Limitações fotossintéticas em folhas de plantas de tomateiro submetidas a crescentes concentrações salinas
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Data
2014-03-19
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Engenharia na Agricultura
Resumo
O objetivo deste trabalho foi avaliar as trocas gasosas, os parâmetros de fluorescência da clorofila a, a concentração de pigmentos fotossintéticos e o potencial osmótico em plantas de tomateiro submetidas a crescentes concentrações salinas. Para esta finalidade, plantas de tomateiro do cultivar Santa Clara foram cultivadas em vasos de 5 dm3 contendo solução nutritiva de Hoagland e submetidas aos tratamentos de 0, 50, 100 e 150 mmol L-1 de NaCl. O experimento foi realizado em casa de vegetação no Campus da Universidade Federal de Viçosa, num delineamento inteiramente casualizado com quatro repetições. Cada unidade experimental foi constituída por um vaso contendo duas plantas. Os resultados mostraram que o potencial osmótico nas folhas e nas raízes apresentaram reduções significativas à medida que se aumentava a concentração de NaCl na solução nutritiva, detectando o aumento do estresse sobre as plantas. A utilização da energia para os processos fotossintéticos e a capacidade de dissipação do excesso de energia na maquinaria fotossintética foi comprometida pelas crescentes concentrações salinas impostas pelos tratamentos, reduzindo a fotossíntese e o rendimento fotoquímico, demonstrado pelas trocas gasosas e pelos parâmetros de fluorescência de clorofila a, evidenciando que houve dano ao aparato fotossintético na fase bioquímica. As concentrações de pigmentos fotossintéticos diminuíram significativamente com o aumento na concentração salina, limitando a absorção da radiação fotossinteticamente ativa.
The aim of this study was to evaluate gas exchange, fluorescence parameters of chlorophyll a, photosynthetic pigment concentration, and osmotic potential in tomato plants subjected to increasing salt concentrations. For this purpose tomato plants, cultivar Santa Clara, were grown in 5dm -3 pots containing Hoagland nutrient solution and subjected to treatments of 0, 50, 100 and 150 mM NaCl. The experiment was conducted in a greenhouse of the University Federal de Viçosa in a completely randomized design with four replications. Each experimental unit consisted of one pot containing two plants. The results showed that the osmotic potential in leaves and roots decreased significantly as the NaCl concentration in the nutrient solution increased by detecting the elevation of stress on the plants. The use of energy for the photosynthetic processes and dissipation of excess energy in photosynthetic machinery was compromised by increasing salt concentrations imposed by the treatments, reducing photosynthesis and photochemical efficiency demonstrated by gas exchange and the fluorescence parameters of chlorophyll a, indicating that there was damage to the photosynthetic apparatus in the biochemical phase. The photosynthetic pigments decreased significantly with increasing salt concentration, limiting the absorption of photosynthetically active radiation.
The aim of this study was to evaluate gas exchange, fluorescence parameters of chlorophyll a, photosynthetic pigment concentration, and osmotic potential in tomato plants subjected to increasing salt concentrations. For this purpose tomato plants, cultivar Santa Clara, were grown in 5dm -3 pots containing Hoagland nutrient solution and subjected to treatments of 0, 50, 100 and 150 mM NaCl. The experiment was conducted in a greenhouse of the University Federal de Viçosa in a completely randomized design with four replications. Each experimental unit consisted of one pot containing two plants. The results showed that the osmotic potential in leaves and roots decreased significantly as the NaCl concentration in the nutrient solution increased by detecting the elevation of stress on the plants. The use of energy for the photosynthetic processes and dissipation of excess energy in photosynthetic machinery was compromised by increasing salt concentrations imposed by the treatments, reducing photosynthesis and photochemical efficiency demonstrated by gas exchange and the fluorescence parameters of chlorophyll a, indicating that there was damage to the photosynthetic apparatus in the biochemical phase. The photosynthetic pigments decreased significantly with increasing salt concentration, limiting the absorption of photosynthetically active radiation.
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Palavras-chave
Estresse salino, Fluorescência da clorofila a, Solanum lycopersicum, Pigmentos fotossintéticos, Trocas gasosas