| Maize is a kind of poor waterlogging resistance xerophytic plants, particularly sensitive to flooding stress in seedling stage, it is necessary to improve the waterlogging resistance of maize, but after artificial domestication cultivation and directional selection, the genetic basis of maize become narrow and it has lost waterlogging resistance. Therefore, the improvement of maize’s waterlogging resistance needs the import of foreign genes.The newly discovered wild relatives of maize - Zea nicaraguensis has excellent waterlogging tolerance. After hybridization with maize, their offspring can produce normal seed. So we can use it to improve maize’s tolerance of waterlogging and put it as an important germplasm resources. In the research, the experimental materials was backcrossed by Zea nicaraguensis and Maize and took its parent maize material 08-641 for comparison, the experimental material was flooded 14d in artificial waterlogging environment. Data measured 8 times of Od, Id,2d,3d,5d,7d,10d,14d after flooding. Measurement items include morphology, physiology and anatomy of observed parameters. Waterlogging tolerance of new material is preliminarily identified and its mechanism is disclosed. The main results were as follows:1. Morphological identification results showed that:After the flooding, symptom’s appearance in two material includes blade withered, plants growth slow, leaf area reducing, root growth slower, but differed on the degree of influence and the time. In this experiment, we observed the number ofgreen leaf, plant height, leaf area. Experimental results showed that both material in flooding experiments have shown growth inhibition, the general trend proximity,and the inbred 08-641 submergence was influenced greatly and was inhibited on the earlier time. After scanning of root, we analyzed the root system of the total length, surface area, volume and number of tips. The results showed that the trend of the first three indicators of the performance of the two materials is consistent. The trend in the fisrt increased and then decreased, and finally increased again.The overall growth rate of new materials was significantly greater than the parental inbred lines 08-641.2. Their Physiological index analysis results showed that: After flood, new materials indicators showed strong adaptability and high vitality in physiological. This study measured chlorophyll content, plant dry weight and shoot soluble sugar content in 14 days after flooding. The results showed that both of the chlorophyll content and soluble sugar content of the ground are on the decline, in which the inbred 08-641 decreased greatly. On the dry weight, both of the two materials have shown an upward trend overall, but the growth rate of new materials is greater than inbred 08-641. Studies have shown that inbred 08-641 was more sensitive to waterlogging environment affected greatly.3. Root anatomy study found: The development of new materials aerenchyma formation and impermeable layers, have shown to generate faster and more complete degree of development. By root slice observation, we found that the site of roots aerenchyma is initially produced from the roots at the apical 3-5cm, extended over time to the ends. Aerenchyma of inbred 08-641 formed slowly, began to produce in 3d and formed a relatively complete aerenchyma in 10d. In the first day after the flood, aerenchyma of new materials roduce a small amount, and form a complete aerenchyma in 3d. In the impermeable layer, the experimental materials exhibit consistent changes, in which the impermeable layer of 08-641 maize inbred development slower and thinner. It can be seen the performance of the reaction speed and control ability of waterlogging stress, new materials was stronger than inbred -8-641.In summary, maize inbred lines 08-641 and new synthetic materials were identified in many aspects, it found that the latter’s performance equal to or better than the former, that the new materials have excellent resistance waterlogging. |
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