The inheritance of flowering time in Townsville stylo (Stylosanthes humilis)

Abstract

The inheritance of flowering time was studied in F₁, F₂ and F₃ populations derived from a diallel cross among nine naturalized Australian lines of Townsville stylo (Stylosnnthes humilis) and in F₁ and F₂ populations from a small number of crosses between naturalized Australian lines and introductions from Mexico and Brazil. Strong dominance for lateness of flowering was observed in both the (Australian x Australian) and the (Australian x Mexican/Brazilian introductions) crosses, and some F₂ and F₃ progenies included small numbers of extremely early plants, flowering up to 55 days earlier than the earliest parent. The flowering time distributions of the (Australian x Australian) crosses could be explained by a three-locus model with multiple alleles at two loci. Proposed genotypes for the four maturity groups are as follows: late, LLM₂M₂EE; late-midseason, LLmmEE; mid-season, l₂l₂M₂M₂EE; early, l₁l₁M₁M₁EE; very early, LLM₂M₂ee.

Only one major dominant gene for lateness of flowering could be detected from the distribution of the two (Australian x introduced line) F₂ populations, but the segregation of extremely early types and the low recovery of the early-flowering phenotype suggested that other gene loci were segregating.