All posts by Avat Shekoofa, Crop Physiologist

Cotton growth stages and water requirements

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While May brought a great deal of rain, June and July have been dry for much of West Tennessee.  We are already beginning to see the impacts on cotton growth and development.  While we still have very good cotton yield potential, we need a good soaking rain in the coming weeks.  This blog highlights impacts of drought on cotton during the growth stage, provides general information on scheduling irrigation and highlights a few scheduling methods.

Ideally, the soil profile needs to provide sufficient plant available water throughout the blooming period. As we begin to move towards the permanent wilting point during the blooming window, fruit retention may begin to decline and maturity may be delayed.  If a rainfall or irrigation event does not ameliorate the stress, yield penalties may develop.  Cotton plants are particularly susceptible to drought during the early boll development stages which immediately follow flowering (Table 1). Keeping soil profile at or near field capacity at early bloom through peak bloom will support earliness and maximize yields.

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Cotton response to saturated soils in West TN

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Authors: Avat Shekoofa and Tyson Raper

Reports of ‘sudden wilt’, ‘parawilt’, or ‘wet wilt’ began Wednesday afternoon and continued through Thursday. This article briefly explains the phenomena and discusses management during recovery. 

Fig. 1: Prolonged periods of saturation resulted in wilt in many areas of West Tennessee following Hurricane Barry. 18 July 2019

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Cover crop residues impact on cotton germination and seedling growth at different termination timings

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Authors: A. Shekoofa, S. Safikhan, T. Raper, and S. Butler

 For those that have cover crops, you’re likely contemplating when to terminate.  While delayed termination can increase the amount of biomass produced and prolong the length of time that biomass remains in the system, delayed termination can also bring a few challenges- one of which is allelopathic impacts on our cash crop.  This article highlights recent research at the University of Tennessee examining how termination timing might allow us to harness these chemicals for weed suppression while minimizing the impacts on our cash crop (Fig. 1).

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Inhibitions of cotton germination and early seedling growth by cover crop residues

Authors: Avat Shekoofa, Sara Safikhan, Tyson Raper, and Shawn Butler

 Cover crops have been used to suppress weeds, reduce erosion, and increase water infiltration for many years. While cover crops can improve soil quality and physical properties, integration of cover crops into row crop production-specifically cotton- remains challenging. One potential negative impact on cotton growth may come from allelopathy.  Allelopathy is defined as the direct or indirect harmful or beneficial effects of one plant on another through the production of chemical compounds that escape into the environment (Fig. 1). Although allelopathic toxicity of cover crops can suppress weeds and therefore assist in weed control, they may also suppress cotton germination and reduce stand. Little is currently known about the actual allelopathic effects of cover crops on germination and seedling growth of cotton. Proper selection of cover crop species and termination timing could potentially reduce the allelopathic toxicity which negatively impacts cotton germination and early seedling growth.

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Soybeans lose gallons of water daily during hot, dry conditions through transpiration. Plants transpire, or lose more than 98% of water taken up by the roots, through leaf tissue. Evapotranspiration (ET) describes the movement of water through evaporation from the soil and transpiration through plant surfaces, which is the movement of water from the soil into plant roots, through plant stems and leaves, and back out into the atmosphere. The rate of ET depends upon the soybean growth stage and the time of the year (Fig 1.) Both transpiration and evaporation need to be Continue reading

Rain-out Shelters

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For farmers including Tennessee’s farmers to grow crops, they need good – or at least decent  weather, including nourishing rain. But sometimes producers must deal with water deficit and drought (especially in West Tennessee, approximately 95% of soybean production is rainfed). If so why not go for a variety that still can survive, still can give you the benefits of growth and yield compared to the one that after a while is gone, the one cannot handle the drought conditions.