Kyi Moe

Effects of co-inoculation of Bradyrhizobium japonicum SAY3-7 and Streptomyces griseoflavus P4 on plant growth, nodulation, nitrogen fixation, nutrient uptake, and yield of soybean in a field condition

ABSTRACT Co-inoculation of nitrogen-fixing bacteria with plant growth-promoting bacteria has become more popular than single inoculation of rhizobia or plant-growth-promoting bacteria because of the synergy of these bacteria in increasing soybean yield and nitrogen fixation. This study was conducted to investigate the effects of Bradyrhizobium japonicum SAY3-7 and Streptomyces griseoflavus P4 co-inoculation on plant growth, nodulation, nitrogen fixation, nutrient uptake, and seed yield of the ‘Yezin-6’ soybean cultivar. Nitrogen fixation was measured using the acetylene reduction assay and ureide methods. Uptake of major nutrients [nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg)] was also measured. This study showed that single inoculation of SAY3-7 significantly increased shoot biomass; nodulation; Relative Ureide Index (RUI %), percent nitrogen derived from N fixation (% Ndfa); N, P, K, Ca, and Mg uptakes; during the later growth stages (R3.5 and R5.5), compared with control. These observations indicate that SAY3-7 is an effective N-fixing bacterium for the plant growth, nodulation, and nitrogen fixation with an ability to compete with native bradyrhizobia. Co-inoculation of SAY3-7 and P4 significantly improved nodule number; nodule dry weight; shoot and root biomass; N fixation; N, P, K, Ca, and Mg uptake; at various growth stages and seed yield in ‘Yezin-6’ soybean cultivar compared with the control, but not the single inoculation treatments. Significant differences in plant growth, nodulation, N fixation, nutrient uptake, and yield between co-inoculation and control, not between single inoculation and control, suggest that there is a synergetic effect due to co-inoculation of SAY3-7 and P4. Therefore, we conclude that Myanmar Bradyrhizobium strain SAY3-7 and P4 will be useful as effective inoculants in biofertilizer production in the future.

Symbiotic effectiveness of different indigenous Bradyrhizobium strains on selected Rj-genes harboring Myanmar soybean cultivars

Many scientists are working to identify effective strains of rhizobia to increase nitrogen fixation and reduce nitrogen fertilizer application. Symbiotic nitrogen fixation of leguminous crops has become an alternative to nitrogenous fertilizer, due to its higher efficiency for nitrogen fixation. This experiment was conducted to select strains for improved nitrogen fixation of soybean (Glycine max L.). Bradyrhizobium strains isolated from Myanmar were evaluated for symbiotic efficacy, using the cultivar Yezin-6 (non-Rj). Five Bradyrhizobium strains, B. japonicum SAY3-7, B. elkanii AHY3-1, B. liaoningense SMY3-1, Bradyrhizobium spp. AHY3-6 and B. yuanmingense SMY6-10 were shown to have superior nitrogenase activity. These five strains were evaluated for their effectiveness on different Rj-genes in soybean cultivars. The nitrogen fixation of B. japonicum SAY3-7, B. elkanii AHY3-1 and B. liaoningense SMY3-1 were higher than other indigenous strains and the standard strain, B. japonicum USDA110. This was particularly the case for the cultivars Yezin-6 (non-Rj) and Yezin-11 (Rj4), but not for the cultivarsYezin-9 (Rj3) and Yezin-10 (Rj2Rj3). Bradyrhizobium japonicum SAY3-7, B. elkanii AHY3-1 and B. liaoningense SMY3-1 were also evaluated on Yezin-8 (non-Rj) and Yezin-3 (Rj4). Bradyrhizobium japonicum SAY3-7 had significantly higher nitrogenase activity on Yezin-8 (non-Rj), although B. japonicum SAY3-7 was not significantly different than B. elkanii AHY3-1 and B. liaoningense SMY3-1 on Yezin-3 (Rj4). Therefore, B. japonicum SAY3-7, which was the most effective nitrogen fixing strain in all the experiments, was selected for inoculant production. According to this study, it can be concluded that the strains were specific to cultivars and,thus, selection of a strain compatible to a specific cultivar is necessary to increase symbiotic nitrogen fixation. Key words: Bradyrhizobium strains, Myanmar, nitrogenase activity, Rj-genes, soybean.

Effects of Pretransplant Basal and Split Applications of Nitrogen on the Growth and Yield of Manawthukha Rice

A field experiment was conducted to investigate the effects of pretransplant basal (surface application, BSF, and incorporation methods, BIC) and split applications of nitrogen (N) on the growth and yield parameters of rice. Using 120 kg N ha−1 except (N0, control), different percentages of N rate were applied at basal, tillering, and panicle initiation in five N split treatments. Growth parameters and dry matter were greater in BIC than BSF until panicle initiation stages. Among N split applications, N2 (25:50:25) using low basal surface N was optimized for maximum dry matter and yield. With large incorporated basal N, N1 (50:25:25) obtained greater dry matter and yield but did not differ from N4 (50:50:0). With omitted N at tillering, N5 (50:0:50) did not increase rice yield or dry matter by either method. This study highlighted that N split-application patterns affect the growth and yield parameters of Manawthukha rice.

NPK Accumulation and Use Efficiencies of Manawthukha Rice (Oryza sativa L.) Affected By Pretransplant Basal and Split Applications of Nitrogen

We investigated the effects of split applications of nitrogen (N) on N, phosphorus, and potassium (NPK) uptake and use efficiency of rice under basal surface-application and incorporation methods. Different amounts of N were applied at the basal, tillering, and panicle initiation stages in five N split treatments. Basal incorporation provided greater NPK uptake than basal surface application until initiation of the panicle. In basal surface application, N2 (25:50:25) resulted in the greatest total NPK uptake, use efficiency, and N recovery efficiency. In basal incorporation, N1 (50:25:25) resulted in greater values for all parameters. The N5 (50:0:50), which included omitting N at tillering, resulted in low N recovery efficiency and uptake, both under basal incorporation and basal surface application. These results emphasize that split applications of N influence N recovery efficiency and total NPK uptake and use efficiency of rice.

Effects of co-inoculation of Bradyrhizobium elkanii BLY3-8 and Streptomyces griseoflavus P4 on Rj4 soybean varieties

ABSTRACT Co-inoculation of selected nitrogen-fixing bacteria with plant growth-promoting bacteria is the promising way for the improvement of soybean production through enhancing plant growth, nodulation, and N2 fixation. Therefore, this experiment was conducted to study the effects of co-inoculation of Bradyrhizobium elkanii BLY3-8 with Streptomyces griseoflavus P4 on plant growth, nodulation, N2 fixation, N uptake, and seed yield of Rj4 soybean varieties. Two experiments with completely randomized design and three replicates were done in this study. N2-fixation ability of soybean was evaluated by acetylene reduction activity (ARA) and relative ureide method. In the first experiment, synergetic effect in N2 fixation and nodulation was occurred in co-inoculation treatment (BLY3-8 + P4) in Yezin-3 and Fukuyutaka. Based on these results, co-inoculation effect of BLY3-8 and P4 was assessed on Yezin-3 and Fukuyutaka varieties at three different growth stages, using Futsukaichi soil under natural environmental conditions. This study shows that co-inoculation of BLY3-8 and P4 significantly increased N2 fixation at V6 stage; plant growth, nodulation, N2 fixation, and N uptake at R3.5 stage; and shoot growth, N uptake, and seed yield at R8 stage, in Rj4 soybean varieties compared with the control. Significant difference in plant growth, nodulation, N2 fixation, N uptake, and yield between co-inoculation and control, not between single inoculation and control, suggests that there is a synergetic effect due to co-inoculation of BLY3-8 and P4.

Effects of Fermented Nori ( Pyropia yezoensis ) Seaweed Liquid Fertilizers on Growth Characteristics, Nutrient Uptake, and Iodine Content of Komatsuna ( Brassica rapa L.) Cultivated in Soil

We investigated the effects of fermented nori (Pyropia yezoensis) liquid fertilizers on plant growth, soil plant analysis development (SPAD) values, and nutrient uptake of komatsuna (Brassica rapa L. var. wakana komatsuna) plants. The four types of fermented nori seaweed liquid fertilizers (SLFs) evaluated in this study were prepared by anaerobic fermentation of unwashed nori (SLF1), aerobic fermentation of unwashed nori (SLF2), anaerobic fermentation of washed nori (SLF3), and aerobic fermentation of washed nori (SLF4). In Experiment 1, the highest plant growth, SPAD, and nutrient uptake values were obtained from treatment with SLF2 and SLF4. There were no significant differences between the effects of basal and foliar application of SLFs, except for iodine (I) content; plants treated with SLF1 had the highest I content. In Experiment 2, plant growth and nutrient uptake decreased with higher concentrations of SLFs. Plants treated with 25% SLF2 + 75% chemical fertilizer (CF) or 25% SLF4 + 75% CF exhibited significantly higher plant growth and nutrient uptake. The highest I content resulted from treatment with 75% SLF1 + 25% CF or 100% SLF1. Taken together, our results showed that 25% SLF + 75% CF produced the best plant growth characteristics, nutrient uptake, and I content relative to the controls. Therefore, basal application of these liquid organic fertilizers can be used to increase productivity, nutrient uptake, and I content and to reduce nitrate-nitrogen content in komatsuna production.