Banca de QUALIFICAÇÃO: MARYELLE CAMPOS SILVA
Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.STUDENT : MARYELLE CAMPOS SILVA
DATE: 27/03/2020
TIME: 14:30
LOCAL: Sala de Seminários 1 - DBG - CB - Campus Central
TITLE:
CIRCADIAN CHARACTERIZATION OF ACUMULATION AND UTILIZATION OF NON- STRUCTURAL CARBOHYDRATES IN Erythrina velutina DURING LATE ESTABLISHMENT
KEY WORDS:
Circadian rhythm, mulungu, seedling establishment, soluble sugars, starch
PAGES: 52
BIG AREA: Ciências Agrárias
AREA: Recursos Florestais e Engenharia Florestal
SUBÁREA: Silvicultura
SPECIALTY: Fisiologia Florestal
SUMMARY:
Although it is clear that the accumulation and the utilization of non-structural carbohydrates in leaves are influenced by the circadian rhythm in plants during the vegetative growth, the involvement of a similar mechanism in this dynamics in the diverse organs during seedling establishment in Caatinga native species is still uncertain.Thus, theobjective of this study was to carry out a circadian characterization of the accumulation and the utilization of non-structural carbohydrates in the different organs of Erythrina velutinaseedlings at late establishment. In this way, seeds were scarified, disinfected, imbibed, sown in towel paper arranged in rolls and maintained under controlled conditions (28 ± 2°C, photoperiod of 12 h and 80 μmol m-2 s-1) for 9 days. After that, seedlings were cultivated in hydroponics in a greenhouse for 8 days. At the end of the experiment, gas exchange measurements were performed in cordiform leaves every 2 h during the daytime (12 h); in parallel, seedlings were harvested and divided into different organs every 4 h along the daytime and the night-time (24 h) to assess the contents of non-structural carbohydrates. In the cordiform leaves, CO2net assimilation was highly synchronized with transpiration in the course of the daytime. Curiously, the seedlings were able to enhance the water use efficiency under high irradiance and this response was accompanied by the paraheliotropic movement of the cordiform leaves. In the source organs, including cordiform leaves and cotyledons, starch was accumulated during thedaytime and it was degradated along thenight-time, avoiding its exhaustion at dawn. Even though a transient increase in the total soluble sugar content has taken place in the cordiform leaves under high irradiance, the non-reducing sugar content remained almost unchanged in the course of 24 h. Although the epicotyl and the shoot apex could be considered as sink organs, their pattern of non-structural carbohydrate accumulation was similar to thatverified in the source ones. Regarding the other sink organs, starch degradation in the root during the daytime might have maintained the levels of total soluble sugars and non-reducing sugars in this organ at thenight-time. By contrast, non-reducing sugar accumulation in the hypocotyl during the daytime could be related to starch synthesis at the night-time. According to these results, it is possible to suggest that the circadian rhythm clearly influences theutilization of non-structural carbohydrates in the source organs, but it does not seem to determine this dynamics in the sink organs at late seedling establishment in E. velutina.The alterations in starch levels in the root and hypocotyl appear to be associated with the maintenance of sugar availability in these organs along the daily course.
BANKING MEMBERS:
Presidente - 1228866 - EDUARDO LUIZ VOIGT
Externa ao Programa - 1516627 - JULIANA ESPADA LICHSTON
Externo ao Programa - 1605704 - SIDNEY CARLOS PRAXEDES