Rhizobium inoculation improves yield and nitrogen

New Zealand Journal of Crop and Horticultural Science

ISSN: 0114-0671 (Print) 1175-8783 (Online) Journal homepage: http://www.tandfonline.com/loi/tnzc20

Rhizobium inoculation improves yield and nitrogen accumulation in soybean (Glycine max) cultivars better than fertiliser Tahsin Sogut To cite this article: Tahsin Sogut (2006) Rhizobium inoculation improves yield and nitrogen accumulation in soybean (Glycine max) cultivars better than fertiliser, New Zealand Journal of Crop and Horticultural Science, 34:2, 115-120, DOI: 10.1080/01140671.2006.9514395 To link to this article: http://dx.doi.org/10.1080/01140671.2006.9514395

Published online: 22 Mar 2010.

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New Zealand Journal of Crop and Horticultural Science, 2006, Vol. 34 : 115-120 0014-0671/06/3402-0115 © The Royal Society of New Zealand 2006

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Rhizobium inoculation improves yield and nitrogen accumulation in soybean (Glycine max) cultivars better than fertiliser

Tahsin Sogut Field Crops Department Faculty of agriculture Dicle university 21280 Diyarbakir Turkey email: [email protected] Abstract This study was conducted to assess the effect of Rhizobium inoculation and nitrogen (n) fertiliser on n accumulation and yield in soybean (Glycine max). Six soybean cultivars belonging to maturity group (MG) II ('Corsoy 79', 'Dwight'), III ('Williams 79', 'Maverick'), and IV ('Cf 492', 'Pyramide') were grown following wheat in a double crop system in a clay soil, free of Bradyrhizobium japonicum, in 2002 and 2003. a split plot design with inoculation or no inoculation (N fertiliser application) as main plots and cultivars as subplot treatments was used, with three replications in both years. The results of these experiments indicated that inoculation increased N content and dry matter in seed and vegetative parts (stem and leaves), N harvest index, and seed yield. The interaction between inoculation and soybean cultivars (maturity group) showed that inoculation was more effective on late maturity cultivars for seed yield. Keywords soybean; maturity group; Rhizobium inoculation; nitrogen fertiliser; nitrogen accumulation

salinisation. in an attempt to reduce these chemical inputs and raise soil quality and sustainability, natural biotechnological practices, such as the application of bacterial inoculates have been investigated in many countries. The importance of soybean (Glycine max L.) as a source of oil and protein, and its ability to grow symbiotically on low nitrogen (N) soils, point to its continued status as the most valuable grain legume in the world. The inoculation of seeds with Rhizobium is known to increase nodulation, N uptake, growth and yield response of crop plants (Dorosinsky & Kadyrov 1975; Patil & Shinde 1980; Herandez & Hill 1983). The soybean-Bradyrhizobium symbiosis can fix c. 300 kg n ha–1 under good conditions (Keyser & Li 1992). Thus, N fertilisation is normally not recommended for cultivation of soybean, since under favorable conditions it is able to grow well on soil n plus n 2 derived from symbiotic fixation. There are, however, instances in which N fertilisation has been recommended to ensure maximum crop yields (Hardarson & Zapata 1984). Biological n fixation is a complex process, and successful symbiosis depends on the genetic background of both symbiotic partners and is strongly affected by environmental factors (hungria & Bohrer 2000). Singh et al. (2003) reported that medium and late maturing varieties will produce more biomass, fix more N, and consequently contribute positively to the n balance of the soil. The aim of the study was to compare the yield and n nutrition of six soybean cultivars differing in maturity receiving traditional n fertiliser with those inoculated with Bradyrhizobium japonicum.

INTRODUCTION a s a consequence of excessive and inappropriate application of mineral fertilisers, all countries in the world suffer from problems such as pollution of agricultural lands, water resources, and soil

H05067; Online publication date 12 April 2006 Received 15 June 2005; accepted 2 February 2006

MATERIAL AND METHODS The field experiments were conducted in 2002 and 2003 at the experimental field of university of Dicle, Diyarbakir, Turkey to test soybean cultivars in different maturity groups (II ('Corsoy 79', 'Dwight'); m ('Williams 79', 'Maverick'); and IV ('Cf 492', 'Pyramide')) for N accumulation and yield under


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inoculant use and n fertiliser application. Diyarbakir province is located in south-east Anatolia, Turkey. The region has a warm climate in summer, and the mean annual rainfall is c. 450 mm, most of which fall in a major cropping season which extents from november to June. Soybean is grown in a double cropping season with irrigation following cereal or food legume-based cropping systems in the region. The type of soil is clay and is free of B. japonicum. Basal phosphorus (P) was applied at the rate of 70 kg P ha–1 as superphosphate (26% P). Starter N was applied at the rate of 50 kg n ha–1 as ammonium nitrate (33% N) for all plots, and N fertiliser treatments according to farming practice was 75 kg ha–1 as ammonium nitrate for uninoculated plots. Seeds of six soybean cultivars belonging to maturity groups H ('Corsoy 79', 'Dwight'), III ('Williams 79', 'Maverick'), and IV ('Cf-492', 'Pyramide') in both experiments were sown after wheat harvest in late June. Cultivars and treatments are listed in Table 1. The experimental design was a split plot with inoculation (B. japonicum commercial inoculant (HiStick) obtained from Becker Underwood Inc., Ames, United States) and N fertiliser of 75 kg ha–1 as top dressing treatments as main plots and six cultivars from MG U, HI, and IV as subplot treatments with three replications in both years. Each plot consisted of four rows 5m long with 0.6m between rows. after emergence the seedlings were thinned to obtain a population 330000 plants ha–1 (20 plants m–1 of row, with an average interplant distance 5 cm). Maturity was taken as the time of occurrence of growth stage R8. In both years, the samples were taken at the R8 stage (Fehr & Caviness 1977) for determining N concentration and % dry matter content of seeds and vegetative parts. Dry matter

content of seeds and stem were established from the sample after drying to constant weight at 70°C for 48 h. The dried samples of seeds and vegetative plant parts were ground and analysed for n concentration (mg g–1) with a LECO FP 528 analyser (LECO Corp., Joseph, MI, United States). N harvest index (nhi) was calculated for each plot as the ratios of seed N at growth stage R8 (Fehr & Caviness 1977) to total n content of above ground parts (including abscised parts) at growth stage R8 (Koutroubas et al. 1998). At R8 (Fehr & Caviness 1977), two rows of each plot were also harvested and threshed for seed yield (kg ha–1). Data were analysed by analyses of variance using general linear model (gLM) procedure provided by the statistical analysis system (SAS 1985). Combined analysis of variance between years was computed with years considered random, whereas genotype and inoculation were considered fixed. All main effects and their interactions were determined via F tests.

RESULTS AND DISCUSSION Significant (P 0.01) differences were observed in vegetative parts and seeds n concentration between the six soybean cultivars (Table 2). n concentration of vegetative parts was higher for M g iii (21.2 mg g–1) and IV (21.3 mg g–1) than MG H cultivars (19.8 mg g–1). Some cultivars, e.g., 'Cf 492' and 'Pyramide' (MG IV) had significantly more N content in seed when compared with M g n and iii cultivars (Table 3). This could suggest, as proposed by Herridge & Betts (1985) and Neuhausenetal. (1988), that soybean lines vary in ability to fix N. Furthermore, Neuhausen et

Table 1 Soybean (Glycine max) cultivars and inoculation treatments used in 2002 and 2003. (N, nitrogen.) Treatments

Cultivars

Cultivars

II Corsoy 79 110 Dwight II 110 Williams 79 116 m Maverick 115 m Cf-492 124 IV Pyramide IV 126 inoculated with Rhizobium japonicum and 50 kg n ha–1 as starter n uninoculated (50 kg n ha–1 as starter N + 75 kg N ha–1 as top dressing (current farming practice)).

inoculation Fertilisation

Maturity group

Days of maturity


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al. (1988) reported that the later maturing lines were superior to the early lines in N fixation. Inoculation significantly increased (P 0.05) n concentration of soybean seeds and vegetative parts. This could probably be attributed to the increase in n fixing efficiency of inoculated plants where more N was fixed and translocated to the seeds and vegetative parts. a similar result was obtained by abdelgani et al. (1999). The significant differences between years were observed for N concentration in seeds. Thus, N concentration in seed was higher in 2003 for both inoculated and n fertiliser treatments. The plants of the six cultivars fertilised with 75 kg N ha–1 had on average a lower n concentration in seed than those inoculated with Rhizobium (Table 3). The mean value was 56.9 mg g–1 in the inoculation treatment, but was 54.6 mg g–1 in the fertiliser treatment. Similarly, N concentration in vegetative parts was reduced from 21.4 to 20.2 g mg–1 for the inoculated and N fertiliser application, respectively, within the all soybean cultivars. Koutroubas et al. (1998) reported that the mean vegetative N content tended to be greater in the inoculated plants; furthermore, inoculation increased N yield (total seed N) at all N levels. Papakosta & Veresoglou (1989) reported that dry matter accumulation of soybean cultivars was influenced by maturity group. The soybean cultivars generally performed better when they were inoculated than when they received N application only and inoculation was found to be necessary for maximum seed and n yields. Statistical differences among cultivars were observed for n harvest index (nhi). The mean n h i s were 0.725, 0.711, and 0.735 for maturity groups n, m , and IV, respectively (Table 4). The N harvest

indexes of all soybean cultivars were not significantly affected by n source (Table 2). The average n h i s for all cultivars were 0.722 and 0.726 for the inoculated and fertiliser application, respectively (Table 3). Thus, the lower NHI of MG n and i n cultivars compared to the MG IV cultivars is mainly attributed to the lower yield of MG n and III cultivars, although cultivar differences in n h i were reported (Jeppson et al. 1978; Papakosta & Veresoglou 1989). Koutroubas et al. (1998) found that the NHI was not affected by N application and inoculation. Similarly, Imsande (1992) reported that the mean NHI of the inoculated plants was approximately equal to mean n h i of N-fertilised plants. Rhizobium inoculation tended to increase the dry matter content in the seeds of the soybean cultivars compared to N fertiliser application, but its effect was not significant (Table 2). Statistical difference was also detected among soybean cultivars for the dry matter content in the seeds (P 0.05), ranging from 48.1% (the cultivar of MG II) to 69.2% (the cultivar of MG IV) (Table 5). Difference in the dry matter content in vegetative parts among soybean cultivars were verified (P 0.01). in relation to yield parameters, dry matter content in vegetative parts was significantly affected by cultivar. The cultivars accumulated dry matter from 62.3% (the cultivar of MG II) to 71.6% (the cultivar of MG IV). Differences between inoculated and n fertiliser application were also detected for dry matter content in the vegetative parts. Rhizobium inoculation increased the dry matter content up to 2.2% compared to N fertiliser application in all soybean cultivars. This is probably because the fertiliser was applied at R1 (Fehr & Caviness 1977) and its effect was observed

Table 2 Results of analysis of variance (mean squares) combined across years, cultivars, nitrogen (N) fertiliser, and inoculation in 2002 and 2003. (d.f., degrees of freedom.) N concentration (mg g–1) Source of variation Year(Y) Cultivar (C) YxC Error Inoculation (I) Yxl Cxi YxCxI Error CV(%)

d.f.

Vegetative

1 5 5 20 1 1 5 5 24

0.011 8.348 P