Abstract

The contents of total soluble, reducing and non-reducing sugars decreased in rice plants due to infection by S. oryzae. But the extent of reduction in plants treated with botanicals followed by inoculation was significantly less. The total soluble and reducing sugar content significantly increased by the spraying of botanicals. The maximum increase being in plants sprayed with the leaf extracts of Acacia leucophloea and Phyllanthus niruri. The maximum reduction of total soluble and reducing sugars was recorded in the case of P. niruri treated plus pathogen inoculated plants. The maximum increase in non-reducing sugars was observed in the plants sprayed with the leaf extracts of Euphorbia hirta and Pongamia glabra. Plants sprayed with P. niruri leaf extract plus inoculation of the pathogen recorded the highest reduction in non-reducing sugar content. In rice plants the highest total phenol content was observed in the plants seven days after inoculation and their content reduced with lapse of time. Spraying of plant products followed by inoculation tremendously increased the total phenols as compared to the plants sprayed with plant products alone (without pathogen inoculation). The total phenol content increased to the maximum extent of 25.50 per cent in the plants sprayed with neem oil followed neem seed kernel extract and leaf extracts of C. arvensis, A. indica, C. roseus and O. tenuiflorum plus pathogen inoculation recording 24.88, 21.41, 21.04, 20.67 and 20.05 per cent increase respectively. The total protein content of the inoculated rice plants increased more with increase (18.39%) in the age of plants. Spraying of plant products resulted in remarkable increase in protein content and the maximum being 27.25 per cent in the plants sprayed with neem seed kernel extract. Plant products treated plus inoculation of the pathogen had resulted in less protein content of the rice plants as compared to plant products treatment alone without inoculation of the pathogen.

Keywords: Rice sheath rot, plant extracts, physiological effects.