Production of Phytophthora infestans oospores in planta and inoculum potential of in vitro produced oospores under temperate highlands and sub- tropical plains of India
Singh. B. P Jhilmil Gupta Roy. S Rana. D K
Annals of Applied Biology ; 2004 [Vol.144] Pages:363-370
Abstract
High moisture content of the host tissue (< 88%) and low ambient r.h. (50-54%) favoured oospore fomiation under controlled environments. It took 14-16 days for oospores to develop; thereafter the number of oospores increased with time and decreased with moisture content of host tissue. High ambient r.h. (> 80%) did not favour oospore formation under fteld or controlled eonditions. Oospore
formation was detected in inoculated plants grown in the field when the ambient r.h. declined to < 74% and moisture content of host tissue decreased to 83.7-85.6%, It took 8 days (cv. Kufri Chandramukhi) to 13 days (cv. Kufri Jyoti and Kufri Badshah) for oospores to develop. Cultivars also differed in their
response to oospore produetion, cv. Kufri Chandramukhi being more responsive (4800 oospores g-1fwt) than ev. Kufri Jyoti and Kufri Badshah (1320 and 390 oospores g-1f wt respectively). Oospores produced in vitro remained viable when buried in soil in the temperate highlands of Himachal Pradesh and sub-tropieal plains of Uttar Pradesh, India for more than 150 days, i.e. beginning of the next crop season. The oospores germinated and initiated late blight infection at the base of the stems after 21 -30 days of incubation of the potato plants raised in oospore-infested soil. It took 2 days for newly formed oospores to genninate and this delay time increased to 75-77 days after 180-days burial. It took 15 days for their germination (47%) in soil extract as compared to 50 days in sterilised distilled water.
Full Text