PHOTOSYNTHETICA

Photosynthetica 2014, 52(3):397-403 | DOI: 10.1007/s11099-014-0043-8

Rice varietal differences in responses of stomatal gas exchange to supplemental nitrogen application

S. Shimoda^1,*, A. Maruyama²

¹ National Agriculture and Food Research Organization, Hokkaido Agricultural Research Center, Shinsei-Minami, Memuro, Kasai, Hokkaido, Japan

² National Agriculture and Food Research Organization, Agricultural Research Center, Ibaraki, Japan

In the field, supplemental application of N fertilizer to rice (Oryza sativa) shortly before the beginning of heading stage increases leaf N content and enhances photosynthesis during the grain-filling period. In search of varietal differences in leaf gas exchange in response to supplemental N application, we examined 13 rice varieties grown in the field during two successive years. The varieties included japonica and indica varieties, both of which are widely grown in Japan. The response to supplemental N application could not be separated clearly between variety groups; some of the japonica varieties, but none of the indica varieties, exhibited significant increase in stomatal conductance (g _s) after supplemental N application. Supplemental N was more effective to increase stomatal aperture in the varieties with inherently lower g _s. Varieties that showed greater response of g _s to supplemental N application might be able to adjust their stomatal aperture with appropriate N control. Although the internal-to-ambient CO₂ mole fraction ratio and the leaf carbon isotopic composition (δ¹³C) differed among varieties as a result of variations in stomatal aperture and the CO₂ requirement of mesophyll, supplemental N application barely influenced these parameters, because it only moderately affected stomatal aperture. Since δ¹³C tended to increase with increasing number of days from transplantation to heading stage in japonica varieties, δ¹³C values were more sensitive to differences in growth rate between years than to N application.

Keywords: carbon discrimination; genotype; leaf nitrogen; nitrogen fertilization; stomatal conductance; yield

Received: March 25, 2013; Accepted: December 10, 2013; Published: September 1, 2014Show citation