Studies On Mechanism Of Physiology And Biochemistry And Resistance Responses Of Different Rice Varieties To Nilaparvata Lugen(St(?)l)

Nilaparvata lugen(st(?)l) is the main pest which has serious damage to rice plants. Practice proves that pest resistance breeding of rice is one of the most effective comprehensive solution to prevent Nilaparvata lugen(st(?)l).This paper aims to study the resistance mechanism of rice to Nilapavata lugens(st(?)l).It is a significant work to pest resistance breeding of rice in theory and practice.The resistances of 8 rice varieties which were R998,Xiangyazhan,27H328, 27H333,Xiang 187,of Xiangwanxian 1,IR36 and IR64,to Nilaparvata lugens (st(?)l)were identified in this experiment.Then some physiological and biochemical indexes of different resistance rice varieties before and after stresses of Nilaparvata lugens(st(?)l) were measured to explain resistance mechanism of rice to Nilapavata lugens(st(?)l).The main conclusions were summarized as follows:1.The resistance varieties of rice to Nilaparvata lugens(st(?)l) were identified by means of field investigation and population seedling appraisal of rice plants.The results were as follows:R998,Xiangyazhan,27H328,27H333 were susceptible varieties,while Xiang 187,Xiangwanxian 1,IR36,IR64 were resistant varieties.2.The total soluble sugar contents in the sheath of all rice varieties at seedling stages of 30d,45d,60d in this experiment decreased after the infestation of Nilaparvata lugens(st(?)l).This could be the defense responses of the rice plant to Nilaparvata lugens(st(?)l).It made soluble sugar convert to secondary metabolite that lowed palatability and prevented the infestation of Nilaparvata lugens(st(?)l).3.The total nitrogen contents in the sheath of all resistant varieties decreased while susceptible varieties increased after the infestation of Nilaparvata lugens(st(?)l). The results showed that nitrogen was necessary nutrient to Nilaparvata lugen(st(?)l), and lower nitrogen content in the sheath of rice inhibited the infestation of Nilaparvata lugens(st(?)l).4.The free amino acid contents in the sheath of all rice varieties at seedling stages decreased after the infestation of Nilaparvata lugens(st(?)l),which could be an important factor that made the rice plant avoid damage from Nilaparvata lugens(st(?)l).5.After the infestation of Nilaparvata lugens(st(?)l),the activity of SOD increased in both resistant and susceptible varieties,the activity of POD decreased in resistant varieties and increased in susceptible varieties,the activity of CAT increased in resistant varieties and decreased greatly in susceptible varieties.The result showed that both resistant and susceptible varieties have strong ability to scavenge superoxide anion radical,however resistant varieties have stronger enzymatic antioxidant function than susceptible varieties,which suggested that the resistant varieties have stronger adapting ability under stresses of Nilaparvata lugens(st(?)l).