Rice Blast, A Major Threat to the Rice Production and its Various Management Techniques

Abstract

Rice (Oryza sativa L.) is the most important staple cereal crop which is consumed by more than 50% of world population. It contributes 23% and 50% of total calories consumed by world and Nepalese population respectively. Among various abiotic factors affecting rice, rice blast is the most disastrous, causing 70-80% yield loss. This disease was originated in China around 7000 years ago. In Nepal, it was first reported in Thimi, Bhaktapur in 1966. It is caused by a filamentous ascomycete fungus Magnaporthe oryzae (Anaemorphic form- Pyricularia oryzae). It infects all the developmental stage of plant and produce symptoms on the leaf, collar, neck, panicle and even in the glumes. It decreases the rice production by an amount, enough to feed 60 million people every year. Cloudy weather, high relative humidity (93-99%), low night temperature (15- 20°C), longer duration of dew is the most favorable condition for the outbreak of disease. The most usual approaches for the management of rice blast diseases are management in nutrient fertilizer and irrigation, application of fungicides and plantation of resistant cultivars. Besides, the use of extracts of C. arabica are reported to have an inhibitory effect on the disease. Seed treatment with Trichoderma viridae @ 5ml/lit of water have also been found effective. The chemical means of controlling blast disease shall be reduced, instead eco-friendly measures like biocontrol agents, resistant varieties, plant extracts can be practiced for disease control. Different forecasting model can be used in order to predict the disease prevalence.

Conventional Breeding and Molecular Markers for Blast Disease Resistance in Rice (Oryza sativa L.)

“…So far, more than 100 major blast resistance genes and 300 quantitative trait loci (QTL) have been identified and documented [8,9]. Many rice varieties have complete resistance to the blast, however, after a few cultivated years; the resistance has been broken down due to blast race changes and the appearance of newer, more virulent isolates of rice blast fungus [10]. Conventional breeding, thus, is still the mainstay for managing blast resistant cultivars to develop highly resistant cultivars to manage the disease.…”

Regulation of Autophagy Machinery in Magnaporthe oryzae

“…Therefore, how to ensure food security has become a common concern of all countries in the world. Many fungal diseases inhibit the growth of rice, notably so rice blast disease caused by Magnaporthe oryzae [ 4 ], which reduces rice production by up to 30% annually around the world [ 5 ], which is enough rice for about 60 million people [ 6 ]. Fungal infection is a leading factor driving agricultural production shortfalls and in the dramatic growth in widespread lesions in immunosuppressed people [ 7 ].…”

Design, Synthesis, and Bioactivities of Novel Trifluoromethyl Pyrimidine Derivatives Bearing an Amide Moiety

“…At present, the fungicides of amide compounds have been used for decades, and the application of fungicides is the most effective measure to control phytopathogenic fungi. The use of fungicides can restore a lot of losses every year (Simkhada and Thapa, 2021;Wang R.-X. et al, 2021).…”