Genetic analysis of resistance to sorghum downy mildew and Rajasthan downy mildew in maize (Zea mays L.)

Sorghum Downy Mildew of Maize – A Review

“…Screening for resistance to the SDM has been carried out in the field (Anahosur and Hegde (1979), Cardwell et al, 1997, George et al, 2003, Yen et al, 2004, Nair et al, 2004and Nair et al, 2005 and in the green house (Jones, 1970, Schmitt and Freytag, 1974, Craig, 1976, and Narayana et al, 1995.…”

“…Effective breeding methods for producing downy mildew resistant inbreds and hybrids would depend primarily on the mode of inheritance of resistance or susceptibility to the disease (Nair et al, 2004). In countries where downy mildews are a major constraint to maize production, independent research programmes had been initiated to determine the genetic basis of resistance to the prevalent downy mildews only within their respective germplasms.…”

“…The downy mildew prevalent in the Udaipur district of Rajasthan State in India, with H. contortus as the collateral host has been recently designated as "Rajasthan downy mildew" (Siradhana et al, 1980) caused by P. heteropogoni. Earlier, this pathogen was considered as a variant of P. sorghi (Nair et al, 2004).…”

“…In India, SDM nursery has been maintained at the University of Agricultural SciencesRegional Research Station (UAS-RRS), Mandya in Karnataka state , George et al, 2003, Yen et al, 2004, Nair et al, 2004and 2005. It is considered to be the National Centre for investigations on maize downy mildew in India (Krishnappa et al, 1995).…”

“…Normally disease assessment has been carried out as per standard procedure given by Lal and Singh (1984) worldwide in case of systemic downy mildew diseases by recording the per cent downy mildew diseased plants. Based on per cent downy mildew incidence, a rating scale has been developed as 0 -10 per cent: resistant (R); >10 -30 per cent: moderately resistant (MR); >30 -50 per cent: moderately susceptible (MS); >50 per cent: susceptible (S) (Yen et al, 2004, Nair et al, 2004and 2005.…”