摘要：

为研究淹水对苗期玉米不同类型根的形态结构和活力的影响,选择代表性玉米品种郑单958(耐涝性强)和蠡玉16(耐涝性弱)为试验材料,在三叶期分别淹水2,4,6,8 d,以不淹水为对照(CK),比较玉米胚根和不定根形态特征及活力对淹水胁迫的响应差异。结果表明,淹水2 d后,玉米初生胚根、次生胚根和不定根的根长、根表面积、根体积、根尖数、根分叉数高于对照,随着淹水时长增加,这些指标显著降低,但根平均直径显著升高,新生不定根形态指标明显优于对照,其中根长和根尖数受淹水伤害最大。淹水后不定根层数和数量增多、角度增大。随淹水时间的延长,除第1层不定根干质量外,郑单958初生胚根、次生胚根和第2层不定根干质量先升高后降低,而蠡玉16一直降低。根冠比随着淹水时间的延长表现为先增大后减小。淹水显著降低初生胚根和次生胚根的根系活力,不定根可以维持4~6 d。淹水对不同类型根的影响表现为初生胚根>次生胚根>不定根,不同品种根系特征对淹水胁迫的响应规律不同。抗涝品种淹水8 d后不定根根系活力和根冠比开始下调。

关键词: 玉米, 淹水胁迫, 根系形态, 干物质, 根系活力

Abstract:

To clarify the impacts of flooding stress on the morphological structure and activities in different types of roots for maize at seedling,two typical maize cultivars Zhengdan 958(ZD958,a tolerant genotype)and Liyu 16(LY16,a susceptible one)were selected,and five flooding durations at three leaf stage were established:0(CK),2,4,6,8 d,to explore the response law involving morphology and root activities of embryonic and adventitious root to excessive moisture.The results showed that after 2 days of flooding,the root length,root surface area,root volume,root tip number and root fork number of primary root,seminal root and adventitious root in maize were significantly higher than those of CK.With the extension of flooding duration,these indexes decreased obviously,but the average root diameter displayed an outstanding enhancement.Compared with CK,the morphological indexes of emerging adventitious root under flooding performed better,and among them,the root length and root tip number suffered the most from flooding.The total number,the layer number and the angle of adventitious root increased after flooding.With the elongation of flooding duration,except dry weight at the first layer of adventitious root,the primary root,seminal root and secondary layer of adventitious root of ZD958 increased first and then decreased,but those of LY16 decreased from the start.The root-shoot ratio rose from 2 days to 6 days,and then declined after that.The root activities of primary root and seminal root were significantly reduced under flooding,however,the function of adventitious root could be maintained for 4—6 days.It is concluded that the negative effects of flooding on different root types indicated primary root>seminal root>adventitious root,and response features were different from both varieties.In addition,the adventitious root activity and root-shoot ratio of flooding resistant variety begin to decrease after 8 days of flooding.

Key words: Maize, Flooding stress, Root morphology, Dry weight, Root activity