Evapotranspiração e eficiência fotossintética em crambe sob estresse hídrico
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Data
2017-03-31
Autores
Soares, Cristiana Araujo [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Devido ausência de trabalhos conclusivos sobre a demanda hídrica do crambe, existe a necessidade de investigar o comportamento da cultura frente à variação do armazenamento de água no solo, já que a cultura é cultivada tipicamente em épocas de pouca ocorrência de chuva. Diante disto, este trabalho teve por objetivo mensurar a evapotranspiração do crambe em diferentes níveis de irrigação, sob condições de ambiente protegido, a fim de avaliar sua capacidade de tolerância ao estresse hídrico. O experimento foi conduzido em dois ciclos, sendo o primeiro no período de 31/08/2015 a 12/12/2015 (média de 99 dias) e o segundo de 02/05/2016 a 21/08/2016 (média de 108 dias), desenvolvido no Departamento de Engenharia Rural, pertencente à Faculdade de Ciências Agronômicas (FCA/UNESP) em Botucatu, SP. Utilizou-se o delineamento inteiramente casualizado com quatro repetições e seis níveis de irrigação (excesso 50%, excesso 25%, “CC” vaso, déficit 25%, déficit 50% e déficit 65%), cada unidade experimental foi composta por um vaso com duas plantas. Inseriu-se também um tratamento em “CC” vaso, porém, com a cobertura do solo vedada para isolar o efeito da evaporação, avaliando assim a fração da transpiração na evapotranspiração da cultura. O manejo da irrigação foi realizado através de pesagens diárias mantendo-se a umidade do solo de acordo com cada tratamento aplicado. Foram avaliadas variáveis fenométricas, produtivas, teor de óleo e eficiência fotossintética, sendo os dados submetidos à análise de variância a 5% de probabilidade e ao teste de Tukey para comparação de médias. Nos tratamentos sem estresse hídrico a evapotranspiração no primeiro e segundo ciclo de cultivo foram 511,0 e 354,0 mm, respectivamente. O crambe pode ser classificado como tolerante ao estresse hídrico, por deficiência, pois a aplicação de déficits hídricos de 25 e 50% apresentaram pequenas reduções em suas taxas de evapotranspiração, quando comparado àquele que manteve a umidade do solo sempre na capacidade de campo. Considerando-se conjuntamente as variáveis fenométricas, produtivas e teor de óleo, em ambos os ciclos de cultivo, o tratamento que manteve déficit hídrico de 25% apresentou comportamento similar ao irrigado para atingir a capacidade máxima de retenção de água no solo. As variáveis de eficiência fotossintética demonstram que os déficits hídricos aplicados na cultura do crambe não causaram danos ao processo fotossintético das plantas.
Due to the absence of conclusive studies about the water demand of crambe, there is a need to investigate the behavior of the crop in relation to the variation of soilless water flow, which is typically cultivated in times of low rainfall. crop is cultivated typically in times of low rainfall. The objective of this work was to measure evapotranspiration of crambe at different irrigation levels under greenhouse conditions to evaluate the capacity to tolerate water stress. The experiment was conducted in two cycles, the first in the period from August 31 to December 12, 2015 (99 days cyclo) and the second from May 02 to August 21, 2016 (108 days cyclo), developed in Department of Rural Engineering, belonging to the College of Agronomic Sciences (FCA / UNESP) at Botucatu, SP. A completely randomized design with four replications and six irrigation levels (50% excess, 25% excess, "CC" vase, 25% deficit, 50% deficit and 65% deficit), each experimental unit composed by one vase with two plants. A treatment in "CC" vase was also inserted, however, with soil cover sealed to isolate the effect of evaporation, thus assessing the fraction of transpiration in evapotranspiration of the crop. Irrigation management was carried out by daily weighing, maintaining the soil moisture according to each treatment applied. The phenotypic, productive, oil content and photosynthetic efficiency variables were evaluated. Data were submitted to analysis of variance at 5% of probability and to the Tukey test for comparison of average. In treatments without water stress the evapotranspiration in the first and second crop cycle were 511.0 and 354.0 mm, respectively. Crambe can be classified as tolerant to water stress due to deficiency, since the application of water deficits of 25 and 50% showed small reductions in their evapotranspiration rates when compared to those that maintained soil moisture always in the field capacity. Considering jointly the phenometric, productive and oil contents, in both cultivation cycles, the treatment that maintained a water deficit of 25% presented a behavior similar to that irrigated to reach the maximum water retention capacity in the soil. The photosynthetic efficiency variables, demonstrate that the water deficits applied in the crambe crop did not cause damage to the photosynthetic process of the plants.
Due to the absence of conclusive studies about the water demand of crambe, there is a need to investigate the behavior of the crop in relation to the variation of soilless water flow, which is typically cultivated in times of low rainfall. crop is cultivated typically in times of low rainfall. The objective of this work was to measure evapotranspiration of crambe at different irrigation levels under greenhouse conditions to evaluate the capacity to tolerate water stress. The experiment was conducted in two cycles, the first in the period from August 31 to December 12, 2015 (99 days cyclo) and the second from May 02 to August 21, 2016 (108 days cyclo), developed in Department of Rural Engineering, belonging to the College of Agronomic Sciences (FCA / UNESP) at Botucatu, SP. A completely randomized design with four replications and six irrigation levels (50% excess, 25% excess, "CC" vase, 25% deficit, 50% deficit and 65% deficit), each experimental unit composed by one vase with two plants. A treatment in "CC" vase was also inserted, however, with soil cover sealed to isolate the effect of evaporation, thus assessing the fraction of transpiration in evapotranspiration of the crop. Irrigation management was carried out by daily weighing, maintaining the soil moisture according to each treatment applied. The phenotypic, productive, oil content and photosynthetic efficiency variables were evaluated. Data were submitted to analysis of variance at 5% of probability and to the Tukey test for comparison of average. In treatments without water stress the evapotranspiration in the first and second crop cycle were 511.0 and 354.0 mm, respectively. Crambe can be classified as tolerant to water stress due to deficiency, since the application of water deficits of 25 and 50% showed small reductions in their evapotranspiration rates when compared to those that maintained soil moisture always in the field capacity. Considering jointly the phenometric, productive and oil contents, in both cultivation cycles, the treatment that maintained a water deficit of 25% presented a behavior similar to that irrigated to reach the maximum water retention capacity in the soil. The photosynthetic efficiency variables, demonstrate that the water deficits applied in the crambe crop did not cause damage to the photosynthetic process of the plants.
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Palavras-chave
Crambe hispanica, Manejo da irrigação, Deficiência hídrica, Management of irrigation, Water deficiency