Acta Scientiarum. Agronomy
ISSN / EISSN : 1679-9275 / 1807-8621
Published by: Universidade Estadual de Maringa (10.4025)
Total articles ≅ 1,480
Latest articles in this journal
Acta Scientiarum. Agronomy, Volume 43; https://doi.org/10.4025/actasciagron.v43i1.51801
This work aimed to characterize the biochar produced from residues of coconut fruit and to evaluate how it might beneficially alter the retention capacity of water and nutrients in soils with a sandy texture. The biochar was produced in a retort furnace and later analyzed to determine its chemical and physical characteristics. Experiments to analyze the retention potential of the biochar for water and nutrients were performed in PVC columns filled to a 400 mm depth, with the upper 300 mm receiving treatments that consisted of 0, 1, 2, 3, 4, and 5% (p p-1) biochar mixed with soil. For the nutrient retention experiment, in addition to the biochar concentrations, the treatments received the same NPK fertilization. The experiments were performed in a completely randomized design with four replications. The water retention in the upper 300 mm, as well as the pH, effective cation exchange capacity (ECEC) of the substrate, base saturation, and concentrations of P and K, increased with increasing biochar concentration. Coconut biochar demonstrated potential for increasing water retention and improving nutrient retention in sandy soils.
Acta Scientiarum. Agronomy, Volume 43; https://doi.org/10.4025/actasciagron.v43i1.58283
Soil contamination by metals threatens both the environment and human health and hence requires remedial actions. The conventional approach of removing polluted soils and replacing them with clean soils (excavation) is very costly for low-value sites and not feasible on a large scale. In this scenario, phytoremediation emerged as a promising cost-effective and environmentally-friendly technology to render metals less bioavailable (phytostabilization) or clean up metal-polluted soils (phytoextraction). Phytostabilization has demonstrable successes in mining sites and brownfields. On the other hand, phytoextraction still has few examples of successful applications. Either by using hyperaccumulating plants or high biomass plants induced to accumulate metals through chelator addition to the soil, major phytoextraction bottlenecks remain, mainly the extended time frame to remediation and lack of revenue from the land during the process. Due to these drawbacks, phytomanagement has been proposed to provide economic, environmental, and social benefits until the contaminated site returns to productive usage. Here, we review the evolution, promises, and limitations of these phytotechnologies. Despite the lack of commercial phytoextraction operations, there have been significant advances in understanding phytotechnologies' main constraints. Further investigation on new plant species, especially in the tropics, and soil amendments can potentially provide the basis to transform phytoextraction into an operational metal clean-up technology in the future. However, at the current state of the art, phytotechnology is moving the focus from remediation technologies to pollution attenuation and palliative cares.
Acta Scientiarum. Agronomy, Volume 43; https://doi.org/10.4025/actasciagron.v43i1.52126
Accurate forest biomass estimates require the selection of appropriate models of individual trees. Thus, two properties are required in tree biomass modeling: (1) additivity of biomass components and (2) estimator efficiency. This study aimed to develop a system of equations to estimate young eucalyptus aboveground biomass and guarantee additivity and estimator efficiency. Aboveground eucalyptus biomass models were calibrated using four methods: generalized least squares (GLS), weighted least squares (WLS), seemingly unrelated regression (SUR), and weighted seemingly unrelated regression (WSUR). The approaches were compared with regard to performance, additivity, and estimator efficiency. The methods did not differ with regard to the mean biomass estimation; therefore, their performance was similar. The GLS and WLS approaches did not satisfy the additivity principle, as the sum of the biomass components was not equal to total biomass. However, this was not observed with the SUR and WSUR approaches. With regard to estimator efficiency, the WSUR approach resulted in narrow confidence intervals and an efficiency gain of over 20%. The WSUR approach should be used in forest biomass modeling as it resulted in effective estimators while ensuring equation additivity, thus providing an easy and accurate alternative to estimate the initial biomass of eucalyptus stands in ecophysiological models.
Acta Scientiarum. Agronomy, Volume 43; https://doi.org/10.4025/actasciagron.v43i1.52045
Producers in the northeastern semiarid region of Brazil have been cultivating irrigated corn. The commercialized product comprises mainly green ears and silage. However, the irrigation of crops for dry grain has been questioned regarding costs and price competitiveness in relation to the same non-irrigated product cultivated in other regions. In recent years, the use of drip tapes and fertigation has spread among corn producers in the region. The aim of this study was to determine the N dose, via fertigation, which provides the maximum economic production of corn for dry grain, in two crop seasons (summer and winter), in the semiarid region of Brazil. The experimental design was performed in randomized blocks, with four replications. In both crops, the treatments consisted of four doses of N (0, 80, 160, and 240 kg ha-1) applied in the form of urea. In the hybrid corn (Bt Feroz), the N content was evaluated in terms of leaves, grain yield, gross and net incomes, the rate of return, and the profitability index. Independent of the crop season, the yield of dry grain (5,441.03 kg ha-1) was highest when the corn was fertigated with a dose of 104.05 kg ha-1 N. The highest net incomes of the dry grain were obtained with 80 kg ha-1 N in summer (R$ 1,190.78 ha-1) and 160 kg ha-1 N in winter (R$ 2,757.54 ha-1). The winter crop was more favorable to the economic production of dry grain.
Acta Scientiarum. Agronomy, Volume 43; https://doi.org/10.4025/actasciagron.v43i1.55105
The initial development of common bean plants (Phaseolus vulgaris L.) relying on symbiotic nitrogen (N) can be limited by delayed active N2 fixation, requiring supplemental N which in turn may inhibit the symbiosis. Five experiments were carried out in hydroponics to identify the initiation of nodulation and nitrogenase activity in common bean cultivars, and the effects of additions of mineral N on plant nodulation and growth. Three experiments evaluated the initial growth of five inoculated bean cultivars in the absence or presence of mineral N, and two experiments evaluated the effect of the moment of mineral N addition until the beginning of reproductive stage. The first root nodules appeared 10 days after plant transplant (DAT) and nitrogenase activity initiated 11 DAT. Cultivars of large seeds had lower initial nodulation and nitrogenase activity than those of small seeds. Inoculated plants showed limited shoot growth that lasted until 21-25 DAT as compared to inoculated plants receiving mineral N. Addition of mineral N reduced nodule mass more intensively than nodule number and more strongly nitrogenase activity. Nitrogen applied until 15 DAT enhanced nodulation and nitrogenase activity without limiting shoot growth, as compared to plants receiving N throughout their growth. Otherwise, plants that received N after 15 DAT had lower nodule mass and nitrogenase activity than plants only inoculated. The results indicate that symbiotic N did not suffice to an adequate growth of common beans and some supplemental N is necessary. This N should be added in the beginning of growth cycle to stimulate plant growth without inhibiting further nodulation and N fixation.
Acta Scientiarum. Agronomy, Volume 43; https://doi.org/10.4025/actasciagron.v43i1.51831
In regions with high temperatures, carrot cultivation is impracticable, as high temperatures tend to reduce yield and quality of the product. However, with the advent of summer cultivars, carrot cultivation in these regions has become viable. The aim of this work was to evaluate the performance of ten carrot cultivars in different planting seasons. The experiments were carried out at the Rafael Fernandes Experimental Farm of the Federal Rural Semiarid University (UFERSA). The experiments were carried out in May, June, July and August of 2017. The experimental design was a randomized block with ten treatments and four repetitions. The characteristics that were evaluated were the root classification (long, average and short roots); commercial, non-commercial and total yield; dry plant weight and root fresh weight. Both the planting season and the cultivar played important roles in agronomic performance throughout the experimental period. In May and June, the highest average yields and plant growth were obtained (43 and 45 t ha-1 yield, respectively). Hybrid cultivars showed better performance than open-pollinated cultivars in terms of yield. The Brasília, BRS Planalto, and Kuronan varieties showed poor performance in all the evaluated characteristics.
Acta Scientiarum. Agronomy, Volume 43; https://doi.org/10.4025/actasciagron.v43i1.51541
The aim of this study was to verify if a growth reduction of yellow passion fruit seedlings’ growth morphophysiology and quality could be changed by paclobutrazol applied through seedling immersion. The experiment was conducted in a greenhouse, with seedlings grown in polyethylene tubes (290 cm3), with substrate. At 40 days after sowing, the seedlings were immersed in an aqueous solution of paclobutrazol at concentrations of 0, 50, 100, 150, and 200 mg L-1. The experiment was conducted in a randomized block design, with five treatments (paclobutrazol concentrations) and four replicates. At 15 and 30 days after treatment, growth characteristics were evaluated. At the end of the assay, destructive evaluations related to mass determination, total leaf area, and seedling quality index were performed. Paclobutrazol treatment induced restrictions in seedling growth, except for fresh and dry mass of root and total fresh mass. Based on these characteristics, the increase in values induced by paclobutrazol was verified. The seedling quality, defined by the major value of the Dickson quality index and a smaller robustness index, was higher when submitted to paclobutrazol treatment.
Acta Scientiarum. Agronomy, Volume 43; https://doi.org/10.4025/actasciagron.v43i1.52095
This study aimed to evaluate the beverage quality of Coffea canephora genotypes in different environments of the western Amazon to assist plant selection and new cultivar development. To analyze beverage quality, samples of cherry coffee beans were collected separately for each genotype from clonal competition trials installed in the municipalities of Ouro Preto do Oeste, Alta Floresta do Oeste, Porto Velho, and Ariquemes in Rondônia State and Rio Branco in Acre State (Brazil). The beverage quality was assessed using the Robusta Cupping Protocol, which attribute to each genotype a score in a range from 0 to 100, highlighting nuances. Analysis of variance and principal components using reference points were used to quantify genotype x environment interaction (G x E). The analysis of variance indicated that genotypic and G x E interaction effects were significant (p < 0.01). By using a centroid dispersion method, we could identify four clones of low, eight of specific (to favorable or unfavorable environments), and seven of broad adaptability to the environments. The clones BRS 2314, 11, and 17 had average quality scores above 80 in all environments, with potential for specialty coffee production. The clones BRS 1216, BRS 3220, and BRS 3193 presented unstable behavior, with beans of higher quality in some of the evaluated environments. Such inconsistency in clone behavior is caused by unpredictable changes in plant performance in different environments. Our results indicate that both genotypic (clones) and G x E interaction effects are important for the expression of coffee beverage quality. However, the clones BRS 3213, BRS 3210, and BRS 2299 had less prominent nuances, with lower potential for specialty coffee production.
Acta Scientiarum. Agronomy, Volume 43; https://doi.org/10.4025/actasciagron.v43i1.52006
Salvia hispanica L. is an alternative crop cultivated by farmers who want to diversify their production. However, this species is sensitive to salinity, which affects its germination negatively. Seed priming with different attenuators is a technique with potential to mitigate the effects of salt stress. Thus, the objective of this study was to evaluate the effect of seed priming with the use of different attenuators on the germination, growth, and organic solute accumulation of S. hispanica seedlings under salt stress. The experimental design was completely randomized, with treatments distributed in a 4 × 5 factorial scheme, corresponding to four seed priming treatments and five osmotic potentials, with four replicates of 50 seeds in each treatment. The seed treatments consisted of presoaking seeds for 4h in salicylic acid, gibberellic acid, and distilled water and the control treatment, which did not involve soaking. These seeds were germinated at osmotic potentials of 0.0, -0.1, -0.2, -0.3, and -0.4 MPa, using NaCl as an osmotic agent to simulate the different salinity levels. Among all the treatments implemented, S. hispanica seed priming with salicylic acid was the most efficient in mitigating the salt stress effects.
Acta Scientiarum. Agronomy, Volume 43; https://doi.org/10.4025/actasciagron.v43i1.53721
The objective of this study was to conduct a meta-analysis and test its efficiency in summarizing the heterogeneous data of heritability estimates for the traits of grain yield (GY) and popping expansion (PE), and to provide reliable estimates of selection gains in popcorn. Therefore, 97 heritability estimates ( ) for popcorn GY and PE in the broad and narrow sense were used. The main procedures underlying the estimation of the combined heritability ( ) using the technique of meta-analysis consisted of i) an exploratory analysis of the set of heritability estimates to detect outliers using a box-plot chart, ii) the verification of the required statistical assumptions, iii) testing the involved heritability estimates for homogeneity, and iv) the calculation of the estimates of combined heritability. The meta-analysis facilitated the synthesis of the information pertaining to heritability in popcorn. The combined heritability estimates ( ) in the broad sense for GY and PE were 0.5208 ± 0.0229 and 0.6356 ± 0.0209, respectively, and in the narrow sense were 0.3290 ± 0.0292 and 0.3083 ± 0.0298, respectively.