Morphological And Physiological Responses Of Roots Of Maize Genotypes With Different Nitrogen Efficiencies To Phosphorus And Iron Deficiency

Under nutrient deficiency,the changes of root morphology and physiology play an important role in the acquisition of nutrient resources.It is important to reveal the response of different genotypes of maize roots to low iron and phosphorus stress and to explore the changes of maize under the interaction of phosphorus and iron are of great significance to the study of phosphorus and iron nutrition in maize.In this thesis,the response of root morphology and nutrient uptake of two different genotypes of maize(ZD958 and XY335)to low iron,low phosphorus stress and coupling of iron and phosphorus were studied by nutrient solution culture experiment,and the relationship between root morphology and nutrient uptake of maize and the acquisition strategy of iron and phosphorus resources were explored.The main results are as follows:1.Regardless of the phosphorus supply,ZD958 has greater phosphorus uptake than XY335.There is no difference in root dry weight between ZD958 and XY335 under low phosphorus.ZD958 has larger seedling dry weight than XY335,while ZD958 has larger seedling dry weight and smaller root dry weight than XY335 under high phosphorus treatment.There was no significant difference in total root length,root surface area,average root diameter and root hairs length between the two genotypes under low phosphorus stress.ZD958 had larger average root diameter and smaller total root length and root surface area than XY335 under high phosphorus stress.There was no significant difference in root hairs between the two genotypes.The results showed that ZD958 had higher citric acid than XY335 under low phosphorus stress and high phosphorus treatment.Malic acid and acid phosphatase had no difference.The phosphorus uptake rate of ZD958 was significantly higher than that of XY335 when the phosphorus concentration was between 12.5 and 250 μM.Therefore,it was considered that two different nitrogen efficiency Genotypes Maize adapted to low phosphorus stress mainly by changing root physiology,and ZD958 is a phosphorus efficient genotype of maize.2.Under low iron stress,ZD958 had higher iron accumulation than XY335,and had the same performance under high iron stress;under low iron stress,it significantly reduced the dry weight of seedlings and roots of two nitrogen-efficient genotypes of maize,and at the same iron concentration,ZD958 had larger dry weight of seedlings and roots than XY335;At the same time,the results showed that under low iron stress,the total root of two maize varieties had greater dry weight than XY335.There was no difference in root length,but ZD958 had larger root surface area,average root diameter and root volume than XY335,and had the same performance under high iron treatment,and ZD958 had larger total root length than XY335.At the same time,it was found that ZD958 had higher iron uptake rate than XY335 when iron concentration was between 12.5 and 200 micrometers.Therefore,this experiment considered that two different nitrogen efficiency genotypes of maize adapted to low iron stress through the interaction of root morphology and physiology,and ZD958 was an iron efficiency genotype of maize.3.Based on the study of low nitrogen and low iron in different nitrogen efficiency genotypes of maize,hydroponic experiments were carried out to study the biomass accumulation and root system of maize under the coupling of iron and phosphorus with ZD 958(phosphorus efficient and iron efficient).Morphology and nutrient absorption change.The results showed that under the condition of phosphorus-iron coupling,the dry weight,root dry weight,total root length,root volume and root surface area increased significantly with the increase of iron concentration.In contrast,the average root diameter was The increase in iron concentration has a tendency to decline.The aboveground part of maize is more affected by low phosphorus stress,and the root is affected by high phosphorus.From the root to medium ratio,corn has obvious advantages under the condition of low phosphorus stress under high phosphorus condition.Phosphorus-iron coupling has a significant effect on the relative chlorophyll content and nutrient uptake of maize.This study found that the absorption of iron by corn was inhibited under high phosphorus conditions.It can be seen that phosphorus and iron interact with the growth of maize roots and the absorption of nutrients.