Examining the Effects of Aphids and Water Stress On Cotton Yield

Over a 10 week field study at the Texas A&M Field Laboratory in Burleson Co. TX, aphids and pulsed water stress were applied to 0.5 acres of cotton. Cotton plants were grown in 0.3m³ (6ft³) cages in the field. Aphids were applied at a density of 25 aphids per plant at either the seedling or squaring stage, or were not present as a control. For water stress, furrow irrigation was applied when plants exhibited a turgor below -1.2 Mpa, determined by a pressure chamber. Control plants received water to keep them above a turgor of -1.2 Mpa. Aphids were counted on treatment plants throughout the study and removed from control plants by hand. COTMAN plant mapping and other plant measurements were taken. Plant samples for determining allelochemicals, ROS scavenging enzymes, amino acid, and carbohydrates concentrations were taken.

     We found major physiological differences between plants that had aphids applied at seedling compared to squaring plants. Seedlings with aphids were significantly smaller and had lower boll retention rates.  Aphids were higher in abundance on squaring plants and fluctuated in population density on stressed plants. During stress recovery, aphid abundance was highest and greater than control. Lint yield was highest in aphid and stress free plants and lowest from seedling cotton with aphids and stress.