Distribution, stem bark formation, growth of Vitex glabrata RBr sapling in Thailand

Name: Kanokporn Promnikorn

LCSH: Kasetsart University -- Theses. M.S. (Botany) 2019

Classification :.LCCS: QK495.L25

LCSH: Kasetsart University. -- Department of Botany -- Theses

LCSH: Lamiaceae -- Thailand

LCSH: Verbenaceae -- Thailand

LCSH: Vitex -- Thailand

LCSH: Vitex glabrata R.Br

Abstract: DHECD (7,8-dihydro-8α-20-hydroxyecdysone) is an active substance with similar functions to brassinosteroid hormones in plants. This chemical could increase productivity and enhance the performances of plants under heat stress. A high amount of substrate used for DHECD synthesis can be found in the bark of Vitex glabrata. Therefore, information about distributions and growth of V. glabrata is required for sustainable uses of this plant. A maximum entropy (MaxEnt) model was used to predict the probability of occurrence and to determine relevant environmental variables influencing the distribution of V. glabrata in Thailand. The presence-only data from both of Thai herbaria and GBIF database, together with environmental variables from WorldClim were used to model the distribution. The model found the high probability of V. glabrata’s occurrence in Southern and some Eastern and Western regions, which accounted for approximately 21% of Thailand. In addition, the temperature seasonality, altitude and precipitation of driest month were also the important environmental variables that contributed the most to the distribution model of V. glabrata. Bark formation and growth of V. glabrata in the sapling stage was followed for one year. The growth parameters, including height, diameter, and biomass of aboveground and belowground, were measured. The bark formation parameters, including bark and wood thickness, were determined. The results indicated that the saplings had a slow growth during the first 6 months and then grew more rapidly for the next 6 months. The results may be influenced by increased rainfall. The bark thickness increased slowly during the first 6 months and more rapidly in the next 6 months. In addition, the wood thickness RGR was only parameter that was significantly correlated with all of the weather variables (p < 0.03). However, the bark RGR was not significantly correlated with all of the weather variables (p > 0.19). This work showed that V. glabrata in nature is well distributed in Southern and some Eastern and Western Thailand, but additional surveys in field will verify our results. Its growth in the sapling stage was relatively slow, especially in the bark increment. Therefore, the sapling stage may be unsuitable as a source of the largescaled DHECD production.

Kasetsart University. Office of the University Library

Address: Bangkok

Email: tdckulib@ku.ac.th

Name: Ekaphan Kraichak

Role: Thesis Advisor

Name: Kanapol Jutamanee

Role: Thesis CO-Advisor

Created: 2019

Modified: 2025-07-05

Issued: 2025-07-05

วิทยานิพนธ์/Thesis

application/pdf

URL: https://www.lib.ku.ac.th/KUthesis/2563/kanokporn-pro-all.pdf

CallNumber: QK495.L25 .K26

eng

Spatial: Thailand

Spatial: Thailand

Spatial: Thailand

DegreeName: Master of Science

Level: Master's Degree

Descipline: Botany

Grantor: Kasetsart University

©copyrights Kasetsart University

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