Effect of sowing date and environmental factors on incidence of sclerotinia rot and dry matter of mustard.

摘要

Field studies were conducted in Kanpur, Uttar Pradesh, India, during the 2003/04 and 2004/05 cropping seasons, to determine the effect of sowing dates and environmental factors on Sclerotinia sclerotiorum incidence in Indian mustard. The treatments consisted of the susceptible cultivars Varuna, Urvashi and Vardan, sowing dates and environmental factors, i.e. temperature, relative humidity and rain. Data on the disease incidence was recorded before harvesting by counting the diseased and healthy plants and the percent disease incidence was calculated for each sowing date. The observation on oil contents was also recorded. Correlation analysis between meteorological factor and disease incidence was carried out. For the dry matter and specific leaf weight (SLW), 3 plants were uprooted carefully from the each plot at the flowering stage and then oven dried at 60 degrees C and their weight was recorded. Results showed that the sowing dates had significant effect on Sclerotinia rot incidence and yield during both years. Among the 3 cultivars tested, Varuna showed the highest disease incidence, followed by Vardan during the 2004/05 cropping season. Urvashi was least affected by the disease and had the highest yields in both years. The environmental factors studied played significant roles in disease development. Correlation analysis showed that there was a significantly positive correlation of maximum and minimum temperature on disease appearance during both years. There was significant variation in the dry weight of plants during both years. Yield and dry matter accumulation were also influenced by the thermal requirements of the sowing dates. Urvashi had the highest seed yield, dry matter accumulation and SLW, followed by Varuna and Vardan during both years.