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Crop water stress index and yield of water-deficit-stressed alfalfa


Hattendorf, M. J. and Carlson, R. E. and Abdul Halim, Ridzwan and Buxton, D. R. (1988) Crop water stress index and yield of water-deficit-stressed alfalfa. Agronomy Journal, 80 (6). pp. 871-875. ISSN 0002-1962; ESSN: 1435-0645

Abstract / Synopsis

The yield relationship of water-deficit-stressed alfalfa (Medicago sativa L.) with the Crop Water Stress Index (CWSI) may be dynamic over the alfalfa harvest period. This investigation was conducted to define the alfalfa yield-CWSI relationship(s), to test possible advantages of using the CWSI over the canopy-minus-air temperature (Tc−Ta) differential, and to combine the yield-CWSI relationship with a growth function. ‘Apollo 11’ alfalfa was grown for 2 yr in 100-L containers set into the ground and protected from rain by a movable shelter. The soil was a Nicollet silt loam topsoil (fine-loamy, mixed, mesic Aquic Hapludoll). Treatments were irrigation levels of 112, 100, 88, 77, and 65% field capacity. Five harvests were taken at 7-d intervals beginning 21 d after an initial clipping. Canopy temperatures were taken daily with an infrared thermometer. A series of exponential yield-CWSI curves resulted from the sequential harvests. Yield reductions of about 10 and 20% resulted from mean CWSI of 0.05 and 0.10, respectively, over 42-d periods. The Gompertz growth function was modified for water-deficit-stress by combining it with the exponential yield-CWSI relationship. Vapor-pressure deficit (VPD) effectively normalized the Tc−Ta data, allowing yield data of the 2 yr to be combined in the yield-mean CWSI relationship. Yield and Tc−Ta data not normalized for VPD showed clear separation by year for slight VPD differences. Alfalfa yield response to water-deficit-stress over time appeared to be adequately described by the combined Gompertz function and the yield-CWSI (Tc−Ta normalized for VPD) curves

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Additional Metadata

Item Type: Article
Divisions: Universiti Pertanian Malaysia
Faculty of Environmental Studies
Publisher: American Society of Agronomy
Keywords: Water-deficit-stressed alfalfa; Crop water stress index
Depositing User: Azhar Abdul Rahman
Date Deposited: 11 Aug 2015 13:48
Last Modified: 11 Aug 2015 13:48
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