Identifying quality protein maize inbred lines with enhanced seed vigour and longevity using multi-trait seed-quality selection.

BACKGROUND: Quality protein maize is a biofortified food crop of significant importance for nutritionally vulnerable populations in low- and middle-income countries. However, poor seed storability and vigour of quality protein maize (QPM) inbred lines remain a major challenge for breeders and the seed industry, limiting the expansion of QPM hybrids. In the current context, it is imperative to evaluate not only yield, but also other equally significant seed quality traits, such as storability and vigour, which substantially affect the marketability and spread of any hybrid.
RESULTS: In this study, 28 advanced QPM inbred lines were evaluated for pre- and post-storage seed viability and vigour using multiple seed quality parameters. The inbred lines exhibited high initial viability but varied in seed vigour and morphological traits. Natural ageing under ambient storage for 18 months led to a faster decline in vigour than in viability, increasing both the time to 50% germination and the mean germination time. Seed longevity, estimated as the half-life period (p50) during dry ageing and as the percentage of normal seedlings after 5 days of accelerated wet ageing, showed significant variation among the inbred lines (p < 0.05). Seed morphological traits, except seed eccentricity, were not significantly associated with seed vigour or longevity. The multi-trait genotype-ideotype distance index (MGIDI) identified four superior inbred lines (MGU-QPM-16, MGU-QPM-47, MGU-QPM-22, and MGU-QPM-31(Opq)) with enhanced pre- and post-storage vigour and seed longevity under both dry and wet ageing conditions. Based on the PCA eigenvalues, the selected quality traits were grouped into three factors, highlighting the strengths and weaknesses of good storers. Among the superior lines, MGU-QPM-47 demonstrated the best longevity and post-storage vigour.
CONCLUSIONS: The study identified contrasting QPM inbred lines with superior and poor seed storability and vigour under both dry natural and wet accelerated ageing conditions. The high heritability of the traits included in the multi-trait index underscores the potential use of the identified good-storer QPM inbred lines in hybrid development and crossing programs to improve seed storability and vigour. The identified contrasting inbred lines can be used for developing mapping populations for seed storability and vigour.