| Silage maize is an important source of roughage in animal husbandry.In recent years,under the guidance of the national national policies,the planting area has gradually expanded.However,land salinization in Huang-Huai-hai region is becoming more and more serious,which seriously affects crop growth and development.In this experiment,30 different silage maize varieties were used as test materials to evaluate the adaptability of saline soil and the salt tolerance at germination stage,screen the silage maize varieties with different salt tolerance,analyze the physiological response of silage maize to salt stress,and preliminarily analyze the molecular mechanism of silage maize response to salt stress through transcriptome sequencing.It provides a theoretical basis for breeding salt-tolerant silage maize varieties and development and utilization of salinized land.The main results are as follows:（1）The evaluation of 16 main indexes of silage maize planted in coastal saline land showed that the yield of Yuqing 386 and Yuqing Yu 3 was significantly higher than that of Zhengdan 958.The relative feeding value of Shengrui 999,Dika 625 and Zhengda1473 was higher than that of Zhengdan 958.In addition,the fresh grass yield of silage maize was positively correlated with plant height,leaf length,stem diameter and number of green leaves.The comprehensive evaluation of grey correlation degree shows that Yuqing 386,Dika 625 and Zhengda 1473 have strong adaptability in coastal salt area.（2）The experimental silage maize varieties were subjected to different concentrations of salt stress at germination stage,and the results showed that,salt stress inhibited seed germination,but low concentration of salt stress promoted the growth of some varieties.The germ is more sensitive to salt stress,under salt stress,the length and biomass of the embryo were inhibited more than those of the radicle.With the increase of stress concentration,germination potential,germination rate,seedling biomass and length all showed a decreasing trend.The salt tolerance was evaluated comprehensively by membership function,Zhengda 1473,Jinling silage 377 and Dajingjiu 26 have high salt tolerance.（3）Physiological and ecological responses of silage maize with different salt tolerance to salt stress showed that with the increase of stress concentration,the antioxidant enzyme activities of all varieties showed an upward trend,but the antioxidant enzyme activities of salt-sensitive varieties began to decrease after reaching the salt tolerance threshold,and SOD and POD activities were sensitive to salt-sensitive varieties,while CAT was sensitive to salt-tolerant varieties.The soluble sugar content of salt-tolerant varieties increased gradually with the increase of stress concentration,while the soluble sugar content of salt-sensitive varieties showed a negative increase at200 mmol·L-1stress.（4）The leaves of Jinling silage 377 and Tieyan 53 were subjected to 200 mmo·L-1stress and transcriptome sequencing analysis.3168 DEGs and 5211 DEGs were identified in the two varieties.There were 2061 differentially expressed genes.Most genes were annotated as"catalytic activity","transcription factor activity"and"antioxidant activity"by GO analysis.KEEG pathway annotation showed that the differentially expressed genes were significantly enriched in phenylpropanoid biosynthesis,flavonoid biosynthesis,anthocyanin biosynthesis and other pathways.At the same time,several transcription factors were identified,among which b HLH,WRKY,NAC and MYB transcription factors accounted for a high proportion,indicating that these transcription factors may play a role in the regulation of salt tolerance of silage maize.From the above analysis,it can be seen that Jinling silage 377,Dajing Jiu26 and Zhengda 1473 have stronger salt tolerance and are more suitable for planting in saline land,further expanding the planting scale of silage maize. |
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