烤烟2种育苗方式干旱胁迫对烟苗生长的影响

Effects of Drought Stress on Biological Characteristics and Physiological and Biochemical of Flue-cured Tobacco in Terminal Stage of Seedling from Floating and Moist Trays System

以烤烟品种K326为材料,在防雨、控水、通风棚内对常规漂浮苗在移栽前15 d进行不同程度的干旱胁迫处理和从播种就进行持续湿润处理的烟苗根系进行研究。结果表明,常规漂浮育苗在移栽前进行适当的干旱处理将促进烟苗主根增长、根系体积增大,但根系干重和根冠比没有显著性差异;而漂湿育苗处理烟苗明显小于其它处理。根系脱氢酶、超氧化物歧化酶(SOD)、脱落酸(ABA)和脯氨酸(Pro)含量受干旱胁迫后迅速升高,前两者在第3天达到最高值,ABA和Pro分别在第6天和第9天达到最高值,之后随天气的变化而呈现不规律的上下波动;而根系活力和IAA含量受干旱胁迫后急剧下降,前者在第6天后又快速上升,随后呈现不规律的变化;IAA直到第12天后才呈现上升趋势。漂湿苗除IAA与对照变化规律相同外,其余指标均与胁迫处理相似。

In attempt to compare the physiological and biochemical responses of the tobacco root system under different levels of drought stress, two sets of treatments of the flue-cured tobacco strain K326 seedlings nursing on the floating seedbed were studied in rain-proof, wa-ter-regulated, and ventilated vinyl house. The first set was treated under different levels of drought stress 15 days before transplanting, and the second set was nursing on moist trays in continuously moist environment after the sowing. The data demonstrated that the tobacco seed-lings under proper drought stress before transplanting promoted the growths of the length and diameter of principal roots. However, the dry weight and the root-shoot ratio among all levels of drought stress did not vary significantly. The above-mentioned indexes were obviously lower in the control set. The biochemical analysis showed that the dehydrogenase, the superoxide dismutase （SOD）, the abscisic acid （ABA）, and the proline （Pro） rapidly increased under drought stress, with the first two substances reached the peak values in the 3rd day after the treatment, while the remaining two reached the peak values in the 6th and the 9th day, respectively. The contents of these four substances fluctuated with the weather condition after reaching the peaks. The activity of root system and the content of indolylacetic acid （IAA） de-creased sharply under all levels of drought stress, with the former index started to increase quickly after six days of the treatment and fluctua-ted afterward, and the later one showed the tendency of increase after 12 days. The content of IAA in the second set varied accordingly with the control set while other biochemical indexes remained similar with the first set.