Efficiency of seed inoculation with Azospirillum brasilense on agronomic characteristics and yield of wheat

Industrial Crops and Products 43 (2013) 393–397

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Efficiency of seed inoculation with Azospirillum brasilense on agronomic characteristics and yield of wheat Gleberson G. Piccinin ∗ , Alessandro L. Braccini, Lilian G.M. Dan, Carlos A. Scapim, Thiago T. Ricci, Gabriel L. Bazo Agronomy Department, State University of Maringá – UEM, Paraná, Brazil

a r t i c l e

i n f o

Article history: Received 4 May 2012 Received in revised form 26 July 2012 Accepted 27 July 2012 Keywords: Triticum aestivum L. Inoculation Bioregulator Yield

a b s t r a c t The aim of this study was to evaluate the efficiency of seed inoculation with Azospirillum brasilense on the agronomic performance and yield of wheat. The experiment was conducted in randomized blocks design with six replications in a factorial scheme (3 × 3 × 2). The factors consisted of three doses of nitrogen (zero, half and full dose); seed inoculation with A. brasilense (without inoculant, liquid inoculant and peat inoculant); two doses of bioregulator (0 and 250 mL ha−1 ) in two growing seasons (2010 and 2011). At the point of harvest, the number of seeds per ear, thousand seed mass, hectoliter weight and yield were evaluated. It is inferred that the A. brasilense is efficient in performing partial nitrogen fixation supplemented by nitrogen fertilization; yield is positively influenced by nitrogen fertilization associated with inoculation, regardless of the type of inoculant. © 2012 Elsevier B.V. All rights reserved.

1. Introduction Wheat is important in the agricultural production system in south-central Brazil, for being an economically viable option during the winter, which provides one of the best soil cover for no-tillage sowing system. Its cultivation improves the sustainability of the agricultural system by reducing the proliferation of weeds. The high yield potential of wheat has been obtained through the use of modern varieties, coupled with the rational and integrated use of soil resources, climate and management techniques. Among the management techniques, according to Megda et al. (2009) highlight the nitrogen fertilization in which nitrogen (N) is one of the nutrients absorbed in greater amount by the culture with positive effects on yield. When considering the need of N for the development of the culture, in addition to chemical and organic fertilizers, another alternative to provide N would be the associations with diazotrophic bacteria. Among diazotrophic bacteria, the genus Azospirillum ssp. can colonize the roots and stems of plants without causing disease symptoms to stand out (Terver and Hollis, 2002). These microorganisms called plant growth-promoting bacteria (PGPB) greatly influence the ability of biological nitrogen fixation; the increase in

∗ Corresponding author at: Universidade Estadual de Maringá, Avenida Colombo, Bloco J45, Maringá – PR, CEP 87020-900, Brazil. Tel.: +55 44 9127 0382. E-mail address: [email protected] (G.G. Piccinin). 0926-6690/$ – see front matter © 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.indcrop.2012.07.052

nitrate reductase activity when grown endophytically in the plants; the production of hormones such as auxins, cytokinins, gibberellins, ethylene and a variety of other molecules; the phosphate solubility; favor beneficial mycorrhizal–plant associations and may act indirectly on growth to protect the plant from soil fungi or phytopathogenic bacteria (Perrig et al., 2007; Cassán and Garcia, 2008; Reis Júnior et al., 2008). Unlike the symbiotic bacteria, the process of biological nitrogen fixation (BNF) by bacteria associations can only partially supply the needs of the plants by excreting only a portion of fixed N directly to the associated plant, subsequently, the mineralization of the bacteria may contribute with input of additional N to the plants (Hungria, 2011). Consequently, associative microorganisms join the plants to promote yields and attribute resistance to biotic and abiotic stresses that can reduce the chemical reaction of N2 to ammonia, which can be assimilated by the plants (Dobbelaere et al., 2003). In this sense, when Azospirillum brasilense is inoculated using seed inoculation, it increases the productivity of wheat (Santa et al., 2008; Piccinin et al., 2011), corn (Saikia et al., 2007; Reis Júnior et al., 2008; Braccini et al., 2012), oat and barley (Santa et al., 2008), providing increased growth of shoot and root of rice seedlings (Embrapa, 2003), millet (Bouton et al., 1985), and sugarcane (Boddey, 1995). Studies performed by Didonet et al. (2000), related to the effect of seed inoculation of wheat with A. brasilense with different N levels at different stages of development, found no effect of the inoculation with the seed yield, nor on the total N accumulated in the seeds.

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Table 1 Scheme of the treatments (T) with seed inoculation of wheat cultivar CD 150, associated to N doses and management of bioregulator application (Maringá – PR, 2010/2011). N

(T)

T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 T13 T14 T15 T16 T17 T18

Absolute control Without N + without inoculant + bioregulatorc Without N + liquid Azospirilluma Without N + liquid Azospirilluma + bioregulatorc Without N + peat Azospirillumb Without N + peat Azospirillumb + bioregulatorc Half dose of N + without inoculant Half dose of N + without inoculant + bioregulatorc Half dose of N + liquid Azospirilluma Half dose of N + liquid Azospirilluma + bioregulatorc Half dose of N + peat Azospirillumb Half dose of N + peat Azospirillumb + bioregulatorc Full dose of N + without inoculant Full dose of N + without inoculant + bioregulatorc Full dose of N + liquid Azospirilluma Full dose of N + liquid Azospirilluma + bioregulatorc Full dose of N + peat Azospirillumb Full dose of N + peat Azospirillumb + bioregulatorc

a Grass masterfix liquid, applied at the dose of 100 mL 50 kg−1 of seeds of Azospirillum spp. b Grass masterfix peat, applied at the dose of 100 g 50 kg−1 of seeds of Azospirillum spp. c Stimulate® biorregulator (kinetin + gibberellic acid + (4-indol-3-ylbutyric acid)).

On the other hand, studies have shown that inoculation of A. brasilense resulted in increased N accumulated in the ear and greater root growth in relation to shoot, providing increased productivity, especially in the presence of N fertilizer (Santa et al., 2004; Sala et al., 2007). Therefore, promising studies with A. brasilense (Ab-V5 and AbV6) in association with grasses, especially the cultivation of wheat in liquid and peat carrier, subjected to different doses of N combined with the application of bioregulators are insufficient, thus requiring for the need to seek information that may help as rationally and economically alternative technologies. In this sense, the study was aimed to evaluate the efficiency of seed inoculation with A. brasilense on agronomic performance and yield of wheat. 2. Materials and methods 2.1. Experiment installation and conduction The experiment was carried out during the agricultural years of 2010 and 2011, installed in Iguatemi Experimental Farm (FEI), part of the Center for Agricultural Sciences, State University of Maringá (UEM), in Maringá in northwestern Paraná State, located at latitude 23◦ 25 south and longitude 51◦ 57 west of Greenwich, with an average altitude of 540 m. The treatments consisted of the absence and presence of seed inoculation with A. brasilense bacteria in liquid and peat formulation, three doses of fertilization with nitrogen (0, 50 and 100 kg ha−1 of N), distributed 1/3 as base fertilization and 2/3 as cover fertilization, associated with foliar application of the plant growth regulator Stimulate® (0 and 250 mL ha−1 ) at tillering. The detailed schemes of the treatments are shown in Table 1. To implement the experiment, the area was desiccated with 3.0 kg ha−1 of the herbicide Roundup WG® (Glyphosate) and then 1 L ha−1 of Aminol 806® (2,4-d-dimethylamine) was applied. The sowing fertilization (N–P2 O5 –K2 O) was expected to produce 3000 kg ha−1 of seeds. The application of nitrogen was divided into 1/3 at sowing and 2/3 as cover fertilization at early tilling, following the Embrapa Wheat (2008) recommendations.

At the time of seed treatment with liquid and peat inoculant the strains Ab-V5 and Ab-V6 were used at the minimum concentration of 1 × 108 viable cells per gram (g) or milliliter (mL). For better adherence of the product, 10% sugar solution was used (10% sugar concentration) at a dose of 100 g mL−1 of the commercial product per hectare, until reaching a volume of 150 mL per 50 kg of seeds, providing a total coating before sowing was performed. Sowing took place on 4/28/2010 (1st year) and 4/29/2011 (2nd year) under a no tillage system for sowing cultivar CD 150 with intermediate growth habit and early cycle, 60–80 viable seeds per linear meter (m) density. The experimental units were composed of 15 5.0 m long rows, spaced 0.15 m between rows, considering as useful plot size six central lines, discarding 0.5 m at both ends (3.6 m2 ). To provide good conditions for growth and development of plants, hand weeding and applications of the herbicide Ally® (Metsulfuron Methyl) and pesticides were carried out to control weeds, pests and diseases, applied with respect to the level of economical damage for an integrated and rational management, applying Macht EC® (Lufenuron) at mL ha−1 , Engeo Pleno® (Lambd-Acialotrina + Thiamethoxam) at 70 mL ha−1 and Tamaron BR® (Methamidophos) at 600 mL ha−1 for the control of caterpillars, aphids and stink bugs; to control powdery mildew, stem and leaf rust, wheat scab and blast disease, Opera® (epoxiconazole + pyraclostrobin) was applied at 750 mL ha−1 and Priori Xtra® (azoxystrobin + cyproconazole) at 300 mL ha−1 . The application of plant growth regulator Stimulate® was conducted by tilling at the dose of 250 mL ha−1 . Applications were foliar via a CO2 propelled backpack sprayer with 2 bar (or 29 PSI) constant pressure, a flow of 0.65 L min−1 , equipped with a pipe containing one XR 110 02 nozzle type TeeJet Series which, working at a height of 50 cm from the target and at a speed of 1 m s−1 , reaching a 50 cm wide strip of application, provided a spray volume of 200 L ha−1 .

2.2. Agronomic characteristics and yield evaluation Assessments of the number of seeds per ear, seed mass, as well as the physiological quality, protein and (N) levels were performed at the Laboratory of Seed Technology of the Center for Applied Research in Agriculture (Nupagri) in Maringa, State of Parana. The hectoliter weight was determined at the C.Vale Agroindustrial Cooperative, Paulistânia warehouse, State of Paraná. To assess the number of seeds per ear, 10 ears were collected randomly from the center of the parcel in the useful, being the area with the least statistical outliers, of the plots, placed in Kraft paper bags, properly labeled and finally subjected to counting in the Laboratory of Seed Technology. At the end of the cycle, the plots were manually harvested and threshed in a stationary threshing machine, cleaned with the help of screens and digital impurities selector, dried in natural conditions and packaged in multiwall Kraft paper bags. From the mass of seeds obtained from the usable area of the plot the productivity of each plot was obtained, which was weighed on an analytical balance, determining the moisture content of the seeds by the drying oven method at 105 ± 3 ◦ C for 24 h, using two subsamples of 5.0 g of seeds for each plot (BRASIL, 2009). The seed moisture was corrected to 13% and then the yield in kg ha−1 was calculated. The mass of one thousand seeds was determined by weighing 8 subsamples of 100 seeds for each field repetition, with the aid of an analytical balance accurate to 1 mg. For all plots the coefficient of variation was less than four, and the results were multiplied by 10 (BRASIL, 2009). The seeds hectoliter weight was determined by weighing on electronic scale with known volume (225 mL) using two repetitions

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Table 2 Average results of the number of seeds per ear as effect of seed treatment without inoculation (W.I.), liquid inoculant (L.I) and peat inoculant (P.I.) with different N doses associated to the application of bioregulator (Maringá – PR, 2010/2011). Dose of nitrogen (kg ha−1 )

2010

2011

W.I a

Without Half Full a b

b

20.66 Cb 24.30 Bb 28.94 Ab

L.I

P.I

W.I

L.I

P.I

25.42 Ba 29.92 Aa 31.32 Ab

27.19 Ca 30.69 Ba 36.37 Aa

23.67 Ba 26.00 ABb 27.38 Ac

25.88 Ba 31.87 Aa 31.77 Ab

24.26 Ba 32.03 Aa 34.92 Aa

Without, half and full: 0, 50 and 100 kg ha−1 of N, respectively. Means followed by equal letters, uppercase in the column and lowercase in the line, do not differ significantly at 5% probability by Student Newman Keuls test.

per plot, obtained in Dalle Molle® device and expressing results in kg hL−1 (BRASIL, 2009). 2.3. Experimental design and statistical analysis The experiments were installed in complete block experimental design, with randomized treatments, with six blocks in 3 × 3 × 2 factorial scheme. The N levels were (zero, half and full dose of N), seed inoculation with A. brasilense (without inoculant, liquid inoculant and peat inoculant), two doses of bioregulator (0 and 250 mL ha−1 ) in two cropping years (2010 and 2011). The results obtained in this study were analyzed following the recommendations of Gomes (2000), for which, in experiments of this nature, the analytical framework adopted is the joint analysis of the experiments, thus making necessary to verify the homogeneity of mean squares errors. If the ratio between the highest and lowest MEError is less than 7, it is possible to adopt the joint analysis of the experiments, thereby, they were subjected to analysis of variance at 5% probability (p < 0.05) and, when significant, the means were compared by the Student Newman Keuls test (p < 0.05), according to Banzatto and Kronka (2008). When comparing the means of bioregulator foliar application the F test was conclusive. 3. Results and discussion 3.1. Number of seeds per ear The results of the partitions for doses and inoculants with Azospirillum ssp., regarding the number of seeds per ear are shown in Table 2. During the experiments, independent of the application of bioregulator, the treatments without N and without seed inoculation led to mild symptoms of N deficiency in the leaves after tillering. These reactions presented by the plants can be attributed to the supply of N (Taiz and Zeiger, 2004). Therefore, it is observed that the best results were obtained when 50 kg ha−1 of N was applied associated with liquid inoculant, which did not significantly differ at 5% probability of the 100 kg ha−1 dose. It was observed that in the second year the best results were obtained using half dose of N, coupled with A. brasilense, independent of the liquid and/or peat form, which promoted additions of approximately six seeds per ear.

This result becomes relevant since seed inoculation with A. brasilense makes possible the partial biological nitrogen fixation (PBNF), which in turn is potentially effective in order to increase the number of seeds per ear with reduction in the nitrogen dose (half dose of N). Dommelen et al. (2009) studied the inoculation of A. brasilense in wheat seeds, discovering that the main form of N assimilation is via the glutamine synthetase enzyme, which usually releases ammonia into the medium. The benefits promoted by inoculation associated to half doses of N contributed to the agronomic performance of wheat. On the other hand, studies indicate that the number of seeds per ear can be influenced by seeding density (Ozturk et al., 2006), water availability (Pires et al., 2004), and development and survival of tillers (Valério et al., 2008).

3.2. Thousand seeds mass For thousand seeds mass (Table 3), it was observed that there were significant effects for doses of N and for inoculants. For the variable in question, in the first year, regardless of the type of inoculant combined with 50 kg ha−1 of N, as well as the liquid inoculant, showed significant responses. In this case, on the second year, it is noted that using the same amount of fertilizer, the performance was significantly (p < 0.05) similar for both inoculants. These results reinforce the fact that the inoculation with A. brasilense contributes to PBNF, when combined with half N dose, which significantly (p < 0.05) increases the thousand seeds mass, favoring the agronomic characteristics of wheat. Given the above, it is very probable that the supply of N contributes to the accumulation of assimilates, one of the main factors responsible for grain filling. Nakagawa et al. (2000) and Jornada et al. (2005) experimented with doses of N in cover and times of application, finding no effect of N on seed mass of black oat or millet. Asseng and Van Herwaarden (2003) explain that grain filling depends on the supply of N and water availability during the crop growth. Surely, PBNF in addition to providing greater amounts of N, may increase the photosynthetic area of plants and provide an increase in the amount of accumulated reserves for translocation in grain filling.

Table 3 Average results of thousand seeds mass, in effect of seed treatment without inoculation (W.I), liquid inoculant (L.I) and peat inoculant (P.I) with different N doses associated to the application of bioregulator (Maringá – PR, 2010/2011). Dose of nitrogen (kg ha−1 )

2010

2011

W.I a

Without Half Full a b

b

30.92 Cb 33.40 Bb 35.36 Ab

L.I

P.I

W.I

L.I

P.I

35.12 Ba 37.72 Aa 38.05 Aa

34.35 Ba 36.85 Aa 38.45 Aa

31.09 Ba 32.20 Bb 34.85 Ab

33.05 Ba 36.40 Aa 37.57 Aa

33.02 Ca 34.93 Ba 38.44 Aa

Without, half and full: 0, 50 and 100 kg ha−1 of N, respectively. Means followed by equal letters, uppercase in the column and lowercase in the line, do not differ significantly at 5% probability by Student Newman Keuls test.

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Table 4 Average results of the hectoliter weight in kg hL−1 , in effect of seed treatment without inoculation (W.I), liquid inoculant (L.I) and peat inoculant (P.I) with different N doses associated to the application of bioregulator (Maringá – PR, 2010/2011). Dose of nitrogen (kg ha−1 )

2010

2011

W.I a

Without Half Full a b

b

74.91 Bb 76.08 Ab 76.41 Ab

L.I

P.I

W.I

L.I

P.I

75.66 Bb 78.25 Aa 78.33 Aa

76.75 Ba 78.50 Aa 78.58 Aa

75.00 Ba 75.00 Bb 77.75 Ab

76.00 Ba 77.58 Aa 78.50 Aab

76.25 Ca 77.91 Ba 79.16 Aa

Without, half and full: 0, 50 and 100 kg ha−1 of N, respectively. Means followed by equal letters, uppercase in the column and lowercase in the line, do not differ significantly at 5% probability by Student Newman Keuls test.

Table 5 Average results of yield in kg ha−1 , in effect of seed treatment without inoculation (W.I), liquid inoculant (L.I) and peat inoculant (P.I) with different N doses associated to the application of bioregulator (Maringá – PR, 2010/2011). Dose of nitrogen (kg ha−1 )

Withouta Half Full a b

2010

2011

W.I

L.I

P.I

W.I

L.I

P.I

1542.8 Cab 2037.1 Bb 2435.5 Ab

1779.3 Ba 2522.8 Aa 2615.7 Ab

1684.4 Ca 2610.0 Ba 3072.3 Aa

1792.0 Cb 2147.0 Bb 2421.5 Ab

2102.6 Ca 2603.6 Ba 3082.2 Aa

2126.0 Ca 2752.8 Ba 3178.4 Aa

Without, half and full: 0, 50 and 100 kg ha−1 of N, respectively. Means followed by equal letters, uppercase in the column and lowercase in the line, do not differ significantly at 5% probability by Student Newman Keuls test.

3.3. Hectoliter weight The results regarding the hectoliter weight are presented in Table 4. The hectoliter weight for respective harvests varied between 74.91 and 79.16 kg hL−1 . However, it is possible to confirm for the first year that the best responses occurred when half dose of N was applied, regardless of the type of inoculant. In this case, it is noted that the use of peat or liquid inoculant, when associated to the half dose of N, exhibited comparable results with the full dose of N. In the second year, the hectoliter weight was also positively influenced by N application and inoculation with A. brasilense. However, regardless of the type of inoculant, the half dose of N showed the best results. The component that most influenced the increase in seed yield of wheat was the hectoliter weight. This fact is important because values above 78 kg hL−1 belong to the type 1 classification, which adds more value when commercializing the production. Therefore, it is likely that the N fertilization associated to seed inoculation with A. brasilense significantly influences (p < 0.05) hectoliter weight, since the lack of this nutrient can reduce the number of seeds per ear and thousand seed mass, and hence, yield. However, it is worth considering that N is easily lost due to leaching, volatilization and denitrification in the soil plant system. Thus, it becomes necessary to perform seed inoculation with diazotrophic bacteria to enhance the absorption efficiency of the considered crop. In general, the N fertilizer used was not a limiting factor for the benefits provided by A. brasilense in hectoliter weight. However, this variable can be influenced by high rainfall at harvest, which was not observed in these experiments. The results also show that the increase in hectoliter weight, in general, is associated to the mass of seeds which, in turn, would probably be associated to a greater availability of N promoted by PBNF during the grain filling period, promoted by seed treatment with A. brasilense combined with the half dose of N. In contrast to these results, Zagonel and Fernandes (2007) showed that high doses of nitrogen can compromise the quality of seeds.

peat inoculant provided yields of 3072.3 kg ha−1 for the first year when using the full dose of N. It is noticed, however, for the seed treatment with liquid inoculant associated with half the dose of N, that it was not significantly different from the 100 kg ha−1 of N. This allows the inference that inoculation of wheat seeds with Azospirillum spp. at a dose of 100 mL 50 kg−1 of seeds associated to the half dose of N overcomes the isolated application of 50 kg ha−1 , under favorable conditions. The studied treatments were effective in increasing productivity by using the same level of N fertilization, which made possible increases in yield, in the order of 20% higher than the N application without seed inoculation. For the second year, the inoculation of wheat seeds with peat inoculant, associated to the full dose of N, when compared to the same N dose, but without inoculation, obtained increments of 756.9 kg ha−1 . These additions can be attributed to the favoring of yield components provided by PBNF. However, it is worth mentioning that the results may be influenced by systems that aim for higher yields through soil conditions, environment and genotype. The above results corroborate Zorita and Canigia (2008) and Piccinin et al. (2011) that, after inoculating wheat seeds with A. brasilense, obtained significant increments in yield. Just as Hungria (2011) observed an average increase of 26% in corn yield and 31% for wheat. According to Dobbelaere et al. (2003) for corn and Santa et al. (2008) for wheat, the increase in yield is directly linked to the BNF contribution by the bacteria association of the genus Azospirillum ssp. related with doses of N. Just as Zagonel et al. (2002) and Heinemann et al. (2006) also found positive effect of doses of N on wheat seeds yield. Braccini et al. (2012) obtained similar results for corn, noting that seed inoculation with A. brasilense in liquid formula increased the plant height and grain yield compared to the control. Thus, confirm the hypothesis that the strains Ab-V5 and Ab-V6 are effective for PBNF when seed inoculation is properly and rationally carried out, which may reduce the application of N fertilizer in wheat crop by 50%, leading to raw materials and labor economy. 4. Conclusions

3.4. Yield The seed yield results of the CD 150 wheat cultivar (Table 5) indicated that the application of the full dose of N associated to

A. brasilense is an alternative technology capable of performing partial biological N fixation supplemented by N fertilization. The application of the half dose of N associated to the use of different

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forms of inoculant, provides positive results on the agronomic performance and yield of wheat. References Asseng, S., Van Herwaarden, A.F., 2003. Analysis of the benefits to wheat yield from assimilates stored prior to grain filling in a range of environments. Plant Soil 256 (1), 217–229. Banzatto, D.A., Kronka, S.N., 2008. Experimentac¸ão agrícola, 4th ed. Funep, Jaboticabal, 237 p. Boddey, R.M., 1995. Biological nitrogen fixation in sugar cane: a key to energetically viable biofuel production. Crit. Rev. Plant Sci. 14, 263–279. Bouton, J.H., Albrecht, S.L., Zuberer, D.A., 1985. Screening and selection of pearl millet for root associated bacterial nitrogen fixation. Field Crops Res. 11, 131–139. Braccini, A.L., Dan, L.G.M., Piccinin, G.G., Albrecht, L.P., Barbosa, M.C., Ortiz, A.H.T., 2012. Seed inoculation with Azospirillum brasilense, associated with the use of bioregulators in maize. Rev. Caatinga 25 (2), 58–64. BRASIL, 2009. Ministério da Agricultura, Pecuária e Abastecimento. Mals/ACS, Brasília, DF, 395 p. Cassán, F.D., Garcia de Salamone, I. (Eds.), 2008. Azospirillum sp.: Cell Physiology, Plant Interactions and Agronomic Research in Argentina. Asociación Argentina de Microbiologia, 268 p. Didonet, A.D., Lima, O.S., Candaten, A.A., Rodrigues, O., 2000. Realocac¸ão de nitrogênio e de biomassa para os grãos, em trigo submetido à inoculac¸ão de Azospirillum. Pesquisa Agropecuária Bras. 35 (2), 401–411. Dobbelaere, S., Vanderleyden, J., Okon, Y., 2003. Plant growth-promoting effects of diazotrophs en the rhizosphere. Crit. Rev. Plant Sci. 22 (2), 107–149. Dommelen, A.V., Croonenborghs, A., Spaepen, S., Vanderleyden, J., 2009. Wheat growth promotion through inoculation with an ammonium-excreting mutant of Azospirillum brasilense. Biol. Fertil. Soils 45 (5), 549–553. Embrapa – Empresa Brasileira de Pesquisa Agropecuária. Avaliac¸ão de Linhagens de Arroz de Terras Altas Inoculadas com Azospirillum lipoferum Sp59b e A. brasilense Sp245. Comunicado Técnico 69. Santo Antonio de Goiás, 2003. Embrapa – Empresa Brasileira de Pesquisa Agropecuária. Informac¸ões técnicas para a safra 2009: trigo e triticale. Organizado por José Roberto Salvadori. Passo Fundo: Comissão Brasileira de Pesquisa de Trigo e Triticale; Embrapa Trigo; Embrapa Transferência de Tecnologia, 2008, 172 p. Gomes, F.P., 2000. Curso de estatística experimental, 14th ed. ESALQ, Piracicaba, 477 p. Heinemann, A.B., Stone, L.F., Didonet, A.D., Trindade, M.G., Soares, B.B., Moreira, J.A.A., Cánovas, A.D., 2006. Eficiência de uso da radiac¸ão solar na produtividade do trigo decorrente da adubac¸ão nitrogenada. Rev. Bras. Eng. Agríc. Ambiental 10, 352–356. Hungria, M., 2011. Inoculac¸ão com Azospirillum brasilense: inovac¸ão em rendimento a baixo custo. Londrina, Embrapa Soja, 36 p. Jornada, J.B.J., Medeiros, R.B., Pedroso, C.E.S., Saibro, J.C., Silva, M.A., 2005. Efeito da irrigac¸ão, épocas de corte da forragem e doses de nitrogênio sobre o rendimento de sementes de milheto. Rev. Bras. Sement. 27 (2), 50–58.

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Megda, M.M., Buzetti, S., Andreotti, M., Teixeira Filho, M.M.C., Vieira, M.X., 2009. Resposta de cultivares de trigo ao nitrogênio em relac¸ão às fontes e épocas de aplicac¸ão sob plantio direto e irrigac¸ão por aspersão. Ciênc. Agrotecnol. 33 (4), 1055–1060. Nakagawa, J., Cavariani, C., Machado, J.R., 2000. Adubac¸ão nitrogenada no perfilhamento da aveia preta em duas condic¸ões de fertilidade do solo. Pesquisa Agropecuária Bras. 35 (6), 1071–1080. Ozturk, A., Caglar, O., Bulut, S., 2006. Growth and yield response of facultative wheat to winter sowing, freezing sowing and spring sowing at different seeding rates. J. Agron. Crop Sci. 192, 10–16. Perrig, D., Boiero, L., Masciarelli, O., Penna, C., Cassán, F., Luna, V., 2007. Plant growth promoting compounds produced by two agronomically important strains of Azospirillum brasilense, and their implications for inoculant formulation. Appl. Microbiol. Biotechnol. 75, 1143–1150. Piccinin, G.G., Dan, L.G.M., Braccini, A.L., Mariano, D.C., Okumura, R.S., Bazo, G., Ricci, T.T., 2011. Agronomic efficiency of Azospirillum brasilense in physiological parameters and yield components in wheat crop. J. Agron. 10 (4), 132–135. Pires, J.L.F., Lima, M.I.P.M., Voss, M., Sheeren, P.L., Wiethölter, S., Cunha, G.R., Ignaczak, J.C., Caierão, E., 2004. Avaliac¸ão de cultivares de trigo em sistema de manejo tradicional e otimizado, Passo Fundo. Embrapa Trigo, Passo Fundo, 26 p. Reis Júnior, F.B., Machado, C.T.T., Machado, A.T., Sodek, L., 2008. Inoculac¸ão de Azospirillum amazonense em dois genótipos de milho sob diferentes regimes de nitrogênio. Rev. Bras. Ciênc. Solo 32 (3), 1139–1146. Saikia, S.P., Jain, V., Sangeeta, K., Samitha, A., 2007. Dinitrogen fixation activity of Azospirillum brasilense in maize (Zea mays). Curr. Sci. 93, 1296–1300. Sala, V.M.R., Cardoso, E.J.B.N., Freitas, J.G., Silveira, A.P.D., 2007. Resposta de genótipos de trigo à inoculac¸ão de bactérias diazotróficas em condic¸ões de campo. Pesquisa Agropecuária Bras. 42 (6), 833–842. Santa, O.R.D., Hernadez, R.F., Alvarez, G.L.M., Ronzelli, P., Soccol, C.R., 2004. Azospirillum sp. inoculation in wheat, barley and oats seeds greenhouse experiments. Braz. Arch. Biol. Technol. 47 (6), 843–850. Santa, O.R.D., Santa, H.S.D., Fernández, R., Michela, G., Ronzelli, P., Soccol, C.R., 2008. Influência da inoculac¸ão de Azospirillum sp. em trigo, cevada e aveia. Rev. Setor Ciênc. Agrárias Ambientais 4 (2), 197–207. Taiz, L., Zeiger, E., 2004. Fisiologia vegetal, 3rd ed. Artmed, Porto Alegre. Terver, I.W., Hollis, J.P., 2002. Bacteria in the storage organs of healthy tissue. Phytopatothol. J. 38, 960–967. Valério, I.P., Carvalho, F.I., Oliveira, F., Almeida, A.C., Benin, M.A., Scheeren, G., Souza, P.D., Hartwig, V.Q.I., 2008. Desenvolvimento de afilhos e componentes do rendimento em genótipos de trigo sob diferentes densidades de semeadura. Pesquisa Agropecuária Bras. 43 (3), 319–326. Zagonel, J., Fernandes, E.C., 2007. Rates and application times of growth reducer affecting wheat cultivars at two nitrogen rates. Planta Daninha 25 (2), 331–339. Zagonel, J., Venâncio, W.S., Kunz, R.P., Tanamati, H., 2002. Doses de nitrogênio e densidades de plantas com e sem regulador de crescimento afetando o trigo, cultivar OR-1. Ciênc. Rural 32, 25–29. Zorita, M.D., Canigia, M.V.F., 2008. Field performance of a liquid formulation of Azospirillum brasilense on dryland wheat productivity. Eur. J. Soil Biol. 30 (9), 1–10.