Correlation Analysis of Physical and Chemical Characteristics with Resistance to Sorghum Aphid(Melanaphis sacchari) in Different Sorghum Genotypes

Several sorghum strains including HN-16,F1 hybrids with resistance to aphid and some lines susceptible to aphid were employed in this experiment to study the mechanism of the aphid resistance through anatomy,biophysical and biochemistry analysis.It was observed that the leaf epidermic cell was ordered more tightly and regularly,the cell size was smaller,the leaf color was lighter,and the leaf was thinner in the resistance strains than that in susceptible ones.The comparative analysis of physiology and biochemistry revealed that PPO and POD enzyme activity expressed at high level in every sorghum strain after infected by aphid,but there was no obvious different between resistance and susceptible sorghum.The PAL enzyme activity was different between resistance and susceptible materials;it was higher in all resistance materials than that of susceptible ones before aphid infected.The activity expressed at high level after induced by aphid,but the change in the resistance materials was not obvious.The increase of PAL enzyme activity was corresponding with degree of hurt.The content of soluble sugar and amino-acid after aphid infected was related to the aphid invasion,but the amino-acid content had nothing with resistance of different sorghum before and after aphid infection.The content of soluble sugar before aphid invasion was different between resistant and susceptible materials,its content of the resistance sorghum strains was higher than that of susceptible materials and the increase after aphid infected in susceptible materials was obvious.