Rhizosphere soil nitrogenase (C2H2reduction) as influenced by the nitrogen management in intermediate deep water rice

1983 ◽  
Vol 101 (3) ◽  
pp. 547-551 ◽  
Author(s):  
J. L. N. Rao ◽  
B. B. Reddy ◽  
V. Rajaramamohan Rao

SUMMARYIn a field experiment, the influence of different forms and methods of application of urea nitrogen on the rice rhizosphere soil nitrogenase was evaluated under simulated intermediate deep water situations. Nitrogenase was high when the soil received small amounts of nitrogen and phosphorus with a water level of 20–25 cm. Moreover, during and after the flash floods the nitrogenase activity was considerably increased. There was a significant reduction in the nitrogenase activity when the nitrogen was applied to the shallow water through urea briquettes, but when it was applied either behind the plough or between the rows, the activity was stimulated. Increased water level of about 50 cm for prolonged periods considerably reduced the nitrogenase activity. Results indicate that the method of application of urea nitrogen and the water level influenced the rhizosphere soil nitrogenase activity under intermediate deep water situations.

1988 ◽  
Vol 110 (1) ◽  
pp. 53-59 ◽  
Author(s):  
M. D. Reddy ◽  
M. M. Panda ◽  
B. C. Ghosh ◽  
B. B. Reddy

SummaryUnder conditions of semi-deep water (51–100 cm) rice varieties with greater plant height produced more dry matter and grain yield as N fertilizer was increased from 0 to 20 and 40 kg/ha. The varieties which performed better in a situation of slow rise in water level to a depth of 120 cm could not survive a quick rise in water level owing to their lesser plant height and elongation ability. The loss of dry matter (dead and dried leaves) was also greater in varieties susceptible to deep water than varieties tolerant of deep water.With the increase in N fertilizer, there was increase in plant height, number of tillers, dry-matter production and grain yield. The loss of dry matter was less in crops given N fertilizer than in those not given N fertilizer. The varieties capable of producing higher grain yield in response to N fertilizer under semi-deep water did not improve their grain yield under intermediate deep water (15–50 cm). With increase in application of N fertilizer from 0 to 40 kg/ha the N concentration in grain increased. N concentration did not vary in straw under intermediate deep water, there was no definite trend in semi-deep water, and it was higher under conditions of semi-deep than intermediate deep water.


1983 ◽  
Vol 100 (3) ◽  
pp. 637-642 ◽  
Author(s):  
J. L. N. Rao ◽  
I. C. Pasalu ◽  
V. Rajaramamohan Rao

SUMMARYThe effect of pesticides on nitrogenase activity in rhizosphere soil from rice fields was investigated. The differential response of insecticides on nitrogenase depended on the method of field application. Results also showed that the differential response to the pesticides of. specific groups of nitrogen-fixing micro-organisms depended upon the method of application.Soil incorporation of carbofuran stimulated the rhizosphere nitrogenase, while endosulfan and hexachlorocyclohexane inhibited it. Carbofuran and hexachlorocyclohexane stimulated nitrogenase when applied to the standing water. Seedling root dips of isofenphos stimulated nitrogenase, while endosulfan, BPMC and carbaryl showed a variable effect. Quinalphos inhibited nitrogenase irrespective of method of application.


1981 ◽  
Vol 59 (3) ◽  
pp. 473-477 ◽  
Author(s):  
R. N. Mahapatra ◽  
V. Rajaramamohan Rao

1985 ◽  
Vol 83 (2) ◽  
pp. 243-253 ◽  
Author(s):  
M. V. Rao ◽  
B. B. Reddy ◽  
B. C. Ghosh ◽  
M. M. Panda

1984 ◽  
Vol 78 (3) ◽  
pp. 433-435
Author(s):  
J. L. N. Rao ◽  
B. B. Reddy ◽  
V. Rajaramamohan Rao

Water ◽  
2021 ◽  
Vol 13 (18) ◽  
pp. 2590
Author(s):  
Qisheng Li ◽  
Yanqing Han ◽  
Kunquan Chen ◽  
Xiaolong Huang ◽  
Kuanyi Li ◽  
...  

Water level is one of the most important factors affecting the growth of submerged macrophytes in aquatic ecosystems. The rosette plant Vallisneria natans and the erect plant Hydrilla verticillata are two common submerged macrophytes in lakes of the middle and lower reaches of the Yangtze River, China. How water level fluctuations affect their growth and competition is still unknown. In this study, three water depths (50 cm, 150 cm, and 250 cm) were established to explore the responses in growth and competitive patterns of the two plant species to water depth under mixed planting conditions. The results show that, compared with shallow water conditions (50 cm), the growth of both submerged macrophytes was severely suppressed in deep water depth (250 cm), while only V. natans was inhibited under intermediate water depth (150 cm). Moreover, the ratio of biomass of V. natans to H. verticillata gradually increased with increasing water depth, indicating that deep water enhanced the competitive advantage of V. natans over H.verticillata. Morphological adaptation of the two submerged macrophytes to water depth was different. With increasing water depth, H. verticillata increased its height, at the cost of reduced plant numbers to adapt to poor light conditions. A similar strategy was also observed in V. natans, when water depth increased from 50 cm to 150 cm. However, both the plant height and number were reduced at deep water depth (250 cm). Our study suggests that water level reduction in lake restoration efforts could increase the total biomass of submerged macrophytes, but the domination of key plants, such as V. natans, may decrease.


2013 ◽  
Vol 671-674 ◽  
pp. 2674-2678 ◽  
Author(s):  
Yan Yun Zhu ◽  
Xiao Li Zhu ◽  
Fang She Yang

Nitrogen-fixing bacteria were screened from the rhizosphere soil of plants in Shaanxi in China. 36 free-living nitrogen-fixing bacterial strains were isolated and their nitrogenase activity were determined by acetylene reduction assay (ARA), two strains named FLNB03 and FLNB09 with higher nitrogenase activity were isolated and identified by 16S rRNA sequencing. The datum showed that FLNB03 was similar to Acinetobacter and their similarity reached 99%, FLNB09 was similar to Agrobacterium sp. and their similarity reached 99%. Then both of them were treated using Dielectric Barrier Discharge (DBD) plasma for mutation and their mutants called FLNB03-2 and FLNB09-3 were obtained. The nitrogenase activity of FLNB03-2 was 0.61±0.10 nmol•107cfu-1•h-1, and that of FLNB09-3 was 0.40±0.05 nmol•107cfu-1•h-1, their nitrogenase activity increased by 22.00% and 14.29% than their original bacteria respectively. FLNB03-2 and FLNB09-3 might be used as microbial fertilizer.


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