Paddy dwarfing

Source: indianexpress

Context :

Scientists at the Indian Agricultural Research Institute (IARI), who had collected samples of plants from farmers’ fields, which showed symptoms of stunting & yellowing have undertaken their electron microscopy analysis & DNA isolation through PCR (polymerase Chain Reaction) technique.

Key Points :

• Agriculture scientists have narrowed down the cause of a mystery disease-causing “dwarfing” of rice plants to either grassy stunt virus or phytoplasma bacteria.
• The vector responsible for their transmission is the brown plant hopper, an insect pest that sucks sap from the stems & leaves of rice plants.
• Scientists at the Indian Agricultural Research Institute (IARI), who had collected samples of plants from farmers’ fields, showed symptoms of stunting & yellowing.
• Preliminary laboratory analysis indicates the ‘phytoreovirus’ or rices grassy stunt virus as the source of infection.
• Phytoreovirus which induces stunting & yellowing of rice plants is transmitted by brown plant hopper.
• The infected plants remained stunted even after the application of the recommended dose of fertilizers.
• The second possible source is Phyto plasma, a bacterial pathogen that is spread by both brown plant hopper and green leaf hopper sucking insect pests.
• Many farmers for the past fortnight or more, have been reporting stunting of paddy plants in their fields.
• Such stunting has taken place typically 30-35 days after transplanting or direct seeding of rice.
• Initially all plants register uniform growth. But at later stages, some stop growing while others continue.
• The proportion of dwarfed plants has been generally reported at 10-25% even exceeding 40% in some cases.

Epilogue :

Due to this dwarfing of paddy, farmers fear a 10-12 MT drop in final output where last year it was 111 million tonnes.

This mysterious dwarfing disease comes at a time when the area under paddy in Kharif season was down by almost 13% when compared with the same period last year.