ABSTRACT
The increasing human population requires greater rice production and methane is the second most potent greenhouse gas emitted from rice soils under anaerobic conditions. To address this, an experiment was carried out in two phases. In the first phase of the experiment, Si content accessed in the rice index leaves and recorded the mean values of 2.50, 2.48, 2.51 and 2.43% at Jagtial, Warangal, Rajendranagar and Rudrur varietal display plots in Telangana. For the second phase of field experiment, one with high Si (JGL-3855) and another with low Si (RNR-2354) content genotypes were selected with each four levels of N (0, 80, 120 & 160 kg ha-1) and Si (0, 200, 400 & 600 kg ha-1) in strip plot design. Conjunctive application of N and Si to both genotypes, JGL-3855 recorded significantly higher grain and straw yield compared to RNR-2354, among the different combinations of Si and N, application 160 kg N + 600 kg Si ha-1 recorded significantly higher grain and straw yields (7180 and 9693 kg ha-1). The treatments which received a higher dose of Si@600 kg ha-1 in combination with N@ 80, 120 and 160 registered the lower emission of methane@ 25.7, 24.6 and 24.3 mg m-2 hr-1 and there was a significant scaling down of pest and disease incidence was noticed in treatments wherever increased Si doses (0, 200, 400 and 600 kg ha-1) were included.
ABSTRACT
Aims: Paddy field is one of the sources of greenhouse gasses such as methane (CH4) and nitrous oxide (N2O), which causes global warming and other negative effects in agricultural sector. An alternative to optimize paddy productivity and reduce emissions of CH4 and N2O is by using methanotrophic bacteria and Ochrobactrum anthropi BL2. Methodology and results: This study consisted of two parts, i.e. positive control and experimental treatments. Positive control consisted of 250 kg/ha NPK inorganic fertilizer NPK (15:15:15) (100% of the recommended normal dose) without any methanotrophic bacteria. Meanwhile the experimental treatment consisted of 50 kg/ha inorganic fertilizers NPK (20% of the recommended normal dose) with methanotrophic bacteria (Methylocystis rosea BGM 1, M. parvus BGM 3, Methylococcus capculatus BGM 9, Methylobacter sp. SKM 14) and N2O reducing bacteria (Ochrobactrum anthropi BL2). Using weight indicator of 1000 grams, all the bacteria are capable of increasing paddy productivity by 42.07%, compared to conventional method which can only increase the productivity by 2.51% (Cepy and Wangiyana, 2011). The increasing productivity and growth of paddy plants were due to the nitrogen fixation activity of M. rosea BGM 1, M. capculatus BGM 9, and Methylobacter sp. SKM 14. In the experimental treatment using bacteria, the emission of CH4 and N2O was reduced with the highest CH4 and N2O sinks of 24018.8 mol CH4/day/ha and 68.48 mol N2O/day/ha, respectively. However, the positive control treatment with 100% of the recommended fertilizer dose showed the highest CH4 and N2O emissions which were up to 74346.45 mol CH4/day/ha and 26.21 mol N2O/day/ha, respectively. Conclusion, significance and impact study: All the methanotropic bacteria and O. anthropi BL2 are significantly increase paddy production, compared to positive control treatment. The addition of bacteria in paddy fields results in CH4 and N2O sinks.