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Water Stress and Stem Radial Contraction of Cotton Plants ( Gossypium hirsutum L.) under Field Conditions 1
Author(s) -
Namken L. N.,
Bartholic J. F.,
Runkles J. R.
Publication year - 1971
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj1971.00021962006300040034x
Subject(s) - water stress , malvaceae , fiber crop , main stem , gossypium hirsutum , agronomy , horticulture , water content , contraction (grammar) , biology , drought stress , botany , endocrinology , geotechnical engineering , engineering
Radial contraction and expansion of cotton plant stems ( Gossypium hirsutum L.) were monitored with linear variable displacement transducers throughout the 1969 and 1970 growing seasons under field conditions. Relative water content and water potential measurements of the leaves were routinely made as indices of water stress of the cotton plant for comparison with stem contraction measurements. The amount of stem radial contraction was directly related to the water‐stress indices of the cotton plant. Stem contraction was more sensitive to plant water stress as stress increased. No contraction occurred until relative water contents were below 79 or 83%, depending on stage of plant growth, or until leaf water potentials were lower than −8.0 bars. The relation between relative water content and stem contraction was influenced by stage of plant growth. A higher degree of plant water stress was required to provide an equivalent radial change during the square and early bloom period when vegetative growth rates were high than during the late bloom and boll development period when vegetative growth rates were low. Stage of plant growth did not affect the relation between leaf water potential and radial stem contraction. Leaf water potential recovered more rapidly than cotton stem contraction. However, the relation was well defined for the desorption phase of the stress cycle from minimum stress in early morning (0600 hr) to maximum stress at about 1400 hr.