STUDIES ON IDENTIFICATION OF NEW SOURCES OF RESISTANCE AGAINST GALL MIDGE, Orseolia oryzae, IN RICE
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Date
2019
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Acharya N G Ranga Agricultural University, Guntur
Abstract
The present work on “Studies on identification of new sources of resistance against gall midge, Orseolia oryzae in rice” was carried out at Agricultural Research Station, Nellore, ANGRAU and Agricultural Research Station, Ragolu, ANGRAU during 2015-17.
A total of 105 accessions were used to evaluate resistance against O. oryzae. The resistant check, Kavya (5.00%) recorded lowest per cent plant damage followed by RGL-1 (6.50) during kharif, 2015 at ARS Nellore at 50 DAT.
From the results of the field experiments (2015-17) at ARS, Ragolu, it was evident that the genotypes RGL 7002 (7.37%), RGL 7003 (7.19%), RGL 7009 (5.83%) and RGL 7010 (6.35%) recorded less than 10 per cent plant damage and were considered for genotyping.
The selected entries were phenotyped under laboratory conditions and the genotypes showed neither positive nor negative hypersensitive reaction in the genotypes RGL 1, RGL 7002, RGL 7003, RGL 7009 and RGL 7010. The selected entries were studied for the presence of reported gene specific SSR markers, it was found that RGL 7003 has the alleles for the genes Gm1 and Gm8. The entry, RGL 1 amplified with Gm8 gene and RGL 7002 with Gm1. All these three entries can be used as potential donors in breeding trials.
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Studies were also carried to find out the existence of gall midge biotype at Nellore by screening of differentials (17) supplied by IIRR, Hyderabad. Conclusive results could not be drawn from the data recorded at ARS, Nellore regarding the identification of the biotype, due to the low pest incidence at the site of experimentation. However, the data recorded based on the reaction pattern at Salmanpuram of Nellore district, revealed that the biotype identified might be biotype VI with no damage in Kavya, W 1263 and ARC 6605 of group I, ARC 5984, Madhuri L9 and BG-380-2 of group II, Aganni and B 95-1 of group IV and the per cent similarity index value of Nellore biotype was 70.1 per cent.
The gall midge population at ARS, Nellore was heterogeneous. The population was less virulent on the differential W1263 and more virulent on Purple (susceptible check), followed by Aganni and RP 2068-18-3-5.
Studies on the genetic diversity of gall midge population across Andhra Pradesh and Telangana revealed that gall midge population in Chittoor showed a closer genetic relation with the gall midge population from Nellore with a similarity coefficient of 0.75 while, the populations from Warangal was placed in second cluster through the dendrogram based on UPGMA. The population from Jagtial was placed in separate cluster indicating that it is distantly related to the gall midge populations in other two clusters.
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D5850
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