Role of Potassium in Cotton Production

Potassium is necessary for the maintenance of osmotic potential and water uptake which aids in drought tolerance. It is also necessary for protein production (and therefore seed development), and is the activator for more than 60 enzyme systems in the plant. Another major role of K is in photosynthesis by directly increasing leaf growth and leaf area index, and therefore, CO₂ assimilation.

In cotton, K plays a particularly important role in fiber development. Potassium affects the fiber quality, micronaire, length and strength. It also reduces the incidence and severity of wilt diseases. The bolls are major sinks for K, and the uptake may reach 3 lbs per acre a day during the intense part of boll development. About 70% of total K uptake occurs after the first bloom.

Many cotton producing regions have adequate potassium in the soil. Yet due to excessive magnesium and sodium, cotton plants have a difficult time extracting potassium from the soil solution. Added to this is the increasing boll load in high yielding varieties and the narrowing window for boll set during the decline of root activity when it is needed the most.

By the time symptoms are seen in the leaves, yield and fiber quality is lost and cannot be recovered. Foliar deficiency symptoms include yellowish spots between the veins and on the leaf margins that turn brown and die. Premature senescence and reduced boll development ensue.