优化高压电场处理对谷子种子萌发期内源激素的影响

Response of endogenous hormone in germination of millet seeds to optimal high voltage electrostatic field

为了探讨高压电场处理谷子种子内源激素含量动态变化对其萌发活力的调控影响,以农大八号谷子种子为试材,运用二次通用旋转组合设计与主成分分析相结合的方法,建模寻优。在优化电场处理条件下,研究种子萌发过程中内源激素含量动态变化。结果表明:高压电场处理谷子种子显著影响其萌发活力(P<0.05);模型决定系数R2为0.979 2,表明模型拟合较好;模型耦合效应表明,高压电场处理谷子种子存在阈值效应,且电场强度影响效应大于处理时间;模型解析得到高压电场优化条件为电场强度340 k V/m,处理时间14 min。谷子种子萌发期内源激素含量动态变化结果表明,优化电场处理条件诱导吲哚乙酸(indole-3-acetic acid,IAA)、玉米素核苷(zeatin riboside,ZR)和赤霉素(gibberellin,GA)含量增加,抑制脱落酸(abscisic acid,ABA)含量增加;种子萌动前后,内源IAA、GA迅速上升、ABA快速下降,ZR在萌动时也达到极值,有利于胚根突破种皮,促进种子的萌动;GA/ABA、IAA/ABA、ZR/ABA比值处理均高于对照(未经电场处理),表明高压电场处理谷子种子后内源激素比值的变化是种子萌发活力提高的诱因,胚根达种子的2倍长后,GA/ABA、IAA/ABA比值都呈现增大趋势,表明幼苗生长与其调控密不可分。研究结果为高压电场技术处理种子在农业生产中的应用提供理论依据。

For the past few years, the HVEF（high-voltage electric field） technology is gradually applied in agriculture, such as seed-selecting, disease-preventing, growth-promoting, and food preservation, etc. Pretreating seeds by HVEF has characteristics of simplicity, high efficiency, short processing time, low power and no pollution, etc, so it has become a hot research subject in agriculture field. Researches indicate that suitable treatment of HVEF is beneficial to the synthesis of adenosine triphosphate（ATP） and the activation of enzymes in seeds, improves the permeability of membrane, and strengthens the ability of resisting adversity and germination activity of the seeds. So far, since the mechanisms of applying HVEF technical involves both biology and physics field, the study of it has no definite conclusion, which restricts its generalization in agriculture to some extent. Millet has great potentialities as the staple food in the northern China due to its extensive adaptability and great nutrient content. As a signal of mieromolecule, endogenous hormones induced by plant cell when accepting the specific environment signals, it can regulate plant physical responses even at the least concentration. So they are used to regulate seed germination directly or interactively. To reveal the control effects of dynamic content changes of endogenous hormone on germination activity of millet seeds treated by HVEF, Nongda 8（millet cuhivar） was used as the testing subject, and an integrated method of combining quadratic general rotary unitized design and principal component analysis was also used to build model for optimal conditions. Under the optimized condition for HVEF, the dynamic content changes of endogenous hormone in the process of millet seeds germination were investigated in this paper. The results showed that pretreating seeds by HVEF can significantly influence germination vigor（P〈0.05）. The test for the fit of model was significant（P〈0.01） and lack of fitting test was no siguifieant（P〉0.05）. The regression determination coefficient R2 reached to 0.9792（P〈0.05）. It indicated the goodness of simulation was better. The optimization scheme was that electric field strength was 340 kV/m and treatment time was 14 rain. The coupling effects of two factors（electric field strength and treatment time） on germination composite index of Nongda 8 indicated there existed threshold in the treating millet by HVEF, and the effects of electric field strength were more than that of treatment time. Dynamic changes of endogenous hormone content in millet germination indicated that the optimal condition of treating millet by HVEF could induce the increase of IAA, ZR and CA content increased but inhibit the increase of ABA. When seed germinating IAA and GA increase quickly while ABA decreases quickly, and ZR was up to the maximum, which was beneficial for radicle to break through the seed coat, and to improve seed germinating. The dynamic content changes of endogenous hormones showed that GA/ABA, IAA/ABA ratio of millet seeds treated by HVEF were higher than control groups（untreated by HVEF）, which indicated that the ratio change of millet endogenous hormones seeds treated by HVEF was incentives to improve germination activity of millet seeds. When radical length equals to twofold of seeds length, the radio of GA/ABA, IAA/ABA continued to increase, which indicated seedling grow had a close relation with its regulation and control. The results provide useful information for the application of HVEF technology in processing seeds in the agricultural production.