Varietal Screening of Rice Genotypes for Stem Rot (Sclerotium oryzae) under Artificial Inoculation Method
Abstract
Rice (Oryza sativa L.)is a staple food in many countries and food security to millions of population in the world and is one of the major food crops of India. Stem rot is the one among major diseases of paddy infect the crop from moderate to severe form and also result in commercial yield losses. Looking to the disease severity, the present investigation was carried out to study the sources of resistance of pathogen in order to minimize the crop losses of rice. Screening of forty four genotypes along with two susceptible checks against stem rot pathogen under artificial inoculation condition during kharif 2019 revealed that, 18 genotypes were found moderately resistant viz., NVSR-317, NVSR-348, NVSR-355, NVSR-2147, NVSR-2566, NVSR-330, NVSR-360, NVSR-365, NVSR-370, NVSR-374, NVSR-405, NVSR-407, NVSR-2102, NVSR-2117, NVSR-2130, NVSR-2140, NVSR-2153 and IET-24336. Whereas, 12 genotypes viz., NVSR-2101, NVSR-328, NVSR-2528, NVSR-331, NVSR-335, NVSR-364, NVSR-384, NVSR-2435, NVSR-368, IET-25470, GR-11 and TN-1 were found susceptible to Sclerotium oryzae.
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Introduction
Rice (Oryza sativa L.)is the most important cereal crop in the developing world and is a staple food of over half the world’spopulation and food security to millions of population in the world. The total area of the world under harvested rice is 167.24 million hectares producing 500 million tonnes of grains in 2017 (Anonymous, 2020). In India, rice is cultivated on 43.19 million hectares with an annual production of 117.47 million tonnes and annual yield 2550 kg/ha (Anonymous, 2019). In Gujarat, Rice is cultivated on 0.84 million hectares with an annual production of 1.93 million tonnes and annual yield 2306 kg/ha in 2016-2017 (Anonymous, 2017). Stem rot is a fungal disease caused by Sclerotium oryzae was first described from Italy by Cattaneo in the sclerotial form in 1876 and he was given name Sclerotium oryzae Catt. Cavara in 1889 later reported Helminthosporium sigmoideum Cav. on rice (Gopika et al., 2016b). Stem rot (Sclerotium oryzae Catt.) perfect state Magnaporthe salvinni Catt., is a destructive disease under favourable weather conditions in rice growing areas of the world which eventually causes substantial spectrum of diseases (Venkateswarlu et al., 2013). Stem rot was considered as a minor disease in earlier, is now one of the major constraint in rice cultivation in East Godavari, Warangal and Khammam districts of Andhra Pradesh in recent years (Gopika et al., 2016a). The pathogen has been reported to cause substantial losses ingrain yield ranging from 5-80 percent (Kumar et al., 2003).
Conclusion
Forty-four genotypes were screened against stem rot pathogen under artificial inoculation condition, highest percent disease severity (45.6%) was recorded in international susceptible check TN-1 followed by genotype NVSR-331 (43.3%) and susceptible state check GR-11 (42.2%). Whereas, lowest percent disease severity (1.1%) was recorded in genotype NVSR-370 and NVSR-2153. Out of 44 genotypes tested along with 2 susceptible check, 18 genotypes were found moderately resistant. Whereas, 16 genotypes were moderately susceptible and 12 genotypes were found susceptible reaction to S. oryzae under artificial inoculation condition.
