Quality protein maize (QPM) has protein quality of opaque 2 (>0.074% tryptopan) with endosperm modifiers which turn its kernels vitreous that is similar to normal maize. Use of QPM as a cereal can significantly improve daily intake of lysine and tryptophan for humans and livestock. However QPM cultivars have lower yields due to trait compensation. Therefore, a breeding programme was carried out to convert parental lines of Shalimar maize hybrid 5 (SMH-5) viz. IML-187 and BML-6 into QPM versions. Marker polymorphism was worked out in donors and recipients. IML-187 was crossed with DQL-2029-1 and BML-6 was crossed with DQL-779-2-9. The first and second backcross generations involving IML-187 as recurrent parent were marked as BC1F1 (A) and BC2F1 (A) respectively, whereas those involving BML-6 were designated as BC1F1 (B) and BC2F1 (B) respectively. The BC2F2 lines derived from two generation of backcrossing coupled with SSR marker and phenotypic background and foreground selection were advanced to BC2F3. Approximately 80–90% of RPG similarity was observed in BC2F2 lines. Eight lines namely IML-187 × DQL-2029-1- BC2F3:06, 07 and 23: BML-6 × DQl-779-2-9: 02,04,09,20 and 13 were identified from BC2F3 to have tryptophan higher than 0.075% and <25% opaqueness. These lines were used for trait fixing and crosses were made to produce QPM version of SMH-5. Six improved versions of SMH-5 were selected for higher grain yield and tryptophan content and are to be employed in further testing and varietal release in Northern Hill Zone (NHZ) in India.

The stored grain weevil, Sitophilus oryzae (Linnaeus), causes significant losses to maize grains in tropical countries. Despite the nutritional superiority of the quality protein maize (QPM), an important concern is the possible vulnerability of QPM genotypes to stored grain weevil infestation. In the present study, the responses of 24 QPM inbred lines, along with several non-QPM inbred lines and hybrids, were evaluated against S. oryzae under laboratory conditions. Two attributes, namely (i) % weight loss in the grains after a fixed period of incubation with the insect and (ii) the number of progeny insects (insect multiplication) generated from six pairs of adult insects, were considered. A cumulative resistance index was computed for each genotype giving equal weight to both attributes. The study revealed DMRQPM-60 and CML167 as the most resistant entries. Shaktiman-1, the released QPM hybrid in India, showed moderate resistance against the grain weevil. However, most of the elite QPM inbred lines as well as some non-QPM inbred lines and hybrids were found to be highly susceptible to the weevil infestation. To explore the possible relationship between enhanced protein quality and varying degree of kernel vitreousness and vulnerability to the grain weevil infestation, both the QPM and the non-QPM genotypes were analysed. The correlations between kernel quality traits and kernel texture with % kernel weight loss due to weevil infestation and insect multiplication were found to be non-significant, indicating possible influence of other factors, including pericarp thickness and endosperm composition, in determining the susceptibility of the QPM genotypes to S. oryzae. The study indicates that QPM genotypes are not necessarily susceptible to the stored grain weevil and identifies promising QPM genotypes with resistance to S. oryzae.