Morpho-Pathogenic Variability in Albugo Candida Isolates, Causing White Rust of Indian Mustard

摘要

The present investigation was carried out to study the morpho-pathogenic variability among the Albugo Candida (white rust) isolates under glass house conditions during rabi 2015-16 at CCS HAU, Hisar. The isolates were collected from the six differentlocations viz., Hisar, Bawal, Bharatpur, Delhi, Ludhiana and Pantnagar; also from different Brassica species grown at Hisar. The isolates showed considerable variation in morphology of sporangia and pustules and high degree of pathological variation wasobserved on set of Brassica host species. The isolates from Pantnagar and Delhi produced slightly spherical shaped sporangia while the sporangia of rest of the isolates were globular shaped. The sporangial size of Ludhiana isolate was bigger (16.34-24.06urn) while the Delhi isolate was smallest (13.62-19.98 im). Hisar isolate was found to have highest per cent sporangial germination (89.18) while lowest in Bharatpur isolate (76.26). The isolates of A. Candida collected from different Brassica speciesproduced globular shaped sporangia; however slight variation in size and germination percentage of sporangia was observed and which varied between 14.07-22.70 (0,m and 84.78 and 89.18 per cent, respectively. With regard to morphology of pustule, all theisolates produced creamy white colour pustules, however considerable variation with respect to size and shape of the pustules was observed among the different isolates. Substantial variation in IP and LP was recorded and which varied between 4-9 days and7-14 days, respectively for isolates of different locations and 4-10 days and 7-14 days for isolates collected from the different Brassica species. Based on the pathogenic reaction on set of Brassica species, Hisar, Bawal, Bharatpur and Ludhiana were seems to be similar. The Pantnagar and Delhi isolates seems to be entirely two distinct isolates from Northern India. The results of cross inoculation studies indicated about existence of variability among the isolates of different Brassica species withinHisar region and five groups were identified among the isolates of A. Candida, one on B. juncea, second infecting B. rapa var yellow sarson and B. rapa var brown sarson, third infecting B. rapa var toria, fourth infecting on B. pekenensis and B. chinensis and last one on B. nigra. The present study indicated about the prevalence distinctness among isolates from Northern India and also within Hisar region from different Brassica species.