Screening of rice cultivars for resistance to sheath rot (Sarocladium oryzae)

Abstract

Rice sheath rot has become a highly destructive rice disease with a high variability in yield loss levels varying from 20 to 85%. It is caused by many pathogenic agents varying depending on the area, grown varieties, prevailing environmental conditions, the farming system, other pests, etc. Therefore, sheath rot disease can be effectively managed through crop improvement strategies viz., discovery of resistance sources from varieties, germplasm, landraces, wild genetic resources and further deploying them in breeding programmes. In this study, the level of resistance to sheath rot in 43 rice germplasm accessions were screened and the results were grouped using Darwin 6.0 statistical package from dissimilarity analysis. The percent disease index (PDI) was calculated and varietal reactions were presented. Out of 43 lines screened against sheath rot, six entries viz., Gowri, NLR 3449, Navara, Soorakkuruvai, Keralakandasala, krishnahemavathi were categorised as moderately resistant. Most of the lines and varieties viz., JGL 348, Abhya, LFR293, MDU5, Kalinga, Annada, Kodaikannan, TP-100008, TP-10106, Kuruvaikalanjium, Kalyani, Maranella, Seeragasamba, Thondi, Kavara, TPS-4, TPS-5, TP 08053 were found as moderately susceptible. However, the germplasm lines Swarna, Kattanur, Dhalaheera and JGL 3855 have been reported to be resistant to sheath rot. Sixteen germplasm lines viz., Bharathi, Uma, CO 39, Neikuruvai, CO 50, Rajalakshmi, Karsamba, JGL 1798, CO 51, BPT 5204, Virendra, JGL 1798, CO 51, BPT 5204 and Aman were designated as susceptible and three germplasm lines viz., Athira, Malampunchan, Adukan were found as highly susceptible. None of the entry in the present study was recorded as immune. The present investigation revealed that the resistant and moderately resistant genotypes viz., Swarna, Kattanur, Dhalaheera, JGL 3855, Gowri, NLR3449, Navara, Soorakuruvai, Keralakandasala, and Krishnahemavathi can be utilised in resistant breeding programmes for the development of sheath rot resistant lines in rice.

Keywords

• Rice sheath rot
• Sarocladium oryzae
• rice cultivars
• Percent disease Index