Studies on Coordination of Soil Phosphorus Supply with Photosynthesis of Rice under Different Nutrient Treatments

Abstract

A 4-year field experiment was conducted from 1999 to 2002 to study coordination of soil phosphorus (P) supply with rice (Orzya sativa L.) leaf photosynthesis. Dynamics of soil Olsen P and photosynthetic rate of rice plants were compared among different nutrient treatments. Possible mechanisms were tested by contrasting and analyzing the effectiveness of nutrient treatments on phosphorus absorption, root morphology and root surface phosphatase activity (RSPA). Treatments were four nutrient regimes: (i) control (CK), (ii) exclusively chemical fertilizers (CF), (iii) integration of farmyard manure (FYM) with chemical fertilizers (CM), and (iv) combined application of chemical fertilizers and wheat straw (CS). Results indicated that the combined application of chemical fertilizers and farmyard manure could markedly increase soil Olsen-P at the middle-latter growth stage and the extent to which soil Olsen-P was related with leaf photosynthesis was greatest after booting of rice (R ² = 0.9083, P < 0.01). The integration of inorganic with organic nutrient source, especially FYM also increased RSPA and improved root morphology at the middle-latter growth stage. This ultimately resulted in a greater proportion of phosphorus taken up by rice plant and higher photosynthetic rate during the filling stage, compared to exclusively chemical fertilizers. As a result, the grain yield for the integrated nutrient treatments with FYM significantly increased compared to the exclusively chemical fertilization treatment.

Keywords:

• Anthropogenic soil
• Farmyard manure
• Olsen P
• Photosynthesis
• Rice
• Root surface phosphatase activity
• Soil phosphorus availability

Acknowledgments

This study was financially supported by National Key Project (No. 1999011802) and Chinese Academy of Sciences (KZCX2-413). The authors would like to thank the Changshu Agroecological Experiment Station (CAES), Chinese Academy of Sciences (CAS) for providing experiment site and assistance. I am grateful to Dr Toshiaki Tadano for constructive suggestions and revisions.