Date of Publication

4-2024

Document Type

Master's Thesis

Degree Name

Master of Science in Chemistry

Subject Categories

Chemistry

College

College of Science

Department/Unit

Chemistry

Thesis Advisor

Drexel H. Camacho

Defense Panel Chair

Marissa G. Noel

Defense Panel Member

Mariafe N. Calingacion
Mariel G. Tecson

Abstract/Summary

Gamma or electron beam-irradiated depolymerized κ-carrageenan was demonstrated to have a significant plant growth-promotion (PGP) effect, which has been commercially applied by farmers in the Philippines. Despite its success in promoting the growth of economically important crops, the mechanism of its plant growth action has not been fully established. Moreover, the use of an irradiation facility makes the technology very restrictive. This work explores the alternative to gamma or electron beam irradiation in depolymerizing κ-carrageenan. Sound waves have been shown to be an effective degradation method of κ-carrageenan, which is more advantageous due to its simplicity and cost efficiency. This study investigated the potential PGP effect of the ultrasonic-treated kappa-carrageenan on the Brassica napus var. chinensis in hydroponics and foliar spray applications. The degradation of κ-carrageenan under ultrasonic conditions afforded oligomers with an average MW of 1,716 Da, which is a 99.85% reduction in MW from the starting κ-carrageenan sample, affording a narrow polydispersity index of 1.007. Mineral analysis of the sonic-treated depolymerized κ carrageenan using EDS afforded relative mineral compositions of 58.84% K, 24.87% Ca, 11.31% Mg, 2.94% Zn, and 2.03% Cu. The PGP effect of the sono-depolymerized κ-carrageenan at 40 ppm concentration under hydroponics conditions showed a 24.75% increase in plant height, a 20.93% increase in leaf width, 52.73% increase in the number of leaves, and a 52.57% increase in fresh weight compared to the negative control. Using a foliar spraying system, the PGP effect at 50 ppm concentration showed a 0.48% increase in plant height, a 0.65% increase in leaf width, a 5.19% decrease in the number of leaves, and a 14.29% increase in fresh weight compared to the negative control. Although statistical comparison with the gamma or e-beam irradiated κ-carrageenan showed no significant difference, correlation studies showed a slight positive correlation between the plant growth parameters with the mineral content and the low average molecular weight. Results of the study showed that ultrasonic treatment is as effective as gamma or electron beam irradiation of κ-carrageenan making it an affordable alternative.


Keywords: ultrasonication, kappa-carrageenan, plant growth promotion, Brassica napus var. chinensis, hydroponics

Abstract Format

html

Language

English

Format

Electronic

Keywords

Ultrasonics; Growth (Plants); Rape (Plant)—Varieties; Hydroponics

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Embargo Period

4-16-2025

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Available for download on Wednesday, April 16, 2025

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