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Experiments were conducted to test the suitability of using irrigation water as a carrier for CO2 to enhance growth and productivity of cotton. The amount of CO2 which can be carried in this manner (1.5 g/1) has a cost which might make the practice profitable if it resulted in significant yield increases. Cotton is one of the most responsive crops to CO2 enrichment. For this reason it is a prime candidate for field enrichment studies. Preliminary to making gaseous or enriched irrigation releases, a greenhouse study to determine whether cotton responded positively or negatively to high CO2 in the root zone seemed advisable. With this in mind two glasshouse studies have been conducted in which cotton was watered daily with CO2-saturated water. Potted plants (cv. DPL-61) were irrigated daily with CO2-saturated water in a greenhouse in Phoenix, AZ. Growth, productivity, and physiological responses of these plants were compared to those irrigated with deionized water. All plants were fertilized twice weekly with a complete Hoagland's solution. Yield as measured by boll load at maturity was increased 70% and 53% in two experiments. Rate of photosynthesis during boll loading was increased 38%. Leaf chlorophyll content and starch content were also increased. However (14)C tracer analysis showed that none of the carbon in lint samples was derived from the CO2 in the irrigation water. Leaf Zn and Mn were deficient in the control plants but sufficient in the CO2-treated plants. The CO2-saturated irrigation increased uptake of Zn and Mn which supported a more robust photosynthetic apparatus in the treated plants. The greater photosynthetic activity during boll loading resulted in a significant increase in yield of the treated plants. A follow-up study in a field near Phoenix was unable to show a similar response of the cotton crop in the field in 1986. |
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©National Cotton Council, Memphis TN |
Document last modified Sunday, Dec 6 1998
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