Nutrient Profiles of Water-Stressed Cotton Grown at Different Temperatures

Judy D. Timpa and Barbara A. Triplett


Nutrient distribution in the cotton plant as it affects fiber quality is under investigation. Nutrient profile changes resulting from different growing temperature or from imposing water stress have been examined. Cotton (Gossypium hirsutum L., Texas Marker-1) was raised in an environmental growth chamber (8'X 12') from germination to harvest under controlled constant temperature (either 25 C or 30 C), relative humidity (60%), and day/night light (10,000 foot candles) conditions of 16/8 hours. Reduced watering (ca. 50% of control treatment by weight) of the stressed plants began at flowering. Well-watered controls were maintained under identical environmental conditions. Flowers were tagged on day of anthesis. The first harvest date was at the time of first boll opening with the second harvest date 30 days later. Assessment of the plant productivity is given by comparison of the highest and lowest values in Table I.

Tagged bolls were removed at harvest for subsequent analysis of fiber properties and cellulose molecular weight distribution determinations. Remaining plant parts were divided into location zones of top, middle, and bottom according to node. Plant parts of mainstem, branches, and leaves for each location were separately analyzed. The position-designated plant parts were dried and ground for X-ray fluorescence analysis and Kjeldahl nitrogen determination. Nitrogen, phosphorus, potassium, calcium, magnesium, silicon, sulfur, aluminum, manganese, iron, copper, zinc, arsenic, and chlorine were monitored.

Statistical analysis of the factors of treatment (water-stressed, control), plant part (leaves, branches, mainstem), location on plant (bottom, middle, top), harvest date (date 1, date 2), and temperature (30 C, 25 C) were carried out. The interactions determined by analysis of variance for those plants grown at constant temperature of 30 C are given in Table II, those grown at 25 C in Table III, while the complete analysis of variance including temperature is presented in Table IV. In cotton the relationship of nutrients and fruiting has been observed such that direct effects on partitioning (vegetative/fruiting) in cotton have been reported for P, K, Ca, Mg, Zn, B, and Na, whereas indirect yield responses are observed for N, S, Mn, and Mo. The ratio of Ca/Mg is related to translocation of carbohydrates. All fifteen of the nutrients measured demonstrated interactions of two factors or greater. Assessment of the data at this stage of analysis indicates that perhaps the complexity of interactions (number of factors in the interaction) is related to the direct or indirect response in cotton in that those elements which have direct effects on partitioning have more complex interactions.

Reprinted from 1990 Proceedings: Beltwide Cotton Production Research Conferences pp. 50 - 51
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998