THE CONCEPT OF FIELD TOLERANCE AND ITS RELEVANCE IN SCREENING FOR RED ROT OF SUGARCANE

Abstract

In sugarcane crop improvement programmes, screening for red rot resistance using the plug and nodal methods of inoculation results in the rejection of several high yielding and high quality genotypes for want of resistance, causing a severe constraint in the availability of suitable cultivars for improving productivity of the crop. However, some cultivars rated as susceptible by these methods are observed to show very low natural incidence of red rot even under endemic conditions suggesting their field tolerance to the disease. Studies have been carried out to develop suitable methodologies to screen for such field tolerance by inoculating field planted setts with the red rot pathogen multiplied on a  suitable substrate simulating debris borne primary infection under field conditions. Results have indicated the potential to identify such field tolerant genotypes using certain  standardized inoculation and evaluation procedures. Also, the possibility of identifying superior commercial clones or genetic stocks with field tolerance to red rot from the early seedling stage in the selection process has been indicated. Systematic use of the techniques, after some fine tuning, is expected to make available more superior cane cultivars for deployment in red rot endemic areas to substantially improve the productivity of the crop.