Cotton, Gossypium hirsutum L., fruits and matures over a relatively long period of time, from first square to 90% open bolls ranging upwards of 120 days in Arkansas. Genotypes of cotton have been developed in recent years that "set" and mature a crop over a shorter period of tire . Work was initiated in 1981 to determine the variability among 7 genotypes in developmental characteristics as they relate to "earliness". Two fast fruiting Yugoslavian lines, 2 cultivars grown in Texas for their earliness characteristics, 2 present day Mid-South cultivars, and 1 obsolete, full-season cultivar were compared. Characters measured included number of days from pin-head square to white bloom, days from white bloom to cracked boll, vertical and horizontal blooming intervals, and fiber diameter development from 16 to 40 days after anthesis at 4-day intervals.

Data from 1981 and 1982 indicate that the Yugoslavian lines were consistently earlier in every character. The Texas cultivars, 'Camd-E' and 'SP-37', obtained their earliness over 'Rex 713', 'Deltapine 611 and obsolete 'Rowden' by faster flowering intervals and in 1981 by requiring fewer days from square to white bloom and white bloom to mature boll. Rex 713 and DPL 61 were not consistently earlier than Rowden during the time intervals of data collection in 1981 or 1982. Fiber fineness of the Yugoslavian lines could be determined by the 24th day after anthesis, while Camd-E and SP-37 required 36 days and Rex 713, DPL 61, and Rowden required 40 days.