Germplasm Identification And Physiological Mechanism Analysis Of Fresh Edible Maize Inbred Line Under Waterlogging Stress At Seedling Stage

Fresh corn refers to a type of special-purpose corn that is harvested during the milk maturity period and eaten with its fresh and tender ears just like vegetables and fruits.In recent years,with the improvement of people’s living standards and the increasing demand for food types,fresh corn has become more and more popular among consumers.The production of fresh corn is easily restricted by water stress,and the cultivation of water-tolerant varieties has become an important task for breeders.The contents of this experiment are as follows:1.Use fresh corn inbred lines to carry out flooding test at seedling stage.The test treatment starts from the two-leaf and one-heart stage,and the treatment time is 7 days.The test results showed that the average plant height difference between the control group and the treatment group after flooding was7.10 cm,and the results of variance analysis showed that there was a significant difference in plant height between the control group and the treatment group after the flooding treatment.After flooding,the difference between the control group and the treatment group in the dry weight of the above-ground part was 0.0554 g,and the underground part was 0.0311 g in the mean dry weight.The analysis of variance showed that the dry weight of the above-ground part and the underground part after the flooding treatment were between the control group and the treatment group.Significant difference between.20water-tolerant germplasm and 20 water-sensitive germplasm were screened using the change rate of plant height and dry weight.2.The selected germplasm was subjected to water flooding treatment,and after the end,photosynthetic indexes such as net photosynthetic rate,intercellular carbon dioxide concentration,stomatal conductance and transpiration rate were measured.The results showed that the net photosynthetic rate of the water-tolerant corn inbred line treatment group decreased by 1.076（?）mol·m^-2·s^-1compared with the control group;the intercellular carbon dioxide concentration treatment group increased by 49.1（?）mol/mol than the control group;the stomatal conductance treatment group Compared with the control group,it reduced by 0.0085（?）mol·m^-2·s^-1;the transpiration rate treatment group was reduced by 0.000322 （?）mol·m^-2·s^-1 compared with the control group.There is a significant difference between the control group and the treatment;the water-sensitive fresh corn inbred line net photosynthetic rate treatment group reduced by 2.8765（?）mol·m^-2·s^-1compared with the control group;the intercellular carbon dioxide concentration treatment group increased by 74.6（?）mol/mol compared with the control group mol^-1;compared with the control group,the stomatal conductance treatment group decreased by 0.0186 （?）mol·m^-2·s^-1;the transpiration rate treatment group decreased by 0.000363 （?）mol·m^-2·s^-1compared with the control group;there was a significant difference between the control group and the treatment group difference.3.The selected germplasm was subjected to water flooding treatment,and physiological indicators such as malondialdehyde,proline,hydrogen peroxide and so on were measured after the end.The results showed that the content of malondialdehyde in the water-resistant inbred line increased by 0.1826（?）mol/L in the treatment group compared with the control group;the content of hydrogen peroxide in the treatment group increased by 9.89 （?）mol/L compared with the control group,and the proline content in the treatment group increased by 9.89 （?）mol/L compared with the control group.Increased by 3.39 （?）g/g;there was no significant difference between the control group and the treatment group in the content of malondialdehyde,the control group and the treatment group had significant differences in hydrogen peroxide,and the proline content was extremely significant;water-sensitive selfing Compared with the control group,the malondialdehyde content treatment group increased by 0.5261（?）mol/L,the hydrogen peroxide content treatment group increased by 16.27 （?）mol/L compared with the control group,and the proline content treatment group increased by 2.37（?）g/g.The content of malondialdehyde between the control group and the treatment group was significant,the content of hydrogen peroxide between the control group and the treatment group was extremely significant,and the content of proline was significantly different.4.It was verified by Real-time PCR that the expression of waterlogging tolerance genes in waterlogging-tolerant maize inbred lines was significantly different;there was no significant difference in the expression of waterlogging tolerance genes in water-sensitive inbred lines.In summary,Flooding stress inhibits the normal growth of maize seedlings,reduces plant height and dry weight,and severely affects photosynthesis;fresh maize inbred line seedlings adapt to flooding stress by changing the content of proline.The content of dialdehyde and hydrogen peroxide can judge the degree of damage to maize by flooding stress;flood tolerance genes adapt to adversity by changing gene expression.The experiment proved the feasibility of screening water-tolerant germplasm and water-sensitive germplasm using plant height change rate and dry weight change rate.