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Crop Science Abstract -

Soil Phosphorus Availability and Pearl Millet Water-Use Efficiency


This article in CS

  1. Vol. 32 No. 4, p. 1010-1015
    Received: Apr 15, 1991

    * Corresponding author(s):
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  1. William A. Payne ,
  2. Drew C. Malcolm,
  3. Lloyd R. Hossner,
  4. Robert J. Lascao,
  5. Arthur B. Onken and
  6. Charles W. Wendt
  1. I CRISAT Sahelian Ctr., B.P. 12404, Niamey, Niger
    D ep. of Horticultural Science
    D ep. of Soil and Crop Sciences, Texas A&M Univ., College Station, TX 77843



Pearl millet [Pennisetum glaucum (L.) R. Br.] production in the West African Sahel is constrained by low, erratic rainfall and low soil nutrient (particularly P) availability. Outdoor pot and growth chamber experiments tested the hypothesis that increasing soil P supply increases transpirational water-use efficiency (WUET), under waterstressed and non-water-stressed conditions. Pearl millet was grown outdoors under semiarid conditions in covered pots containing 85 kg of acid, P-deficient Betis sand (sandy, siliceous, thermic Psammentic Paleustalf). Plants were treated with four P levels and two water treatments, and harvested at 14-d intervals. Significant main and interactive effects on WUET due to P level, water treatment, and time of harvest were found. The slope of the curve relating DM to cumulative transpiration (Tcum) increased with P level and water stress when data from all harvests were pooled. In the growth chamber, WUET of nonwater-stressed plants ranged with increasing P level from 3.22 to 9.12 g kg−1 at 29 days after sowing (DAS) in pots containing 6 kg soil, and from 0.84 to 9.24 g kg−1 at 49 DAS in pots containing 18 kg soil. The ratio of leaf net photosynthetic rate to transpiration 0,WUEGMS,) at 500 μmol m−2 s−1 photosynthetic photon flux density (PPFD) ranged from 1.88μg mg−1 for plants receiving no P to 10.25μg mg−1 for those receiving 0.310 g P 6 kg−1 soil. Between PPFD levels orS00 and 2000 μmol m−2 s−1, plants receiving no P increased WUEGAS to only 3.60 μg mg−1, whereas those receiving higher levels of P increased WUEGAS to as much as 18.2μg mg−1. Our finding that increasing soil P avail° ability increases WUET under water-stressed and non-water-stressed conditions reinforces previous conclusions that water supply in the Sahel and similar semiarid environments cannot be effectively managed for improved crop production without addressing soil fertility constraints.

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