Crescimento da alface americana em função dos ambientes, épocas e graus-dias

Araújo, Thiago Silva; Filho, José Fideles; Kumar, K. Karuna; Rão, Tantravahi Venkata Ramana

doi:10.5039/agraria.v5i4a480

Cited by 10 publications

(11 citation statements)

References 8 publications

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“…The accumulated degree-days (DD) were 666, with a maximum dry mass production of 16.8 g plant -1 . Araújo et al (2010) obtained phytomass yields ranging from 8 g plant -1 with 514 degree-days to 19 g plant -1 with 557 degree-days, that means a large range of productivity as a function of several factors besides temperature. Madariaga & Knott (1951) published a classic onepage article pointing to the inefficiency of the thermal accumulation system for predicting lettuce harvest.…”

Section: Resultsmentioning

confidence: 95%

“…(1) where DD= cumulative day degree; Taveg= average air temperature (ºC); and Tb= base temperature, which for this experiment were considered 10.0ºC, and n= number of days at harvest (Araújo et al, 2010).…”

Section: Methodsmentioning

confidence: 99%

“…In addition to the effect of light on growth, it is critical to consider the temperature that significantly affects growth (Frantz et al, 2004). The thermal accumulation, consolidated in the Degrees-Day concept, is the simplest means of productivity comparability as a function of the difference between the average temperature and the basal temperature of the crop, below which the crop stops growing (Araújo et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

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Evaluation of photosynthetic photon flux in lettuce cultivation at different shading levels

et al. 2020

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Protected cultivation has grown in Brazil. Generally, greenhouses are covered with transparent plastic film and shading screen. The plastic, over time, loses its transparency due to pollution residues, dust and other debris. The loss of transparency reduces lightness, photosynthesis and leads to losses of productivity and product quality. The losses are not always detectable by the farmer. Additionally, internal shading screens are used to reduce heating transmission to the ground. The objective of this study was to evaluate the impact of shading on lettuce crop productivity and to determine the optimum shading to reach the highest productivity. Plots were set up inside and outside the greenhouse, with four shading levels with black screens (0, 35, 50 and 75%). The treatments were converted to real shading from the photosynthetic photon flux measurement. The results of fresh and dry phytomass were treated and analyzed by regression as a function of the real shading. In ambient conditions of photosynthetic photon fluxes around 1000 μmol m-2 s-1, reaching up to 2000 μmol m-2 s-1 at some hours of the day, typical of tropical environment, lettuce may support a shading of up to 50% without risk of productivity reduction; under these conditions, shading between 20 and 35% is beneficial, and can guarantee its maximum productivity in lettuce cultivation. It is recommended that the lettuce producer in protected cultivation monitors the shelf life of the plastic, avoiding that the shading exceeds 50%. In order to compare shading experiments, one should use the incident photon flux (FFI) for the whole crop cycle, indicating the minimum limit value of FFI = 600 mol m-2 cycle-1 for the crispy lettuce at an average temperature close to 21oC.

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Section: Resultsmentioning

confidence: 95%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Evaluation of photosynthetic photon flux in lettuce cultivation at different shading levels

et al. 2020

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“…Entretanto, em canteiro sem mulching nenhuma cultivar atingiu valor superior a 380 g, enquanto nos canteiros com mulching obteve-se média de MFC de até 413 g. Valor superior de MFC de 559,3 g foi encontrado por na cultivar Lucy Brown, quando cultivada no interior de túnel alto com mulching preto, no período de setembro a novembro, nas condições agroclimáticas de Santo Antônio do Amparo -MG. Entretanto Mota et al (2002), durante o verão em Santana da Vargem -MG, cultivando no interior de túnel alto com mulching, obtiveram rendimento de 266,6 g, resultado inferior ao obtido pelo presente estudo para cultivar Lucy Brown. Santana et al (2009) na região do sub-médio São Francisco -BA, em condições semelhantes de cultivo sob canteiro convencional, obtiveram rendimento de 304 e 351 g para as cultivares Grandes Lagos e Rafaela, valores superiores aos do presente estudo em condição climática favorável para alface americana, conforme apontado por Araújo et al (2010).…”

Section: Resultsunclassified

“…Temperaturas acima de 20 °C estimulam o seu pendoamento, que é acelerado à medida que esse fator climático aumenta, o que se torna mais crítico associado a dias longos (SANTI et al, 2010), resultando em colheita antecipada e plantas de baixa qualidade (ARAUJO et al, 2007;RODRIGUES et al, 2008). Na alface americana, o desenvolvimento ideal se dá em temperaturas na faixa de 15,5 a 28,3 °C (SANDERS, 1999;ARAÚJO et al, 2010). Nesse tipo de alface, temperaturas muito elevadas podem levar a distúrbios fisiológicos (FRANTZ et al, 2004;DE SOUZA et al, 2013).…”

Section: Introductionunclassified

Desempenho de cultivares de alface americana cultivadas com e sem mulching em período chuvoso da Amazônia

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Filho

2015

AGRO@MBIENTE

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Resumo: Na Amazônia, a exploração comercial de hortaliças se dá empregando variedades e/ou cultivares previamente avaliadas, tendo-se como critério prioritário, os rendimentos médios mais elevados nos ensaios de competição e adaptabilidade. As condições agroclimáticas aliadas a práticas fitotécnicas podem interferir diretamente nos níveis de produtividade e qualidade da alface. Neste sentido, objetivou-se com este ensaio avaliar a produtividade, sanidade foliar e estabilidade morfológica de cultivares de alface americana, cultivadas em condições de campo no período chuvoso entre os meses de abril a junho de 2011, em canteiros convencionais na região de Presidente Figueiredo no Estado do Amazonas. O delineamento experimental utilizado foi de blocos ao acaso em esquema fatorial, provenientes da combinação de 20 cultivares de alface americana e duas condições de cultivo (com e sem mulching sobre os canteiros), com quatro repetições. Todas as cultivares apresentaram melhor desempenho, sobre as características agronômicas e sanidade de folhas exteriores, exceto para comprimento do caule, quando cultivadas em canteiro com mulching, evidenciando que esta prática contribuiu para melhorar as características de produtividade e qualidade das plantas. Dentre as cultivares estudadas na presença ou ausência de mulching, Gloriosa, Havassu, Healtmaster, Kaiser, Lucy Brown e Tainá apresentaram melhor comportamento sobre as características desejáveis para fins de comercialização e podem ser recomendadas para o cultivo em condições agroclimáticas similares ao presente estudo. Palavras-chave:Fitossanidade. Lactuca sativa L. Plasticidade morfologica. Sistema de cultivo. Abstract:In the Amazon, the commercial exploitation of vegetables takes place using previously assessed varieties and/or cultivars, having as the main criterion the highest average yield in tests of competition and adaptability. Agroclimatic conditions, allied to phytotechnical practices, can directly interfere with quality and levels of productivity in the lettuce. The aim of this test therefore, was to evaluate the productivity, the health of the leaves and the morphological stability of lettuce cultivars grown under field conditions in conventional beds, during the rainy season between the months of April to June of 2011, in the region of Presidente Figueiredo in the State of Amazonas, Brazil (AM). The experimental design was of randomised blocks in a factorial scheme, resulting from the combination of 20 lettuce cultivars and two systems of cultivation (in beds with and without mulching), with four replications. All the cultivars performed better as regards the health of the outer leaves and agronomic characteristics, except for stem length, when grown on beds with mulching, demonstrating that this practice helped to improve characteristics of productivity and quality in the plants. Among the cultivars being studied with or without mulching, Gloriosa, Havassu, Healthmaster, Kaiser, Lucy Brown and Taina displayed better behaviour for the characteristics desired fo...

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Agronomic performance of lettuce cultivars submitted to different irrigation depths

et al. 2019

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The use of cultivars adapted to the climate and soil conditions associated with adequate irrigation supply maximizes lettuce agronomic performance. The aim of this work was to evaluate the agronomic performance of four lettuce cultivars submitted to five different drip irrigation depths under a protected environment in Viçosa-MG, Brazil. A randomized block design was applied in a split plot scheme with four replications, and several agronomic characteristics were evaluated by analysis of variance, Tukey range tests, regression and principal component analysis. A higher chlorophyll concentration in the Raider Plus cultivar promoted the production of more leaves, leading to a higher phytomass. The Luara cultivar presented a higher number of commercial leaves per plant than the other cultivars, regardless of the irrigation depth, reflected in a larger diameter and volume of the aerial part of the plants. The Raider Plus and Luara cultivars presented better root development than that of the other cultivars, reducing the effect of plant water stress even under lower irrigation depth conditions. Although higher water productivity (WP) was observed for the lowest irrigation depth (50% of ETc), important variables reached the maximum values at depths higher than 100% water replenishment. Therefore, Raider Plus and Luara cultivars with an irrigation depth of 110% of crop evapotranspiration provided better commercial lettuce quality and are recommended for lettuce cultivation in the research region and under conditions similar to those of the present study.

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Crescimento da alface americana em função dos ambientes, épocas e graus-dias

Cited by 10 publications

References 8 publications

Evaluation of photosynthetic photon flux in lettuce cultivation at different shading levels

Evaluation of photosynthetic photon flux in lettuce cultivation at different shading levels

Desempenho de cultivares de alface americana cultivadas com e sem mulching em período chuvoso da Amazônia

Agronomic performance of lettuce cultivars submitted to different irrigation depths

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