The relationships between carbon isotope discrimination and photosynthesis and rice yield under shading

Document Type: Research Paper

Authors

1 Key Laboratory of Crop Ecophysiology and Farming System in Southwest China, Ministry of Agriculture, Sichuan Agricultural University, Chengdu 611130, China

2 Mianyang Institute of Agricultural Sciences, Mianyang 621023, China.

3 Key Laboratory of Crop Ecophysiology and Farming System in Southwest China, Ministry of Agriculture, Sichuan Agricultural University, Chengdu 611130, China.

Abstract

The measurement of carbon isotope discrimination (∆) provides an integrated insight into the
response of plants to environmental change. To investigate the potential use of ∆ for identifying
shade tolerance in rice, five rice varieties were selected and artificially shaded (53% light
reduction) during the grain-filling period in 2010 and 2011, in Sichuan, China. Shading
treatment had a significant influence on the ∆ of rice organs, resulting in clear increases in the ∆
of stems plus sheaths (∆Sm), rice grains (∆Gm) and rice flour (∆Fm) at maturity, but a reduction
in the ∆ of leaves (∆Lg) at the grain-filling stage. The relationships between ∆ and leaf
photosynthetic and chlorophyll fluorescence characteristics and grain yield showed a close
dependence on plant organs and light regimes. Under shading treatment, photosynthetic rate
was negatively associated with ∆Gm and the ∆ of stems plus sheaths at the grain-filling stage
(∆Sg), whereas ∆Sm was significantly (PPSII (PSII), photochemical quenching (qP) and non-photochemical quenching (NPQ).
Moreover, grain filling and grain weight under shading treatment were positively correlated
with ∆S
g, but negatively related to ∆Sm in 2011. In contrast, a significantly (Passociation between grain weight and ∆Lg was observed in 2010. It was found that lower values
of ∆L
g, ∆Sm and ∆Gm in rice indicated better light-harvesting and light-use capability and also
higher grain filling and grain weight of rice.


Keywords