RESEARCH WORK

Effect of livestock vermicomposts on some physiological indicators of Triticum aestivum var. buck pingo

Hilda E. Pedranzani¹, O. A. Terenti², Olga M. Ruiz², Andrea M. Quiroga²and Ada L. Giulietti ²

¹Laboratorio de Fisiología Vegetal. Facultad de Química, Bioquímica y Farmacia. Universidad Nacional de San Luis. Ejército de los Andes 950 (5700), San Luis, Argentina
²Laboratorio de Fisiología Vegetal, Departamento de Ciencias Agrarias. Facultad de Ingeniería y Ciencias Agrarias. Universidad Nacional de San Luis. Avda. 25 de Mayo 385 (5750) Villa Mercedes, San Luis, Argentina
E-mail: hildaelizz@gmail.com

ABSTRACT

In order to evaluate the effect of the use of livestock vermicomposts on some physiological indicators, a study was conducted on wheat. For such purpose seeds of Triticumaestivum var. buck pingo were used as well as 28 substrata elaborated from four vermicomposts from cow (A), horse (B), goat (C) and hen manure (D), in six increasing concentrations and mixed with soil (10:90; 20:80; 30:70; 40:60; 50:50 and 100:0), besides a control (100 g of soil and absence of vermicompost, 0:100). The design was completely randomized blocks and the experimental unit consisted in ten plants in each block. The treatments were placed under conditions of a photoperiod of 8 h light at 30 ºC and 16 h darkness at 20 ºC, with irrigation at field capacity. The germination percentage (GP) was calculated, and the leaf (LL) and root length (RL); the fresh and dry weight of the foliage (FFW and FDW), and the fresh and dry weight of the roots (RFW and RDW), were evaluated. A, B and C caused increase of the GP with regards to the control. The LL and RL increased with substrata A, C and D in almost all the concentrations, while B only did it at 100 %. Substrata B, C and D caused increases in FFW, RFW, FDW and RDW for all the concentrations. It is concluded that, in general, the vermicomposts positively influenced the main physiological indicators of T. aestivum.

Keywords: Biomass, growth, germination.

The soils in the San Luis province, Argentina, are little evolved, of scarce horizons and weakly developed; 70 % of the provincial surface belongs to Entisols, 20 % to Mollisols and 10 % to Aridisols.

The average wheat (Triticumaestivum) surface of the province, for the last 10 campaigns, was 4 400 ha; in an important part of that surface complementary irrigation is used, and the campaign with the highest surface was 2007-2008 with 7 300 ha. Concerning management, the utilization of high-fertility lots is recommended, or otherwise the application of high doses of nitrogen, because it influences the protein content. Thus, urea dissolved in water (up to 50 kg of urea/ha in 150 L of water) is used to achieve an increase in the protein and gluten content (Belmonte et al., 2010).

Many of the recent studies in the field of agricultural production have been aimed at the search for sustainable practices, with minimum impact on the ecosystems, through the appreciation of natural resources in terms of conservation, recycling and use of alternative materials (Giulettiet al., 2008a). Earthworms, as soil engineers, play an important role in the soil functionality (Jouquetet al., 2006); promote aeration and water infiltration; influence the microbial activity and diversity; stimulate organic decomposition and facilitate nutrient recycling, which is beneficial for the plants (Lavelle and Spain, 2001); and increase mineral nutrition and plant cover (Larchevêqueet al., 2005). The organic residues processed by the earthworm, frequently called vermicomposts, are of fine size, with high porosity, aeration and drainage (Ndegwa and Thompson, 2000); due to their physical, chemical and biological characteristics, they have been used as organic fertilizer with favorable effects on the development of horticultural crops and ornamental plants in greenhouse (Brown et al., 2000).

According to Albiachet al. (2000), Marinari et al. (2000), Arancon et al. (2003) and Domínguezet al. (2010), their addition to the cultivation media increases germination, growth, flowering, fructification and resistance to pathogens, and they contain four times more nitrogen, twenty five times more phosphorus, and two and a half times more potassium than the same weight of cattle manure. Vermicomposts constitute a source of slow-release nutrients and they also have a biological mechanism of plant growth stimulation, ascribed to the free enzymes, humic acids and growth-regulating substances (Domínguezet al., 2010) and also to the changes occurred in the physical, chemical and biological composition of the soils (Ferreraset al., 2005).

In Argentina there are few studies in high-impact species, such as wheat, and even fewer are the studies with diverse substrata derived from livestock manures and in different concentrations; for which the objective of this work was to study the effect of four vermicomposts from livestock manures (cow, horse, goat and hen) on the main physiological indicators of wheat (T. aestivum var. buck pingo).

MATERIALS AND METHODS

Seeds of T. aestivum var. buck pingo and vermicomposts from cow (A), horse (B), goat (C) and hen manure (D), obtained from livestock production residues of the rural zone of Villa Mercedes (San Luis) and from a soil of limey sand-sandy texture, collected at the Livestock Research Station San Luis, National Institute of Livestock Production Technology (INTA for its initials in Spanish), Argentina, were used.

The substrata used consisted in the mixture of the above-mentioned soil with the vermicomposts, in different proportions: 1) 0:100; 2) 10:90; 3) 20:80; 4) 30: 70; 5) 40:60; 6) 50:50 and 7) 100:0, according to Giuliettiet al. (2007). The control consisted in 100 g of soil and absence of vermicompost (treatment 1). For obtaining the vermicompost the Californian red earthworm was used and it was reared for three months (moment at which the humus was extracted), in drawers which were 0,40 m wide and 0,60 m long, covered with half shade. The chemical composition of the vermicomposts was generally within the following limits: N: 0,0090 % ± 0,0010; P: 35,99 mg/kg ± 1,40; OM: 1,88 % ± 0,33; pH: 7,75 ± 0,01. The chemical composition of the soil was: N: 0,0004 %; P: 10,02 mg/kg; OM: 0,011 %; pH: 6,50 (Giuliettiet al., 2007).

Fifty seeds of T. aestivum var. buck pingo were sown per substratum tray, and three repetitions were made for each treatment. The trays were placed in germination chamber, with 8 h light at 30 ºC and 16 h darkness at 20ºC, and were weekly irrigated with distilled water to field capacity. The germination percentage (GP) was calculated on the third week after planting. Thirty days after sowing, the following physiological indicators were evaluated: foliage length (FL) and root length (RL), fresh foliage weight (FFW) and fresh root weight (FRW) in ten plants (replications) per treatment. The samples were placed in stove at 60 ºC during 48 h and the dry foliage weight (DFW) and root dry weight (RDW) were measured.

Statistical analysis.The design was completely randomized blocks and the experimental unit consisted in ten plants in each of the blocks. The variance analysis (ANOVA) was used and the data were subject to a multiple range test by the statistical method SAS (General Linear Models Procedure); this test controls type I errors where ± = 0,05df = 16 and MSE = 6,208333, for a number of means equal to 8 and a critical range from 4,305 to 4,893.

RESULTS AND DISCUSSION

Germination.Vermicomposts A and B increased (p< 0,05) the GP in all the combinations of the substrata with regards to the control, which proved that the concentrations from 10 to 100 % were beneficial for wheat germination (table 1). The vermicompost from goat manure (C) showed lower germination percentage (p< 0,05) than the control, although it is necessary to clarify that the seeds germinated in 84 % or more, adequate value for this species (Belmonte et al., 2010). In studies conducted with vermicompost from goat manure in Digitariaeriantha, cvs. Sudafricana and Mejorada INTA, the concentrations of 40 and 50 % were beneficial for germination (Giulettiet al., 2007). The different mixtures of the vermicompost from hen manure propitiated high germination values in all the treatments, similar to the control, although in the treatment without soil (100:0) it decreased significantly (table 1); this coincides with the results reported by Riggle (1998) and Subleret al. (1998), who found the best response in vegetable and ornamental plants when substituting between 10 and 20 % of the total volume of the commercial growth medium with the different types of earthworm humus.

In that sense, Ngo et al. (2012) stated that the use of vermicomposts causes increases of the soluble organic matter and of the carbon reserve, with regards to the initial soil without vermicompost, and this can have influence on germination due to the direct contact with the seeds.

Leaf and root length. Figures 1a, 1b, 1c and 1d show the values of the leaf and root growth of T. aestivum 30 days after sowing, according to the different concentrations of vermicomposts. Vermicompost A (fig. 1a) produced a significant increase in LL and RL in the substrata 5, 6 and 7, while in substratum 4 only RL increased.

In the treatments with vermicompost from horse manure (fig. 1b) the LL did not differ among treatments, and there was only a significant increase in the RL with 100 % of this vermicompost.

Vermicompost C (fig. 1c) produced a significant increase of the leaf length only in substratum 7, while the RL was significantly higher in substrata 3, 4, 5, 6 and 7.

The vermicompost from hen manure (fig. 1d) significantly increased the LL in substrata 4, 5, 6 and 7, and regarding the RL treatments 1 and 2 showed the lowest value, with significant difference from the rest.

It was observed that, in general, the vermicomposts were more effective at root level, compared with the aerial part. Giulettiet al. (2008a) stated that iron is concentrated in substrata A and B, calcium, in C and D; while potassium and phosphorus, more specifically in D. The trace elements double the concentration of the control substratum. The vermicomposts from cow and hen manure in concentrations of 20, 30, 40 and 50 % promoted foliage growth, but substrata B and C only did it when applied in higher concentrations. In previous studies it could be observed that in forage species, such as D. eriantha, vermicompost A only produced effect on growth with a high concentration (100 %); while B had incidence on the vegetative growth when 50 % was used (Giulliettiet al., 2007). Treatment C, rich in organic matter, nitrogen and phosphorus, had a positive effect on seed germination, root and foliage dry weight and length; while D identically influenced the increase of the number of plants, growth and germination (Giulliettiet al., 2008b).

In a study about the emergence, growth and biomass of tomato seedlings (Lycopersiconesculentum Mill.) under hothouse conditions (Zaller, 2007), a good balance was observed in the nutrient composition of the vermicomposts used, so that it was not necessary to supplement with extra nutrition and there was a favorable increase in the studied physiological indicators.

Fresh weight and dry weight.Vermicompost A did not increase the FFW or the RDW of the seedlings of T. aestivum var. Buck Pingo; however, the FDW increased when substrata 6 and 7 were applied, and the RDW increased when substratum 7 was used (table 2).

When using the substratum with vermicompost from horse manure significant differences were found in the FFW in favor of substrata 6 and 7, which did not differ between themselves; while the RFW was lower in the control treatment, just like the FDW, without significant differences among the other treatments. Regarding the RDW, substrata 6 and 7 showed the best result, with differences from the other treatments (table 3). The vermicompost from horse manure, in spite of showing little effect on leaf length, could increase in general the biomass of the wheat plant.

The vermicomposts from goat and hen manure (tables 4 and 5) did not show significant differences among the different substrata used for the variables FFW, RFW and FDW, although they differed significantly from the control treatment. The RDW of the wheat fertilized with vermicompost from goat manure (C) was lower (p d» 0,05) in the substratum that had lower concentration (10 %), which did not differ from the control. The best substratum turned out to be T5. Vermicompost C did not influence the increase of leaf length, but it influenced the biomass production. In the case of D there was the same trend as in C for the RDW, although the substrata with more than 10 % did not differ among themselves.

In tropical species such as Carica papaya L, the effect of vermicompost has been tested on physiological indicators such as: leaf area, plant height, stem diameter and dry mass, under nursery conditions as well as 180 days after transplant, with full exposure to sunlight (Acevedo and Pire, 2004); and in South African forage plants such as D. eriantha a significant increase of the leaf and root dry weightwas observed with the increase of the vermicompost concentration, which was more marked in the synthetic cultivar Mejorada INTA with regards to the cv. Sudafricana (Giulliettiet al., 2007). In tomato, the higher biomass production suggested that the physical and chemical properties of the vermicomposts not only stimulated plant growth, but there were also indirect favorable effects, through the inhibition of the infection by pathogens (Szczech, 1999; Zaller, 2006). In the above-mentioned plant, the root biomass production was 30 % lower when fertilized with 100 % of vermicompost (Zaller, 2006).

In general, all the vermicomposts were beneficial for the evaluated physiological indicators, because the wheat plants showed more vigor and health and increased their yields; which presupposes that, indirectly, there were increases in the metabolism and photosynthesis. Similar substrata have been previously used to obtain vermicomposts and they have generally been essayed on horticultural and ornamental species, for which this study proved the possibility of its use in grain species highly used in the fields of the San Luis zone, Argentina.

CONCLUSIONS

Vermicomposts A and B increased the GP in all the combinations of substrata with regards to the control, which showed that the concentrations from 10 % to 100 % were beneficial for wheat germination.

All the vermicomposts were adequate for the aerial growth of wheat; although, in general, they turned out to be more effective at root level compared with the aerial part, and increased the crop yield.

The results of this study enhance the approach of organic production, because the recycling of organic livestock production residues through the composting process, is promoted.

Received:April 23, 2015
Accepted: October 14, 2015