Genetic Variation and Relationships among Seedling Vigor Traits in Sorghum

Seedling vigor in sorghum [Sorghum bicolor (L.) Moench] is important for improving stand establishment of the crop, particularly in arid regions and in areas where low soil temperatures prevail at planting time. This study was conducted to examine the genetic variation, heritability, and relationships among seedling vigor traits in a recombinant inbred (RI) sorghum population developed from two contrasting inbreds. One hundred RI lines and their parents [‘SRN39’, an African caudatum and ‘Shan Qui Red’ (SQR), a Chinese kaoliang] were evaluated for seedling vigor in experiments conducted in the field, in an incubator, and in a greenhouse. Data on 100‐kernel weight, visual seedling vigor scores, percentage germination at 12 and 22°C, percentage emergence, seedling height, and shoot dry weight were collected. Genotypic differences were significant for many of these seedling vigor traits. Significant genetic and additive variances were observed for field vigor scores as well as for those traits measured in the more controlled environments. Heritability estimates for visual scores, percentage germination, emergence, and seedling height were high, while those for seedling dry weight were low to medium. Genetic correlation coefficients of visual seedling scores with the different estimates of vigor were significant except for 100‐seed weight. Significant genetic interrelationships were revealed among traits measured in the greenhouse and incubator at 22°C. Visual scores taken in field experiments appeared effective in integrating germination, emergence at high temperatures, and shoot dry weight. The significant additive genetic variances obtained indicate that the superior seedling vigor observed in the kaoliang parent, SQR, can be effectively utilized for improving germination in cold temperature, as well as germination, emergence, seedling growth, and development at optimum temperature.