| Study on drought resistance, hydrotropism and anatomic structure of root system of maize inbred lines with different genotypes |
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| DOI：10.7606/j.issn.1000-7601.2016.05.01 |
| Key Words: maize inbred line root system seedling stage root hydrotropism anatomic structure drought resistance |
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| Abstract: |
| To study the different changes in root morphology, physiology and biochemistry, anatomic structure of maize inbred lines with different genotypes at the seedling stage under dry stress, to provide reference index and method for screening of drought resistant maize germplasms, and also to investigate the genetic mechanism of drought resistance for inbred lines at the seedling stage, this research was carried out. 14 maize inbred lines were employed by PEG-6000 stress treatment to determine 13 indexes which are closely related to morphological and physiological and biochemistry characteristics of drought resistance for root of maize inbred lines at the seedling stage. Through the analyses of variance, correlation and cluster, a comprehensive evaluation on the drought resistance of different maize genotypes was carried out, and two obvious differences inbred lines in drought resistance were selected for further observation on the differences in root structure by paraffin section and microscope. Under drought stress, root dry mass per plant, shoot dry mass per plant, root length, root diameter, number of lateral roots, root elongation rate, root dehydration rate, and root reducing capacity of different maize inbred lines at the seedling stage showed a trend of becoming declined at varying degrees. Soluble sugar content and proline content in roots showed a trend of being increased at varying degrees, and had obvious variations in different inbred lines. With the increase of the slope angle, root hydrotropism of different inbred lines was increased, and had obvious differences between different inbred lines. Under the condition of high humidity gradient, root hydrotropism of Mo17 was increased by 134%, which was the biggest among all, and that of WN897 was increased by 20%, which was increased less. Using weighted drought index, a comprehensive evaluation of drought resistance of different genotype maize inbred lines was given and 14 inbred lines were classified into four groups including strong drought resistant, moderate drought resistant and drought sensitive, and drought highly sensitive ones. According to the results of paraffin sections, cultivars showing significant variations in drought resistance had obvious different root system structures. The ratio of root cortex width to root diameter of the drought resistant inbred line Chang 7-2 was lower than that of the non-drought resistant inbred line WN897 that also had larger root vessel diameter. Through the combination of the methods including the analysis of variance, correlation analysis and cluster analysis, an evaluation on drought resistance of different maize inbred lines at seedling stage was given, which can better reveal the relationship between root traits and drought resistance. Root reducing capacity, soluble sugar content, root length, and root hydrotropism were sensitive to drought stress than other indexes, which can serve as the prior identification indexes for drought resistant ability and breeding selection for drought resistant inbred line. Under drought stress, the differences in root anatomy between maize inbred lines were significant. In the seedling stage, the root cortex width of the strong drought resistance was small, and the ratio of root cortex width to root diameter was lower, and the root vessel diameter was higher than the drought sensitive inbred lines. |
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