Indoleacetic acid(IAA)is an important regulator that plays a crucial role in plant growth and responses to abiotic stresses.In the present study,a sand cultivation experiment was carried out to investigate the effects of IAA at different concentrations(0,0.01,0.1,0.5,1,and 2.5 mmol/L)on maize growth,root morphology,mineral elements(Ca,Mg)and Cd uptake under 20 mg/kg Cd stress.The results showed that 0.01 mmol/L is the optimal IAA concentration for enhancing the Cd tolerance of maize.Compared with the control treatment,0.01 mmol/L IAA promoted maize growth,with significant increases in the height,shoot and root biomass by 34.6%,25.0%and 16.3%;altered the root morphology,with increases in root length,root tip number,and root tip density by 8.9%,31.4%and 20.7%,respectively;and enhanced the mineral element uptake of maize,resulting in signifi-cant increases in the Ca content in shoots and roots by 640.6%and 1036.4%and in the Mg content in shoots by 205.8%,respectively.In addition,0.01 mmol/L IAA decreased the Cd content and uptake in the shoots by 51.9%and 39.6%,respectively.Furthermore,the Cd content and uptake exhibited a significant negative correlation with Ca content in roots and a significantly positive correlation with root morphology,and the Cd content in shoots was significantly and negatively correlated with root tip number.Thus,0.01 mmol/L IAA was effective in enhancing the Cd tolerance and plant growth of maize.
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