Pathogenicity of the rice root nematode, Hirschmanniella oryzae to rice seedlings

Sprouted rice seeds of the variety Jaya were raised in pots with Hirschmanniella oryzae @ 0, 10, 100, 1000, 10000 per seedlings and observations on the growth characteristics were recorded at weekly intervals. On 7th day, the height and number of leaves of seedlings receiving 10,000 nematodes were significantly less over other treatments. In addition to this, 10% and 60% mortality was recorded in the above treatment on 14th and 21st day respectively. The height and number of leaves of seedlings were slightly more in treatments receiving 10, 100 and 1000 nematodes over control, upto 14th day. However on 21st day, the number of leaves started showing gradual reduction in these treatments too over control. Maximum number of tillers were recorded in the control followed by 10, 100 and 1000 levels respectively with zero tiller in the highest level. On 29th day, the height also recorded inversely proportional reduction as also, number of leaves and tillers. The same trend was noticed on 37th day in the above characteristics. Leaf area and fresh weight of shoot and root were also reduced.