| In this paper,we simulated Low light and Waterlogging stress treatment at the flowering stage of maize,Zheng Dan 958 and Xun Dan 20 were used as experimental materials grown in field pot culture.The days of stress treatment were 3d,6d and 9d,respectively.The effects of different stresses and lasting days on carbon and nitrogen metabolism of maize were explored,the main research results were as follows:1.Effects of Low light and Waterlogging stress on growth and development of maizeThe plant height and spike height of W,S and WS increased by 8.3%,15.7%,19.2%,5.7%,9.8% and 9.0%,respectively,compared with CK.With the extension of stress time,the effect on plant height and spike height was more obvious.The stress reduced the accumulation of dry matter in maize,and the changes in each treatment were manifested as CK>W>S>WS,W,S and WS decreased by 7.2%,9.9% and 13.5% respectively compared with CK.The longer the stress treatment time,the slower the growth rate of dry matter.When 9d was treated,the difference of dry matter between treatments was the largest,W,S and WS were reduced by 5.5%,12.2% and 14.8% respectively compared with CK.Stress affected dry matter accumulation and distribution of stem,leaf and ear,increased matter accumulation and distribution of stem and leaf decreased matter accumulation and distribution in fruit ear.With the extension of stress time,there were significant differences in dry matter accumulation among stems,leaves and ears.At the stress treatment 3d,6d and9 d,and at the mature stage,WS was 14.8%,40.2%,and 57.4% higher than CK,respectively,while the fruit ear was 18.4%,31.4%,and 45.9% lower.Moreover,with the increase of treatment days,the difference in distribution proportion increased.The effect of Low light and Waterlogging combined stress on the growth and development of Zheng Dan 958 was greater than that of Xun Dan 20.2.Effects of Low light and Waterlogging stress on carbon metabolism of maizeUnder the stress of Low light and Waterlogging,the chlorophyll content in leaves decreased,and the variation trend between treatments was WS<S<W<CK.Among them,W,S and WS were 4.2%,7.2%,9.0%(chlorophyll a),6.1%,11.6%,17.2%(chlorophyll b),5.0%,8.5%,and 12.0%(chlorophyll)lower than CK,respectively.With the extension of stress time,the content of chlorophyll a continued to decrease,and the content of chlorophyll b and the total chlorophyll content first decreased and then increased.Low light and Waterlogging stress reduced the activity of photo synthase Ru BP carboxylase,PEP carboxylase,and SPS.Among them,the enzyme activities of WS,W,and S were 16.0%,18.3%,26.6%(Ru BP carboxylase),16.0%,19.6%,25.2%(PEP carboxylase),6.9%,8.1%,and 16.2%(SPS enzyme),respectively.With the extension of stress time,the enzyme activity decreased by a larger extent.Among them,the enzyme activity of WS treated with 3d stress was 16.9%,12.3% and 13.1% lower than that of CK,and the enzyme activity of WS treated with 9d stress was 36.7%,38.1% and 19.0% lower than that of CK.Low light and Waterlogging stress inhibited the accumulation of soluble sugar content in plants,and the soluble sugar content between treatments was WS<S<W<CK,and the soluble sugar content of W,S and WS was reduced by 10.1%,9.4% and 15.8%,respectively.With the extension of stress time,the decrease of soluble sugar content increased.In tasseling stage,stress treatment on 3d,6d and 9d decreased by 5.9%,14.4% and 21.8%,respectively.The contents of soluble sugar in the stems of W,S and WS were increased by 65.0%,98.5% and 139.0% than those of CK in the mature stage,and the contents of soluble sugar in the seeds of W,S and WS were decreased by 28.7%,30.7% and 48.3% than those of CK in the mature stage.Under the low light and Waterlogging combined stress,the carbon metabolism of Zheng Dan 958 was more obvious than that of Xun Dan 20.3.Effects of Low light and Waterlogging stress on nitrogen metabolism of maizeUnder the stress of Low light and Waterlogging,the NR enzyme activity and soluble protein content in leaves decreased,and the change trend between treatments was CK>W>S>WS,W,S and WS decreased by 19.2%,16.4%,33.6%(NR enzyme activity),21.6%,22.4%,34.3%(soluble protein content),respectively compared with CK.The decrease of NR enzyme activity and soluble protein increased with the extension of stress time,and the decrease of enzyme activity and soluble protein was13.5%,31.9%,16.5% and 36.5%,respectively,at 3d and 9d stress.Low light and Waterlogging stress reduced the nitrogen content of maize plants,W,S and WS were 23.4%,6.2% and 25.7% lower than CK nitrogen content,respectively.With the extension of stress time,the nitrogen content of plants decreased by 10.6% and 21.4%,respectively,in the tasseling stage.Low light and Waterlogging stress had different effects on nitrogen contents of different organs.The nitrogen contents of stems and seeds of W,S and WS were reduced by 10.7%,-30.2%,4.5%,34.5%,26.0% and 44.6%,respectively,compared with those of CK.With the increase of stress degree,the nitrogen content of stem increased gradually,the nitrogen content of grain decreased gradually,and the nitrogen content of leaf and ear changed little.The effect of Zheng Dan 958 on nitrogen metabolism under low light and Waterlogging combined stress was greater than that of Xun Dan 20.4.Effects of Low light and Waterlogging stress on maize antioxidant enzymesUnder the stress of Low light and Waterlogging,the antioxidant enzyme system of maize plants was destroyed,and the activities of antioxidant enzymes SOD,POD and CAT in panicle leaves were decreased.W,S and WS decreased by 22.4%,23.0%,40.7%(SOD),18.5%,20.1%,27.7%(POD),14.9%,16.9%,and 30.3%(CAT),respectively,compared with CK.The accumulation of antioxidant enzyme products MDA and H2O2 increased by 11.0%,15.1%,30.1%(MDA),2.6%,7.0%,and 11.2%(H2O2),respectively,compared with CK.SOD,POD,CAT,MDA and H2O2 decreased by 20.1%,11.7%,14.4%,-13.0% and 1.3% respectively under 3d stress.SOD,POD,CAT,MDA and H2O2 decreased by 31.0%,35.6%,27.4%,-24.3% and-15.5% respectively under 9d stress.stress can resist oxidase system damage and accelerate leaf senescence.The degree of antioxidant enzymes in leaves of Zheng Dan958 was significantly higher than that of Xun Dan20.5.Effects of Low light and Waterlogging stress on C/N ratio and yield of maize seedsThe C/N ratio of grain was significantly changed and the yield of maize was decreased under Low light Waterlogging stress.Under the stress of W and WS,the C/N RATIO of seeds increased significantly,S reduced the C/N ratio of maize seeds,and 6d stress,the difference of each treatment reached the maximum,the C/N ratio of each treatment of Zheng Dan 958 showed as W>WS>CK>S,W,S and WS increased by 25%,-5.46% and 9.45%,respectively,than that of CK.Under the stress of Low light and Waterlogging,the ear length of maize becomes shorter,the ear thickness becomes fine,the row grain number decreases,the ear grain number decreases,and the 100-grain weight increases,finally resulting in the decline of maize grain yield.The yield per plant of W,S,and WS decreased by 20.0%,30.2%,and 45.2%,respectively,compared with CK.With the extension of stress time,the yield decreased more.At stress 9d,W,S and WS reduced by 31.9%,42.9% and 60.5%,respectively,compared with CK.The effect of Low light and Waterlogging combined stress on the yield of Zheng Dan 958 was significantly higher than that of Xun dan 20.6.Effects of Low light and Waterlogging combined stress on carbon and nitrogen metabolismTreatment of W,S,WS has different degrees of carbon and nitrogen metabolism in maize.W mainly reduces the nitrogen metabolism capacity of maize,reduces the enzyme activity,and the total nitrogen content of the plant;treatment S mainly reduces carbon metabolism,reduces photosynthetic pigment content,photosynthetic enzyme and metabolic enzyme activity,thereby reducing the soluble sugar content of the plant;WS vs.carbon Nitrogen metabolism pathways have caused interference,causing the plant’s carbon and nitrogen metabolism levels to reach a new equilibrium. |
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