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This article in AJ

  1. Vol. 67 No. 5, p. 629-632
    Received: Aug 10, 1974

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Recovery of Leaf Water Potential, Transpiration, and Photosynthesis of Cotton During Irrigation Cycles

  1. H. Bielorai and
  2. P. A. M. Hopmans1



The ability of a plant to recover from temporary and/or prolonged stress and the rate of recovery are of great importance in crop production. However, the information available on this subject is relatively scarce. A study was conducted to evaluate the recovery of irrigated cotton (Gossypium hirsutum L. ‘Acala 15–17’) following soil moisture stress of various durations through the measurements of soil moisture stress (Ψs) using 1) the soil-moisture retention function, leaf water potential (Ψl), by pressure bomb, and 2) leaf diffusion resistance (Rl), by diffusive resistance porometer. Photosynthesis was measured by an infrared gas analyzer, and transpiration by weighing. The experiment was conducted in a controlled climate room. Leaf water potential (Ψl) was linearly related to that in the soil (Ψs) (Ψl = 0.609 Ψs − 9.77 atm). Diffusion resistance of the leaves showed a curvilinear dependence on Ψs with a marked inflection between −10 and −14 atm. Neither leaf resistance nor transpiration fully returned to pre-stress conditions after irrigation, and even the partial recovery required several days. Continuous measurements of net photosynthesis also showed a delayed and only partial recovery from soil water stress. It is concluded that the observed reduction in dry matter increase is due mainly to the failure in net photosynthesis recovery after re-irrigation.

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