A Novel Strategy to Measure Cotton Boll Maturity

Cotton (Gossypium hirsutum) typically requires termination due to its perennial growth habit.  Evaluating end-of-season maturity is an important management tool that helps producers make time-sensitive decisions regarding irrigation termination and harvest aid application.  Plant maturity is generally determined by traditional techniques such as cutting bolls open to determine the last harvestable boll, or estimating heat unit accumulation.  However, each of these subjective methods has its own limitations.  The physiological principal behind this project is to quantify the reduction in boll moisture content as the boll matures and correlate the moisture content to boll age.  If the cotton boll age can be accurately quantified and is robust, then crucial management decisions on irrigation, harvest-aid application, and crop protection chemicals can be more uniform and precise.  The objective of this research was to identify a quick, objective measurement method for estimating cotton boll maturity based on boll moisture.  To evaluate the relationship between boll moisture and boll age, cotton blooms were tagged at white flower on three day intervals for 21 days to create seven boll ages.  The youngest and oldest bolls were 18 and 35 days after white flower, respectively, with the 35-day-old bolls being mature with boll sutures splitting.  White flowers were tagged in both irrigated and dryland settings in adjacent fields.  When the earliest tagged blooms were determined to have reached full maturity, a hand-held soil moisture meter (Delta-T Devices model HH2) and soil moisture probe (Theta Probe ML 2X) were utilized to quantify  the moisture content of cotton bolls of the different ages.  Moisture readings were taken from both boll locks and sutures to identify any significant moisture differences in the probing location and technique.  The data were then analyzed to determine the correlation between boll moisture and boll maturity.  Additional information will be presented in the poster.