Resumo em Inglês:

ABSTRACT This study aimed to evaluate the biometric and productive characteristics of carrot (Daucus carota L.) under different irrigation levels and soil covers. Experiments were carried out at the Federal University of Viçosa in 2019 and 2020, to evaluate the effect of five irrigation levels (20, 40, 60, 80, and 100% of the daily irrigation depth) and soil coverings (control, plastic mulching, and paper mulching), on the variables soil moisture (U), actual water consumption (AWC), root length (R) and diameter (D), leaf height (H) and temperature (T), normalized difference vegetation index (NDVI), yield (Y) and dry root biomass (DB). Irrigation management was performed with tensiometers. There was no significant interaction (P < 0.05) between the factors. Irrigation significantly influenced D, H, T, NDVI, Y, and DB, while the soil cover treatment affected R, D, H, NDVI, Y, and DB. The highest yields were found in 100% irrigation (34.89 t ha-1) and with paper mulching (30.55 t ha-1). The results can guide future adaptations to the carrot production system currently in force in Brazil. As for biometric characteristics, yield, and sustainability in the use of water for irrigation were studied.

Resumo em Inglês:

ABSTRACT In view of the problems of the uneven spatial distribution of particle fertiliser and unstable depths of side-deep fertilisation, caused by existing fertiliser application devices in fertile ditches, the influence of key factors of fertiliser application devices on the depth of fertilisation was studied, in combination with the agronomic characteristics of side-deep fertilisation for the direct seeding of rice in the middle and lower reaches of the Yangtze River. By analysing the incident mud process of fertiliser particles, the factors influencing the impact of mud resistance were determined. Through the theoretical and simulation analysis of the fertilisation device, it was determined that the impact distance, the impact surface radian and the fertiliser particle diameter have the greatest impact on the fertilisation depth of the device. Single factor and orthogonal tests were carried out, with three key factors as test factors and fertilisation depth as the test index. The test results revealed that the influence of the three factors on fertilisation depth follows the order of fertiliser particle diameter > impact distance > impact surface radian. With the maximum fertilisation depth as the objective, the optimal combination of the working parameters was identified as fertiliser particle diameter = 16.0 mm, impact distance = 56.5 mm, and impact surface radian = 29.6°. Furthermore, field tests were carried out in paddy fields with a water content of 37.00 ± 2.60%. When the fertilisation depth was pre-set as 50 mm, the relative error between the pre-set value and actual fertilisation depth was lower than 8.8%. The fertilisation depth can meet the agronomic requirements of side deep fertilisation and the results provide an important reference for the design of a non-contact fertilisation device for direct rice seeding.

Resumo em Inglês:

ABSTRACT Mobile application development advances, particularly for smartphones and tablets, have allowed farmers to make decisions more assertively in their agrobusiness management. This article addresses the development and evaluation of an app aimed at people who deal with the pesticide application technology in coffee farming, more specifically, adjustment and calibration of sprayers. This mobile app provides the main data necessary for a correct calibration of air-blast sprayers to apply pesticides in coffee planting. Its functionalities include calculation of the application rate for each situation (L ha-1) based on data obtained in the field, such as canopy volume. The app, called SprayCafé, was developed for the Android platform using the Java programming language in the integrated development environment Android Studio. After the development, the application was evaluated, based on a questionnaire answered by 139 users, who ranked the following requirements: ease of use, loading time, adequacy of screen resolution, data relevance, sequence of information, and applicability, among others. The system proved to be simple and robust; it was thus assessed as adequate to the field and to be of great value for coffee planting, especially because it allows safer and more adequate pesticide application. The graphical user interface is interactive and easy to use.

Resumo em Inglês:

ABSTRACT Information related to the phenological growth of oregano grown in a protected environment associated with water and nutritional availability is scarce. In this context, this study aimed to investigate the performance of oregano plants grown with bokashi organic fertilizer under water deficit. The experiment was carried out in randomized blocks in a 6×4 factorial scheme, consisting of six levels of water replacement (60, 70, 80, 90, 100, and 110% of crop evapotranspiration – ETc) and four bokashi doses (0, 100, 200, and 300 g m−2), with five replications. The number of branches, leaf area, mass accumulation, and oil concentration and yield were evaluated to characterize the plant performance. The data were analyzed using analysis of variance, multivariate analysis for equation determination, construction of response surface plots and dendrogram charts, and linear correlation. The interaction of the factors water replacement and bokashi organic fertilizer application was significant for the analyzed variables. Morphological components presented better responses under conditions of high water replacement and bokashi organic fertilizer application. The deficit irrigation adopted during cultivation associated with bokashi organic fertilization potentiated the concentration and yield of oregano essential oil.

Resumo em Inglês:

ABSTRACT As the wind pressure distribution on plastic greenhouses in valley areas is different from that of greenhouses on plains, it is necessary to find out the variation trend of the wind pressure coefficient on greenhouses in the valley areas. Based on the ‘Realizable k-e turbulence’ model, the wind pressure characteristics on plastic greenhouses located in valley and plain areas are studied by using the verified numerical simulation method. The wind pressures on greenhouses and the corresponding fitting formula are obtained for different distances between the greenhouse and the foot of the mountain with a 0-degree wind angle. The results show that, with an increase of distance to the mountain, the positive wind pressure on the windward side of a plastic greenhouse increases and the negative wind pressure on the leeward side, roof surface and crosswind sides of the greenhouse decreases. The results from the proposed formulae are very close to those derived from the numerical simulation method, and the relative errors are all within 10%. The influence of canyon wind on the wind pressure distribution on plastic greenhouses should be considered in the design. This research can provide a reference for the wind resistance design of plastic greenhouses built in valley areas.

Resumo em Inglês:

ABSTRACT Peanut (Arachis hypogaea L.) is a legume belonging to the Fabaceae family, whose production aims at high pod yields and quality. This study aimed to investigate peanut physical traits and point out their relationship with total pod mass. Therefore, we evaluated total pod mass and the pod physical components: grain mass, pod shell mass, pod length, greatest and smallest transverse pod diameters, number of grains per pod, pod area, pod perimeter, and fruit volume. Initially, these morphological variables were correlated by Pearson’s coefficient, and a correlation network was used to graphically express the obtained results. Path analysis identified that pod total mass has a cause-and-effect relationship with the variables number of grains per pod, grain mass, and pod shell mass. As a result, these variables can be used in indirect selection for higher crop yields; therefore, monitoring pod total mass before harvest is a strategy to predict the final yield of peanuts.

Resumo em Inglês:

ABSTRACT Lowland rice is traditionally irrigated by flood systems, demanding high water consumption. Localized irrigation by subsurface dripping is proposed as an alternative, in addition to the replacement of the source of water intended for human consumption with another of lower quality, such as saline water. However, plants can be affected by saline and/or water stress in both conditions, and the use of thermal imaging emerges as a tool to assess the plant status. In this context, this study aimed to identify the stress of subsurface drip-irrigated arborio rice under different salt concentrations and soil moisture by thermographic images. The design consisted of randomized blocks in a (2×4)+2 factorial with three replications, totaling 30 experimental plots. Soil solution salinity was assessed by electrical conductivity. The thermal images were processed by an algorithm to determine the normalized relative canopy temperature (NRCT) index at different crop development stages. Saline stress was identified by the NRCT index, with higher sensitivity of plants at the flowering stage with a rebalance over time, confirmed at grain filling and harvest stages.

Resumo em Inglês:

ABSTRACT Rhizobium sp.I 3 and Agrobacterium sp.I 37 bacteria can increase plant growth and have the potential to become a member of the plant growth-promoting rhizobacteria (PGPR). Rhizobium bacteria can increase nitrogen availability for legume plants by forming nodules. Rhizobium sp. and Agrobacterium sp. are closely related; therefore, we speculated that Agrobacterium sp. can also form nodules. The study was based on completely randomized design and conducted from July 2019 to December 2019 in laboratories of the Faculty of Agriculture, Universitas Sebelas Maret, Central Java, Indonesia. The study included 11 different treatments of biofertilizer: P0, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, and P11 with each treatment in triplicate to obtain 36 experimental units. The results showed that the control treatment (P0) had 0 nodules, 8.26 g biomass, and 3.54% tissue nitrogen uptake. The three best treatments were in the order: P4 ( Rhizobium biofertilizer) with 174.3 root nodules, 14.77% tissue nitrogen (four times higher than that of control), and 24.05 g biomass; P8 ( Rhizobium biofertilizer) with 167 nodules, 12.42% tissue nitrogen (three times higher than that of control), and 19.26 g biomass; P5 ( Agrobacterium biofertilizer) with 146.6 root nodules, 13.15% tissue nitrogen (three times higher than that of control), and 16 g biomass.

Resumo em Inglês:

ABSTRACT Action planning and decision-making in the sugarcane management chain depend on yield estimates, which, in turn, vary with the soil. This study aimed to describe an applicable method of classifying sugarcane productivity into three categories, based on soil properties (medium, low, and high), determining which is most associated with biomass production. To this end, we applied the machine learning methods Naïve Bayes, Decision Trees, and Random Forest, as they proved to be useful tools for faster and more accurate results. Our results indicate that Random Forest is the most suitable for classifying all yield categories, and Naïve Bayes had good results for classification into “medium” and “low” and potential for solving multiclass problems in agriculture. Organic matter was the property most closely related to sugarcane biomass yield by the Random Forest and Decision Trees algorithms. The methods described can be used to obtain subsidies for sugarcane chain management, contributing to more sustainable decisions.

Resumo em Inglês:

ABSTRACT The harvesting of straw by the flail knife type straw cutting device will cause loose contacts between straw roots and soil, affecting the straw feed's impurity content. In this study, a theoretical analysis of the straw cutting process was conducted to explore the factors influencing the root-soil disturbance. A pulling force test device was designed to test the pulling force of the corn stalk. The response surface method was used to study the effects of various factors on the straw pulling force under different conditions of draft angles (20°, 30°, 40°), soil moisture content (15.23%, 17.62%, 20.47%), and different straw root diameters. The test results showed that the straw pulling force was directly proportional to the straw root diameter and inversely proportional to the soil moisture content. The straw pulling force decreased first and then increased with the increase of the draft angle. According to the established second-order regression model, when the draft angle was 28.5°, the soil moisture content was 20.47%, the root diameter was 22 mm, the minimum pulling force of straw was 189.635N. The test results can provide a reference for the design of straw feed harvester.

Resumo em Inglês:

ABSTRACT In this study, to meet the requirements of mechanized planting of the wide and narrow double-row ridging cassava cultivation mode, solve the problem of the real-time cutting cassava planter in which cassava stalk cutting length has poor uniformity, and improve the operation performance of the existing precut cassava planters, a rotary dibble-type cassava planter was designed. With its rotary dibble-type stalk metering device, transmission system and other components, the planter can complete the sowing, ditching, soil covering and suppression operations simultaneously. The results of a performance evaluation and an analysis of field trials showed that the variation coefficient of the planting distance was less than 30%, and the planting qualification rate was greater than 95%. The order of factors affecting the variation coefficient of the planting distance was determined to be transmission ratio followed by the forward speed. The order of factors affecting the planting qualification rate was determined to be transmission ratio followed by the forward speed. The results of the variance analysis showed that the influences of the transmission ratio and forward speed on the accuracy of planting distance and the planting qualified rate were significant. The forward speed of the planter operation was recommended to be 0.56 m/s.