Ácido salicílico na mitigação de estresses em tomateiro
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2022-11-25
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Universidade Estadual Paulista (Unesp)
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O objetivo deste estudo foi avaliar as respostas fisiológicas, bioquímicas e produtivas provocadas pela aplicação foliar de ácido salicílico (AS) em plantas de tomateiro. Assim, dividimos essa pesquisa em dois capítulos; com capítulo I investigamos a resposta de tomateiro cultivado em ambiente protegido e submetido à aplicação de doses de AS. O delineamento experimental utilizado foi em blocos ao acaso (DBC), com cinco tratamentos: 0,0; 0,5; 1,0; 1,5 e 2,0 mM de AS e quatro repetições. As aplicações foram realizadas semanalmente dos 15 aos 60 dias após o transplantio (DAT). Analisou-se aos 45 e 60 DAT a atividade das enzimas SOD, CAT e POD, peroxidação lipídica, prolina, fluorescência da clorofila a, trocas gasosas e altura das plantas. Ao final do experimento computou-se a produção total, comercial e peso dos frutos. A aplicação foliar de AS reduziu o estresse ambiental, através da ativação de enzimas antioxidantes que reduziram a peroxidação lipídica, também reduziu o qNP e aumentou a eficiência do fotossistema II e ETR. As tocas gasosas também foram melhoradas pela ação do AS amentando a gs, que favoreceu A e A/Ci. Por fim, a dose entre 0,5 e 0,8 mM de AS favoreceu a produção total e comercial do tomateiro. Assim, a aplicação foliar de AS reduz estresse oxidativo e aumenta a eficiência fotossintética e produtiva em plantas de tomate. No capítulo II, objetivou-se avaliar o efeito mitigatório do AS em tomateiro sob défice hídrico, as aplicações das doses 0,0; 0,5; 1,0; 1,5 e 2,0 mM de AS foram realizadas semanalmente dos 15 aos 60 DAT, avaliamos a assimilação de CO2 (A), condutância estomática (gs), transpiração (E), eficiência no uso da água (EUA) e eficiência de carboxilação (A/Ci) aos 15, 30 e 45 dias de défice hídrico continuo, como também, a produtividade de plantas de tomateiro em ambiente protegido, em dois anos consecutivos (2019 e 2020). Os resultados mostram que o défice hídrico reduziu a A, gs, E e A/Ci das plantas de tomateiro e a aplicação foliar de AS aumentou esses parâmetros em todas as épocas de avaliação, resultando em valores semelhantes ou até maiores que em plantas sem restrição hídrica. Além disso, o estresse hídrico causou aborto floral nas plantas de tomateiro, sem a aplicação de AS, reduzindo o número de frutos e produção total e comercial. Em contrapartida, plantas que receberam cerca de 1.3 mM de AS aumentaram a A e A/Ci e translocaram os fotoassimilados, principalmente, para as flores e frutos, reduzindo o aborto floral e aumentando a produção total e comercial de frutos. Assim, a aplicação foliar de AS é eficiente na mitigação dos efeitos deletérios do défice hídrico em tomateiro sobre as trocas gasosas e produção. A aplicação foliar desse regulador vegetal pode ser indicada para condições de campo em regiões com baixa disponibilidade hídrica ou em supressão hídrica por motivos climáticos.
The objective of this work was to evaluate the physiological, biochemical and productive responses caused by the foliar application of salicylic acid (SA) in tomato plants. Thus, this research was divided into two chapters; with chapter I, the response of tomato plants grown in a protected environment and submitted to the application of doses of SA was investigated. The experimental design used was in randomized blocks, with five treatments: 0.0; 0.5; 1.0; 1.5 and 2.0 mM AS and four replicates. Applications were made weekly from 15 to 60 DAT. At 45 and 60 DAT, the activity of SOD, CAT and POD enzymes, lipid peroxidation, proline, chlorophyll a fluorescence, gas exchange and plant height were analyzed. At the end of the experiment, the total and commercial production and fruit weight were calculated. Foliar application of SA reduced environmental stress, through the activation of antioxidant enzymes that reduced lipid peroxidation, also reduced qNP and increased the efficiency of photosystem II and ETR. The gas burrows were also improved by the action of SA on gs, which favored A and A/Ci. Finally, the dose between 0.5 and 0.8 mM of SA favored the total and commercial production of tomato. Thus, foliar application of SA reduces oxidative stress and increases photosynthetic and productive efficiency in tomato plants. In chapter II, the objective was to evaluate the mitigating effect of AS on tomato under water deficit, the applications of doses 0.0; 0.5; 1.0; 1.5 and 2.0 mM SA performed weekly from 15 to 60 DAT, we evaluated the assimilation of CO2 (A), stomatal conductance (gs), transpiration (E), water use efficiency (WUE) and carboxylation (A/Ci) at 15, 30 and 45 days of continuous water deficit, as well as the productivity of tomato plants in a protected environment, in two consecutive years (2019 and 2020). The results show that the water deficit reduced the A, gs, E and A/Ci of tomato plants and the foliar application of SA increased these parameters in all evaluation times, resulting in similar or even higher values than in plants without restriction water. In addition, water stress caused floral abortion in tomato plants, without the application of SA, reducing the number of fruits and total and commercial production. In contrast, plants that received about 1.3 mM of SA increased A and A/Ci and translocated the photoassimilates, mainly to flowers and fruits, reducing floral abortion and increasing total and commercial fruit production. Thus, foliar application of SA is efficient in mitigating the deleterious effects of water deficit in tomato on gas exchange and production. The foliar application of this plant regulator can be indicated for field conditions in regions with low water availability or in water suppression for climatic reasons.
The objective of this work was to evaluate the physiological, biochemical and productive responses caused by the foliar application of salicylic acid (SA) in tomato plants. Thus, this research was divided into two chapters; with chapter I, the response of tomato plants grown in a protected environment and submitted to the application of doses of SA was investigated. The experimental design used was in randomized blocks, with five treatments: 0.0; 0.5; 1.0; 1.5 and 2.0 mM AS and four replicates. Applications were made weekly from 15 to 60 DAT. At 45 and 60 DAT, the activity of SOD, CAT and POD enzymes, lipid peroxidation, proline, chlorophyll a fluorescence, gas exchange and plant height were analyzed. At the end of the experiment, the total and commercial production and fruit weight were calculated. Foliar application of SA reduced environmental stress, through the activation of antioxidant enzymes that reduced lipid peroxidation, also reduced qNP and increased the efficiency of photosystem II and ETR. The gas burrows were also improved by the action of SA on gs, which favored A and A/Ci. Finally, the dose between 0.5 and 0.8 mM of SA favored the total and commercial production of tomato. Thus, foliar application of SA reduces oxidative stress and increases photosynthetic and productive efficiency in tomato plants. In chapter II, the objective was to evaluate the mitigating effect of AS on tomato under water deficit, the applications of doses 0.0; 0.5; 1.0; 1.5 and 2.0 mM SA performed weekly from 15 to 60 DAT, we evaluated the assimilation of CO2 (A), stomatal conductance (gs), transpiration (E), water use efficiency (WUE) and carboxylation (A/Ci) at 15, 30 and 45 days of continuous water deficit, as well as the productivity of tomato plants in a protected environment, in two consecutive years (2019 and 2020). The results show that the water deficit reduced the A, gs, E and A/Ci of tomato plants and the foliar application of SA increased these parameters in all evaluation times, resulting in similar or even higher values than in plants without restriction water. In addition, water stress caused floral abortion in tomato plants, without the application of SA, reducing the number of fruits and total and commercial production. In contrast, plants that received about 1.3 mM of SA increased A and A/Ci and translocated the photoassimilates, mainly to flowers and fruits, reducing floral abortion and increasing total and commercial fruit production. Thus, foliar application of SA is efficient in mitigating the deleterious effects of water deficit in tomato on gas exchange and production. The foliar application of this plant regulator can be indicated for field conditions in regions with low water availability or in water suppression for climatic reasons.
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Estresse abiótico, Fotossíntese, Regulador vegetal, Solanum lycopersicum L., Abiotic stress, Photosynthesis, Plant growth regulator