Banca de DEFESA: KELLIS FERNANDA AMANCIO MOREIRA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : KELLIS FERNANDA AMANCIO MOREIRA
DATE: 27/09/2023
TIME: 08:30
LOCAL: VIDEOCONFERÊNCIA
TITLE:

Water requirement and production of zinnias (Zinnias elegans Jacq.) cultivated with silicate fertilization and automated irrigation levels

KEY WORDS:

Keywords: Flower production. Silicon. Cut flowers. Post-harvest longevity

PAGES: 30
BIG AREA: Ciências Agrárias
AREA: Agronomia
SUBÁREA: Ciência do Solo
SUMMARY:

Zinnia cv "Gigante da California" is gaining popularity as a cut flower in North America, with growth expected in Brazilian market. A key factor in cut flower production is water availability and techniques such as controlled water deficit has proven effective in maximizing water use efficiency. Silicon is a non-essential element with bio-stimulant effects, and it has been used in agriculture to mitigate the effects of water stress. This study aimed to evaluate the production, quality, and post-harvest longevity of zinnia floral stems cultivated under different irrigation levels and doses of potassium silicate (K2SiO3). In the greenhouse, zinnia seedlings were grown in 8 L pots filled with a mixture of sandy soil and bovine manure (2.0:0.5). The experiment was conducted in randomized blocks (DBC) in a 4x4 factorial scheme, with five repetitions. The irrigation levels corresponded to 59, 72, 85, and 100% of the plant's water requirement (NH), associated with 0, 75, 150, and 300 mg plant-1 Si in the form of potassium silicate (K₂SiO₃), applied at seven-day intervals, totaling five applications. Irrigation management was performed through an automatic controller, with the sensor installed in the treatment corresponding to 100% NH and doses of 300 mg plant-1 of Si (control). During the experiment, chlorophyll a, b, and total were evaluated in the initial phase of seedlings and at the beginning of harvesting phase. During the harvest, measurements such as stem length, number of leaves, stem and flower diameter, leaf area, fresh mass, and dry mass of flowers, leaves, and stems were taken, in addition, their classification according to commercial standards were evaluated. During the post-harvest period, variations in fresh weight (VPF), water absorption rate (TAA), senescence scale, and silicon levels in leaves and flowers were assessed. The volume of water applied during the experiment corresponded to irrigation levels of 3.3, 3.9, 4.4, and 5.2 L plant-1. Among the production parameters analyzed, it was observed that irrigation influenced stem length, flower diameter, and fresh mass, with higher irrigation levels resulting in longer stems, larger flowers, and higher biomass. In addition, doses of 150 mg plant-1 Si showed the highest production of dry mass for both leaves and flowers. There was also an interaction between treatments regarding flower diameter and fresh mass. Increasing doses of silicon negatively affected flower diameter, with higher silicon doses leading to smaller flowers. Furthermore, the classification of stems showed that higher irrigation levels resulted in more stems meeting commercial standards. The results also indicated an interaction between treatments in chlorophyll levels and leaf area. A significant interaction was observed between doses of 150 mg plant-1 Si and irrigation levels of 4.4 L plant-1 in chlorophyll b and total. The highest irrigation level (5.2 L plant-1) resulted in a larger leaf area, and a general trend of increasing leaf area with increasing silicon doses was observed, although this trend was not uniform across all irrigation levels. Irrigation levels influenced silicon levels in zinnia leaves, with higher Si concentrations observed as irrigation levels increased, ranging from 1.4 to 2.4%, while flowers maintained an average concentration of 0.5% of Si, regardless of the treatment. Regarding post-harvest, water absorption and fresh weight of zinnia stems followed a similar pattern, with an initial increase in the first 24 hours after harvest, stability for about five to six days, and subsequent loss of fresh weight. The commercial longevity of the stems was 6.4 days, with no significant difference between treatments, but total longevity ranged from 9.7 to 12.7 days, influenced by irrigation levels, with a significant increase in longevity in plants treated with 75 mg plant-1 Si under irrigation levels of 3.9 and 4.4 L plant-1. In general, replenishing the water requirement of zinnias results in higher production and quality, while the addition of silicon to the soil increases leaf area and stem biomass, although higher doses may reduce flower diameter. However, lower doses extend stem longevity, highlighting the need for further research on the bio-stimulant effects of silicon in flower production.

COMMITTEE MEMBERS:
Externo à Instituição - CARLOS RODRIGUES PEREIRA - UFF
Presidente - 1224578 - DANIEL FONSECA DE CARVALHO
Externo ao Programa - 2181674 - LEONARDO OLIVEIRA MEDICI - null