Status on downy mildew, Perenospora parasitica and genetic variability for resistance in yellow sarson, Brassica campestris var. yellow sarson

摘要

The oilseed crops especially Brassica species play a pivotal role in the agricultural economy of India. Among these Brassica campestris (var. yellow sarson) is an important rabi (post-rainy) crop of eastern India comprising Uttar Pradesh, Bihar, WestBengal and Assam. This crop together with foria (B. campestris var. foria) and Indian mustard [Brassicajuncea (L) Czern and Coss] is grown over an area of 6.75 m.ha with 1007 kg/ha productivity. But the rate of yield and hectarage is highly imbalanced. Amajor contributor to the low productivity are foliar diseases, particularly Alternaria blight, white rust and downy mildew (Singh and Bhajan, 2005; Singh and Singh, 2005a). Downy mildew caused by Perenospora parasitica affects these crops in seedling/vegetative stage. Published information on this disease from eastern India in respect of yellow sarson appears to be scanty. Therefore, investigations were undertaken to study its occurrence, severity and varietal resistance.