In:
Plant Physiology, Oxford University Press (OUP), Vol. 130, No. 4 ( 2002-12-01), p. 1999-2010
Abstract:
Acclimation to irradiance was measured in terms of light-saturated photosynthetic carbon assimilation rates (Pmax), Rubisco, and pigment content in mature field-grown rice (Oryza sativa) plants in tropical conditions. Measurements were made at different positions within the canopy alongside irradiance and daylight spectra. These data were compared with a second experiment in which acclimation to irradiance was assessed in uppermost leaves within whole-plant shading regimes (10% low light [LL], 40% medium light [ML] , and 100% high light [HL] of full natural sunlight). Two varieties, japonica (tropical; new plant type [NPT] ) and indica (IR72) were compared. Values for Rubisco amount, chlorophyll a/b, and Pmax all declined from the top to the base of the canopy. In the artificial shading experiment, acclimation of Pmax (measured at 350 μL L−1 CO2) occurred between LL and ML for IR72 with no difference observed between ML and HL. The Rubisco amount increased between ML and HL in IR72. A different pattern was seen for NPT with higher Pmax (measured at 350 μL L−1CO2) at LL than IR72 and some acclimation of this parameter between ML and HL. Rubisco levels were higher in NPT than IR72 contrasting with Pmax. Comparison of data from both experiments suggests a leaf aging effect between the uppermost two leaf positions, which was not a result of irradiance acclimation. Results are discussed in terms of: (a) acclimation of photosynthesis and radiation use efficiency at high irradiance in rice, and (b) factors controlling photosynthetic rates of leaves within the canopy.
Type of Medium:
Online Resource
ISSN:
1532-2548
,
0032-0889
Language:
English
Publisher:
Oxford University Press (OUP)
Publication Date:
2002
detail.hit.zdb_id:
2004346-6
detail.hit.zdb_id:
208914-2
SSG:
12
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