Banca de DEFESA: MARCOS DE OLIVEIRA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : MARCOS DE OLIVEIRA
DATE: 06/07/2023
TIME: 14:00
LOCAL: Auditório do prédio Mateus Rosas Ribeiro (Prédio de Solos)
TITLE:

Borate fertilization via stipe in green dwarf coconut: nutritional status, productivity and physical-chemical quality of coconut water.

KEY WORDS:

Stipe fertilization; boron nutrition; coconut palm.

PAGES: 90
BIG AREA: Ciências Agrárias
AREA: Agronomia
SUBÁREA: Ciência do Solo
SPECIALTY: Fertilidade do Solo e Adubação
SUMMARY:

The productivity of coconut on sandy soils has been limited by boron (B) deficiency. This deficiency has been corrected by the application of B via soil or leaf axils. However, soil application has promoted high losses by leaching, especially during periods of high rainfall. On the other hand, application via leaf axils is time consuming, and when in the production phase, it is impractical. In this perspective, the use of the endotherapy technique may be a promising alternative. For this, it is necessary to quantify adequate doses and to know which sources of B can be used.  Thus, the objective of this work was to study the physiology, biochemistry and nutrition of coconut plant, as well as to evaluate the yield and water quality of the fruit of the dwarf green coconut submitted to application of increasing amounts of B via stalk and soil. The research was carried out in a commercial coconut farm, located in the Neopolis plateau region of the State of Sergipe, in a randomized block design, in a factorial design (5 x 2) + 3, with four repetitions, being five doses of B (2; 4; 6; 8 and 10 g plant-1), using Bortrac as a source of B, two forms of application (via stipe and soil) and two additional controls (no application of B; application of B as boric acid via soil and via stipe). Boric acid application was performed using a single dose of 5 g plant-1. For application of B, where the stipes were perforated with an impact drill, with subsequent installation of a commercial catheter, and the application of the doses was performed using a syringe. The nutritional state was evaluated: B contents in the leaf diagnose at 15, 30, 60, 90 and 120 days, efficiency of nutrient utilization, critical level of B in the leaf and coconut water; Physiology and biochemistry: chlorophyll a, b, chlorophyll a/b ratio, carontenoids, electrolyte leakage, hydrogen peroxide concentration and lipid peroxidation; Production components: number of leaves, fruit abortion, fruit weight, number of fruits per bunch, volume of coconut water, productivity in liters of water per plant year-1, productivity in number of fruits per plant year-1; Physicochemical quality of coconut water: electrical conductivity, pH, total titratable acidity, total soluble solids contents, Relationship between total soluble solids and titratable acidity contents and B contents in coconut water. The application of B via the stipe promotes an increase in chlorophyll a levels, and a reduction in electrolyte leakage, reactive oxygen species (H2O2) and lipid peroxidation damage. In addition, it provides a longer residual period of B in the leaf over time, being the most efficient way to absorb this element. The critical level of B in coconut leaf and water was 33.48 mg kg-1 and 465.44 µg L-1, respectively, for a yield level of 315 fruits per plant year-1. The 7.9 g plant-1 dose applied via the stem provides maximum fruit yield. Application of B via soil in the source of bortrac (10 g plant-1) and boric acid (5 g plant-1) is insufficient to promote an increase in fruit yield. Thus, larger doses should be tested. The application of B via stipe in the bortrac source promotes an increase in the physicochemical quality of coconut water, with emphasis on the levels of total soluble solids, titratable acidity and the ratio of total soluble solids / titratable acidity, and levels of B. Application of B B via the stipe, regardless of the source, promotes necrosis of the internal tissues of the coconut tree. Therefore, the next lines of research should look for specific nutritional solutions using these sources for application via the stipe, focusing on the reaction in the vascular system of the green dwarf coconut tree, aiming at the sustainability of the technique in the medium and long term.

COMMITTEE MEMBERS:
Presidente - ***.127.174-** - FERNANDO BRUNO VIEIRA DA SILVA - UFRPE
Interno - ***.127.174-** - FERNANDO BRUNO VIEIRA DA SILVA - UFRPE
Externo à Instituição - EDUARDO CEZAR MEDEIROS SALDANHA
Externo à Instituição - MACIO FARIAS DE MOURA
Externo à Instituição - RENATO LEMOS DOS SANTOS - IFPE