ABSTRACT Exposing seeds to agents that elicit tolerance to abiotic stress, such as phytohormones and organic acids, during hydration and dehydration cycles can determine their response to later stimuli, e.g. exposure to salt stress. The aim of this study was to evaluate the action of priming cycles with different eliciting agents of salt stress tolerance on seeds of the cowpea varieties Sempre Verde and Pingo de Ouro. The seeds were subjected to the following treatments: 0.0 mM NaCl (control); 100 mM NaCl (salt stress); salt stress + three seed-priming cycles (PC) in water; salt stress + PC in gibberellic acid; salt stress + PC in hydrogen peroxide; salt stress + PC in salicylic acid; salt stress + PC in ascorbic acid. The following variables were analysed: germination, growth, dry weight, salt tolerance index, total soluble sugars, total free amino acids and proline. Salt stress (100 mM NaCl) reduced germination, length and biomass accumulation in the Sempre Verde and Pingo de Ouro varieties. These showed the best response to the priming cycles with gibberellic and salicylic acids, which promoted greater germination potential, length and biomass under a salt stress of 100 mM NaCl, affording greater tolerance via osmotic regulation, especially in the Sempre Verde variety.

ABSTRACT The estimation of evapotranspiration (ET) and crop water requirements are crucial for the proper management and allocation of water resources in terms of quantity, quality, and timeliness. Therefore, remote sensing estimation of ET using the SEBAL algorithm (Surface Energy Balance Algorithm for Land) can provide spatio-temporal, non-punctual data, unlike traditional calculations relying on the nearest meteorological station. This research analyzed ET using SEBAL, based on ten Landsat 8 satellite images processed with a program developed in the Model Builder of ArcGis® version 10.2. The analysis was conducted during the vegetative period of starchy corn from May to October 2016. Validation of the results happened with a drainage lysimeter installed in a monitoring plot. Additionally, the statistical indices - such as percentage relative error (PRE) (0,09), root mean square error (RMSE) (0,30), R2 (0,92), and Nash-Sutcliffe efficiency (NASH) (0,91) - indicated a good correlation of ET for starchy corn in the central highlands of Peru. The ET identified at ten monitoring points ranged from 1,05 to 7,79 mm d-1.

ABSTRACT Chia (Salvia hispanica L.) seeds have attracted great economic interest for their high levels of linoleic and α-linolenic acids. In Brazil, there is a lack of studies on the agronomic characteristics and physiological quality of chia, necessitating research on germination processes and strategies to enhance yield under field conditions. There are no studies assessing the development of seeds with different coat colors in the presence of fungicides. This study aimed to assess the physiological quality of chia seeds as a function of coat color and fungicide treatment. The experiment followed a completely randomized design with a 2 × 2 factorial arrangement and six replications. For this, seeds were divided into two groups according to coat color (black and white) and subjected or not to treatment with carboxin + thiram. Germination speed index, germination rate, and shoot length were evaluated in plants sown at 0, 90, and 180 days after seed treatment. Germination rate and speed index differed significantly between coat colors, with white seeds having higher vigor than black seeds. Shoot length, however, differed only for seeds sown on the day of treatment, indicating that treated seeds were more vigorous.

ABSTRACT Due to the importance of grain production, and the need to work the soil under limited moisture, the aim of this study was to develop computer software to predict the tractive capacity of wheeled tractors for two types of tyre, the effect of different inflation pressures and levels of soil moisture. A mathematical model was developed to predict the tractive capacity of a 4 x 2 AFT tractor. Software was developed and tested by comparing the computational data with those from tests of a working tractor in the field. The parameters under evaluation were drawbar force and front and rear drive wheel slip. At both moisture levels, the bias tyres had the lowest front to rear slip ratio at the lower pressure; the ratios were similar when equipped with radial tyres. The bias tyres show maximum force at a slip ratio of 1.09 at the higher pressure and 1.03 at the lower, while for the radial tyres the ratio was 1.05 at the higher pressure and 1.07 at the lower. Software was developed to process data from the model, with the results used for estimating the tractive force of the tractor. The tractive force was overestimated by the model, which needs further adjustment for direct application in the field.

ABSTRACT The aim of this study was to verify the response of the melon accessions MR1 and C14 to gamma radiation in terms of germination and morphology.The melon accessions came from the germplasm collection of the Federal Rural University of the Semi-arid Region, and were submitted to five doses of gamma radiation (0, 100, 200, 300, 400 Gy) in four replications, each comprising 25 seeds, at the Center for Nuclear Energy in Agriculture of the University of São Paulo. The seeds were grown in a greenhouse at UFERSA employing a completely randomised design. The germination potential, rate and index were evaluated during the first stage of the trial. During the second stage, the germinated plants were transplanted into eight-litre buckets containing substrate and sand, in four replications of 15 plants each. The inflorescence, leaf blade and fruit were evaluated. The IMAGE J image analysis software was used to obtain the leaf and fruit data. The germination potential varied for the gamma-ray doses being tested, while the germination rate and index were not affected; phenotypic variations were seen in the leaves. The gamma-ray doses had no effect on the germination process.

ABSTRACT Given the large differences in the results of inoculation and co-inoculation in the bean crop, an experiment in cultivating winter beans was carried out in 2019 under greenhouse conditions with the aim of evaluating the performance of the beans and a possible increase in plant growth and grain production, using seeds inoculated or co-inoculated with Rhizobium tropici and Azospirillum brasilense, with and without fungicide and/or insecticide, in sandy and clayey soils. A total of 112 pots were used, and 14 treatments were applied in a completely randomised experimental design, with four replications. The Scott-Knott test was used to analyse the results, and showed that whether using untreated seeds or carrying out complete chemical treatment with fungicide and insecticide plus co-inoculation with R. tropici and A. brasilense, winter bean production was reduced in clayey soil, while the joint use of fungicide and insecticide, fungicide and R. tropici, or fungicide, insecticide and R. tropici, favoured shoot development. Inoculating with A. brasilense, without R. tropici and with insecticide, or insecticide and fungicide, favoured greater root growth in clayey soil. In sandy soil, grain production was higher using seeds treated solely with insecticide, solely with R. tropici, or with a combination of both. Production was lower in the joint treatment with fungicide, insecticide and the co-inoculation of bacteria, or when using insecticide together with A. brasilense.

ABSTRACT Proper waste management is a major worldwide concern; waste is disposed of directly into the environment, affecting water, soil and air quality. The development and production of green energy sources is strongly encouraged in modern society. The aim of this study, in accordance with Sustainable Development Goals (SDGs) 1, 2 and 7 of the 2030 Agenda of the UN, is to combine the correct disposal of animal waste with the generation of energy to mitigate the energy insecurity of families in an extremely vulnerable semi-arid region in the north-east of the country using biodigesters. To this end, a conceptual proposal was drawn up for a low-cost, easy-to-maintain and easy-to-use biodigester. A small-scale prototype was used to assess its operation by evaluating the main factors that affect biogas production (pH, temperature and the biomass properties: total solids, fixed solids, volatile solids, concentration of volatile fatty acids and C/N ratio). Evaluation of the test prototype gave satisfactory results that corroborate other studies and make it possible to propose an economically viable and efficient full-scale biodigester for biogas production.

ABSTRACT There is great interest in varieties with greater competitive ability against weeds. This can be facilitated by path analysis, which involves the statistical evaluation and interpretation of the relationship between yield and its components. In this analysis, the occurrence of multicollinearity results in inconsistent estimates of the coefficients, and overestimates of the direct effects of the explanatory variables on the response variable. The aim of this study was to identify the characteristics with the greatest direct effect on pod yield and green and dry bean yields in traditional cowpea varieties, evaluated in competition with weeds in two experiments. In addition, the presence of multicollinearity was investigated in the analyses. In Experiment-1, twelve varieties with the highest bean yields in a preliminary evaluation were assessed in a randomized block design with five replications. In Experiment-2, six varieties, selected in the preliminary evaluation, were assessed using two methods of weed management: three of the most productive and three of the least productive. Randomized blocks and split plots were used, with five replications. Multicollinearity, indicated by the number of conditions and the variance inflation values, was greater in Experiment-2. In the six cases under study (three yields x two experiments), the number of pods per plant had the greatest direct effect on yield.

ABSTRACT The physiological quality of soya bean seeds is a determining factor in establishing the crop in the field. The aim of the present study was to evaluate the physiological quality of soya bean seeds produced by plants grown from seeds of different sizes in two crop seasons. The BS 2606 SOYTECH, NS 6700 IPRO, NA 5909 RR, BS IRGA 1642 IPRO and LANÇA 58i60 IPRO cultivars were used, sown in 2019/2020 and 2020/2021. The experimental design was of randomised blocks, with treatments comprising seeds from plants grown from seeds of three sieve sizes (5.5, 6.0 and 6.5 mm for cultivars BS2606, NS 6700 IPRO, NA 5909 RR, LANÇA; and 6.0, 6.5 and 7.0 mm for the BS IRGA 1642 IPRO cultivar). The following tests were conducted: germination, first germination count, shoot and root length, total seedling dry weight, seedling emergence, accelerated ageing and electrical conductivity. The results were subjected to analysis of variance, and the mean values were compared using Tukey’s test at 5% probability. The size classification of the soya bean seeds has no effect on the germination of the seeds that are produced. Higher seed vigour in the NA 5909 RR cultivar, determined by the seedling emergence test, and accelerated ageing in NS 6700 IPRO, were obtained from seeds produced by plants grown from seeds classified as a sieve size of 6.5 mm. For the other cultivars, the size classification of the seeds had no effect on the vigour of the produced seeds.

ABSTRACT The aim of this study was to characterise the lignocellulosic fractions of pruning waste from tree species showing potential for furniture production in Acaraú, Ceará. The experiment was conducted in a completely randomised, split-plot design, with the plots corresponding to two water regimes (irrigated for one year and irrigated for three years) and the sub-plots to eight tree species, with three replications. The chemical attributes were determined after seven years. Except for the insoluble lignin content, there was a significant effect from the different species in terms of the chemical properties of the wood. The results for the lignocellulosic fractions show the possibility of developing technological ways of adding value to these waste products, especially considering their lignin content. The different species also showed potential for use in producing cellulose pulp, with the exception of Handroanthus impetiginosus due to its high ash content. The results of this study offer new perspectives for future research into the use of forestry waste.

ABSTRACT The search for more sustainable systems of rice cultivation, especially in relation to water use, has included the evaluation of more-efficient irrigation systems in addition to alternative water sources. The aim of this study was to conduct a phytosociological survey of weeds in rice crops irrigated by subsurface drip with different concentrations of treated dairy effluent, maintaining the soil moisture at saturation or field capacity. A pilot scale experiment was carried out in a protected environment using a randomised block design in a 5 x 2 factorial scheme, with four replications. The IAC 301 cultivar (Arborio rice) was chosen. The phytosociological surveys were carried out on four different dates, and considered the composition as well as the distribution of plant species in each of the applied treatments, using the importance value index (IVI) to evaluate the influence of each treatment. The results showed that cultivating irrigated rice, giving priority to water management, altered the ecology of invasive plants. Fourteen weed species were identified, distributed over 10 families. The effluent dose did not alter the incidence of invasive plants, and only at the final evaluation was there a reduction in the IVI value at effluent concentrations of 50% and 75%. For soil moisture, the highest IVI values occurred on the first two days of the survey under saturated conditions; this result was reversed closer to plant maturity, when the IVI values were higher at field capacity.

ABSTRACT The spatial variability of soil attributes in terraced areas is poorly studied in the semi-arid region. Considering that multivariate analysis enhances the diagnosis of spatial variability from geostatistics, soil attributes were studied in different zones between terrace channels in semi-arid region, more precisely in a retention terrace area in Canindé (Ceará, Brazil). Soil samples (n = 100) were collected at depths of 0.0 - 0.1 and 0.1 - 0.2 m for descriptive and geostatistical analysis. For multivariate analysis, samples from three zones relative to the terrace channel (Upper, Middle, and Lower) in the 0.0 - 0.2 m layer were considered, with 30 replicates. There was spatial dependence of soil attributes in the two layers studied. Near the channel, in the respective layers, there was higher clay content (13.7% and 14.7%) and higher degree of flocculation (61.3% and 71.7%) compared to the other zones. Water-dispersible clay was higher in the Upper zone (6.5% and 7.7% in the respective layers), while the Middle zone showed higher potential acidity in the evaluated layers (4.8 and 4.5 cmolc dm-3, respectively) compared to the other zones. In the multivariate analysis, there were highlights for the higher sum of bases in the Upper zone (18.9 ± 0.8 cmolc dm-3), higher sand content in the Middle zone (72.6 ± 0.6%), lower potential acidity (2.1 ± 0.2 cmolc dm-3) and higher phosphorus content (12.8 ± 3.0 mg kg-1) in the Low zone. The zone above the terrace channel loses mainly clay and requires practices to increase water and nutrient retention.

ABSTRACT Arbuscular mycorrhizal fungi increase water and nutrient absorption from the soil by plants. However, its benefits to plants vary depending on the inoculated species. This study aimed to determine the influence of different species of mycorrhizal fungi on the development and productivity of grain sorghum cultivars. The experiment was conducted in a greenhouse in a completely randomized design in a 2 x 5 factorial scheme, consisting of two sorghum cultivars (BRS 310 and BRS 330) and five treatments (control without inoculation and four species of arbuscular mycorrhizal fungi: Gigaspora margarita, Glomus formosanum, Acaulospora scrobiculata, and Scutellospora pellucida), with four replications. Plant height, stem diameter, leaf area, length, volume, specific surface area, root diameter, shoot dry mass, root dry mass, thousand-grain weight, grain productivity, colonization, dependence, and mycorrhizal efficiency were evaluated. The results showed that inoculation with the species S. pellucida induced higher root and shoot development of plants of the cultivar BRS 310, as well as higher productivity of sorghum grains. The cultivar BRS 330 showed higher root development when inoculated with the species G. formosanum and a higher shoot development when inoculated with the species A. scrobiculata. Mycorrhizal dependence for grain productivity was low and varied with the inoculated species of mycorrhizal fungi. The mycorrhizal efficiency for shoot dry mass was higher with the inoculation of A. scrobiculata and S. pellucida in the cultivar BRS 310 and A. scrobiculata and G. margarita in the cultivar BRS 330.

ABSTRACT Pineapple is a non-climacteric infructescence that needs to be harvested at the highest quality, and it is crucial to determine the ideal harvest point. This work evaluates changes in quality, bioactive compounds, expression and enzymatic activity and antioxidant metabolism during maturation of cv Vitória pineapple, recently introduced in commercial orchards, in order to define the harvest point. ‘Vitória’ pineapple infructescence were harvested from commercial planting in five maturity stages and five replications: 100% green (TG), break (B), 75% green and 25% orange (GO), 25% green and 75% orange (OG), 10% green and 90% orange (PO), and 100% orange (TO). In ‘Vitória’ pineapple during maturation, color evolution was clearly shown by the color index (CI) and firmness was higher in TG, G, BP stages. Soluble solids and titratable acidity increased as a function of the maturity stages. The ascorbic acid content was higher in the TG and G, while the yellow flavonoids, PET, and carotenoids higher from OG to PO maturity stages. Antioxidant activity by ABTS•+ and DDPH radicals were higher in the PO stage. The moleculr weight of the antioxidant enzymes regardless the maturity stages was estimated at 47 kDa POD, 28 kDa SOD, and 37 kDa APX. By gel electrophoresis, the SOD, APX, and POD accumulations were higher at earlier maturity stages, whereas the activities were higher at the TO maturity stage. Altogether, the highest quality and functional properties in ‘Vitória’ pineapple, as defined by the highest contents of bioactive compounds and higher antioxidant, activity, were found mainly in the maturity stage PO, which surely value fresh consumption.

ABSTRACT The application of pesticides is essential in modern agricultural production. The concept of drift refers to the undue displacement of a product, which moves to areas outside the intended target, usually due to air currents. The aim of this study was to evaluate the drift potential of conventional spray tips and those incorporating drift reduction technology, at wind speeds both suitable and unsuitable for application. The following spray tips were used: ConeJet TXVS12, Teejet TT 110-02, Teejet TTI 110-02, and Hypro GA110-03. A wind tunnel was used to generate and control the flow of air. The pressure used was 300 kPa. The wind speeds were 6 and 10 km h–1. The spray bar was mounted with the spray tip 50 cm from the ground. The spray solution included water and tracer dye. Polyethylene thread was used for the collectors, which were placed at four different distances (1, 2, 3, and 4 m) and five different heights (0.1, 0.2, 0.3, 0.4, and 0.5 m). The liquids were analysed in a spectrophotometer. At a wind speed of 10 km h–1, a distance of 1 m and a height of 0.1 m, the drift values were 13.41%, 7.15%, 3.13%, and 5.11% for the ConeJet TXVS12, TT 110-02, TTI 110-02, and GA110-03, respectively. It was found that drift potential increased with the increase in wind speed but was reduced with the increase in distance and height. Drift reduction technology using air induction proved to be the best strategy when choosing the correct spray tip for reducing drigt.