A study of lint and seed development in cotton as influenced by environmental factors

Studies were made to determine the influence of soil type, climatic conditions, and soil moisture on the development of lint and seed in cotton. Plants were grown in two very different types of soils in large galvanized iron cans to study the influence of soil type. For studying climatic and soil moisture responses plants were grown in the field, protected against rainfall, and irrigated at different intervals. Determinations were made on each boll for length of lint, weight of boll, number of seeds, weight per seed, weight of lint per seed, weight of lint per unit weight of seed, and percentage of lint. Soil type did not affect any of the characters studied. Cotton grown in soil from the Mississippi Delta produced lint and seed which were in all respects like that grown in Norfolk sandy loam soil from Alabama. Temperature, humidity, and evaporation had no measurable influence on the characters of seed cotton. Apparently cotton can tolerate the extremes of any of these encountered during this test without being adversely affected. The amount of available moisture in the soil was the only factor studied which influenced the development of lint and seed in cotton. The influence of soil moisture may be briefly summarized as follows: 1. The length of lint was markedly affected by the amount of soil moisture. A low moisture content caused a short lint to be formed. The critical period in the elongation of lint was for approximately 16 days, beginning on the date of blossoming. It was possible to reduce the length of lint at least 3 mm (1/8 inch) by reducing the soil moisture to a critical point. There appeared to be a certain minimum and maximum length of lint for this strain of cotton. 2. The weight per boll, weight per seed, weight of lint per seed, and lint index were reduced by a lack of soil moisture. The critical period in determining these characters extended from 1 to 42 days after blossoming. 3. The percentage of lint and the weight of lint per unit weight of seed were increased by a deficiency in soil moisture. The period during which the lint percentage and the weight of lint per unit weight of seed were determined extended 1 to 42 days after blossoming. The percentage of lint varied less with soil moisture changes than did the lint index. 4. The number of seed per boll was not markedly dependent on the environmental conditions. There was a tendency for the number to be reduced by extremely drouthy conditions. A heavy boll was largely due to an increase in the weight per seed and weight of lint per sm. 5. Favorable soil moisture conditions produced heavy bolls with a long lint, heavy seed, large lint index, and low percentage of lint.