Department of Soi1 Science, College of Agriculture, G.B.P.U.A.& T., Pantnagar

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1 Scientific registration n o : 1560 Symposium n o : 10 Presentation: poster Response of soybean to native rhizoblal population of a mollisol of nainital Tarai Réponse du soja aux populations rhizobiennes natives dans un mollissol de Nainital Tarai SINGH R.K., PANT Lalit Mohan Department of Soi1 Science, College of Agriculture, G.B.P.U.A.& T., Pantnagar INTRODUCTION Results of several workers suggest that major limiting factor controlling the nitrogen fixation under field condition may be found in plant (Erdman, 1944 ; Johnson et ai., 1965 Pulver, 1982 Zimet et ai., 1985 ; Herridge et al Weiser et al ; Gress Hoff, 1990 ; Thompson et al ). Therefore it is necessary to select soybean varieties whichd respond maximum to indigenous rhizabial population in terms of nodulation, nitrogen fixation and ultimately the yield. This will not only allow the farmers to get higher yields without or limited use of chemical nitrogen but it may also eliminate the use of inoculants under Indian situation because still most of the farmer's are not aware about their use and quality of inoculant is poor in most of the cases. Secondly, the higher nodulation and N-fixing ability of certain varieties may be transferred to other cultivars through breeding programmes. In the ~present investigation response of soybean germplasm fines and varieties to the native and inoculated rhizobia in terms of nodulation, nitrogen fixation and grain yield was examined. MATERIALS AND METHODS Screening of Germplasms 243 soybean fines from germplasm collection of Department of Plant Breeding, G.B. Pant Univ. of Agril. & Technology, Pantnagar, were screened for nodulation by planting single rows during Kharif Observations on number of nodules were recorded at 78 DAS. Plants with 1-10 nodules was rated as poorly nodulated whereas nodules plant were moderate, nodules plant l as good and more than 30 nodules plant 1 were rated as excellently nodulated. Response of soybean varieties and fines to native rhizobial population A pot experiment was conducted usina two mollisols : one (S-1) from the field which had been under soybean cultivation for several years and other (S-2) from a field in which soybean had never been grown. Five varieties and 15 fines of soybeans were 1

2 planted in both the soils with 6 replications for each treatment. Observations on various plant parameters were recorded at 60 DAS and yield at maturity. Surface sterilized soybean [Glycine max (L.)l seeds were 10 seeds per pot filled with 5 kg soif of each type. Five plants per pot were maintained after thinning at 15 DAS. Observations on number of nodules, dry weight of nodules and plant was recorded at 60m DAS. Total nitrogen was determined usina micro kjeldahl method (Bremner, 1965). At crop maturity 1000 grain weight was recorded. Field Evaluation of selected soybean to B. japonicum inoculation A field experiment during the year 1994 usina 3 soybean varieties namely PK 416, JS 335 and PUSA 16 and four strain of B. japonicum vizualised SB-120, TAI-94, UASB-229 and Prabhani was conducted in a Mollisol with 3 replications in Randomized Block Design. Observations on the number of nodules, dry weight of nodules and plant was recorded at 50% flowering stage and grain yield was taken at maturity. RESULTS AND DISCUSSION 1. Screening of soybean germplasms for nodulation by native rhizobia There was a wide variability in the response of soybean germplasm to native B. japonicum population in terms of number of nodules per plant. Although all the germplasm plants were nodulated by native rhizobium. The results indicated that most of the soybean termplasms had produced moderate nodulation with maximum and minimum number of nodules being produced by UPSV-17 (61 nodules/plant) and PLSO-37 (3 nodules/ plant) respectively (Table 1 & 2). Similar to the results were also reported by Kevin et al. (1981). 2. Response of soybean varieties and fines to native rhizobial population in two soils : All the genotypes used in the study were found to nodulate in soif S-1, in which soybean was been cultivated several years but there was a wide variation in the numbers of nodules produced by different genotypes. Soybean variety PK 416 and PK 1042 recorded significantly higher number of nodules(69.6 and 71.0/plant, respectively) then any othergenotype. Lowest nodulation was observed in PK 1113 (5.6 nodules/plant). In soif S-2, which was new to soybean, 6 genotypes out of 20 genotypes did not produce any nodules but in this soif too PK 416 and PK 1042 produced highest number of nodules per plant. Nodule dry weight was also higher ln PK 416 and PK 1042 than other genotypes in eoil S-1 and soif S-2 (Table 3). Caldwell and Vest (1968) had also repdorted host genotype response. Similar trend in response to native rhizobia was observed ln dry master production and nitrogen content of plants which was more in soif S-1 than S-2. Growing soybean for several years in soif SS-1 must have built up a large population of native rhizobia resulting in increased dry master and nitrogen fixation in plants. The maximum dry weight of plants in both the soils was observed in genotype PK 1042 (18.80 g and 2

3 18.50 in soif S-1 and S-2, respectively (Table 4). Senaratene et al. (1987) alsod reported that plant dry weight was strongly influenced by specific combination of host genotype and rhizobial strain. The genotype PK 1042 which had recorded maximum number of nodules, plant dry weight and nitrogen content, also gave maximum 1000 grain weight in soif S-1 ( g) and in soif S-2 it was at par with PK 416 and PK Even in the genotypes which had not nodulation in soif S-2, the 1000 grain weight was comparatively higher in soif S-1 where they had been nodulated by the native rhizobia. Therefore, poor y.ield in soif S-2 may be attributed to absence of specific rhizobia for effective symbiosis. 3. Evaluation of promising B. japonicum strains against soybean varieties : Significant differences due to variety, inoculant and variety x inoculant interactions were observed. The response of soybean varieties to different strains of B. japonicum varied in terms of number of nodules and nodule dry weight per plant. Strain SB-120, UASB-229 and Prabhani recorded highest number of nodule and dry weight of nodules in variety PK-416, which was significantly higher than variety POSA-16 and JS-335 (Table 5). Various treatments and their interactions recorded significant difference in terms of dry master production at 50% flowering stage. Combination of soybean variety PK-416 and B. japonicum strain Prabhani which had recorded maximum nodulation also recorded significantly higher dry weight of plant (34.6 g/plant) than dry master production in variety POSA-16 and JS-335. As compared to variety POSA-16 and JS-335, soybean variety PK-416 recorded higher grain yield in all the treatments including uninoculated control. Combination of strain SB-120 and variety PK-416 recorded the maximum grain yield ( kg) which was significantly higher than combination of UASB-229, Prabhani with variety PK-416. The results of grain yield have also indicated that as compared to other varieties, PK-416 was more dresponsive to inoculation with different B. japonicum strains. KEY WORDS : Glycine max. (L) B. japonicum, Nodulation, N2 fixation, yield, symbiosis. BIBLIOGRAPHY Bremner, J.M Total nitrogen. In : Methods of soif analysis. C.A. Black, ed. Part - 2, American Society of Agronomy, Madison Wisconsin, U.S.A. pp Caldwell, B.E. and Vest, G Nodulation interaction between soybean genotypes and sero groupe of Rhizobium japonicum. Crop Science, 8, Erdman, L.W New development in legume inoculation. Soil Science Society of American Proceedings. 8, Gress hoff, P.M The importance of biological nitrogen fixation to new crop development. In. Advances in new crops (Janik, J. and Simon, J.E. eds)

4 Herridge, D.F. and Brockwell, J Contribution of fixed nitrogen and soif nitrate to the nitrogen economy of irrigated soybean. Soil Biol. Biochem., 20(5), Johnson, H.W. MacUra & Weber, C.R Competition for nodule sites between strains of R. japonicum applied as inoculum & strains in the soil. Agronomy Journal, 57, Kevin, C.S. Ham, G.E. and Lambert, J.W Recovery of introduced R. japonicum strains by soybean genotypes. Agronomy Journal, 73, Pulver, E.L. ; Kuenemao, E.A. ; Rao-Ranga, V Identification of promiscous nodulating soybean efficient in N2 fixation. Crop Science. 25 : Senaratene, R. ; Amornpimal, C. and Hardarson, G Effect of combined nitrogen on nitrogen fixation of soybean (Glycine max L. merr.) as affected by cultiver rhizobial strain. Plant and Soil. 103, Thompson, J.A. ; Bhromsiri, A. ; Shutsirung, A. and Lillakan, Native root nodule bacteria of tradidional soybean - growing areas of Northern Thailand. Plant and Soil. 135 : Wiser, G.C. ; Skipper, H.D. and Wollumll, A.C Exclusion of inefficient B. japonicum sero groupe by soybean genotypes. Plant and Soil, 121, Zimet, A.R. ; Albrecht, S.L. and Sinclair, T.R Interaction of B. japonicum isolated from Florida soils with southern soybean cultivars. Tr. Nitrogen fixation Research Progress (Evan, ti.j. ; E`ottomley, P.J. and Newton, W.E., Eds.), 2, 699. Keywords : Glycine max. (L) B. japonicum, nodulation, N2 fixation, yield, symbiosis. Mots clés : Glycine max. (L) B. japonicum, nodulation, fixation de l azote, rendement, symbiose 4

5 Table 1. Response of soybean germplasm to Native Rhizobial population in terms of nodule number in rainfed conditions. Number of Nodules/ Group Number of germplasms plant 0 No nodulation Poor nodulation Moderate nodulation Good nodulation 57 > 31 Excellent nodulation 21 Table 2. Screening of soybean germplasm NODULATION GROUP GERMPLASM Maximum number of nodule Minimum number of nodule 1. Poor TG C PLSO 37 (10 nodules/plant) (3 nodules/plant) 2. Moderate JS-340 UPSV 35A (20 nodules/plant) (11 nodules/plant) 3. Good UPSL-156B WT-182 (30 nodules/plant) (21 nodules/plant) 4. Excellent UPSV-17 PLSO-71 (61 nodules/plant) (31 nodules/plant) 5

6 Table 3. Response of soybean varieties and fines to native rhizobial population in terms of number of nodule in soif previously cultivated with soybean (S-1) and in a soif new to soybean cultivation (S-2) Number of nodules/ Nodule dry weight/ plant plant (g) S.No. Variety/Lines S-1 S-2 S-1 S-2 1. PK PK PK PK PK LINES 6. PK PK PK PK PK PK PK PK PK PK PK PK PK PK PK C.D. at 5% SEM+/

7 Table 4. Response of soybean varieties and ]ines to native B. japonicun population in tèrms of plant dry weight, plant nitrogen content in soif S-1 and soif S-2. Thousand grain Plant dry weight (g) Plant nitrogen (%) weight (g) S.No. Variety/ S-1 S-2 S 1 S-2 S-1 S-2 1. PK PK PK PK PK PK PK PK PK S PK PK PK PK PK PK PK

8 17. PK PK PK PK C.D. at 5% SEM +/

9 Table 5. Evaluation of promising B. japonicum strains against different varieties of soybean. _S.N Treatment At 50% flowering Grain yield (Kg/ha) Number of nodule/plant Nodule dry wt./plant (g) Plant dry wt./plant (g) PK- 416 JS-335 PUSA-16 PK 416 JS-335 PUSA-16 PK-416 JS-335 PUSA-16 PK-416 JS-335 PUSA SB-l20 18' ' TAL C UASB ' Farbhani óó S. Uninoculated C. D. at 5% Variety 0.83* 5, * 62.29* Inoculants 0.64* 4.22* 1.36* 49.79* Z33teraction 1.43* 9.43* 3.06* * 9