Cotyledons in Upland Cotton: How Important Are They?

Seedlings of upland cotton ( Gossypium hirsutum L.) are vulnerable to the partial or complete loss of their cotyledons due to an array of biotic and abiotic causes. These experiments were conducted in the field over a 4‐yr period to determine the effects of such losses in the early vegetative cotyledon growth stage on lint yield, selected lint yield components, and fiber traits. Loss of half a cotyledon apparently stimulated the cotton plant to over compensate for lint yield by 4 to 6%. Overcompensation was not detected for the lint yield components or fiber traits. The plant compensated for the loss of up to one cotyledon in all traits except fiber strength in one year. Loss of one and one‐half cotyledons reduced lint yield (11–33%), picked lint percentage (up to 2.1%), pulled lint percentage (0.4%), micronaire (up to 0.2 units), and fiber elongation (up to 0.3%). Loss of both cotyledons reduced lint yield (81–100%), picked lint percentage (up to 4.6%), pulled lint percentage (4.7%), boll size (0.85 g boll −1 ), micronaire (up to 1.6 units), and fiber elongation (up to 1.4%). Fiber length and length uniformity were not affected at any level of cotyledon removal. Fiber strength exhibited significant differences among treatments in one experiment, but no trend. The elimination of both cotyledons when the first true leaf was about the size of a dime was considerably less harmful to the plant than when done earlier in the season.