Submitted to: Biotronics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 1, 1997
Publication Date: N/A
Interpretive Summary: Aldicarb is a systemic insecticide widely used in the U.S. to control early season insects in cotton. However, it is not known how aldicarb affects cotton root growth and distribution under various day/night temperature regimes. Information on root growth at a wide range of temperatures and root distribution at various soil depths would be particularly useful for developing precise models for irrigation and fertilization scheduling. The objectives of this study were 1) to characterize the growth and development of cotton roots in various day/night air temperature regimes, and 2) to evaluate the effects of aldicarb and air temperatures on root distribution patterns at various soil depths. Our results showed that the optimum range of temperature for cotton root growth is 30/22 to 35/27 degrees Celsius, and that both high temperatures and aldicarb altered the distribution of roots favoring more deeper root systems under optimum water and nutrient conditions.
Technical Abstract: Studies on root growth and root distribution patterns are few. The purpose of this study was to determine how cotton root growth at differnt soil depths responded to temperature during the early growing stages, so that these responses could be incorporated into plant growth models used to manage cotton crops. In addition, the effect of aldicarb, a systemic insecticide widely used in the cotton growing regions, on root growth was also evaluated. Cotton plants (cv. DES-119) were grown in outdoor sunlit environmental growth chambers at four day/night temperatures. Aldicarb was applied to soil at sowing at a rate of 0.84 kg ha-1 and at initial squaring at a rate of 2.24 kg ha-1. Root number, length, and distribution in various soil depths were determined weekly during a 56 day experimental period. Plants grown at 30/22C produced more growing roots than those grown at either 20/12C or 40/32C. Root length at 30/22 and 35/27C was also 20% greater than that at 40/32C. Total root dry weight at 30/22C was 1.5 and 5 times as much as those at 40/32 and 20/12C, respectively. Increases in day/night temperatures resulted in increases in rooting depth and the percentages of root distribution in the deeper soil depths. Aldicarb not only increased total root dry weight, but also altered root distribution in favor of >20 cm soil depths over the top 20 cm layer. Our results showed that the optimum range of temperature for cotton root growth is 30/22 to 35/27C, and that both high temperatures and aldicarb altered the distribution of roots favoring more deeper root systems.