Banca de DEFESA: JOICY LIMA BARBOSA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : JOICY LIMA BARBOSA
DATE: 31/08/2021
TIME: 14:00
LOCAL: Videoconferência - Google meet
TITLE:

DIURNAL VARIATIONS IN GAS EXCHANGES, EFFICIENCY OF THE PHOTOSYSTEM II AND BIOCHEMICAL RESPONSES OF TABEBUIA AUREA (BIGNONIACEAE) SUBMITTED TO FLOODING STRESS

KEY WORDS:

Hypoxia; Craibeira; Photosynthesis; Chlorophyll a fluorescence

PAGES: 86
BIG AREA: Ciências Biológicas
AREA: Botânica
SUBÁREA: Fisiologia Vegetal
SPECIALTY: Ecofisiologia Vegetal
SUMMARY:

Global climate change is responsible for large variations in the rainfall regime, increasing the possibility of non-uniform and excessive rainfall, causing floods. Thus, the study of the physiological and biochemical behavior of plants under these conditions can be considered a relevant ecological indicator of the adaptations of plant species, as well as provide support for projects for the recovery of degraded areas. In this sense, the objective was to evaluate the diurnal variations in gas exchange and photosystem II efficiency, as well as to analyze possible biochemical alterations in Tabebuia aurea seedlings submitted to flooding stress. The experimental design used was completely randomized (CRD), with treatments arranged in a factorial scheme (2 x 12), with five replications. In the first factor, the following water treatments were evaluated: (1) control, in which the plants were cultivated under field capacity, being hydrated daily throughout the experiment. And (2) flooded, in which the plants were subjected to soil flooding. And in the second factor, the number of measurements performed on the plants throughout the day (a total of 12 measurements). Flooding was induced in pots flooded with a 2 to 3 cm layer of water above the ground, and the experiment was carried out for a period of 10 days. On the first day, the plants that received the treatments were flooded simultaneously. This same water was drained on the sixth day and the recovery of the plants monitored until the tenth day. Data collection was carried out between 06:00 am and 05:30 pm, on the first, sixth and tenth days of the experiment, for the gas exchange variables and the maximum quantum efficiency and effective quantum yield of photosystem II. On the same days, the water potential and the chlorophyll content index were determined at noon. At the same time, one set of leaves was collected for determination of photosynthetic pigments and a second set for further analysis of amino acids, proteins, proline and total soluble sugars. In the period studied, the results obtained showed that the soil flooding reduced the photosynthetic rates, stomatal conductance, intracellular concentration of CO2, transpiration, water use efficiency, maximum quantum efficiency (FV/FM) and effective quantum yield (ΦPSII) of photosystem II in the sixth day of the experiment. However, it recovered after stress suppression on the tenth day. Furthermore, on the sixth day of the experiment, it was found that flooding stress in Tabebuia aurea plants significantly reduced amino acids and increased levels of proline and soluble sugars. Finally, it was observed that flooding did not significantly affect leaf water potential, Spad index, proteins, chlorophyll a, chlorophyll b, total chlorophylls, chlorophyll a/b ratio and carotenoids in Tabebuia aurea plants during the experimental periods. Therefore, the physiological responses presented by Tabebuia aurea plants indicate that it can survive during short periods of soil flooding.

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