Change in the Nutrient Acquisition and Root Characteristics over 70 Years of Breeding in Cotton

Cotton (Gossypium hirsutum L.) is an important cash crop in the United States, grown mainly for the fiber production and plays a significant role in feed and oil industries. Cotton lint yields have increased during this century through plant breeding programs and management. However, there is limited information available on nutrient concentration, nutrient uptake, and root characteristics of different cotton cultivars that have been changed over the last 70 years of breeding. A field study was conducted at EV Smith (EVS) Research Center, Alabama during 2019 in a randomized complete block design, and each treatment was replicated four times. The experimental site received 43% lower rainfall during the first four months of crop growth the as compared with the last five years average. Result showed significant effect of cultivar on lint yield, the lowest lint yield (494 kg ha^-1) was reported in the oldest cotton cultivar “Auburn56” used in the study. Newer cultivars sampled at 10 days after flowering showed a consistent decrease in total nitrogen, phosphorus, and potassium uptake in comparison with the older ones. Cultivars with low nutrient uptake showed low root length density and surface area, but there was not relationship between root characteristics and year of release. We observed that the cultivars with higher root density and root surface area showed higher potassium content in leaf. This information can provide useful guidance for future breeding and crop management to allow further cotton yield improvements by ensuring improved root architecture with increased nutrient use efficiency.