Effect of an Antitranspirant and Irrigation on Leaf Photosynthesis, Leaf Resistance, and Lint Yield of Cotton.

C.R. Shumway and J.T. Cothren


 
ABSTRACT

Field experiments were conducted in 1986 and 1987 to evaluate the effect of an experimental antitranspirant and irrigation on cotton lint yields, leaf resistance, and leaf photosynthesis. In both years 'Stoneville 825' was planted on April 16. In 1986, irrigation treatments were irrigated (furrow) and nonirrigated. The experimental antitranspirant treatments were applied at three times (prebloom, bloom, and postbloom) and at two application rates (1.12 and 2.24 kg a.i. ha-1). In 1987 a line source irrigation system was utilized; irrigation levels were high, moderate, and nonirrigated. The antitranspirant was applied at 1.12 kg a.i. ha-1 at bloom, bloom + 10 days, and bloom + 20 days.

A LiCor 1600 steady state porometer was used to measure leaf resistance and leaf transpiration on the adaxial and abaxial leaf surfaces of treated leaves in 1986 and 1987. In 1987, a LiCor 6000 portable photosynthesis system was used to measure single leaf photosynthetic rates. Measurements were taken on treated leaves in the upper canopy at two and seven days after application (DAA) of the postbloom treatment (1986) and bloom + 20 days treatment (1987).

In 1986, cotton lint yields were significantly affected by antitranspirant treatments, but not by irrigation treatments. Cotton lint yields were significantly lower at the 2.24 kg a.i. ha-1 application rate when applied at the postbloom stage. No other treatments differed significantly from the control. In 1987 the antitranspirant treatments did not significantly affect yield, but irrigation significantly reduced yield by 22% and 34%, respectively in moderate and nonirrigated treatments compared to the high irrigation level. No significant treatment by irrigation interaction was observed either year.

Application of the antitranspirant resulted in increased leaf resistance on the adaxial leaf surface and decreased leaf resistance on the abaxial leaf surface when compared to control plants. This resulted in a decreased leaf transpiration rate. In 1987, leaf photosynthesis was decreased by approximately 11% in irrigated plants and 20% in nonirrigated plants when compared to control plants.



Reprinted from 1988 Proceedings: Beltwide Cotton Production Research Conferences pp. 81 - 82
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998