Quantitative trait loci (QTLs) of maize involved in mediating resistance to Peronosclerospora sorghi, the causative agent of sorghum downy mildew (SDM), were detected in a population of recombinant inbred lines (RILs) derived from the Zea mays L. cross between resistant (G62) and susceptible (G58) inbred lines. Field tests of 94 RILs were conducted over two growing seasons using artificial inoculation. Heritability of the disease reaction was high (around 70%). The mapping population of the RILs was also scored for restriction fragment length polymorphic (RFLP) markers. One hundred and six polymorphic RFLP markers were assigned to ten chromosomes covering 1648 cM. Three QTLs were detected that significantly affected resistance to SDM combined across seasons. Two of these mapped quite close together on chromosome 1, while the third one was on chromosome 9. The percentage of phenotypic variance explained by each QTL ranged from 12.4% to 23.8%. Collectively, the three QTLs identified in this study explained 53.6% of the phenotypic variation in susceptibility to the infection. The three resistant QTLs appeared to have additive effects. Increased susceptibility was contributed by the alleles of the susceptible parent. The detection of more than one QTL supports the hypothesis that several qualitative and quantitative genes control resistance to P. sorghi.

This study was conducted to determine the chemical composition and estimating nutritive value of soybean meal, sunflower meal, rapeseed meal and cotton-seed meal using in vitro gas production technique. The experimental samples (200 mg DM from each) were incubated in vitro with rumen liquor taken from three canulated rams at 2, 4, 6, 8, 12, 24, 36, 48 and 72 h in three replicates. The results showed that there are significant differences between gas production values of samples at all incubation times (p<0.0001). Sunflower meal and soybean meal had the lowest and the highest gas production at 24 h incubation, respectively. There were significant differences in metabolizable energy (ME), net energy for lactation (NEL), organic matter digestibility (OMD) and short chain fatty acid (SCFA) of samples (p<0.0001). The sunflower meal has the lowest and soybean meal has the highest ME, NEL, OMD and SCFA compared with those of the others (8.69 MJ/kg DM, 5.48 MJ/kg DM, 55.14%, 0.60 mmol for sunflower meal and 12.98 MJ/kg DM, 9.03 MJ/kg DM, 85.03%, 1.13 mmol for soybean meal). In conclusion, it can be said that comparative nutritive value of Iranian oil seed meals which are tested in current study as below: soybean meal> rapeseed meal> cotton-seed meal> sunflower seed meal.