Cotton plant mapping, in which fiber properties and yield are quantified at the boll or field-block level, has revealed extensive modulation of fiber properties by the growth environment (Bradow, et al., 1997a; 1997b; 1997c). Use of the AFIS particle-sizer, which is capable of handling small fiber samples [ca. 200 to 10,000 fibers] from individual bolls and locules (Bradow et al., 1997a; 1997c), has made possible documentation of significant genotype responses to irrigation timing, amount, and method, planting and flowering date, and boll thermal microenvironment (Bradow et al., 1997b).