Sodium as the acetate was added to irrigation waters to study the effects of higher Na levels in water and soils upon cotton fruiting and shedding, growth, and yields. One Acala variety (1517D) and one American Pima variety (Pima S-2) were included in the 2-year study, conducted in outdoor lysimeters. Boll and fiber properties were also examined.
Virtually all effects of added sodium (increased from 58 percent in the water to 71 and 80 percent) were undesirable, and most of these adverse effects were highly significant.
They included: (1) reductions in growth and yields, (2) increases in square and boll shed, (3) reductions in numbers of fruiting forms initiated, (4) decreases in weights of seed cotton, seed, and lint per boll, and (5) decreases in fiber length, strength, and micronaire. A reddish leaf mottling of older leaves was a visible characteristic of high Na.
Under field conditions the adverse effects of Na reported herein may be offset by the balancing effects of other ions. However, in light of this study, sodium must be considered to have specific toxic effects on cotton in addition to its osmotic influence. The effect on fiber properties is of particular significance.
