Resumo em Inglês:

ABSTRACT We tested a new type of wind-transported particle collector (multidirectional traps, MDt) in southeast Spain to forecast particle movement in three different soil types. The MDt collectors are easy to manufacture from thermoplastic filaments with an industrial 3D printer. The collectors tested were very efficient. Our research was carried out on unplowed Calcisols and on orange and olive-cropped Fluvisols and Luvisols, respectively. The results from the logs of nine vaned masts, each with four MDt collectors at different heights, on Calcisols, Fluvisols and Luvisols were compared with the wind erodible fraction of these soils (EF) empirically estimated and with their erosion rates calculated in a wind tunnel of our own design with a built-in laser scanner. These new collectors can differentiate the collected sediments by their direction of origin and arranged in a network of masts, enabling to distinguish overall particle loss or deposition, which is not detectable with the wind tunnel due to the work scale and no windward deposits, as it is a closed device. Comparison of the calculated EF and the total mass of transported particles recorded by the MDt collectors showed very good correlation (R2 = 0.9144) with an even better relationship between the results of the wind tunnel and collectors (R2 = 0.9741). Required precision, financing, and execution time are important in determining the use of the device. We conclude that this device shows good potential.

Resumo em Inglês:

ABSTRACT Models of development are tools that connect the effects of development on the environment, allowing their applications in several studies. Nevertheless, studies are scarce on models of development for native forest species in Brazil. This study aimed to predict the development of two native forest species - Citharexylum myrianthum Cham. and Bixa orellana L. - with two agrometeorological models, being one linear (Phyllochron) and another nonlinear (Wang and Engel, 1998). Both models predict the cumulative leaf number (CLN) on a daily basis, which generates the seedling phase duration (SPD) when integrated to time. Data were used from two years of experiments conducted during 2015 and 2016 growing seasons and 12 sowing dates in Itajubá, Minas Gerais State, Brazil. These species × sowing dates × years experiments provided a rich dataset for calibrating and evaluating both models. Although both models used in the study allowed predicting the dynamics of leaf development, CLN, and SPD in two native forest species, the Wang and Engel model provided a more accurate prediction of CLN and SPD for C. myrianthum species, with an overall root mean square error (RMSE) of 1.82 leaves (CLN) and 5.9 days (SPD). For B. orellana, the Phyllochron model was slightly better, with an overall RMSE of 1.48 leaves (CLN) and seven days (SDP).

Resumo em Inglês:

ABSTRACT Methods for genetic improvement of semi–perennial species, such as passion fruit, often involve large areas, unbalanced data, and lack of observations. Some strategies can be applied to solve these problems. In this work, different models and approaches were tested to improve the precision of estimates of genetic evaluation models for several characteristics of the passion fruit. A randomized block design (RBD) model was compared to a posteriori correction, adding two factors to the model (post–hoc blocking Row–Col). These models were also combined with the frequentist and Bayesian approaches to identify which combination yields the most accurate results. These approaches are part of a strategic plan in a perennial plant breeding program to select promising genitors of passion to compose the next selection cycle. For Bayesian, we tested two priors, defining different values for the distribution parameters of effect variances of the model. We also performed a cross–validation test to choose a priori values and compare the frequentist and Bayesian approaches using the root mean square error (RMSE) and the correlation between the predicted and observed values, called Predictive capacity of the model (PC). The model with the post–hoc blocking Row–Col design captured the spatial variability for productivity and number of fruits, directly affecting the experimental precision. Both approaches applied to the models showed a similar performance, with predictive capacity and selective efficiency leading to the selection of the same individuals.

Resumo em Inglês:

ABSTRACT Alternatives to enhance the consensual low phosphorus (P) use efficiency of agriculture may include use of phosphate rock (PR) and plant species with unequal ability to get soil and rock P interplanted in cropping systems to allow plants with higher ability to facilitate access to P of plants with lower ability. This study investigated (i) the maize and three soil cover crops on their capacity to acquire P from PR and (ii) measured P acquisition of maize interplanted with the soil cover crop with the highest capacity to acquire P shown in (i). Experiments were carried out in a greenhouse, with plants grown in single and mixed cropping in pots containing a sandy, low–P soil amended with Monocalcium Phosphate (McP) or the Brazilian PR Itafós. Plant biomass production with PR, in relation to McP, was 83.7 % for buckwheat, 83.6 % for forage radish, 51.8 % for maize, and 0.3 % for pigeon pea. Buckwheat showed capacity of acquiring P from PR; nevertheless, it did not increase growth or P nutrition of maize interplanted in the soil amended with PR, showing no significant P facilitation. The soil amended with McP showed competition between the two plants in the pots. Maize had a greater growth in mixed than in single cropping and this occurred at the expenses of buckwheat. Despite the P mobilization potential of buckwheat, its simple interplanting with maize did not produce positive results.

Resumo em Inglês:

ABSTRACT The enhancement of rice production numbers can be achieved by using quality rice cultivars and fertilizers. The double rice cropping model has given rise to an important rice production system in southern China. Exploring the possibility of whether hybrid vigor could make a substantial contribution to early and late season rice production, and how the heterosis expression of hybrid rice functions under different levels of fertilizer application is of great significance. The objective of this study was to evaluate the grain yield and associated plant traits of popular hybrid and inbred rice varieties with large–scale promotion under conditions of customary (high) and combined (low) fertilization in the early and late seasons of 2017–18 in Changsha County, Hunan Province, China. We found that hybrid rice varieties displayed their respective advantages in the early and late rice seasons, but the advantages in their relative yield traits varied. The leading advantages of early season rice were effective panicle number per hill (EPN), 1000–grain weight (KGW), harvest index (HI), yield, and nitrogen use efficiency (NUE), whereas in late season rice, the foremost advantages were grain number per panicle (GNP), HI, yield, and NUE. The EPN was the prime advantage of early season hybrid rice with a short growth period, and the GNP was the main advantage of late season hybrid rice with a long growth period. Notably, the main yield advantage of hybrid rice was stronger under combined (low) fertilization than under customary (high) fertilization. Hence, high yield can be achieved by selecting the best hybrid rice varieties supported by combined fertilization (lower fertilizer use with higher efficiency).

Resumo em Inglês:

ABSTRACT An important concern with the use of genetically modified (GM) plants expressing Bacillus thuringiensis (Bt) insecticidal toxins is the deleterious effect on non–target organisms. The predatory stink bug Podisus nigrispinus (Dallas) (Hemiptera: Pentatomidae) is used in biological control programs and may be exposed to Bt toxins. This study evaluated the indirect effects of different Cry proteins on P. nigrispinus with the prey Spodoptera frugiperda (J.E. Smith, 1797) (Lepidoptera: Noctuidae), fed on simple or pyramided Bt maize genotypes. The experiment was carried out in a completely randomized design with three treatments: i) Isohybrid (not Bt), ii) Herculex® (transgenic maize encoding Cry1F protein) and iii) PowerCore® (pyramidal transgenic maize encoding the Cry1F, Cry1A.105, and Cry2Ab2 proteins), which were used to feed S. frugiperda for 48 h. The caterpillars were used as prey by P. nigrispinus females. We evaluated the presence of Cry proteins, consumed prey biomass (predation), oviposition period, number of postures, number of eggs, number of eggs per posture, number of nymphs, egg viability, embryonic period, female longevity and development, and survival rates of immature. The results show that different Cry proteins move through the food chain of P. nigrispinus and provide evidence that the ingestion of three different proteins does not lead to unexpected synergistic effects. However, Cry toxins promoted histopathological changes in midgut cells of P. nigrispinus.

Resumo em Inglês:

ABSTRACT Cachaça is a typical Brazilian spirit of significant economic and social relevance. The spirit may contain organic and inorganic contaminants that impair its quality, such as ethyl carbamate (EC), which is potentially carcinogenic. The study of factors that cause EC incidence is extremely important to produce cachaça with good physicochemical and sensory quality and for public health reasons. Therefore, this study aimed to analyze and quantify nitrogen (N) in sugarcane juice and correlate it with the EC levels, with copper (Cu) as precursor, in cachaça from stills, produced from the sugar of three different sugarcane varieties (RB857515, RB966928 and RB855453). We used the plantation systems without fertilization and with organic and conventional fertilization. The EC and Cu levels were below the legislation threshold and the N levels were correlated with EC formation in different planting systems.

Resumo em Inglês:

ABSTRACT Water deficit can alter the morphological, agronomic, physiological, and technological traits of the common bean plant, affecting bean grain yield. In addition to yield aspects, the grain post-harvest quality is a decisive factor for the adoption of a new cultivar. Thus, this study evaluated the effect of water deficit on the physiological, morphoagronomic, and technological traits of common bean. The experiment was carried out at in a greenhouse in a randomized block design with a 30 × 2 factorial arrangement, consisting of 30 carioca common bean genotypes and two water regimes (with and without water stress), with three replications. The water deficit affected most morphological, agronomic, and physiological traits; however, it was not significant on the darkening of the seed coat. Cultivars IAC 1849 Polaco, ANFc 5, ANFc 9, BRSMG Madrepérola, IAC Carioca Aruã, TAA Dama, and Branquinho exhibited high yield potential under water stress treatment as well as slow seed coat darkening during nine months of storage. The selection of bean genotypes with slow seed coat darkening could be performed at 30 days of storage.

Resumo em Inglês:

ABSTRACT Chenopodium quinoa Willd. is an Andean crop with great nutritional value, economic potential, and a broad genetic and phenotypic diversity with adaptation to different conditions. In Colombia, C. quinoa is cultivated mainly in Cundinamarca, Nariño and Boyacá, where studies have been conducted to characterize the germplasm and lack of seed materials, some challenges for the quinoa crop. This work assessed agromorphological characteristics of 50 quinoa genotypes from the germplasm collection of Boyacá the using a completely randomized design on the farm in Tunja. The multivariate analysis followed by a clustering approach were conducted on agromorphological descriptors, in which 16 were qualitative descriptors (e.g, panicle shape, episperm color, leaf shape) and five quantitative descriptors (e.g, plant height, panicle number). The results showed that higher coefficients of variation were found in characteristics associated to yield. The principal component analysis (PCA) of the quantitative variables showed that the first two components explained 88 % of the total variation with the characteristics of plant height, length, diameter, and panicle number showing the highest variability. The quantitative characteristic clusters comprised length and diameter panicle, weight 1,000 seeds, and plant height, while the qualitative characteristic clusters comprised stem shape, branching habit, panicle shape, and color of the axils. The factorial analysis of mixed data discriminated the materials with outstanding morphoagronomic characteristics. Agromorphological characterization revealed a broad variability, which should be conserved and used in genetic improvement programs of C. quinoa.

Resumo em Inglês:

ABSTRACT Hydrogels have potential as soil conditioners due to their high capacity to retain water and mitigate soil salinity. However, investigations under saline conditions are necessary because there are losses in both water absorption and salinity mitigation depending on the composition of hydrogel and ions involved in salinity. In this work, we studied a commercial hydrogel in two experiments. The first experiment was conducted in the laboratory to evaluate the absorption by the hydrogel of water with electrical conductivity (EC) of 0.5, 1.5, 3.0, and 4.5 dS m–1, promoted by NaCl. The second experiment was conducted in a greenhouse in a 2 × 4 factorial scheme (with and without hydrogel × EC of the first experiment). Although salinity reduced water absorption by hydrogel by 84 %, the polymer applied in a sandy soil under saline conditions reduced water losses by 58 %. However, hydrogel did not increase the final soil moisture (~ 0.10 g g–1). The polymer reduced Na+ concentration in leachate from 1,499 to 1,219 mg L–1 at the highest salinity level (4.5 dS m–1), but it increased Na+ soil availability by 0.1 mg kg–1 in comparison with polymer absence. Hydrogel application increased Na+ content in plants from 9 to 13 mg kg–1 at the highest salinity, while K+ content was 10 to 16 mg kg–1 lower than that observed without a polymer. Hydrogel 0.07 % (w/w) reduced maize biomass, indicating damage by monovalent ions, compromising the polymer potential under salinity.

Resumo em Inglês:

ABSTRACT Electromagnetic sensors are widely used to monitor soil water content (θ); however, site-specific calibrations are necessary for accurate measurements. This study compares regression models used for calibration of soil moisture sensors and investigates the relation between soil attributes and the adjusted parameters of the specific calibration equations. Undisturbed soil samples were collected in the A and B horizons of two Ultisols and two Inceptisols from the Mantiqueira Range in Southeastern Brazil. After saturation, the Theta Probe ML2X was used to obtain the soil dielectric constant (ε). Several readings were made, ranging from saturation to oven-dry. After each reading, the samples were weighted to calculate θ (m3 m–3). Fourteen regression models (linear, linearized, and nonlinear) were adjusted to the calibration data and checked for their residue distribution. Only the exponential model with three parameters met the regression assumptions regarding residue distribution. The stepwise regression was used to obtain multiple linear equations to estimate the adjusted parameters of the calibration model from soil attributes, with silt and clay contents providing the best relations. Both the specific and the general calibrations performed well, with RMSE values of 0.02 and 0.03 m3 m–3, respectively. Manufacturer calibration and equations from the literature were much less accurate, reinforcing the need to develop specific calibrations.

Resumo em Inglês:

ABSTRACT The concept of production environments, which is widely used to classify the yield potential of soils, and magnetic susceptibility (MS), is emerging as an important tool for mapping ultra-detailed areas. Given this background, this paper aims to evaluate the use of MS as a tool for the identification of areas with different potential the enhancing of sugarcane yield and quality, and the allocation of varieties. An area of 445 ha was sampled at 1 point every 7 ha, and 14 points were determined for stratified sampling following the top of the landscape. Particle size and MS of samples at depths of 0.0-0.2 and 0.2-0.4 m were analyzed. The data on yield and quality of raw material were obtained from a nine crop season database and biometry performed in the 2018/19 crop season. The multivariate analysis of historical results showed the formation of three groups with different yield and quality potential, with a difference of up to 17.28 mg of cane per hectare between the group with the highest and lowest potential, based on soil MS. An analysis of the performance of the varieties involved showed that MS is effective in identifying areas with different potential for sugarcane yield and quality, differentiating by up to 34.5 % the performance of the same variety in different MS classes and by up to 38.5 % the performance of different varieties in similar MS classes. Thus, MS is an effective tool for identifying areas with different potential for sugarcane yield and quality, and can be used for allocating varieties in the field.

Resumo em Inglês:

ABSTRACT Adequate potassium (K) fertilization is essential for agricultural production in soils of the Brazilian Savanna (Cerrado biome) due to the high demand by crops (especially cotton), likelihood of leaching losses, and the dependence on fertilizer importations. Therefore, sustainability requires improvements in the soil efficiency management. This study evaluated the influence of soil management and crop succession or rotation combinations with cotton on K dynamics and exchangeable reserves in the soil profile, and the partial balance of K after nine years of cultivation in a clayey Oxisol in the Cerrado. The soil was sampled in layers up to 100 cm depth in four cotton production systems treatments: 1) conventional soil tillage (CST) with cotton monoculture; 2) CST with annual cotton-soybean-cotton succession; 3) CST with cotton/soybean/maize rotation; and 4) no-tillage system (NTS) with cotton/soybean/maize rotation and Urochloa ruziziensis (ruzigrass) as a cover crop in the off-season after grain crops. The experiment was conducted using a randomized block design with four replications. CST with cotton monoculture favored the leaching of K surplus from fertilization. Crop rotation including ruzigrass in the NTS allowed better control of K dynamics, ensuring its circulation in the soil-plant compartments and reducing leaching. The increased organic matter (OM) in this system enlarges the storage capacity of K in the topsoil. The adoption of no-tillage crop systems integrating ruzigrass is viable to improve the efficiency of K fertilizers in cotton cultivation in highly weathered tropical soils.