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Open Access journal
ISSN (Print) 0006-8705 - ISSN (Online) 1678-4499
Published by SciELO [791 journals]
- Germination test as a fast method to detect glyphosate-resistant sourgrass
Abstract: The occurrence of weed species with different levels of resistance to glyphosate has increasingly spread in agricultural areas. In Brazil, sourgrass is among the main species presenting issues in this regard. Thus, fast and reliable methods to detect glyphosate resistance are of special interest for this specie, either for research or rational management purposes. This study was carried out to verify the feasibility of using the germination test to detect glyphosate resistance in sourgrass. The experiment was conducted with two sourgrass biotypes, with different levels of susceptibility to glyphosate. The seeds were previously imbibed in solutions composed of 0, 0.1875%, 0.25%, 0.75%, 1.5%, 3% and 6% of glyphosate during two periods, five and ten minutes, and submitted to germination tests. The results indicate the germination test as a feasible and time-saving approach to evaluate glyphosate-resistant sourgrass, with results available in seven days.
- Effects of surface application of dolomitic limestone and
calcium-magnesium silicate on soybean and maize in rotation with green
manure in a tropical region
Abstract: Although lime is currently the material most frequently used to ameliorate soil acidity in Brazil, silicate could efficiently replace this source because of its greater solubility and its greater silicon content, which are beneficial for plant development. This study aimed to evaluate the effects of superficial lime and silicate application on soil chemical attributes as well as on soybean and maize nutrition and grain yields when these crops are grown in rotation with green manure. The experimental design was a complete randomized block with sixteen replicates. Plots were treated with one of two materials for acidity correction (dolomitic lime and calcium/magnesium silicate) or with no soil correction, as a control. Silicate corrected soil acidity and increased exchangeable base levels in soil at greater depths faster than does liming. The application of both acidity-correcting materials increased N, Ca and Mg leaf concentrations, and all yield components and grain yield in soybean; but in maize, just silicate also increased N and Si when compared with lime, whereas both acidity-correcting increased just two yield components: grains per ear and mass of 100 grains, resulting in highest grain yield. The application of both acidity-correcting materials increased dry matter production of green manures, but for pigeon pea the silicate provided the best result in this dry-winter region.
- Uptake of seed-applied copper by maize and the effects on seed vigor
Abstract: Seed treatment is a low-cost and efficacious method to deliver a diversity of compounds to field crops. This study evaluated the uptake of seed-applied Cu by maize and the effect on seed vigor. The treatments were composed of a control (untreated seeds) and five dosages of Cu: 0.11, 0.22, 0.44, 0.88 and 1.76 mg Cu seed–1, applied as cuprous oxide and copper oxychloride formulations. Seedling emergence and the speed of seedling emergence were determined in three periods: 1, 60 and 120 days after Cu application. Evaluations of root and shoot dry mass, Cu tissue concentration and efficiencies of Cu uptake and incorporation were conducted with two-leaf stage maize plants. Seed-applied Cu reduces the speed of maize seedling emergence, while the final emergence percentage is not affected. Shoot dry mass tends to increase with the application of Cu, while there is no interference on root dry mass within the dosages tested. Cu tissue concentration of both roots and shoots increases as higher dosages of Cu are applied to seeds, with higher accumulation in roots. Cuprous oxide promotes higher uptake of Cu by maize roots compared to copper oxychloride.
- Systemic insecticidal effect of neem-based nanoformulations against
Bemisia tabaci (Hemiptera: Aleyrodidae) biotype B in tomato
Abstract: Este estudo avaliou a ação inseticida sistêmica e o efeito residual de nanoformulações à base de derivados de nim (Azadirachta indicaA. Juss, Meliaceae) sobre ninfas de Bemisia tabaci biótipo B (Hemiptera: Aleyrodidae), espécie-praga de diversas culturas de importância econômica. Suspensões coloidais contendo nanocápsulas carregadas com produtos derivados de A. indica foram preparadas utilizando polímeros biodegradáveis como poli-ε-caprolactona (PCL) e poli-β-hidroxibutirato (PHB). A matriz encapsulada era composta por uma formulação comercial contendo uma quantidade enriquecida e conhecida dos limonoides azadiractina e 3-tigloilazadiractol (Azamax® 1,2 CE). Inicialmente foi estimada a CL50, para ninfas de B. tabaci, de soluções contendo óleo de nim, que foram aplicadas via água de irrigação (solo) em tomateiro. Posteriormente, dois lotes de nanoformulações, com variação no tipo e quantidade dos polímeros e na quantidade do óleo comercial, foram testados quanto à ação sistêmica. As nanoformulações NC L5-2 (com nanocápsulas de PCL) e NC L6-1 (com nanocápsulas de PHB), as mais eficazes entre as testadas, foram avaliadas quanto ao efeito residual. A CL50 estimada foi de 180,67 mg L–1 de azadiractina. Constatou-se também que a ação sistêmica de óleos e nanoformulações contendo compostos de nim dependem das condições ambientais em que são aplicados. O Azamax® não apresenta efeito deterrente sobre a oviposição, nem age sobre o desenvolvimento embrionário da mosca-branca quando aplicado via água de irrigação no solo no momento da infestação. As nanoformulações selecionadas são bioativas mesmo cerca de 30 dias após a aplicação, não diferindo do produto comercial.This study evaluated the systemic insecticidal action and the residual effect of neem-based nanoformulations (Azadirachta indica A. Juss, Meliaceae) on Bemisia tabaci biotype B (Hemiptera: Aleyrodidae) nymphs, a pest of several economic important crops. Colloidal suspensions containing nanocapsules loaded with derived products from A. indica were prepared by using biodegradable polymers such as poly-ε-caprolactone (PCL) and poly-β-hydroxybutyrate (PHB).The encapsulated matrix was a commercial formulation, which contained not only enriched amount of limonoids azadirachtin and 3-tigloilazadiractol, but also in known quantities (Azamax® 1.2 CE). Initially, it was estimated the LC50 of solutions containing neem oil, which were applied through irrigation water (soil) in tomato in order to control nymphs of B. tabaci. Afterwards, two lots of nanoformulations, varying in type and amount of polymers and in quantity of commercial oil, were evaluated for systemic action. The nanoformulations NC L5-2 (nanocapules in PCL) and NC L6-1 (nanocapsules in PHB) caused higher mortality among others and for this reason were assayed for residual effect. The estimated value for LC50 was 180.67 mg L–1 of azadirachtin. The results showed that systemic action of oils and nanoformulations containing neem compounds depends on environmental conditions. Azamax® did not show either deterrent effect of oviposition or effect on whitefly embryogenesis when applied in soil irrigation at the time of infestation. The nanoformulations selected are bioactives even about 30 days after application and do not differ of commercial product.
- Resistance of sweet potato clones to meloidogyne incognita races
1 and 3
Abstract: The objective of this study was to evaluate sweet potato clones for resistance to root-knot nematode, Meloidogyne incognita races 1 and 3. For each nematode physiological race, a greenhouse experiment was set up in a randomized block experimental design with three replications and six plants per plot. Fifty-eight sweet potato clones from the UFVJM germplasm bank were evaluated, plus five commercial cultivars (Brazlândia Rosada, Brazlândia Branca, Palmas, Princesa and Coquinho), plus the cv. Santa Clara tomato (susceptible to Meloidogyne spp.). Stems were planted in 72-cell expanded polystyrene trays, filled with commercial substrate and inoculated with the pathogen thirty days after planting. Forty-five days after inoculation, the eggs were extracted, counted, and later evaluated. Resistance level classification was performed based on reproduction factor (RF) and reproduction index (RI). Among the 63 analyzed clones, a percentage of 78% were classified as resistant to M. incognita race 1.79% to race 3 and 67% showed multiple resistance to both M. incognita races.
- Branches contribution and leaf area index evolution in modern cultivars of
Abstract: Os objetivos neste trabalho foram quantificar a contribuição das ramificações e a evolução do índice de área foliar em cultivares modernas de soja com diferentes grupos de maturação, tipos de crescimento, semeadas em diferentes épocas e regiões produtoras de soja no Rio Grande do Sul. Experimentos de campo foram conduzidos durante o ano agrícola 2013/2014 em Santa Maria, Júlio de Castilhos e em três lavouras comerciais de soja nos municípios de Restinga Sêca, Tupanciretã e Água Santa. Avaliaram-se (data de ocorrência) os estágios reprodutivos e a determinação do índice de área foliar total, máximo, da haste principal e das ramificações em treze cultivares de soja. O índice de área foliar das ramificações contribui com cerca de 31%, 12,3% e 11% do índice de área foliar total nas cultivares determinadas, e com 20,2%, 11,8% e 9% do índice de área foliar total nas cultivares indeterminadas nas semeaduras de setembro, novembro e fevereiro, respectivamente, em Santa Maria. A maioria das cultivares apresentou uma redução no índice de área foliar total, máximo, da haste principal e das ramificações com o atraso da época de semeadura, independentemente do grupo de maturação e tipo de crescimento.The purposes of this study were to quantify the branches contribution and the leaf area index evolution in modern cultivars of soybean with different maturity groups, stem termination, sowing in different dates and producing regions of soybean in Rio Grande do Sul. Field experiments were conducted during the growing season 2013/2014 in Santa Maria, Júlio de Castilhos and in three soybean crops on the municipalities of Restinga Sêca, Tupanciretã and Água Santa. It were carried out analysis (occurrence date) of reproductive stages and determination total, maximum, of main stem and of branches of leaf area index in thirteen cultivars of soybean. The leaf area index on the branches contributes with about 31%, 12.3% and 11% of the total leaf area index on the determinate cultivars and with 20.2%, 11.8% and 9% of the total leaf area index on the indeterminate cultivars sowing in September, November and February, respectively, in Santa Maria. Most cultivars showed a reduction on total leaf area index, maximum, of main stem and of branches with the delay on planting date, independently of the maturity group and stem termination.
- Physiological and agronomical responses of Syrah grapevine under protected
Abstract: The performance of Syrah grapevine under protected cultivation with different plastic films was evaluated during 2012 and 2013 seasons in South of Minas Gerais State. Agronomical and physiological measurements were done on eight years old grapevines, grafted onto ‘1103 Paulsen’ rootstock cultivated under uncovered conditions, covered with transparent and with diffuse plastic films. Both plastic covers induced the highest shoot growth rate and specific leaf area. The diffuse plastic induced greater differences on leaf area, pruning weight and leaf chlorophyll content as compared to uncovered vines. Grapevines under diffuse plastic also had the lowest rates of photosynthesis, stomatal conductance and transpiration. Leaf starch, glucose and fructose contents were not affected by treatment, but leaf sucrose was reduced by transparent plastic. The leaf and stem water potential were higher under diffuse plastic. In 2013, grapevines under diffuse plastic showed the highest yields mainly due to decreased rot incidence and increased cluster weight. Furthermore, berries under diffuse plastic showed the highest anthocyanins concentration. The use of diffuse plastic induces more agronomical benefits to produce Syrah grape under protected cultivation.
- Plot size and number of repetitions in evaluation times in millet crop
Abstract: Os objetivos deste trabalho foram determinar o tamanho ótimo de parcela (Xo) e o número de repetições para avaliar a massa verde de parte aérea de milheto em épocas de avaliação. Foram conduzidos 42 ensaios de uniformidade de 6 m×4 m (24 m2), sendo cada ensaio dividido em 24 unidades experimentais básicas (UEB) de 1 m×1 m (1 m2). Aos 52, 69 e 82 dias após a semeadura, foram avaliados, respectivamente 18, 6 e 18 ensaios, nos quais se pesou a massa verde das plantas de cada UEB. O Xo foi determinado pelo método da curvatura máxima do modelo do coeficiente de variação, e as comparações de médias entre as épocas de avaliação foram realizadas pelo teste t de Student. O número de repetições, para experimentos nos delineamentos inteiramente casualizados e blocos ao acaso, em cenários formados pelas combinações de i tratamentos (i=3, 4, ..., 50) e d diferenças mínimas entre médias de tratamentos a serem detectadas como significativas a 5% de probabilidade, pelo teste de Tukey, expressas em percentagem da média do experimento (d=10%, 12%, ..., 30%), foi realizado por processo iterativo até a convergência. O tamanho ótimo de parcela para avaliar a massa verde de parte aérea de milheto é de 4,46 m2, para as três épocas de avaliação. Para avaliar até 50 tratamentos, nos delineamentos inteiramente casualizados e blocos ao acaso, quatro repetições são suficientes para que diferenças entre médias de tratamentos de 28,75% da média do experimento sejam significativas, pelo teste de Tukey, a 5% de probabilidade.The objectives of this work were to determine the optimum plot size (Xo) and number of repetitions, to evaluate the fresh weight of aerial part of millet, in evaluation times. Forty-two uniformity trials with 6 m×4 m (24 m2) were conducted. Each trial was divided in 24 experimental units basic (UEB) with 1 m×1 m (1 m2). At 52, 69 and 82 days after sowing were evaluated, respectively, 18, 6 and 18 trials, where the fresh weight of plants was weighed in each UEB. The Xo was determined by the method of maximum curvature of the model coefficient of variation and the means compared, among evaluation times, by Student’s t test. The number of repetitions for experiments on completely randomized and randomized block designs, in scenarios of combinations of i treatments (i=3, 4, ..., 50) and d minimal differences between treatments means, to be detected as significant, 5% probability by Tukey test, expressed in percentage of the average of the experiment (d=10%, 12%, ..., 30%), was determined by iterative process until convergence. The optimum plot size to evaluate the fresh weight of aerial part of millet is 4.46 m2, to the three evaluation times. To evaluate up to 50 treatments, in completely randomized and randomized block designs, four replications are sufficient for differences between treatment means of 28.75% of the average experiment are significant at 5% probability, by Tukey’s test.
- Determination of optimum levels of nitrogen, phosphorus and potassium of
oil palm seedlings in solution culture
Abstract: Balanced nutrient elements in fertilizer play a critical role in oil palm seedling successful growth and development, and at the same time reduces of fertilizer losses in the environment. This study examines the effect of different levels of N, P2O5 and K2O for oil palm seedlings in solution culture on growth traits, nutrient uptake in plant tissues and biomass accumulation under nursery conditions. Five concentration levels of N (50, 100, 300, 600 and 900 mg L–1), P2O5 and K2O (15, 30, 60, 90 and 120 mg L–1) were used in a completely randomized design (CRD) with five replications for each. Parameters measured during the growing period include - plant height, leaf number/plant, stem diameter, SPAD chlorophyll value, and at harvest – total leaf area, root dry weight, shoot dry weight and total dry weight. Different levels of N, P2O5 and K2O showed significant effects on all the parameters studied. The highest values for diameter, plant height, leaf number/plant, total leaf area, root dry weight, shoot dry weight and total dry biomass were obtained using 100, 90 and 300 mg/L levels of N, P2O5 and K2O, respectively. Most of the growth parameters, declined with lower levels of N, P2O5 and K2O. The results of this study provide a new knowledge to produce oil palm plant with better nutrient management at the nursery under solution culture.
- Genotype x environment interaction in semiprostrade cowpea genotypes via
Abstract: A metodologia de modelos mistos (REML/BLUP) tem sido empregada para estudar os efeitos da interação genótipo x ambiente (G x E) em várias culturas, como: arroz, feijão, cana-de-açúcar, cajueiro e eucalipto, porém ainda não foi aplicada em feijão-caupi. Assim, o objetivo deste trabalho foi selecionar simultaneamente genótipos de feijão-caupi semiprostrado cultivados no Estado do Mato Grosso do Sul, via modelos mistos, que reúnam alta adaptabilidade, estabilidade e produtividade de grãos. Foram conduzidos quatro ensaios de valor de cultivo e uso com genótipos de genótipos de feijão-caupi nos anos de 2005 e 2006 em Aquidauana, Chapadão do Sul e Dourados. O delineamento experimental utilizado foi o de blocos completos casualizados, com 20 genótipos e 4 repetições. Os parâmetros genéticos foram estimados pela metodologia REML/BLUP, e a seleção baseou-se no método da média harmônica do desempenho relativo dos valores genéticos (MHPRVG), em três estratégias: seleção com base no valor genético predito, tendo-se considerado o desempenho médio dos genótipos em todos os ambientes (sem efeito de interação) ou o desempenho em cada ambiente (com efeito da interação); e seleção simultânea quanto à produtividade de grãos, estabilidade e adaptabilidade. Os genótipos BRS Paraguaçu, MNC99-542F-5 e MNC99-508G-1 podem ser cultivados em vários ambientes, pois reúnem alta produtividade de grãos, adaptabilidade e estabilidade. A herdabilidade da média dos genótipos apresentou magnitude variando de moderada a alta, fato que indica excelentes possibilidades para a seleção, permitindo acurácia seletiva de 82%.The mixed model methodology (REML / BLUP) has been used to study the effects of genotype x environment interaction (G x E) in various crops, such as: rice, common bean, cane sugar, cashew and eucalyptus, but still was not applied in cowpea. The aim of this work was to select simultaneously semiprostrade cowpea genotypes grown in the state of Mato Grosso do Sul, via mixed models, bringing together high adaptability, stability and yield grain. It were conducted four growing amount of trials and use of genotypes of cowpea genotypes in 2005 and 2006 in Aquidauana, Chapadão do Sul and Dourados. The experimental design was a randomized complete blocks with four replications and 20 genotypes. The genetic parameters were estimated by REML/BLUP methodology and, the selection was based on the MHPRVG method (harmonic mean of the relative performance of genetic values) in three strategies: selection based on predicted breeding value, having considered the performance mean of genotypes in all environments (no interaction effect) or performance in each environment (with interaction effect); and simultaneous selection for grain yield, stability and adaptability. BRS Paraguaçu, MNC99-542F-5 and MNC99-508G-1 genotypes can be grown in various environments, as they bring together high grain yield, adaptability and stability. The heritability of the average of genotypes found indicates moderate to high, a fact which indicates excellent possibilities for selection, allowing selective accuracy of 82%.
- Production system and harvesting stage influence on nitrate content and
quality of butterhead lettuce
Abstract: Leafy vegetables such as lettuce grown under different production systems may accumulate different concentrations of nitrate which may reach to the levels potentially toxic to humans. Moreover, nitrate accumulation varies in various plant parts and physiological age of the plant. Therefore, to determine the effect of production system and harvesting stage on nitrate accumulation and quality of butterhead lettuce, a study was conducted considering two lettuce production systems namely hydroponic and organic, and four different harvesting stages such as 35, 38, 41 and 44 days after transplanting (DAT). The experimental design was complete randomized design (CRD) with four replications. Hydroponic and organic systems performed similar in terms of yield, quality and nitrate content of butterhead lettuce. Delaying harvesting can not only increase yield but also can minimize nitrate accumulation and health hazard risk as well. Delay in harvesting stage may result in quality deterioration of lettuce and increased production cost. Thus, a compromise is necessary to consider 41 DAT as the optimum stage to harvest butterhead lettuce with significantly higher reduction of nitrate content in both outer adult leaf blades and young leaves of hydroponic lettuce. Fresh weight, firmness and color of butterhead lettuce at this stage were still acceptable.
- Assessment of spectral-temporal dynamics for mapping the main summer crops
in the Rio Grande do Sul State
Abstract: O objetivo deste trabalho foi desenvolver uma metodologia de baixo custo para o mapeamento das culturas de verão no Estado do Rio Grande do Sul, a partir do comportamento espectro-temporal de índices de vegetação e o Modelo HAND. O estudo foi realizado no Estado do Rio Grande do Sul, e o período foi a safra 2011/2012. Utilizaram-se imagens EVI do Sensor MODIS e dados SRTM. Para avaliar os resultados, foram usados dados de campo e dados do IBGE, além de um mapa referência elaborado com imagens RapidEye. Os resultados da classificação MODIS e os dados do IBGE geraram um coeficiente de correlação (r) de 0,98 para o arroz e 0,89 para a soja. Na validação dos dados coletados em campo, a cultura do arroz irrigado obteve um coeficiente Kappa de 0,66 e a cultura da soja 0,61. Na análise de similaridade Fuzzy, a cultura do arroz irrigado obteve uma similaridade de 87% contra 81% da soja. Portanto, o uso de dados multitemporais do sensor MODIS, aliado à delimitação de áreas de inundação, utilizando o modelo HAND, torna possível disponibilizar dados de estimativa de área cultivada das principais culturas de verão no Estado do Rio Grande do Sul.This study aimed to develop a low-cost method for mapping summer crops in the Rio Grande do Sul State, from the spectral-temporal behavior of vegetation indices and the HAND Model. The study was conducted in the Rio Grande do Sul State in the 2011/2012 harvest. It was used EVI images from the MODIS sensor and SRTM data. To evaluate the results, we used field data and IBGE data and a reference map elaborated with RapidEye images. The results of the MODIS classification and the IBGE data generated a correlation coefficient (r) of 0.98 for rice and 0.89 for soybeans. Validation with data collected in the field, irrigated rice obtained a Kappa coefficient of 0.66 and soybean, 0.61. In the Fuzzy similarity analysis, the irrigated rice achieved a similarity of 87% and soybean, 81%. Therefore, multi-temporal MODIS data, combined with the delineation of flood areas, using the HAND model, allow to estimate the area planted with the main summer crops in the Rio Grande do Sul State.
- Sensitivity of the sorghum yield to individual changes in climate
parameters: modelling based approach
Abstract: Based on sensitivity analyses the effect of changing in climate on sorghum has been investigated. This has been achieved by conducting crop modeling experiments carried out with weather observations and output of global climate models. As can be anticipated results demonstrated that the sorghum yield is more sensitive to rainfall, solar radiation and CO2 concentration. However, the increase in CO2 concentration has a positive effect on yield in years that the crop is submitted to water stress. This effect is extremely reduced under well watered conditions and therefore is subject to the climate inter-annual variability. Accumulated solar radiation along the sorghum cycle below 1900 MJ m–2 has also been shown to reduce the yield. Compared to other weather variables the sorghum yield is less sensitive to changes in relative humidity. In this sense, changes in stomatal closure and therefore photosyntesis is not highly dependent on water vapor pressure. These finds can be applied for both climate observations and global models output.
- Using temporal NDVI/MODIS profiles for inferences on the crop soybean
Abstract: Um dos maiores desafios para a modelagem de rendimentos de grãos, no contexto das estimativas de safras feitas de forma operacional para grandes áreas, está relacionado à identificação no tempo dos períodos em que as culturas anuais apresentam maior suscetibilidade a estresses ambientais. Para a cultura da soja, cultivada no período de primavera-verão no sul do Brasil, o principal fator de risco é a ocorrência de estresse hídrico no florescimento e enchimento de grãos. Esses subperíodos ocorrem em períodos distintos ao longo da região de produção como consequência de práticas de manejo diferenciadas dos produtores. Este trabalho teve como objetivo relacionar o calendário agrícola da cultura da soja a perfis temporais do índice de vegetação por diferença normalizada (NDVI/MODIS), com intuito de apresentar/validar uma tecnologia de baixo custo e adequada acurácia para fins de monitoramento e previsão de safras. Para tanto, foram analisados os dados de calendário agrícola (subperíodos de floração, enchimento de grãos e maturação) da cultura da soja em regionais da EMATER (RS) e imagens NDVI do sensor MODIS. Os resultados mostraram que os perfis temporais de NDVI permitem acompanhar a evolução temporal da biomassa da cultura da soja e determinar a ocorrência dos subperíodos do ciclo. As diferenças no valor do NDVI entre safras, regionais e subperíodos do ciclo da cultura demonstram a sensibilidade deste índice em detectar as respostas das plantas de soja às condições ambientais. Como consequência dos dados de NDVI serem gerados a partir das imagens MODIS, é possível a espacialização da informação acerca dos subperíodos para todas as safras e em todo o Estado, o que permite maior detalhamento temporal e espacial comparativamente à atual disponibilidade dos dados.A major challenge for grain yield modeling in the context of estimates made operationally for large areas is related to the identification of periods in which annual crops show greater susceptibility to environmental stress. For soybean grown in the spring-summer period in southern Brazil, the main risk factor is the occurrence of water stress during flowering and grain filling. These subperiods occur at different times across the production region due to differences in management practices of each farmer. This study aimed to relate the soybean crop calendar to the temporal profiles of normalized difference vegetation index (NDVI/MODIS), in order to present/validate a low cost technology with adequate accuracy for crop monitoring and harvest prediction. Thus, we analyzed data from soybean crop calendar (subperiods of flowering, grain filling and maturation) from EMATER (RS) regions and NDVI MODIS images. The NDVI temporal profiles allow monitoring the development of the soybean crop biomass and determining the occurrence of subperiods. Differences in NDVI values between harvests, regions and subperiods demonstrate the sensitivity of this index in detecting the responses of soybean plants to environmental conditions. Because NDVI data are generated from MODIS images, it is possible to create maps with information about the subperiods for all harvests and throughout the State, which enables greater temporal and spatial details compared to data currently available.
- Development and quality of pineapple guava fruit in two locations with
different altitudes in Cundinamarca, Colombia
Abstract: Fruit growth is stimulated by different weather conditions. The aim of this study was to determine the influence of weather conditions on the physicochemical properties of pineapple guava fruit growth. Twenty trees were marked in two production areas located at different altitudes (1,800 and 2,580 m.a.s.l.), and measurements were performed every 7 days from 99 and 141 days post-anthesis to harvest at altitudes of 1,800 and 2,580 m.a.s.l., respectively. The results indicate that altitude and weather conditions greatly influence the growth and development of pineapple guava fruit, and these effects are primarily manifested in the physical characteristics of the fruit. The weight and size of the fruit at harvest are directly related to the altitude of the production area. The weather condition that has the greatest impact on total titratable acidity at harvest is cumulative radiation during fruit growth; the highest value of total soluble solids at harvest corresponds to the location with the higher altitude, lower rainfall and relative humidity and higher cumulative radiation during the fruit growth period. The hue angle and pulp firmness at harvest are not influenced by the location or weather conditions at any location and do not determine the fruit quality at harvest time.