PHYSIOLOGICAL AND BIOCHEMICAL CHANGES ASSOCIATED WITH THE DEVELOPMENT OF BROWN SPOT DISEASES IN RICE LEAVES

The healthy and diseased leaves of twelve rice samples collected from six local and six improved cultivars, were assessed for physiological and biochemical changes during brown spot infection. The photosynthetic related parameters like chl a, chl b and carotenoids were studied using spectrophotometry and changes in ionic composition like sodium, potassium, magnesium, calcium and iron were evaluated using flame photometry. The result reveals reduction in calcium, potassium, iron, chl.'a', chl.'b' and total chlorophyll and increase in magnesium, sodium, total soluble sugar and carotenoids contents after brown spot incidence. The study concludes that understanding of host-plant interaction for developing a relevant defense mechanism must be given priority and use of resistance cultivars by local growers is highly recommended.