旺盛生长期和肉质根迅速膨大期喷施5.78×10-4 mol·L-1外源GA31~3次,能显著降低高原夏季胡萝卜苗期肉质根日鲜重增长速率与库活力,促进肉质根木质化。与对照相比,喷施外源 GA3,可显著降低苗期肉质根内源 GA3、IAA、GA4、ABA、DHZR与 IPA含量,显著提高肉质根内源ZR含量；显著降低叶片旺盛生长期肉质根内源GA3、IAA、GA4、IPA含量,显著提高内源ZR含量；显著提高迅速膨大期肉质根内源 IAA、GA4、ZR 含量；显著降低肉质根迅速膨大期之前的 IAA/ZR 和GA4/ZR比值。随着外源GA3喷施次数的增多, IAA/ZR和GA4/ZR比值在肉质根迅速膨大期有逐渐增高的趋势。外源GA3通过改变内源激素含量及其平衡状态来影响高原夏季胡萝卜肉质根的发育。

This study determined the mechanism of the effect of exogenous GA3 on the development of fleshy carrot roots and to provide theoretical base for efficient and safe cultivation of summer carrots planted on plateau areas of the Northwest China. To do so, the study analyzed the effect of exogenous GA3 on immature bolting carrot cultivar （‘Xinxiusanhong’） in terms of fleshy root thickening, lignification and endogenous hormones contents. The results showed that weight, growth rate and sink activity of fleshy roots of carrot significantly reduced after spraying with 5.78 × 10-4 mol·L-1 of exogenous GA3 once during vigorous leaf growth period （45 days after seedling emergency） or during root thickening period （75 days after seedling emergency）. The weight, growth rate and sink activity of fleshy roots of carrots also significantly reduced following 3 rounds of continuous spray of 5.78 × 10-4 mol·L-1 of exogenous GA3 at seedling stage （25 days after seedling emergency）, vigorous leaf growth period and root thickening period. However, the level of lignification of fleshy roots of carrot was enhanced by spraying 5.78 × 10-4 mol·L-1 of exogenous GA3. Compared with CK （the control）, fleshy carrot root contents of endogenous GA3, IAA, GA4, ABA, DHZR, IPA were significantly reduced and ZR significantly increased at seedling stage after spraying with exogenous GA3. GA3, IAA, GA4 and IPA contents significantly decreased at vigorous leaf growth stage while endogenous IAA, GA4, ZR contents significantly increased during the period of rapid thickening of fleshy carrot roots. Also, ZR content increased at vigorous leaf growth stage of carrot. The ratios of endogenous IAA/ZR and GA4/ZR significantly decreased before the period of rapid thickening of fleshy carrot roots after spraying one to three times with exogenous GA3. IAA/ZR and GA4/ZR ratios significantly increased during the period of rapid thickening of fleshy carrot roots following several rounds of spraying with exogenous GA3. Exogenous GA3 influenced the development of fleshy roots of summer carrots cultivated in the plateau region of the Northwest China by changing the content and balance of endogenous hormones.