Selecting for productivity within a strain of cotton, Gossypium hirsutum L., in three environments

The effectiveness of selecting cotton (Gossypium hirsutum L.) plants solely for productivity was examined in three climatic zones of the San Joaquin Valley. Individual plant selections (F7) were made from the breeding line 12302 (later released as Acala SJ-1 cultivar) in 1965 at locations in the northern, western, and southern zones of the valley. Increased production of seed cotton was shown for selections in each zone when compared with the parental check in replicated trial in 1968.Selecting at the northern zone resulted in a higher proportion of high yielding lines than was attained by selections at other zones. Observations indicated productivity in the northern zone of the valley may be closely associated with early maturity.Fiber quality was also affected to a greater extent for the northern selections, with the more productive selections showing a greater reduction in fiber length.These findings suggest that selecting plants or progenies in a marginal environment can aid in identifying variation due to cryptic variability that remains following pure line breeding in a favorable environment.