Throughout the Cotton Belt, irrigation systems run throughout the summer. With escalating input costs, some cotton growers may be tempted to turn off the water sooner than later, running the risk of losing yield and fiber quality. 

Before you make the decision to shut off the well, it’s important to consider the crop stage and impact water deficit could have at harvest. 

Review these insights to better understand how water use impacts cotton plant physiology and development. And contact your local PhytoGen team as a resource to help navigate irrigation and other agronomic decisions from now through harvest.

• Water is critical for plant development and assists with:
  • Maintaining turgor pressure. Plant turgidity protects structural integrity, assisting cell elongation and increasing growth.
  • Keeping plants cool. Transpiration is the process by which water vapor is released through the plant, serving as a cooling mechanism during the hot days of summer.
  • Nutrient uptake. Without water, vital nutrients needed for plant and boll development remain unused in the soil.
    • Water, carbon dioxide and sunlight are the necessary building blocks for transforming light energy into usable chemical energy for plant growth.
• Total seasonal water use for cotton is between 23 and 28 inches. Cotton is a drought-tolerant crop compared with other row crops and requires less water than corn, sorghum and peanuts. But cotton plants still use approximately 2 feet of water per season, with a maximum daily use of 0.30 inch.
• Irrigation decisions must be made on a field-by-field basis. Soil water holding capacity varies greatly by soil type. Coarse sand may only hold 0.25 to 0.75 inch of water per foot, while silt loam can hold as much as 2 to 2.5 inches per foot.
• Healthier roots lead to better water utilization. Root-knot and reniform nematode resistance means healthier, more prolific root systems for better water utilization and nutrient uptake.
  • Varieties with these PhytoGen Breeding Traits^™ provide benefits all-season long and improve irrigation efficiency.

Cotton Development Specialist Ken Legé, Ph.D., has studied the impact of water deficiency in cotton and emphasizes the importance of maintaining adequate water availability in irrigated fields to protect yield and fiber quality potential.

Legé says seasonal water use increases through squaring and bloom, peaking during boll fill. On average, water use is highest for cotton plants approximately 80 to 100 days after planting, from peak bloom to cutout.

From first bloom to peak bloom, a water deficiency in cotton can have a major impact on both yield and fiber quality. During this time frame, plants establish total harvestable bolls and develop fiber length. A water deficiency prior to peak bloom could cause shorter staple cotton.

From peak bloom to open boll, a water deficiency has a moderate impact on yield, but a higher impact on fiber quality, especially micronaire. See the graph below to visualize how a cotton plant’s water use changes throughout the season.

This summer, some growers may be tempted to save input costs by turning the well off early on irrigated acres. Growers could inadvertently shut off irrigation when plants need water most. Consider the potential impact on yield and fiber quality as you are making irrigation decisions for the season.

For question about irrigation or other agronomic issues, contact your local PhytoGen team at https://phytogencottonseed.com/team. 

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