Is carbon isotope composition a relevant ecophysiological indicator of genetic variation in water use efficiency of rubber tree?

Name: Nicha Kanpanon

LCSH: Kasetsart University -- Dissertations. Ph.D. (Horticulture) 2017

Classification :.LCCS: SB291.H4

LCSH: Kasetsart University. Department of Horticulture -- Dissertations

LCSH: Hevea -- Breeding

LCSH: Hevea brasiliensis

LCSH: Carbon -- Isotopes

Abstract: The rubber (Hevea brasiliensis) plantations extend to non-traditional area in Thailand where drier conditions has been reported to impair the growth of rubber trees and latex production. Essential physiological parameters, such as water use efficiency (WUE), are required for breeding adapted genotypes. Carbon isotope discrimination is widely used as a proxy for WUE that can easily be used for selection and breeding programs for drought tolerance. We studied carbon isotope composition (δ13C) in several clones of rubber addressing the question whether δ13C is a relevant ecophysiological indicator of genetic variation in water use efficiency of rubber tree. The relationship between δ13C and intrinsic WUE (WUEi) at leaf level could confirm that δ 13C predicts well clonal differences in WUEi. Leaf δ 13C and leaf gas exchange were measured on young saplings of 10 rubber clones growing in pot in a common garden. The range of leaf δ13C among 10 clones was narrow (-29.9 ‰ to -31.5%) and the correlation between δ13C and WUEi was significant under high vapour pressure deficit only, which means the prediction of WUE by δ13C would have low precision. We compared δ 13C of rubber tree leaves in rainy and dry seasons in a collection of 49 wild genotypes of rubber in northeastern Thailand to see whether there is a potential genetic variability for δ13C. There were large δ13C variations among the genotypes at all seasons. δ 13C was rather stable with a good correlation between rainy and dry season. In rainy season, there was a positive significant correlation between δ13C, leaf mass per area (LMA) and leaf nitrogen (NA). This study shows that the genetic variability of δ 13C is promising for breeding if a good correlation between δ13C of leaf and WUE can be established. The temporal variations of δ 13C of latex (δ13C-L) and of leaf soluble compounds (δ13C-S) collected from tapped and untapped 20-year-old rubber trees were studied to check whether they are related to each other and related to canopy inherent WUE (IWUE). The lowest δ13C-S values were recorded in August (-31.6‰ in tapped and -30.3‰ in untapped trees) when IWUE was low. δ13C-L was higher and more stable across seasons than δ13C-S, with a maximum seasonal difference of 0.7‰ for tapped trees and 0.3‰ for untapped trees. The lack of correlation between δ13C-L and δ13C-S suggests that recent photosynthates are mixed in the large pool of stored carbohydrates that are involved in latex regeneration after tapping. Thus, δ13C of latex is not a relevant indicator of WUE of rubber trees.

Kasetsart University. Office of the University Library

Address: Bangkok

Email: tdckulib@ku.ac.th

Name: Poonpipope Kasemsap

Role: Thesis Advisor

Name: Daniel Epron

Role: Thesis Co-Advisor

Name: Boonthida Kositsup

Role: Thesis Co-Advisor

Name: Philippe Thaler

Role: Thesis Co-Advisor

Created: 2017

Modified: 2023-06-21

Issued: 2023-06-21

วิทยานิพนธ์/Thesis

application/pdf

URL: https://kasetsart.idm.oclc.org/login?url=https://www.lib.ku.ac.th/KUthesis/2560/nicha-kan-all.pdf

CallNumber: SB291.H4.N53

eng

DegreeName: Doctor of Philosophy

Level: Doctoral Degree

Descipline: Horticulture

Grantor: Kasetsart University

©copyrights Kasetsart University

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