Study On The Resistant Performance And Its Mechanisms Of The Near-isogenic Lines Of Rice With Resistance To The Whitebacked Planthopper, Sogatella Furcifera (homoptera: Delphacidae)

The whitebacked planthopper, Sogatella furcjfera, is one of the most important insect pests of rice. Recently, the study and utilization of resistant rice varieties are getting more and more important in the integrated management of S. furc/era. The understanding of its resistant mechanisms will definitely enhance and fascinate the breeding for rice resistant to S. furczfera. In the present study, the major agronomtc characters and resistant performance of hefu 802 kangnear-isogenic lines of rice with resistance to S. furcjfera) were comparatively observed and its resistant mechanisms were studied further. Rathu Heenati (RHT) and Taichung Native (TN 1) were used as resistant and susceptible check, respectively. OBSERVATION OF MAJOR AGRONOMIC CHARACTERS There is not significant difference in plant height, total leaf number, number of tillerings, heading date and number of effective panicles between hefu 802 kangand Zhefu 802. However, there still exits the obvious difference in grain number per panicle, effective grains per panicle, percentage of seed-setting and 1 000-grain weight. RAPD ANALYSIS In 100 random primers screened by RAPD analysis, one of them amplified polymorphic DNA products between the pair of near-isogenic lines. The polymorphic fragment at 0.43kb amplified with the primer S30 could be found in hefu 802 kang(NIL) and RHT (resistant donor), none for Zhefu 802 (recurrent parent) and TN1 (susceptible), possibly linked to the resistant gene. STUDY ON THE RESISTANT MECHANISMS. The results from both mass screemng test and individual seedling test revealed that the resistant level of hefu 802 kangto S.furcjfera was close to RHT?s. Zhefu8O2 and TN 1 were very susceptible. The orientational response of S. furcjfera to the test materials in paddy field indicated that both adults and nymphs on RHT and hefu 802 kangwere low, showing remarkable resistance. In contrast, on Zhefu8O2 and TN1 the number of adults and their offspring was obviously higher, indicating that they were very susceptible and resulting in hopperburn in a paddy field. The number of adults and nymphs on the susceptible and resistant rice materials had no significant difference at 4h after infestation of S. furcjfera on rice seedlings of 20, 40 and 60 day. At 24h after infestation, adults on hefu 802 kangwas significantly lower than that on Zhefu 802. Measurement of honeydew excreted by S.furcjfera demonstrated that RHT and hefu 802 kangpossessed feeding inhibition property and none for Zhefu8O2 and TN 1. S. furcjfera laid more eggs and had highest percentage of nymph hatching on TN 1, least and high on RHT, and no difference between hefu 802 kangand Zhefu8O2. Therefore, it may assume that the expressional products from resistant gene perhaps inhibited insect feeding and had no influence on egg-laying and hatching rate of nymphs. ANALYSIS OF RICE VOLATILES There were remarkable difference in volatile components among the tested rice materials, not only in number and amount of volatiles but also in ratio of components. hefu 802 kanghad largest number of valotiles, following by RHT, TN1 and Zhefu8O2. Heneicosane and Heptacosane could only be found in the volatile components of RHT and hefu 802 kang?, not in Zhefu8O2 and TN1, and may be related to varietal resistance to S. furcfera.