Characterization of maize genotypes using microsatellite markers associated with QTLs for kernel iron and zinc

224-234Crop genetic resources rich in Fe and Zn provide sustainable and cost-effective solution to alleviate micronutrient malnutrition. Maize being the leading staple crop assumes great significance as a target crop for biofortification. We report here wide genetic variation for kernel Fe and Zn among 20 diverse maize inbreds lines, majority of which were bred for quality protein maize (QPM) and provitamin-A. Kernel Fe ranged from 30.0 - 46.13 mg/kg, while kernel Zn ranged from 8.68-39.56 mg/kg. Moderate but positive correlation was observed between the micronutrients. Characterization using 25 Single sequence repeats (SSRs) linked to QTLs for kernel Fe produced 58 alleles. Similarly, 86 alleles were identified from 35 SSRs linked to QTLs for kernel Zn. One unique allele for kernel Fe and three unique alleles for kernel Zn were identified. The mean polymorphic information content (PIC) was 0.40 for both kernel Fe and  Zn. Jaccard’s dissimilarity coefficients varied from 0.25 - 0.91 with a mean of 0.58 for kernel-Fe while 0.27- 0.88 with a mean of 0.57 for kernel Zn. Principal coordinate analysis depicted diversity of inbreds. Cluster analysis grouped the inbreds into three major clusters for both kernel Fe and Zn. Potential cross combinations have been proposed to develop micronutrient rich hybrids and novel inbreds with higher Fe and Zn. The information generated here would help the maize biofortification programme to develop nutritionally enriched hybrids

Genetics of resistance to stored grain weevil (Sitophilus oryzae L.) in maize

Stored grain weevil (Sitophilus oryzae) has emerged as important storage grain pest of maize, causing substantial economic losses. Owing to high costs and environmental hazards of pesticides, host plant resistance holds promise for effective control of weevils. In the present study, a set of experimental maize hybrids generated using line × tester mating design were evaluated against S. oryzae. Significant variation for grain weight loss (GWL) (6.0–49.1%), number of insect progeny emerged (NIP) (17.8–203.3), grain hardness (GH) (263.1–495.4 N), and pericarp thickness (PT) (60.3–161.0 μm) was observed. Strong positive association was observed between GWL and NIP. GH and PT did not show any correlation with GWL and NIP. Additive and non-additive gene actions were important for both GWL and NIP. Promising inbreds and experimental crosses identified can be effectively utilized in the resistance breeding programme. In majority of promising crosses having desirable SCA effects, one of the parents had desirable GCA effects, indicating that selection of inbred parents based on per se performance for generating resistant crosses may be possible. The commercial hybrid checks were highly susceptible compared to experimental hybrids. The inbreds and experimental hybrids identified hold promise in developing weevil resistant maize cultivars offering sustainable solution to management of weevils in maize