Effects Of Low Temperature Stress On The Growth And Development Of Maize Seedlings

Maize is an important food crop in China,which is of great significance to national food security.Maize is a warm-loving,short-day C₄ crop,which has high temperature requirements during the growth period and is susceptible to low temperature and chilling damage,which seriously affects its yield and quality.The sowing time of spring maize is generally from late March to early April in Hunan province.At this time,it is the low temperature and rainy season in early spring,and the phenomenon of“cold in spring”occuers frequently,which has an impact on the maize yields.Low temperature in early spring has also become the main limiting factor for spring maize production in Hunan province.In order to study the effects of low temperature stress on the growth and development of spring maize seedlings in Hunan province,four maize cultivars Zhengdan958,Zhengda 999,Yudan 9953 and Lishou 1 were used as materials in this paper,and four temperatures t10℃,15℃,20℃and 25℃t were set to carry out seed germination and low temperature stress experiments on maize seedlings,to study the effects of low temperature stress on maize seed germination and seedling growth and development.This will provide theoretical basis for the sowing of spring maize in Hunan and the selection of cold-resistant,and to provide theoretical basis for maize Safety production.The main experimental results are as follows:1.Effects of low temperature stress on seed germination of maizeUnder low temperature stress,the germination potential and germination rate of four maize cultivars increased with the increase of temperature,and there were obvious differences among different cultivars.The average germination potential at 20℃is 69%and47%higher on average than those at 10℃and 15℃,and the average germination potential at25℃i s 80%and 58%higher than those at 10℃and 15℃.The germination rate at 20℃was52%and 26%higher than those at 10℃and 15℃on average,and 56%and 30%higher than that at 25℃and 15℃.Except at 25℃,the germination potential and germination rate of Lishou 1 were significantly different from those of Yudan 9953 and Zhengda 999.2.Effects of low temperature stress on growth and root activity of maize seedlingsUnder low temperature stress,the fresh weight of aboveground part,fresh weight of underground part and plant height for the four maize varieties increased with the increase of temperature,and increased as a whole with the extension of stress time.When the stress time was 12 days,the fresh weight of aboveground part at 10℃was 17.9%-28.0%,14.6%-27.0%and 8.3%-20.0%higher than that at 15℃,20℃and 25℃,the fresh weight of underground part was 19.6%-22.5%,11.6%-20.8%and 9.8%-14.8%,and the plant height was 12.0%-16.6%,5.4%-11.1%and 2.0%-7.6%,respectively.The lower the temperature,the greater the change range.The root activity of maize seedlings increased with the increase of temperature,and with the extension of low temperature stress time,the root activity decreased at 10℃and 15℃,and increased at 20℃and 25℃.3.Effects of low temperature stress on plasma membrane permeability and osmotic regulatory substances in maize seedlingsUnder low temperature stress,the MDA content in maize seedling leaves increased with the extension of stress time,while the content of relative conductivity,soluble protein and soluble sugar increased first and then decreased.When the stress time was 9 days,the relative conductivity of maize seedling leaves at 10℃,15℃and 20℃increased by 33.0%-75.2%,12.3%-64.1%and 10.2%-43.2%,respectively,compared with 25℃c The soluble sugar content increased by 22.2%-43.7%,13.5%-32.9%and 3.9%-21.7%,respectively.The overall changes range of soluble protein and soluble sugar content in leaves of Yudan 9953seedings were smaller than those of other cultivars.4.Effects of low temperature stress on activity of antioxidant enzymes in maize seedlingsUnder low temperature stress,with the extension of time,SOD and CAT activities increased first and then decreased,while POD activity decreased first and then increased.When the low temperature stress time was 6 days,compared with 25℃,SOD activity of maize seedling leaves at 10℃,15℃and 20℃increased by 2.7%-33.8%,11.4%-47.3%and2.8%-39.2%,respectivelyc and CAT activity increased by 36.9%-85.3%,34.9%-64.8%and19.3%-34.2%,respectivelyc While POD activity decreased by 4.9%-9.9%,0.7%-89.3%and0.3%-21.1%,respectively.Under 10℃treatment,the SOD,CAT and POD activities of Yudan 9953 were lower than those of other cultivars,indicating that Yudan 9953 had strong stress resistance.5.Correlation analysis of physiological and biochemical indexes of maize seedlings under low temperature stressThere was a extremely significant positive correlation between temperature and root activity and POD activity of maize seedings tr=0.628,r=0.352t,and a extremely significant negative correlation with relative conductivity and soluble sugar tr=-0.578,r=-0.41t.Except for soluble protein,there was a significant or extremely significant t P<0.01 or P<0.05t correlation between stress time and other physiological and biochemical indexes.There were significant or extremely significant t P<0.01 or P<0.05t correlations among various physiological and biochemical indexes.