Abstract
ABSTRACTAn effective strategy for increasing crop production is increasing the rate of photosynthesis. In this study, we conducted gas exchange and chlorophyll fluorescence measurements for a high-yielding rice cultivar, Takanari, to identify the leaf physiological properties that contribute to high capacity for photosynthesis of the uppermost leaves before (panicle initiation stage) and after heading (grain-filling stage) in the Tsukuba free-air CO2 enrichment (FACE) facility. The higher photosynthesis rate of Takanari compared with that of the commonly cultivated cultivar, Koshihikari, was mainly attributed to the greater stomatal conductance for CO2 (gsc) at the panicle initiation stage and to the greater mesophyll conductance (gm) at the grain-filling stage in both current and elevated atmospheric CO2 concentrations [CO2]. Takanari had a higher level of leaf nitrogen content (Nl) compared with Koshihikari at the grain-filling stage, which led to greater gm and maximum carboxylation rate (Vc,max), but Nl alone did not explain the variations of gm within the variety. A clear correlation was found between Vc,max and Nl. Calculating Vc,max taking gm into consideration removed the artifact of Vc,max25 in relation to Nl that was observed when gm was assumed to be infinite. Our results emphasize the need to separate the roles of Vc,max and gm to accurately understand the ecophysiological processes that control leaf photosynthesis in Takanari.
Highlights
In the face of the world’s growing population, global crop production needs to be increased
Using a newly-released photosynthesis system (LI-6800, LICOR, USA), this study aims to redefine the physiological traits of Takanari and determine why Takanari has a high rate of leaf photosynthesis
Takanari had a higher An than Koshihikari under both CO2 treatments and in both panicle initiating and grain-filling stages (Figure 1(a,b) and Table 2)
Summary
In the face of the world’s growing population, global crop production needs to be increased. Increasing the rate of photosynthesis is one strategy to increase crop production These changes do not impact the academic content of the article. Supplemental data for this article can be accessed here.
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