EFFECT OF RHIZOBIUM SEED INOCULATION AND NITROGEN FERTILIZER ON THE GROWTH OF GREEN GRAM, BENGAL GRAM AND GROUNDNUT CROPS

About Authors:
Dr. M.B.SULOCHANA, PRASHANTH GADGI
Department of Biotechnology,
Gulbarga University,
Gulbarga, Karnataka,India

ABSTRACT
To determine the effect of rhizobium inoculation and nitrogen fertilizer on performance of Green gram, Bengal gram and Groundnut. Investigations were done in pot culture experiment under natural conditions. The research material consists of Green gram, Bengal gram and Groundnut varieties with treatment of seeds and Nitrogen fertilizer at 60kg/ha for green gram and Bengal gram, 120kg/ha for Groundnut. These treatments were compared against control (no inoculation). Data were recorded on Plant Growth parameters (seed germination, nodulation index, plant height at maturity, wet weight and dry weight) and soil nitrogen levels at the end of experiment. Among all treatments plant with seed inoculation was found effective in all three legume varieties compared to soil with nitrogen fertilizer and control.

Reference Id: PHARMATUTOR-ART-1219

INTRODUCTION
There is a great possibility to increase production of legume plants by exploiting better colonization of their root and rhizosphere through rhizobial inoculation, which can fix atmospheric nitrogen and protect nature from pollution. Legumes, has the ability to fix atmospheric nitrogen through symbiotic association with Rhizobia. The ability of symbiotic fixation may offer an opportunity to improve nitrogen status of the soil and crop productivity under rainfed conditions.
Traditional use of chemical fertilizers in agriculture production can not be over emphasized. The cost of chemical fertilizers is becoming un-affordable for the farmers of rainfed areas in addition to creating soil and water hazards. There is great need to supplement or substitute chemical fertilizers with organic manures or to explore biological means to improve the soil health. The organic manures are not available in the Bidar region and what ever is available, the people use it as fire wood rather than to use it for soil fertility. Therefore, there is need to explore the potential of Rhizobia as legume inoculants under agro climatic conditions of the Bidar region.
Rhizobium spp. invades the root hairs of legumes and result in the formation of nodules, where free air nitrogen is fixed. These bacteria, although present in most of the soils vary in number, effectiveness in nodulation and N-fixation. It has been argued that usual native soil rhizobial populations are inadequate and are ineffective in biological nitrogen fixation. To ensure an optimum rhizobial population in the rhizosphere, seed inoculation of legumes with an efficient rhizobial strain is necessary. This helps improve nodulation, N2 -fixation solicit crop growth and yield of leguminous crops (Henzell, 1988).
Rhizobia is one of the dominant symbiotic nitrogen fixing bacteria with legumes but a number of factor including low number of Rhizobia and ineffective native Rhizobia lead to poor nodulation and nitrogen fixation in legumes. Legume and Rhizobium symbiosis contributes at least 90 x 106 metric tonnes of N per year all over the world (Subba Rao, 1982). Many researchers carried out experiments on rhizobium inoculation with and without fertilizers on legume crops (Malik et al., 2002; Ashraf, 2003; Hayat et al., 2004; Muhammad et al., 2004; Nadeem et al., 2004) and found increased nitrogen contents of seed, number of nodules, yield and yield components.
Singh and Tarafdar (2001), Hoque and Haq (1994) and Khurana et al. (1995) have recorded significantly increased yield of lentil by inoculating with Rhizobium compared with uninoculated plants receiving no nitrogen fertilizer. Although lots of studies are already being conducted else where on the subject but the soil is diversified and dynamic nature. In rapidly changing climatic conditions it is imperative to study the effectiveness of rhizobia in fixing atmospheric N and its subsequent effect on legume crop in a given soil. Therefore, a new study on scientific lines on the Rhizobium inoculation to generate latest information in order to reduce the costly inputs of fertilizers may prove helpful for the farming community of Bidar.
In view of the above facts, a study was conducted with objective to compare Rhizobiuminoculation methods on the performance of Green gram,Bengal gram and groundnut crops under rainfed conditions of Bidar regions.

MATERIALS AND METHODS
For evaluating the response of Grenn gram,Bengal gram,Groundnut to seed inoculation with Rhizobium and use of Nitrogen fertilizer,a pot culture experiment was conducted under natural conditions.The plants were sown by using ten seeds per pot and 5kg of sterlised soil (autoclave) was added in each pot.Nitrogen fertilizer at 33.3g per pot(50 kg per ha) for Green gram and Bengal gram,80g per pot(120kg per ha) for Ground nut were applied in the form of Diammonium phosphate (DAP).DAP was used because of large scale application of this fertilizer on pulses in Bidar (Karnataka) region.Fertiliser were applied at the time of sowing.For seed inoculation,seeds were coated with paste of rhizobium inoculum containing 10^{7­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­ ­}cells per gram and soen in pots. All agronomic practice were kept uniform and normal for all treatments.Total of Nine treatments as three each for Green gram,Bengal gram and Groundnut were done.Three Controls,Three seed inoculated and three Nitrogen fertilizer added were used. Experiment was carried out for seven weeks. Data on seed germination, nodulation index, plant height at maturity,wet weight and dry weight was recorded. Five plants were randomly selected and uprooted from pot and washed in tap water. Then plants height and wet weight were recorded. Dry weights of these plants were recorded after keeping them in hot air oven at 60 ⁰C for 8 hours.Nodules from seed inoculated plant were removed from root with the help of a sterlised blade and rhizobial cells were isolated by squash method. Soil nitrogen levels were monitored in each pot using soil testing kit at the end of experiment.

RESULTS
Seed germination (Table I) wass observed earilier in Green gram (3 Days), later in Bengal gram (4 Days) and then in Groundnut (8 Days).However seed inoculation with rhizobium and Nitrogen fertilizer found to have no significant role in seed germination.May be the, seed quality and soil humidity, rather than nutrition available for plants play important role in seed germination.
Seed inoculation with rhizobium was significantly increased the plant growth as compared to Nitrogen fertilizer added and control in all three crops (Table II, III and IV).
Seed inoculation with rhizobium and nitrogen fertilizer was significantly increased the Wet weight of crops as compared to control. Maximum Wet weight (4.9 g) was observed in Ground nut seed inoculation comparing to Green gram (1.6 g) and Bengal gram (2.85 g).Soil with Nitrogen fertilizer added was also shown significant increase in Wet weight of crops as compared to control. Lowest wet weight was recorded in the control crops.
Dry weight of crops was significantly affected by Rhizobium inoculation and nitrogen fertilizer added as compared to control. Maximum dry weight (1 g) was observed in Groundnut compared to Green gram (310 mg) and Bengal gram (382 mg). Soil with Nitrogen fertilizer added was also shown significant increase in Wet weight of crops as compared to control. Lowest wet weight was recorded in the control crops.

Application of seed inoculation significantly affected plant height.The maximum plant height (43.6 cm) was observed in Bengal gram seed inoculation as compared to Green gram (30.2 cm ) and Ground nut (40.9 cm).Nitrogen fertilizer added also shown significant plant height (42.2 cm) in Bengal gram, (38.6 cm) in Green gram and (28.2 cm) in ground.Lowest was recorded in controls. These results are in line with the findings of Patra and Bhattacharyya (1998), who reported that seed inoculated plants exhibited significantly greater root and shoot length as compared to un-inoculated control plants.
The highest number of nodules per plant (38) was observed in seed inoculation of Groundnut comparing to Green gram (28) and Bengal gram (30).However significant nodules were not observed in Ntrogen fertilizer added soil and in control. Ramaswami and Oblisami (1986) reported the increase in nodules due to inoculation application. Increase in nodules per plant due to application of inoculation in combination with nitrogen fertilizer was also reported by Rashid et al. (1999).
The above results are in agreements with the results of Singh et al. (1992a and 1992b), Das et al. (1997 and 1999), Eusuf Zai et al. (1999), Khanam et al. (1999), Bhuiyan et al. (2001), Zammurad et al. (2006) who worked on lentil, mungbean and garden pea.

TableI.Effect of seed treatment with Rhizobium and nitrogen fertilizer on % seed germination.

Table II. Effect of seed treatment with Rhizobium and nitrogen fertilizer on Green gram.

Table III. Effect of seed treatment with Rhizobium and nitrogen fertilizer on Bengal gram.

Table IV. Effect of seed treatment with Rhizobium and nitrogen fertilizer on Groundnut.

Soil nitrogen level was tested after havesting the crops.Soil with seed treatment showed increased quantity of nitrogen level in all three crops compared to nitrogen fertilizer added and control.This qualitative analysis was done based on colour observation using soil testing kit.Similar kinds of observations were reported by Daterao et al. (1990) who recorded increased soil nitrogen after the harvest of green gram. The increase in nitrogen uptake by plant due to inoculation application was also reported by Basu and Bansyopadhyay (1990) and Rashid et al. (1999).

CONCLUSION
Inoculation of seed with Rhizobium significantly influenced the plant growth parameters and N- content of soil which consequently led to improved soil fertility and can reduce the production cost of next crop through reduced input in the form of nitrogen fertilizers, which in turn also minimize the health hazard effects. Rhizobial inoculation was found to be more effective and produced better yield through positive effect on yield components when compared with no inoculation.More field trial are imperative in the agro-ecological regions of Bidar to confirm these findings.

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