Characterization of Coleus x hybridus Voss. 'Goldbound' water requirements
Al-Hemaid, Abdalrahman
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https://hdl.handle.net/2142/19287
Description
Title
Characterization of Coleus x hybridus Voss. 'Goldbound' water requirements
Author(s)
Al-Hemaid, Abdalrahman
Issue Date
1995
Doctoral Committee Chair(s)
Spomer, L. Art
Department of Study
Crop Sciences
Discipline
Horticulture
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Biology, Plant Physiology
Language
eng
Abstract
Plant water deficit is the major factor limiting global crop productivity. Yield loss caused by water stress is estimated to exceed total loss from all other causes. Moreover, availability of agricultural water is declining worldwide because of increasing demand and decreasing quality. Consequently, knowledge of plant water requirement is mandatory for increasing water use efficiency and reducing ground water pollution.
This study intended to determine Coleus x hybridus Voss. 'Goldbound' water requirement based on physiological responses most directly related to yield--expansion, stomatal conductance, net photosynthesis, dark respiration, and survival(injury). Fully-expanded, mature leaves proved the most representative and consistent indicators of whole plant water status as measured with a pressure chamber and vapor pressure osmometer. The most consistent time for water status measurement was at night or under other low transpiration conditions.
Coleus survived dehydration up to 6 days with no perceptible injury, and 46 days based on ability to resume growth. Leaf expansion proved most sensitive to dehydration and even ceased before wilting could be perceived. Stomatal conductance and subsequent reduced intercellular CO$\sb2$ level was decreased next followed by net photosynthesis, which ceased at a water potential of $-$0.72 MPa. Although reduced, dark respiration never stopped throughout the water deprivation period. Leaf abscission began at very low water potential with all mature leaves eventually lost at $-$1.05 MPa.
Coleus appeared to develop morphological and physiological resistance to subsequent dehydration when subjected to water deficits less than or equal to about $-$0.65 MPa.
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