Samples Needed for Estimation of Plant Height of Pima Cotton¹

Abstract

Plant populations giving the highest lint yield of American pima cotton (Gossypium burbdense L.) grown in 1‐m spaced rows change as plant heights change. Therefore, plant height should be considered in future plant population studies with pima cotton. This study was conducted to determine the number and type of plant height measurements needed to give a satisfactory estimate of mean plant height for a plot. Plant height uniformity data were obtained from 12 plots (four locations with three plots per location) in Arizona. Soils were Torrifluvents Haplostolls, Anthropic Torrifluvents, and Thermic Torrifluvents. Measurement of four to eight plants per plot, half of the number on each end, appeared to be adequate to characterize the plant height of a plot. Plant heights were normally distributd. A systematic selection produced lower variation (about onehalf as many plants needed to be measured) but over‐estimated mean plant height by an average of 12.5%.