Phenotyping of Partial Physiological Resistance to Rice Sheath Blight uri icon

abstract

  • Sheath blight, caused by Rhizoctonia solani, is one of the most important rice diseases worldwide especially under irrigated agro-ecosystems. To date, no rice accession with complete resistance to sheath blight has been reported. However, a number of genotypes with varying levels of resistance have been reported. Twelve genotypes (including mega varieties) viz. Tetep, Jasmine 85, Te-Qing, Duduruchi, Betichikon, Khatochalani, D-6766, D-256, Swarna, Sarju-52, MTU-1010 and Samba Mashuri were evaluated for quantitative measurement of partial physiological resistance to sheath blight under controlled conditions using detached tiller method. Three independent experiments, each involving three replications, were conducted. Seven days after inoculation, the following disease variables were measured: number of lesions, lesion length, vertical sheath colonization (VSC) on the tiller, disease severity, relative vertical sheath colonization (RVSC) and survival of the leaf blade. Variation between rice genotypes was observed for all the disease variables. Disease severity and VSC were the two most correlated variables, whereas the number of lesions and mean lesion length were the least correlated variables. The ranking of varieties often differed depending on the disease variable considered. Amongst the genotypes tested, D-256, Tetep and Jasmin-85 had the lowest number of lesions and disease severity. Similarly, Tetep and D-256 showed the lowest levels of RVSC, whilst Jasmine-85 was found to be intermediate. D-6766, Samba Mashuri and Betichikon showed the highest levels of disease variables. The fraction of dead leaves ranged from 0.00 to 0.38. No dead leaves were observed in Te-Qing, Swarna and MTU-1010. The highest fraction of dead leaves was observed for Betichikon (0.38) followed by Duduruchi and D-6766 (0.33). Our results suggest that this method in combination with other phenotyping methods could be used to quantify partial resistance to rice sheath blight.

publication date

  • 2013
  • 2013