Scielo RSS <![CDATA[Revista Ceres]]> vol. 67 num. 5 lang. en <![CDATA[SciELO Logo]]> <![CDATA[Pre-harvest desiccation in biomass sorghum with herbicides]]> ABSTRACT The purpose of this study was to assess the effect of different herbicide treatments on moisture removal and calorific power of biomass sorghum for co-generation of electric energy through burning. The experiment was conducted in randomized complete block design with four replicates per treatment and a 6x4 factorial scheme (six herbicide treatments x four intervals between spraying and harvesting). The herbicide treatments were: two different doses of glyphosate (1.92 kg a.i. ha-1 and 3.84 Kg a.i. ha-1), paraquat (0.4 Kg a.i. ha-1), a commercial mixture of paraquat + diuron (0.6 + 0.3 Kg a.i. ha-1), glufosinate-ammonium (0.8 Kg a.i. ha-1) and control (unsprayed). The intervals between spraying and harvesting assessed were 7, 14, 21 and 28 days after desiccation (DAD). It was assessed: the number of leaves per plant, moisture content of leaves, panicles, culm and whole ground plants and Superior Calorific Power (SCP). The herbicides paraquat and paraquat + diuron promotes defoliation, after 14 DAD. Glyphosate, paraquat, paraquat + diuron and glufosinate-ammonium reduce leaf and panicle moisture, despite only glyphosate reduces moisture in the culm. The herbicides do not affect the SCP of biomass sorghum. Therefore, the herbicides, especially glyphosate, have high potential for pre-harvest desiccation in biomass sorghum. <![CDATA[Study using a CFD approach of the efficiency of a roof ventilation closure system in a multi-tunnel greenhouse for nighttime microclimate optimization]]> ABSTRACT The thermal efficiency of naturally ventilated greenhouses is limited due to the permanent exchange of air through the vents, especially during the night hours. The objective of the work consisted in evaluating a system of inflatable air ducts that close the roof vents during the night as a strategy to reduce the energy loss during these hours. For the development of this work, we applied the computational fluid dynamics (CFD) method to a passive multi span greenhouse operating under the dominant nocturnal climatic conditions of the Bogota savannah (Colombia). The results indicated that the use of the ducts system reduces the value of the negative thermal gradient between the interior and exterior of the greenhouse. The CFD model used was validated by comparing experimental data and simulated data and by calculating goodness-of-fit parameters, finding that the numerical model predicts satisfactorily and with an adequate degree of fit the actual thermal behavior of the greenhouse evaluated. <![CDATA[Effect of planting date on postharvest quality of roots of different carrot cultivars grown in the Brazilian semiarid region]]> ABSTRACT In regions with high temperatures, carrot cultivation is difficult because high temperatures tend to reduce the size and pigmentation of the root and, consequently, the yield and quality of the product. However, with the advent of summer cultivars, the cultivation of quality carrots under high temperatures has been viable. The aim of this work was to evaluate the postharvest quality of ten carrot cultivars as a function of different planting dates. The experiments were carried out on the Rafael Fernandes Experimental Farm of the Universidade Federal Rural do Semi-Árido (UFERSA). Four experiments were carried out in May, June, July and August 2017. The experimental design was a randomized block with ten treatments and four replications. The following was evaluated: white halo percentage, soluble solids content, total soluble sugars, total titratable acidity, soluble solids/titratable acidity ratio and beta-carotene content. The interaction between the carrot cultivars and planting date had a significant influence on the postharvest quality of carrot roots. The hybrid cultivars had an overall better post-harvest quality. The carrots sown in July had better quality traits; however, they were more affected by the “white halo” disorder. <![CDATA[Physiology and production of yellow passion fruit with hydroabsorbent polymer and different irrigation depths]]> ABSTRACT The yellow passion fruit is grown under different edaphoclimatic conditions. Irrigation standardizes and increases the development and productivity of the plants. The objective of this study was to evaluate the physiological and productive aspects of yellow passion fruit with application of hydroabsorbent polymer at different irrigation depths. The experimental design was in randomized blocks in a 2 × 5 factorial arrangement. The treatments were soil with and without polymer and five dephts of irrigation (60 to 100% of crop evapotranspiration). Initial, maximum, and variable chlorophyll fluorescence, physiology (photosynthetic rate, internal carbon concentration, transpiration, stomatal conductance, water use efficiency, and instantaneous carboxylation efficiency) and production of yellow passion fruit were the variables analyzed. The hydrogel probably retained water in its structure, reducing the ability to dissipate excess energy. Setting the irrigation depth at an estimated 82% of crop evapotranspiration increased photosynthetic rate, stomatal conductance, and water use efficiency of yellow passion fruit plants. Maximum yield was 17.2 t ha-1 in irrigated plants at 100% evapotranspiration (ETc) in soil without hydrogel. <![CDATA[Yield and morphological attributes of bell pepper fruits under biological fertilizers and application times]]> ABSTRACT Bell pepper (Capsicum annuum) is one of the most consumed vegetables around the world. Balanced fertilization is essential for growing this vegetable. The objective of this study was to evaluate the yield and morphological attributes of bell pepper under doses and times of application of biological fertilizers. Two experiments were carried out with applications of biological fertilizers prepared from manure and enriched organic compounds with cattle manure and sheep manure. The experimental design was a randomized complete block design, in a 4 x 3 + 1 factorial scheme, with three replications, referring to doses of biological fertilizers (100, 200, 300 and 400 L ha-1), times of application (0, 30 and 60 days after transplanting - DAT) and control. The evaluated variables were: total fruit weight (TFW), number of commercial fruits (NCF), number of non-commercial fruits (NNCF), fruit weight (FW), fruit diameter (FD), fruit length (FL), resistance of fruit peel (RFP), number of flower buds (NFB) and productivity (P). Biological fertilizers caused positive effects on TFW, NCF, FW and P of bell pepper. The application of cattle manure at 60 DAT and sheep manure at 30 DAT promoted a larger fruit diameter. The FW, FL and RFP were influenced by the doses and times of application of biological fertilizers. The application of biofertilizers is efficient in the production of bell pepper. <![CDATA[Association of genes from different sources of resistance to major cacao diseases]]> ABSTRACT This study aimed to select genotypes resistant to witches’ broom (WB) and black pod (BP), major cacao diseases in Brazil, as well as incorporate resistance genes to moniliasis supplemented by clones EET75 and UF273, forming populations of second-cycle recurrent selection. Moniliophthora perniciosa (2 × 105 basidiospores/mL) was inoculated on 30-day-old seedlings from 72 different progenies, being assessed 60 days later, and a mixture of four isolates of Phytophthora palmivora (3 × 105 zoospores/mL) was inoculated on leaf discs from 58 progenies, observing lesions after seven days. Significant effects of progeny were observed in the tests of resistance to both diseases (p &lt; 0.05). Scavina-6 expressed resistance to both pathogens, 26 crosses did not differ from free-pollinated progenies of Scavina-6 for WB, and ten crosses were higher and 27 similar for BP. Eight crosses were largely resistant to both diseases. <![CDATA[Effectiveness of coffee leaf miner control associated with spray deposition in coffee leaves]]> ABSTRACT Coffee production faces challenges due to the susceptibility of the crop to insects. Owing to the coffee leaf miner Leucoptera coffeella, which is one of the main insect pests, the technology for the application of phytosanitary measures becomes the main challenge for coffee growers. This study aimed to evaluate the effectiveness of coffee leaf miner control using different methods of application. The study was conducted in an experimental site in the municipality of Monte Carmelo - Minas Gerais. Spray depositions in different positions of the plant canopy and the effective control of coffee leaf miner were evaluated using the following application treatments: a hydropneumatic sprayer with varying spray volumes (200 and 400 L ha-1), two hollow-cone spray nozzles with the presence and absence of agricultural adjuvant, and electrostatic application using a spray volume of 200 L ha-1 with and without spray adjuvant. The addition of an adjuvant to the spray did not influence coffee leaf miner control; in contrast, a spray volume of 200 L ha-1 combined with the application of coarse droplets was efficient in the management of insect pest. The reduction in the rate of the application using coarse droplets increased the operational capacity and reduced spray drift potential. <![CDATA[Exogenous gibberellin and cytokinin in a novel system for <em>in vitro</em> germination and development of African iris (<em>Dietes bicolor</em>)]]> ABSTRACT The availability of reliable and reproducible micropropagation systems is a decisive step to successfully propagate plant species with slow growth and low germination rate. The effect was investigated of gibberellin (GA) and cytokinin (CK) in the in vitro germination and development of Dietes bicolor (Steud.) Sweet ex Klatt. Seeds were inoculated in Water + Agar; in Murashige e Skoog (MS) medium without plant growth regulators (PGRs) and in MS medium supplemented with 1 or 2 mg L-1 gibberellic acid or 6-benzylaminopurine. The germination, growth, and architecture of the plants presented significant alterations according to the treatments. Germination percentage increased at 2 mg L-1 GA. Plants grown on the GA-supplemented medium also showed larger leaves. The presence of CK in the culture medium induced the activation of axillary shoot buds and reduced the root length. CK and GA had antagonistic effects on the thickness of the leaf tissues. The activation of multiple shoots in plants cultured with CK in the medium allowed the in vitro propagation of approximately three plants per germinated seed. The results obtained in the present study bring an unprecedented description of a germination system for a higher yield in D. bicolor micropropagation. <![CDATA[<strong>Soybean varieties suitability in agroforestry system with <em>kayu putih</em> under influence of soil quality parameters</strong>]]> ABSTRACT The existence of soybean varieties and soil type interaction causes differences in productivity of soybean varieties in agroforestry systems with kayu putih. Soil quality parameters (physical, chemical and biological characteristics) will affect the productivity of soybean varieties. The objective of this study was to reveal the relationship between soil quality parameters with soybean varieties suitability in agroforestry system with kayu putih over three locations in which their soil type were different, i.e. Lithic Haplusterts, Ustic Epiaquerts and Vertic Haplustalfs. The study was conducted from May to August, 2018 in Menggoran Forest Resort, Playen District, Gunungkidul Regency, Special Province of Yogyakarta, Indonesia. The highest yield of soybean per hectare on Dering I grown in Lithic Haplusterts and Ustic Epiaquerts was 1.38 and 1.27 tons.ha-1, respectively, while Grobogan in Ustic Epiaquerts 1.24 tons.ha-1. Dering I showed the mean of the highest yield and most suitable in all soil types, while Gema showed the mean of the lowest yield and not suitable in all soil types. Soil quality parameters that had a significant influenced on the production of soybean varieties in agroforestry systems with kayu putih were chemical characteristic consisting of availability of P, Mg, NH4 +, Mn and Ca. <![CDATA[<strong>Inoculation of rhizobia increases lima bean (<em>Phaseolus lunatus</em>) yield in soils from Piauí and Ceará states, Brazil</strong>]]> ABSTRACT The inoculation of rhizobia in lima bean can increase its yield and contribute to smallholder farms. In this study, the potential of rhizobia in increasing the lima bean yield was evaluated in two regions from Piaui and Ceará states. The experiments were conducted in field comparing three rhizobia strains (UFPI32, UFPI38, UFPI59), one strain of reference to Phaseolus vulgaris (CIAT899) and two controls (with and without nitrogen). The parameters of nodulation, N accumulation and yield varied between treatments and locations. The nodule biomasses were higher in UFPI59 and UFPI32 (Piauí), and CIAT899 and UFPI32 (Ceará). The highest values of nodule size were found in treatments UFPI59 in both locations. Lima bean presented highest values of leaf N in UFPI59 and CIAT899. The highest values of grain yield were found in the treatment UFPI59 as compared to CIAT899 and the controls. The results confirmed the potential of UFPI59 in promoting nodulation, N accumulation, plant growth and yield of lima bean in both locations.