Scielo RSS <![CDATA[Bragantia]]> http://www.scielo.br/rss.php?pid=0006-870520180001&lang=es vol. 77 num. 1 lang. es <![CDATA[SciELO Logo]]> http://www.scielo.br/img/en/fbpelogp.gif http://www.scielo.br <![CDATA[Genotypic differences in cyanogenic glycosides levels of compatible <em>Prunus persica P. persica</em> and incompatible <em>P. persica P. mume</em> combinations]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0006-87052018000100001&lng=es&nrm=iso&tlng=es ABSTRACT Graft incompatibility is a phenomenon associated with complex physiological, biochemical, and genetic interactions between scion and rootstock. The main objective of this work was to assess the role of cyanogenic glycosides (CGs), amygdalin and prunasin, in the graft incompatibility of Prunus and possible biochemical effects in compounds of the phenylpropanoid pathway. Graft compatibility, amygdalin and prunasin content, phenylalanine ammonia-lyase activity, total phenolic compounds content and antioxidant activity, were studied in different graft combinations (Chimarrita/Capdeboscq; Chimarrita/Tsukuba 1; Chimarrita/Umezeiro; Maciel/Capdeboscq; Maciel/’Tsukuba 1; Maciel/Umezeiro) and ungrafted genotypes. The results indicate that there was graft incompatibility of Chimarrita and Maciel cultivars grafted into Umezeiro rootstock. Combinations identified as incompatible showed higher prunasin concentration and phenylalanine ammonialyase (PAL) activity in rootstock and greater concentration of total phenolics compounds and antioxidant activity in scion and rootstock. The results indicate that large differences in CGs concentration, especially prunasin, can be the graft incompatibility cause between Prunus persic. and P. mume. The prunasin concentration may be considered a promising marker to predict graft compatibility between P. persica and P. mume. <![CDATA[The role of phytochromes in cadmium stress responses in tomato]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0006-87052018000100013&lng=es&nrm=iso&tlng=es ABSTRACT It is well known that phytochromes mediate a wide range of photomorphogenic processes in plants. In addition, many studies have demonstrated the involvement of phytochromes as part of abiotic stress signaling responses. However, little is known about cadmium (Cd) stress regulation by phytochromes. Thus, in this study, we used the phyA (far red-insensitive; fri), phyB1 (temporary redinsensitive; tri) and phyB2 (phyB2) tomato (Solanum lycopersicum L.) mutants to investigate the roles of these three phytochromes on Cd stress responses. The plants were grown over a 21-d period in the presence of Cd. We evaluated plant growth, Cd and chlorophyll content and anatomical changes in the leaves. The results indicated that all genotypes were affected by Cd and showed reduced growth of the shoots and roots, as well as reduced chlorophyll content. The accumulation of Cd was similar for all genotypes, and a higher Cd content was found in roots. Anatomical analysis of the vascular bundles revealed that fri and tri seem to be more disrupted by Cd. Overall, these results indicate that phytochromes do not determine Cd stress tolerance in tomato plants. <![CDATA[Source-sink relationships in two soybean cultivars with indeterminate growth under water deficit]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0006-87052018000100023&lng=es&nrm=iso&tlng=es Abstract Water deficit is a major factor limiting crop yield in rainfed areas. We hypothesized that under water deficit the decrease of photosynthetic production stimulates: carbohydrate remobilization from leaves, stems and roots to reproductive organs; and decreasing flowering intensity and pod development. The present work aims to study the effect of water deficit during bloom and grain pod-filling stages in two indeterminate soybean cultivar, Vtop and Nidera. The following physiological parameters were evaluated by means of daily CO2 assimilation rate (Ai), dynamic of carbohydrates in tissues, plant growth, grain yield and yield components. The study was conducted in a greenhouse with plants sown in tanks of 0.5 m3. Regardless of the phenological phase, water deficit reduced Ai, plant growth and number of pods and seeds per plant. The fact that grain yield was less affected by water deficit at bloom than at grain pod-filling stage was attributed to larger seeds found at bloom. In both treatments, a sharp reduction on carbohydrate content was found in leaves, stem and roots at the beginning of pod formation. The high amounts of carbohydrates remobilized for seed growth, along with the high values of Ai observed in well-watered plants, indicate that grain yield of soybeans is source rather than sink limited. On the other hand, in water deficit treatments, a new stimulus for carbohydrate storage was found in the leaves and stem at the beginning of grain maturity, suggesting that grain yield was limited by sink capacity. <![CDATA[Popcorn germplasm resistance to fungal diseases caused by <em>Exserohilum turcicum</em> and <em>Bipolaris maydis</em>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0006-87052018000100036&lng=es&nrm=iso&tlng=es ABSTRACT Compared with the common corn, popcorn shows greater susceptibility to pests and diseases occurrence, being the use of resistant cultivars the most efficient strategy. In this regard, Germplasm Banks deserve special attention because they contain accessions that can be used as sources of resistance in breeding programs. The State University of Northern Rio de Janeiro (UENF) maintains a popcorn Germplasm Bank with accessions from tropical and temperate countries, including Diversity Centers for the species. In this study, we investigated the performance of 37 popcorn accessions landraces, hybrids, and inbreed lines ― from the Germplasm Collection of UENF’s Popcorn Breeding Program with respect to the fungal leaf diseases northern leaf blight (NLB) and southern leaf blight (SLB), caused by Exserohilum turcicum and Bipolaris maydis, aiming to select promising accessions for genetic resistance to be used in future crosses to generate new resistant cultivars for farmers. The dendrogram scattering by the UPGMA multivariate technique was efficient in discriminating resistant accessions. Satisfactory results were obtained for resistance to NLB in accessions L71, L75, L76, P7, and PARA-172, which can thus be considered remarkable sources of resistance. For resistance to SLB, the superior accessions that can be indicated as sources of resistance are ARZM-05083, ARZM-07049, and PARA-172. <![CDATA[Fiber composition of a diversity panel of the world collection of sugarcane (<em>Saccharum</em> spp.) and related grasses]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0006-87052018000100048&lng=es&nrm=iso&tlng=es ABSTRACT The world collection of sugarcane (Saccharum hybrids. and related grasses (WCSRG) is an important source of genes for sugarcane and energycane breeding. The core collection or diversity panel of the WCSRG was created in Canal Point with 300 accession and 10 checks to evaluate its diversity. The fiber components of the species and accessions within the WCSRG are unknown, so a shredded and dried fiber sample was taken from each accession and sent for fiber analysis. The acetyl groups, acid insoluble lignin, acid soluble lignin, arabinan, glucan, holocellulose, total lignin, structural ash, and xylan were quantified on a % fiber basis and nonstructural ash on a % total basis. There were significant, but not large differences between species for holocellulose, lignin, acetyl, acid soluble lignin, nonstructural ash, and glucan. For each trait, Saccharum spontaneum had significantly more holocellulose, glucan, lignin, and nonstructural ash and less acetyl and acid soluble lignin than other species. In all populations, glucan and holocellulose were positively correlated and glucan and lignin were negatively correlated. In hybrids, internode length correlated positively with holocellulose and nonstructural ash and negatively with lignin. Principal component analysis indicated that a large amount of diversity exists within each of the species. The results suggest that strategic use of the WCSRG could provide both positive and negative selection for fiber-related traits could be made within all species of the collection. <![CDATA[Bioactive compounds and juice quality from selected grape cultivars]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0006-87052018000100062&lng=es&nrm=iso&tlng=es ABSTRACT Grape juices have been valued due to their potential health benefits, which have demanded increased grape productivity and quality. Five grape cultivars grown in Brazil, Isabel Precoce, Carmem, Violeta, Concord and Bordo were evaluated in 2013 and 2014 seasons for bioactive components and also for juice processing quality traits. Production cycle was the longest for Carmem but lower and similar for Violeta, Isabel, Bordo and Concord. Isabel showed higher productivity (5.4 kg∙plant-1) but lowest soluble solids content (16.9 °Brix), anthocyanins (26.7 mg∙100 g-1) and total phenolics (110.7 mg∙100 g-1). The highest anthocyanins contents were observed in Violeta (189.9 mg∙100 g-1) and Bordo (133.8 mg∙100 g-1). These cultivars were also rich in phenolics (356.1 and 239.5 mg∙100 g-1, respectively). The highest anthocyanin and total phenolics concentrations were found in Violeta juice (2.68 and 6.33 g∙L-1) followed by Bordo (1.44 and 2.86 g∙L-1). Isabel juice had the lowest content, 0.14 and 1.29 g∙L-1, respectively. Biogenic amines were found at low concentrations only in the juices. Putrescine and spermidine were the major amines detected in juices. Phenylethylamine was detected only in Bordo juice from 2013 season and tryptamine was detected only in 2014 season. Blends were preferred over varietal juices except for Carmem. <![CDATA[Factors that influence in <em>Jatropha curcas</em> L. latex production]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0006-87052018000100074&lng=es&nrm=iso&tlng=es ABSTRACT Latex from Jatropha curcas L. exhibits biotechnological potential for the development of biodiesel and drugs. Little is known about the collection methods and latex productivity of this species. In order to garner information on the use of J. curcas latex, factors that influence production by this species were assessed. As a result, no significant difference was found between the volume of latex collected in the stem and the branches. With respect to environmental characteristics, climatic conditions, such as low temperatures and rainfall, affected production. The period of low temperatures and leaf fall occurs after fruit harvest and, in the absence of strong sinks, the plant can use the assimilates to generate greater latex production. Multiple regression analysis demonstrated that latex production is positively associated with plant height and negatively associated with fruit production and other variables that maximize it. During the fruiting process the plant uses most of the assimilates for fruit development and a lower percentage to produce secondary compounds, resulting in less availability of these metabolites for latex production. In general, the latex production obtained from this species is low and limits commercial exploitation of this compound, despite its possible pharmacological potential. <![CDATA[Organography of greenhouse and field accessions of wild <em>Arachis</em>species (section <em>Arachis</em>)]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0006-87052018000100083&lng=es&nrm=iso&tlng=es ABSTRACT Peanut or groundnut (Arachis hypogaea L.) is a globally important oilseed crop, with important nutritional qualities, and a rich source of amino acids and protein. Another 80 species have been described in the genus Arachis, 64 of which are found in Brazil, and even though their morphology and agronomic traits remain largely unknown, they have been cultivated for forage and for landscaping and have great potential for breeding with cultivated peanut. Thus, the morphological characterization of wild Arachis species is essential for their conservation and use. In this study, we present a morphological and agronomic characterization of 29 diploid accessions of eleven wild Arachis species and one of the tetraploid A. monticola (section Arachis) with A and B genomes and determine their intra- and interspecific variability in greenhouse and field conditions. In total, 35 morphological descriptors were developed a priori from greenhouse accessions in the first crop year and used in field accessions in the second crop year. Significant differences in descriptors compiled in the greenhouse and the field support the use of different descriptors for different experimental conditions. PCA analysis showed that the distribution of accessions accorded with the taxonomy of species. The ten morphological descriptors that were important in differentiating section Arachis accessions were seed length, lateral branch length, right apical leaflet length, right apical leaflet width, height and diameter of main stem, branch color, standard petal base color, number of flowers, and presence of bristles on rachis. <![CDATA[Bacterial halo blight of coffee crop: aggressiveness and genetic diversity of strains]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0006-87052018000100096&lng=es&nrm=iso&tlng=es ABSTRACT Bacterial halo blight, caused by Pseudomonas syringae pv. garcae, is an important disease of coffee crop occurring in Brazil and other countries. In recent years, outbreaks of this disease have damaged several coffee crops in Brazil. Aggressiveness and genetic diversity of 25 strains of P. s. pv. garcae, obtained between the years 1958 and 2011, in 23 cities of São Paulo and Minas Gerais states, as well as three strains from Kenya were evaluated in this study. The strains were inoculated on coffee seedlings cultivar Mundo Novo, and their genetic diversity was evaluated by ERIC-PCR, REP-PCR, and their combination. All the strains were pathogenic to the coffee seedlings; the results of pathogenicity tests, in both experiments, could be divided in four aggressiviness classes (highly aggressive; aggressive; moderately aggressive and less aggressive). The Kenyan strains grouped separately from the Brazilian strains with ERIC-PCR and the combination of ERIC- and REP-PCR. The Brazilian strains could be grouped in two sub-clusters, the first including the older strains, obtained from 1958 to 1978, and the other comprising the remaining strains. With a few exceptions, strains isolated from 1997 to 2011, grouped mainly by their region of origin, were predominantly isolated from higher altitude regions, above 800 m. This probably occurred because the climatic conditions that prevail in these regions, characterized by milder temperatures and regular rainfall, are favorable for the coffee crop and for the production of high quality coffee beverage, but can be also favorable to bacterial halo blight. <![CDATA[Evaluation of forage grass resistance to <em>Mahanarva fimbriolata</em> (Stål)]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0006-87052018000100107&lng=es&nrm=iso&tlng=es ABSTRACT The aim of this study was to select forage grasses with potential resistance to Mahanarva fimbriolata by assessing effects on insect. No-choice assays were conducted with 12 genotypes and laboratory-reared insects. The following parameters were assessed: mortality and duration of the nymphal stage; adult weight and longevity; pre-oviposition period; number of eggs/female; viability and duration of the embryonic period. As main result it was verified that the mortality of nymphs reared on Panicum maximum cv. Paredão is almost complete and that this forage grass may be characterized as resistant to this insect by antibiosis. Further, the grasses can be divided into three groups following a cluster analysis: P. maximum cv. Aries, Setaria sphacelata cv. Kazungula, Brachiaria humidicola, A. gayanus and P. maximum cv. Aruana, which are insect-resistant grasses; Brachiaria decumbens cv. Basilisk, B. dictyoneura, B. brizantha cv. MG-4 and B. ruziziensis, which are moderately resistant grasses; and B. brizantha MG-5 and B. brizantha ecotype BB185, which are susceptible grasses. <![CDATA[Impact of <em>Tetranychus ogmophallos</em> (Acari: Tetranychidae) on different phenological stages of peanuts]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0006-87052018000100116&lng=es&nrm=iso&tlng=es ABSTRACT Peanut red mite, or Tetranychus ogmophallos Ferreira and Flechtmann, is considered the major emerging pest of peanut in Brazil. Its impact on peanut farming is still unknown but can be harmful. Thus, it is essential to understand how this mite influences peanut for a successful pest management program. This study aimed to investigate the impact of T. ogmophallos on peanut plants at different growth stages in order to clarify whether or not it is worth controlling this pest throughout the peanut growing season. For that, four experiments were carried out in a greenhouse to evaluate the impact of T. ogmophallos infestation on peanut plants at different phenological stages. Results showed that peanut seedlings of up to 60 days emergence and infested with red mite did not complete the reproductive cycle. In addition, infestation at 90 days after seedling emergence (late season) led to considerable yield reduction. As a result, we may infer that infestation can significantly peanut yield, regardless of plant phenological stage. Thus, controlling this emerging pest is necessary even if infestations occur in the final stages of plant development. The adopted level of infestation is above the economic threshold given the importance of the impact on growth and yield of these plants. Because of this, establishing an economic threshold level at different plant developmental stage is crucial to determine when control measures should be taken. <![CDATA[Antixenosis to <em>Chrysodeixis includens</em> (Lepidoptera: Noctuidae) among soybean genotypes]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0006-87052018000100124&lng=es&nrm=iso&tlng=es ABSTRACT The soybean looper Chrysodeixis includens is one of the main defoliating pests of soybean cultures in Brazil. This work aimed to evaluate the effect of offering different soybean genotypes to this insect to verify the occurrence of antixenosis. In a greenhouse, assays were carried out to determine the attractiveness of C. includens adults given free-choice tests. This experiment used a randomized block design with five replicates. A second experiment assessed oviposition preference using no-choice tests, employing a completely randomized design with five replicates. Seventeen soybean cultivars were used; several of these had previously been reported as carriers of resistance to more than one species of insect. In the laboratory, a morphological analysis was carried out by quantifying the number of trichomes on leaf surfaces and evaluating the color of the leaf blade of the germplasm. In the attractiveness assay, genotypes ‘IAC 19’, ‘IAC 18’, ‘IAC 23’, L1-1-01, PI 274453, PI 229358, PI 171451, ‘IAC 100’, ‘IAC 24’, ‘IAC 17’ and IAC 74-2832 were classified as repellents. In the oviposition preference experiment, PI 171451, PI 274453, ‘IAC 18’, L1-1-01 and ‘IAC 23’ showed the fewest eggs. The high density of trichomes presented by the genotypes PI 227687 and PI 274453 stand out as a possible C. includens resistance factor. The genotype L1-1-01 presented intermediate luminosity (L*) and more intense green (a*) and yellow (b*) colors compared to other genotypes. There was no correlation between oviposition and trichome density or leaf coloration. <![CDATA[Quality peach produced in fertilizer doses of nitrogen and green pruning]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0006-87052018000100134&lng=es&nrm=iso&tlng=es ABSTRACT The increasing consumer demand for fruit quality justifies the development of researches that combine orchards management and consumers’ perception of the quality of the product. The aim of this study was to evaluate the effect of nitrogen fertilization combined with green pruning intensity on fruit quality of ‘Chimarrita’ from high density peach trees during three consecutive harvest seasons. For this purpose, urea composed of different nitrogen rates (0, 40, 80, 120, 160, 200 and 240 kg.ha-1.year-1) was applied, under two intensities of green pruning (annual – once per season; or continuous – four times per season) in a factorial scheme (7 × 2). Fruits have been subjected to physical, chemical and sensorial analysis, made by 60 non-trained evaluators in each of the harvest seasons. The results showed that the cumulative effect of applying N in the third harvest season improved SS attributes, SS/TA ratio and fruit skin color to the dose of N of 148 kg.ha-1 .year-1. There is no difference between green pruning intensity and peach fruit quality. <![CDATA[Copper and zinc accumulation, fractionation and migration in vineyard soils from Santa Catarina State, Brazil]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0006-87052018000100141&lng=es&nrm=iso&tlng=es ABSTRACT The purpose of this study was to evaluate Cu and Zn migration and fractions in sandy soil of vineyards. In Urussanga (SC), Brazil, soil samples were collected from a 4-year-old and 15-yearold vineyard, and from a forested area. In the soils, the chemical characteristics of Cu and Zn were analyzed by the EDTA method, which determines the fraction available in soil; 3050B method of the USEPA for total concentrations, which represents the pseudo-soil contents in the soil; and chemical fractionation, which estimates soluble fraction, exchangeable fraction, fraction associated with clay minerals, fraction associated with organic matter and residual fraction. The results show that there is accumulation of Cu and Zn in sandy soils cultivated with grapevines and with frequent fungicide applications. These higher levels were found in soils with longer cultivation time (15 years old), but were restricted to the superficial layers of the soil. Most of the Cu was extracted by EDTA method, and it may be considered as available to plants. The EDTA also extracted a small part of Zn. Most of the Cu in the vineyard soils can be characterized by low geochemical mobility, but in the uppermost soil layers of the oldest vineyard, there was an increase in Cu content associated with soil organic matter. Most of the Zn in the vineyard soil was associated with minerals, which indicates low mobility and also low potential for toxicity to plants and microorganisms. <![CDATA[Glucose mineralization in soils of contrasting textures under application of S-metolachlor, terbuthylazine, and mesotrione, alone and in a mixture]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0006-87052018000100152&lng=es&nrm=iso&tlng=es ABSTRACT Microbial adaptation may occur in surface soils under agricultural uses exposed to herbicides. However, little is known about herbicide mixture effects in the soil, especially in tropical regions like Brazil. The aim of this study was to evaluate glucose mineralization in soils of contrasting textures (sandy clay and sandy loam) from areas cultivated with maize under application of S-metolachlor, terbuthylazine and mesotrione, alone and in a mixture. The methodology was established according to the soil microorganisms: carbon transformation test with 14C-glucose solution (D-[U-14C] glucose) in biometric flasks. After the addition of 14C-glucose, the amount of 14C in cumulative CO2 of microbial respiration was measured several times during the 28-day incubation. For unamended soil control (without herbicide), microbial activity followed a similar behavior to amended soil with herbicides in total 14CO2 released and accumulated, ranging from 23 to 27%. Overall, mineralization constant rate (k) values for all treatments were also similar, with an average value of 0.0038% CO2.d–1. Consequently, mineralization half-life times (MT50) were from 173 to 198 d. Microbial respiration for all treatments was slightly higher in the sandy clay compared with sandy loam soil; although soil samples with application of herbicides (alone and in a mixture) did not show decreased basal microbial respiration or mineralization rates of glucose. To corroborate these findings, additional research with different organic substrates and in cultures with different applications of herbicides are needed to prove the non interference of these herbicides on the microbial respiration in the soil. <![CDATA[Ethanol on the postharvest control of anthracnose in ‘Kumagai’ guava]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0006-87052018000100160&lng=es&nrm=iso&tlng=es ABSTRACT The aim of this study was to evaluate the effects of ethanol on the control of Colletotrichum spp. in ‘Kumagai’ guava and on the fruit physical-chemical attributes. For this purpose, three assays were carried out. For the first assay, fruit were exposed to ethanol vapor (0, 1, 2, 4, and 8 mL∙kg-1), applied in hermetic containers. On the second, ethanol was applied by immersion for 2 minutes in different concentrations (20, 30, 40, and 50%). On the last assay, fruit were immersed in 30, 40, and 50% ethanol for 2, 5, and 10 minutes. Fruit that were not exposed to volatile (first assay) or water treated (second and third assay) were used as control. In all assays, guavas were first inoculated with a conidial suspension of Colletotrichum spp. and after 2 hours, fruit were subject to ethanol. Fruit were stored at 25 °C / 80% RH for 8 days and assessed for incidence, rot severity and physical-chemical properties. Conidial germination and mycelial growth of Colletotrichum spp. were evaluated on in vitro assays. It was observed that 40 and 50% of ethanol, applied by fruit immersion for 2 min, reduced incidence and anthracnose severity with no changes in the guava physical-chemical attributes, when fruit were stored at 25 °C. Applied as a vapor, ethanol reduced only the incidence, but did not reduce anthracnose severity in guavas stored at 25 °C. Under cold storage, fruit treated with 40% ethanol exhibited a reduction of 19% in anthracnose severity. In vitro, ethanol vapor at 70 and 140 µL∙L-1 inhibited Colletotrichum spp. mycelial growth rate and when incorporated in potato-dextrose-agar, ethanol (30, 40 and 50%) inhibited Colletotrichum spp. mycelial growth rate and conidial germination. <![CDATA[Energy balance partitioning and evapotranspiration from irrigated Muskmelon under Semi-Arid Conditions]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0006-87052018000100168&lng=es&nrm=iso&tlng=es ABSTRACT The Mossoró-Assu-Baraúna district, Rio Grande do Norte State (RN), is recognized by the intense production of horticulture, mainly muskmelon for export. However, this region is often devastated by intense droughts. Thus, the muskmelon production is predominantly under irrigated condition and, due to constant threat of water resources collapse on the region, a rigorous irrigation water management in the region is needed. The main objective of this article was to analyze the seasonal pattern of energy balance partitioning and evapotranspiration on irrigated muskmelon crop on the region around Mossoró-RN. The study was carried out in two areas of commercial production of muskmelons in the Mossoró-Assu-Barúna district, during two growth seasons from 2012-Jun to 2012-Nov. The components of energy balance and evapotranspiration were determined by using the Bowen Ratio Energy Balance method. It was observed that more than 60% of the net radiation (Rn) was converted into latent heat flux (λE), while 21 and 11% of Rn was converted into sensible heat flux (H) and soil heat flux (G), respectively. The ratio λE/Rn varies according to the change of leaf area index (LAI) while the ratios H/Rn and G/Rn vary inversely with the LAI. The agreement λE/Rn and LAI is also evidenced by similarity between curves of crop evapotranspiration (ETc) and LAI, particularly when the melon crop reaches its maximum vegetative growth (LAI &gt; 3). The muskmelon ETc ranged from 265 to 289 mm, values that are similar to those found by other researcher. <![CDATA[Microclimate alterations caused by agricultural hail net coverage and effects on apple tree yield in subtropical climate of Southern Brazil]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0006-87052018000100181&lng=es&nrm=iso&tlng=es ABSTRACT The use of hail net coverage on plants is an effective measure to mitigate damage caused by hailstorms. In southern Brazil, areas with apple orchards under hail net coverage have increased in recent years. However, little is known about the possible effects on the microclimate and, consequently, on plant growth, crop yield and fruit quality. The hypothesis of this study was that hail net promotes microclimate and yield changes in apple orchards. The objective was to characterize the microclimate and production of apple trees cultivated under hail nets and to consequently generate numeric parameters that can be used in the management of apple orchards and in crop modeling. The study was conducted in commercial orchards growing under hail net and open sky. Continuous measurements of photosynthetically active radiation (PAR), air temperature and humidity, wind speed and rainfall were performed. Production was assessed based on the number and weight of fruits per plant. The hail nets reduced PAR by 32.8% and the wind speed by 30%. In contrast, coverage did not alter the air temperature, humidity or rainfall. The yield of apples tends to be higher under hail net and this is more pronounced when one hailstorm event occur. These results are important for researchers, and apple farmers to establish criteria for decision making regarding the implementation of hail net coverage and to develop appropriate management systems for protecting orchards to ensure and improve fruit production. Overall, the effects of long-term micrometeorological factors are essential to perform modeling of agricultural production. <![CDATA[Agroclimatic zoning for urucum crops in the state of Minas Gerais, Brazil]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0006-87052018000100193&lng=es&nrm=iso&tlng=es ABSTRACT Hardier crops are needed in the arid regions of the Brazilian state of Minas Gerais, and annatto (Bixa orellana L.) is a good candidate. Producers, however, do not know if their areas are suitable for its cultivation and so are not investing in its implementation. Agroclimatic zoning would provide guidance to the producers. Identifying potential areas for the production of this crop would thus contribute to the agroclimatic zoning of B. orellana in Minas Gerais. We collected data for air temperature and precipitation from 852 meteorological stations in the state to classify regions as suitable, marginally suitable, or unsuitable for the crop. Suitable regions had an air temperature between 22 and 27 °C and precipitation between 800 and 1600 mm.y-1. Marginally suitable regions had an air temperature between 22 and 27 °C and precipitation less than 800 mm.y-1. Unsuitable regions had air temperature less than 22 °C or greater than 27 °C. A geographic information system was used for the spatial interpolation of air temperature and precipitation for all meteorological stations using kriging. The agroclimatic zoning of annatto crops for Minas Gerais was obtained by interpolating the two maps, air temperature and precipitation. Minas Gerais has great potential for urucum production, and agroclimatic zoning enabled the classification of regions by climatic suitability. The northern, western, northwestern, and part of the eastern regions of Minas Gerais have favourable climates suitable for the cultivation of B. orellana. <![CDATA[Impacts of climate change on drought: changes to drier conditions at the beginning of the crop growing season in southern Brazil]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0006-87052018000100201&lng=es&nrm=iso&tlng=es ABSTRACT The intensification of drought incidence is one of the most important threats of the 21st century with significant effects on food security. Accordingly, there is a need to improve the understanding of the regional impacts of climate change on this hazard. This study assessed long-term trends in probability-based drought indices (Standardized Precipitation Index and Standardized Evapotranspiration Index) in the State of São Paulo, Brazil. Owing to the multi-scalar nature of both indices, the analyses were performed at 1 to 12-month time scales. The indices were calculated by means of a relativist approach that allowed us to compare drought conditions from different periods. The years 1961-1990 were used as the referential period. To the authors’ best knowledge, this is the first time that such relativist approach is used in historical trend analysis. The results suggest that the evapotranspiration rates have intensified the regional drought conditions. The time scale used to calculate the indices significantly affected the outcomes of drought trend assessments. The reason behind this feature is that the significant changes in the monthly regional patterns are limited to a specific period of the year. More specifically, virtually all significant changes have been observed during the first trimester of the rainy season (October, November and December). Considering that this period corresponds to critical plant growth stages (flowering/regrowth/sprouting) of several major crops (e.g. Sugarcane and Citrus), we may conclude that these significant changes have increased the risk of crop yield reductions due to agricultural drought.