Seed Health Management for Better Productivity - Govind Ballabh ...

(Seed Health Management for Better Productivity)Approaches for Healthy Seed Production in SugarcaneO.K. SinhaIndian Institute of Sugarcane Research, Lucknow- 226 002 (UP)Sugarcane diseases cause about 19 per cent losses in cane productivity. Such diseasesare transmitted through seed cane or air/soil. The economically important diseases like red rot,smut, wilt, ratoon stunting, leaf scald, grassy shoot and mosaic are transmitted through seed cane.Non-seed transmitted diseases like rust, eye spot, yellow spot, pineapple sett rot, etc., becomeoccasionally important. Among seed-transmitted diseases, red rot is a dreaded disease whichleads to cent per cent mortality of plants in an affected area.For healthy seed production in sugarcane, basic requirement is the Nucleus Seed which isfurther multiplied to Breeder Seed, Foundation Seed and Certified Seed. For nucleus seedproduction, variety resistant to red rot and recommended for the region is selected. Moreover,nucleus seed crop may get infected by the pathogens of seed transmitted diseases throughvarious means.For seed production, freedom of seed is absolutely necessary. For this,thermotherapy of seed cane is practised. Thus, varietal resistance and thermotherapy are twoimportant aspects for healthy seed production of sugarcane.i) Varietal resistance: At national level, the sugarcane genotypes are evaluated atmultilocations against red rot, smut and wilt under All India Coordinated Research Project onSugarcane. Of these, red rot is given greater emphasis. A few genotypes like Co 7314 and Co7704 have been identified as a good general combiner sources of resistance to red rot. Severalother genotypes like BO 91 and CoS 767 as well as clones of Saccharum spontaneum are goodsources of red rot resistance. Such resistant donors are being utilized in sugarcane breedingprogramme for development of red rot resistant varieties.Virulence diversity of red rot pathogen (Colletotrichum falcatum) is monitored in the countryevery year. So far, 11 pathotypes of this pathogen have been identified, 11 in sub-tropical and 4 intropical India. For varietal evaluation, regional pathotypes are used for inoculation purpose.Biotechnological tools are also being used for developing disease resistant varieties.However, limited success have been achieved so far. Somaclones resistant to smut, eye spot,downy mildew and rust have been developed. Attempts have been made through in vitro selectionusing pathotoxin of eye spot pathogen. Dual culture of host and pathogen may be useful inevaluation for resistance.Recently, plant defence response genes have been identified and could be utilized indeveloping transgenics resistant to a disease. Although marker assisted selection for diseaseresistance have been successful in some crops, it is yet to be explored in sugarcane.ii)Thermotherapy : It is an important component of healthy seed production as it hasproved most effective in eliminating seed-borne pathogens. Out of four methods viz., hot water- 102 -