| Spring rape is one of the main oil crops in Inner Mongolia area.Phyllotreta humilis is one of the most important pests in rape seedling period,and the rape is endangered seriously in the seedling of rape by this pest.They are the keys to improve the yield of rape that.humilis should be controlled effectually and the survival rate of seedlings may be improved.Silicon is a beneficial element that plays an important role in improving resistance to abiotic and biotic stresses in plant.Plant resistance can be affected by insect feeding and mechanical damage also.This paper mainly studied the effects of silicon fertilizer,P.humilis feeding and mechanical damage on growth and resistance to pest of rape seedling.The results were as follows:1.Effect of different Silicon fertilizer application rates Dahuang rape.(1)Effect on growth and victimization of Dahuang rape.The growth of rapeseed was affected mostly when silicon fertilizer of 75.0kg/hm2 was applied.The plant height,fresh weight and dry matter accumulation of seedlings were higher than those of other fertilizers.The yield of rapeseed was 2004.67kg/hm2,which was significantly different from that of non-silicon fertilizer(1733.33kg/hm2),and it was the highest among these different treatments(P<0.05).On the other hand,the application of silicon fertilizer reduced the insect population density of P.humilis,and insect population density was the lowest in 75.0kg/hm2 of silicon fertilizer.The damage index of the leaves also showed the same trend.(2)Effect on the nutrient contents.Compared with the control,silicon fertilizer could increase the nutrient content of rape leaves.When the amount of fertilizer was 75.0kg/hm2,the nutrient contents of rape leaves were the highest,the soluble protein content was 12.26mg/g,the soluble sugar content was 9.97mg/g,and the chlorophyll content was 0.97mg/g,which was different from the control significantly(P<0.05).(3)Effect on activities of defensive enzymes.The activities of four defense enzymes in rapeseed seedlings were increased with the increasing of application of three different silicon fertilizers.The activities of SOD,POD,PPO and PAL were higher than those of control in rapeseed leaves when the application rate of silicon fertilizer was 75.0kg/hm2(P<0.05).There was no significant difference between the other two treatments of silicon fertilizer.2.Effect of feeding and mechanical damage on Dahuang rape.(1)Effect on the nutrient contents.The content of soluble protein,soluble sugar and chlorophyll in the leaves of Dahuang rape decreased with the feeding of P.humilis and mechanical damage.The greater the damage degree of leaves,the greater the decrease extent of nutrients content,which was different from the control significantly(P<0.05).(2)Effect on activities of defense enzymes.Compared with the control,the activities of four defensive enzymes increased after feeding and mechanical damage.The activities of SOD,POD,PPO and PAL were higher than those of the control significantly when the grade of damage was 3 or the mechanical damage was severe(P<0.05).3.Effect of severe mechanical damage on leaves of Dahuang rape.(1)Effect on the nutrient content.The contents of nutrients and chlorophyll in rape leaves decreased to the lowest level at 12h or 24h,the contents increased after severe mechanical damage.Overall,the nutrient contents of damaged leaves recovered at 120h,and there was no significant difference from the control.(2)Effect on activities of defense enzymes.The activities of SOD,POD,PPO and PAL were induced to increasing after severe mechanical damage.POD activity of Dahuang rape was induced most obviously,which increased by 66%compared with the control at 12h. |
PDF Full Text Request