Sprinkler‐Induced Flower Losses and Yield Reductions in Cotton (Gossypium hirsutum L.)

Cotton ( Gossypium hirsutum L.) pollen is highly sensitive to water, rupturing within 1 to 2 min of contact. Flowers sprayed with known volumes of water showed that a single spray with 1 mL of water reduced seed set by 55%. Additional spray applications resulted in further losses and ultimately flower shedding. Field studies in 2000 and 2001 used a center pivot equipped with sprinklers and drag socks to determine the effect of timing and water application methods on fruit losses. Treatments included different application times (0800 to 1000 h, 1000 to 1200 h, 1200 to 1400 h, and 1400 to 1600 h) with 77 m 3 of water. The plots were irrigated eight times from 1 Aug. to 1 Sept. 2000 and 11 times from 10 July to 21 Aug. 2001. Flowers were tagged before irrigation and tracked throughout the season. No significant differences in fruit losses were observed in the 0800‐ to 1000‐h treatment; however, fruit losses progressively increased under the sprinkler treatments compared with the drag sock treatments as the day progressed. Maximum fruit losses occurred in the 1400‐ to 1600‐h treatments. The time course of sprinkler‐induced fruit losses tracked the opening of the flower and dehiscence of the pollen. Evaluation of seasonal lint yields showed a 21% reduction in 2000 and 11% yield reduction in 2001 under sprinkler irrigation compared with drag sock irrigation. These results emphasize the need to use production practices that limit water contact with open cotton flowers.