Identification and characterization of a novel long juvenile resource AGS 25

Abstract

Soybean [Glycine max (L.) Merr.], a quantitative short day crop, readily flowers with a little vegetative biomass under short day conditions and poses a challenge for developing high yielding soybean cultivars for tropical and sub-tropical countries. The long juvenility trait helps in gaining biomass under short days by delaying flowering and has helped to establish soybean as a commercially cultivated crop in these countries. A new soybean long juvenile (LJ) germplasm resource AGS 25 was identified by planting germplasm for 2 years under normal (22 June) and shorter (21 July and 21 August) day lengths. Evaluation of AGS 25 along with 252 germplasm accessions in 2 years at eleven locations (19.2610° N to 29.0222° N) could confirm its latitudinal consistency. Inheritance studies conducted under short day winter conditions identified a single recessive allele controlling long juvenility in four F2 populations. The genomic region for this trait was located at chromosome 16 and it explained 30% of the total phenotypic variation. Evaluation of 13 popular varieties and one hundred twenty seven advanced breeding lines (ABLs) (AGS 25 × three conventional juvenile varieties), during short day winter conditions of lower latitudes (19.2644° N), revealed that AGS 25 took maximum days to first flower (R1) (57 days) and attained good plant height (49.6 cm). Evaluation of ABLs identified high yielding segregants with early maturity (up to 90 days). Identified resource opens the possibility for development of early maturing high yielding long juvenile soybean varieties suitable for delayed as well as winter sown conditions.