Measurements of Internal Boll and Canopy Temperatures of Four Diverse Cotton Cultivars

High  to supra-optimal temperature stress is an abiotic stress factor that endanger the performances and yields of various crops worldwide.  Cotton, the most important fibre crop, is detrimentally affected by high temperature stress, especially during the reproductive fruiting stage.  Optimum temperature thresholds for boll growth and development of fibers is 25 °C, which are frequently exceeded according to internal boll temperatures measured during a field study in 2015 at Marianna, Arkansas.  Four diverse cultivars (Arkot 9704, VH260, DP393 and DP210) were evaluated for internal boll temperatures, at 15 minute intervals for a month during the flowering and fruiting stage of cotton.  The aim of the study was to obtain canopy and internal boll temperatures and correlate that to crop yields.  The hypophesis was that some cultivars transpire more, which cools off the leaves and bolls of cotton plants, and results in higher yields.  During the field trial at Marianna, VH260, resulted in boll and canopy temperatures that were mostly equal to each other when measured at 12h00 midday, whereas the sensitive DP393 mostly had higher boll temperatures than canopy temperatures.  If a cultivar has the ability to prevent fruits from heating above threshhold or optimum temperatures, yields can be higher.  The screening and identification of heat and drought tolerant cotton cultivars is a priority for future production management practices.