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Measurement and modelling of photosynthetic response of pearl millet to soil phosphorus addition

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Relation http://oar.icrisat.org/7616/
http://dx.doi.org/10.1007/BF00029275
 
Title Measurement and modelling of photosynthetic response of pearl millet to soil phosphorus addition
 
Creator Payne, W A
Drew, M C
Hossner, L R
Lascano, R J
 
Subject Millets
Soil Science
 
Description There have been no studies of the effects of soil P deficiency on pearl millet (Pennisetum glaucum (L.) R. Br.)
photosynthesis, despite the fact that P deficiency is the majorxonstraint to pearl millet production in most regions
of West Africa. Because current photosynthesis-based crop simulation models do not explicitly take into account
P deficiency effects on leaf photosynthesis, they cannot predict millet growth without extensive calibration. We
studied the effects of soil addition on leaf P content, photosynthetic rate (A), and whole-plant dry matter production
(DM) of non-water-stressed, 28 d pearl millet plants grown in pots containing 6.00 kg of a P-deficient soil. As soil
P addition increased from 0 to 155.2 mg P kg- 1 soil, leaf P content increased from 0.65 to 7.0 g kg-1 . Both A and
DM had maximal values near 51.7 mg P kg- 1 soil, which corresponded to a leaf P content of 3.2 g kg- 1. Within
this range of soil P addition, the slope of A plotted against stomatal conductance (gs) tripled, and mean leaf internal
CO2 concentration ([CC^];) decreased from 260 to 92 pL L~'., thus indicating that P deficiency limited A through
metabolic dysfunction rather than stomatal regulation. Light response curves of A, which changed markedly with
P leaf content, were modelled as a single substrate, Michaelis-Menten reaction, using quantum flux as the substrate
for each level of soil P addition. An Eadie-Hofstee plot of light response data revealed that both Km, which is
mathematically equivalent to quantum efficiency, and Vmax, which is the light-saturated rate of photosynthesis,
increased sharply from leaf P contents of 0.6 to 3 g kg-1 , with peak values between 4 and 5 g P kg-1 . Polynomial
equations relating Km and Vmax, to leaf P content offered a simple and attractive way of modelling photosynthetic
light response for plants of different P status, but this approach is somewhat complicated by the decrease of leaf P
content with ontogeny.
 
Publisher Springer International Publishing
 
Date 1996
 
Type Article
PeerReviewed
 
Format application/pdf
 
Language en
 
Rights —
 
Identifier http://oar.icrisat.org/7616/1/Plant%20and%20Soil_184_67-73_1996.pdf
Payne, W A and Drew, M C and Hossner, L R and Lascano, R J (1996) Measurement and modelling of photosynthetic response of pearl millet to soil phosphorus addition. Plant and Soil, 184 (1). pp. 67-73. ISSN 0032-079X