Effect of various inter and intra row spacing on the intensity of downy mildew of onion.

摘要

Studies on the effect of inter- and intra row spacing on the intensity of onion downy mildew and its effect on the yield were conducted at the Plant Pathology Section, Agricultural Research Institute, Tarnab during 2002-04 growing seasons. The lowest disease severity of 24% and the highest yield of 35.978 tons-1 ha were recorded when row to row (R) and plant to plant (P) spacing was maintained at 30 cm and 9 cm, respectively i.e., R3P2 (30x9 cm) followed by second lowest disease severity of 25.75% and second highest yield of 34.611 tons-1 ha recorded for R2P3 (20x11 cm). Data recorded for 2003-04 followed similar pattern, although the disease was more severe this year than previous year. Lowest disease severity of 46.66% and highest yield of 11.500 tons-1 ha were recorded again for R3P2 (30x9 cm) followed by disease severity of 47% with the yield of 10.548 tons-1 ha for the treatment R2P3 (20x11 cm). The disease severity decreased gradually with the increasing row to row and plant to plant distance. The increase in the yield per unit area followed a similar pattern..