caa a22 4500 477109365 CHVBK 20180405111604.0 cr unu---uuuuu 170330e19960301xx s 000 0 eng 10.1007/BF00029275 doi (NATIONALLICENCE)springer-10.1007/BF00029275 Measurement and modelling of photosynthetic response of pearl millet to soil phosphorus addition [Elektronische Daten] [W. Payne, M. Drew, L. Hossner, R. Lascano] 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 major constraint 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 ([CO2]i) decreased from 260 to 92 μL L−1, 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. Kluwer Academic Publishers, 1996 pearl millet nationallicence Pennisetum glaucum (L.) R. Br nationallicence phosphorus nationallicence photosynthesis nationallicence modelling nationallicence Payne W. ICRISAT Sahelian Center, B.P. l2404, Niamey, Niger aut Drew M. Department of Horticultural Science, Texas A and M University, 77843, College Station, TX, USA aut Hossner L. Department of Soil and Crop Sciences, Texas A and M University, 77843, College Station, TX, USA aut Lascano R. Texas Agricultural Experiment Station, Rte 3, Box 219, 79401-9757, Lubbock, TX, USA aut Plant and Soil Kluwer Academic Publishers; gopher://gopher.wkap.nl 184/1(1996-03-01), 67-73 0032-079X 184:1<67 1996 184 11104 https://doi.org/10.1007/BF00029275 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00029275 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Payne W. ICRISAT Sahelian Center, B.P. l2404, Niamey, Niger aut NATIONALLICENCE 700 1- Drew M. Department of Horticultural Science, Texas A and M University, 77843, College Station, TX, USA aut NATIONALLICENCE 700 1- Hossner L. Department of Soil and Crop Sciences, Texas A and M University, 77843, College Station, TX, USA aut NATIONALLICENCE 700 1- Lascano R. Texas Agricultural Experiment Station, Rte 3, Box 219, 79401-9757, Lubbock, TX, USA aut NATIONALLICENCE 773 0- Plant and Soil Kluwer Academic Publishers; gopher://gopher.wkap.nl// 184/1(1996-03-01), 67-73 0032-079X 184:1<67 1996 184 11104 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer