柳枝稷苗期发育速度差异显著的2类幼苗生理特性比较

旨在生理生化水平上探索柳枝稷苗期慢发育的机理。采用栽培品种‘Alamo’的2个单株(编号为Ma和Mg)收获的种子为材料,在播种后16、24和32d分别对生长发育快(简称快发育苗)和生长发育慢(简称慢发育苗)的2类幼苗进行生长相关的生理指标测定和比较分析。结果表明:慢发育苗地上部分和地下部分鲜质量、干质量显著小于快发育苗,且根长较短,根数较少,但两者根冠比、根系活力无显著差异;慢发育苗与快发育苗相比还原型谷胱甘肽(GSH)质量分数在前期较低,但两者叶绿素、可溶性糖、淀粉、纤维素、可溶性蛋白、全氮和游离氨基酸质量分数总体上无显著差异;慢发育苗脱落酸(ABA)质量分数总体上比快发育苗高,赤霉素(GA)质量分数24d时较低,IAA/ZR比值32d时较低。Ma和Mg同种类型幼苗根长、16d时GSH质量分数、32d时IAA/ZR比值存在显著差异,根数、ABA质量分数和24d时GA质量分数无显著差异。柳枝稷苗期根系不发达,前期GSH质量分数较低,内源激素ABA质量分数较高,中期GA质量分数和后期IAA/ZR比值较低对柳枝稷苗期慢发育的形成有重要影响。

Comparison of Physiologic and Biochemical Characteristics between Fast- and Slow-growing Seedlings in Swithgrass

To investigate the slow-growing mechanism of switchgrass at the physiological and biochemical levels,an experiment was conducted using seeds harvested from two plants(Ma and Mg) of Alamo ecotype. Since 16,24 and 32 days after planting,physiological and biochemical indexes related to growth characteristics were examined and compared between two types of seedlings characterized as fast and slow growth. The results showed that fresh and dry mass of the shoot and root tissues in slow growing seedlings were significantly lighter than those in the fast growing seedlings. In addition,slow growing seedlings had few and short roots,whereas no significant differences in root/shoot ratios and root activities were observed between the slow and fast growing seedlings. Even though GSH mass fraction in slow growing seedlings during early stage was lower than that in fast growing ones,the mass fraction of chlorophyll,starch,cellulose,soluble protein,total nitrogen and free amino acids showed no overall differences between the two types of seedlings. Compared with fast growing seedlings,slow growth seedlings were overall high in ABA mass fraction ,low in GA mass fraction on the 24th day,and low in IAA/ZR value on the 32nd day. Significant differences in root length and GSH mass fraction at the 16th day and in IAA/ZR ratio on the 32nd day were found between seedlings of the same variety for both varieties. Nevertheless,no significant differences were observed in root number,ABA mass fraction and GA mass fraction on the 24th day. Furthermore,significant differences were noticed in root length and GSH mass fraction on the 16th day and IAA/ZR ratio on the 32nd day between Ma and Mg,while no significant differences were noted in root number,ABA mass fraction and GA mass fraction on the 24th day. These results indicated that slow growing seedlings had a poorly developed root system with low GSH mass fraction at early stage,high ABA mass fraction ,low GA mass fraction and IAA/ZR value,which probably resulted in the slow developmental rate during the seedling stage.