Nitrogen nutrition and use efficiency in rice as influenced by crop establishment methods, cyanobacterial and phosphate solubilizing bacterial consortia and zinc fertilization

ABSTRACT

A field experiment was conducted at the ICAR-Indian Agricultural Research Institute, New Delhi during wet season of 2013 and 2014, involving three crop establishment methods (CEMs) viz. puddled transplanted rice (PTR), system of rice intensification (SRI), and aerobic rice system (ARS). Three rates of nitrogen (N) and phosphorus (P) application (0%, 75%, and 100% of recommended dose of N and P) (RDN) (120 kg N ha^–1 and 25.8 kg P ha^–1) and two sources of N and P (fertilizer and cyanobacterial-bacterial inoculation) were tested with and without zinc (Zn) fertilization in all CEMs. The concentration of N in PTR and SRI was significantly higher than ARS with higher uptake of 10.3 and 11.1 kg ha^–1 in PTR and SRI over ARS. Treatment with 100% RDN led to significantly higher N availability and uptake than 75% RDN and absolute control, i.e. 14.5 and 32.0 kg ha^–1, respectively. Application of Anabaena-Pseudomonas biofilm formulation (MC2) in conjunction with 75% RDN increased total uptake of N by 12.7 kg ha^–1 compared to 75% RDN only. A positive correlation was found between N concentration and acetylene reductase activity at 70 days after sowing (DAS) (R² = 0.52) and 100 DAS (R² = 0.38) based on mean of 2 years study. Zn fertilization significantly increased N concentration in rice straw and milled rice irrespective of the crop establishment methods. Our study signifies the importance of microbial inoculation, optimal N fertilization along with SRI and PTR as more effective crop establishment methods for deriving greater benefits in terms of N nutrition in rice.

KEYWORDS:

• Acetylene reductase activity
• aerobic rice system
• Anabaena-Pseudomonas (An-Ps) biofilmed formulations
• nitrogen

Acknowledgments

The first author duly acknowledges ICAR-Indian Agricultural Research Institute, New Delhi (India) for providing financial support in the form of Senior Research Fellowship during his PhD degree program. Authors would also like sincerely thanks to Head and Professor, Division of Agronomy, ICAR-Indian Agricultural Research Institute, New Delhi, India for providing facilities required for field experiment.