Emerging Minor Diseases of Rice in India: Losses and Management Strategies

Abstract

Rice (Oryza sativa L) being one of the imperative food crops of the word contributes immensely to the food and nutritional security of India. The cultivation of rice is changed over the decades from a simple cultivation practices to the advanced cultivation to increase yield. Increased in rice yields especially after 1960s is mainly due to the introduction of high yielding semi-dwarf varieties which requires more inputs like chemical fertilizers, water and other resources. As a result, India achieved self sufficiency in rice and currently producing more than 115 MT of rice to meet country’s demand. Now India is exporting rice to other nations and earning foreign returns. With the change in rice cultivation practices, problems also aroused side by side. A number of biotic and abiotic stresses emerged as major constraints for rice cultivation in diverse agro-climatic conditions and growing ecologies. Diseases are the major biotic constraints to rice which can reduce the yields by 20–100% based on severity. Major diseases like blast, brown spot, bacterial blight, sheath blight and tungro still causing more damage and new minor diseases like bakanae, false smut, grain discoloration, early seedling blight, narrow brown spot, sheath rot have emerged as major problems. The losses due to these diseases may 1–100% based on the growing conditions, varietal susceptibility etc.., At present no significant source of resistance available for any of the above emerging diseases. But looking into the severity of these diseases, it is very important to address them by following integrated management practices like cultural, mechanical, biological and finally chemical control. But more emphasis has to be given to screen gerrmplasm against these diseases and identify stable source of resistance. Finally utilizing these sources in resistance breeding program by employing molecular breeding tools like marker assisted selection (MAS), marker assisted back cross breeding (MABB), gene pyramiding and transgenic tools. The present chapter discusses the importance of these emerging minor diseases of rice, the losses and possible management measures including resistance breeding.