Functional trait variations and drought tolerance among teak (Tectona grandis Linn.f.) provenances

Abstract

The present study investigated, functional trait variations among six provenances of Tectona grandis L. f, in the 90 year old provenance trial plot at Aravallikavu, Nilambur consisting of Anamalai, North Burma, Nilambur, South Bombay, South Burma and Travancore provenances. In addition, genetic diversity among these six teak provenances using ISSR markers and drought tolerance of these six provenances were also studied. Functional traits such as height, GBH, crown width, and self-pruning activity of teak provenance showed significantly different variation. However, leaf thickness not showed significantly different variations among the provenances. The South Burma provenance showed highest height (28.48m), crown width (9.05m) and self-pruning activity (0.82), whereas Nilambur provenance showed highest GBH of 168.06cm. The South Burma provenance showed highest stem straightness. In addition, foliar nitrogen concentration showed significantly different variations among the provenances. South Bombay provenance showed highest leaf nitrogen concentration of (2.54%). However, both phosphorous and potassium concentration did not significantly vary among provenances. Genomic DNA from six teak provenance was extracted using the modified CTAB protocol, yielding DNA concentrations ranging from 117.3 to 284.11 ng µL-1, with OD260/280 values between 2.06 and 2.21. Amplified bands resulted in 37 observed alleles, of which 32were polymorphic, demonstrating genetic diversity, while 5 were monomorphic. The Jaccard dissimilarity coefficient between Anamalai and South Bombay was 0.43, suggesting their genetic similarity. Whereas highest dissimilarity was observed between South Bombay and South Burma with coefficient of 0.67. Morpho-physiological and biochemical responses of teak ramets to drought stress were evaluated. Based on morphological indicator (percent leaf retained), Anamalai and South Bombay provenances were classified as "moderately Tolerant," whereas South. Burma was "Susceptible". Photosynthesis varied, with South Bombay maintaining the highest rate (3.27μmol CO2 m-2 s-1) and Travancore exhibiting the lowest (1.75μmol CO2 m-2 s-1) under xvi drought. Provenance displayed diverse responses under drought for relative water content (56.61%- Travancore to 84.62%-South Bombay) and total chlorophyll content (4.94 mg g⁻¹ South Bombay to 2.84 mg g⁻¹-Travancore). Maximum proline was produced by South Bombay (9.11μg g-1). Similarly, South Bombay displayed higher peroxidase activity (8.53μmol min-1). Hierarchical cluster analysis categorized teak provenances into Susceptible (Nilambur and Travancore), Moderately Tolerant (North Burma and South Burma), and Highly Tolerant (Anamalai and South Bombay) categories. The study enhances understanding of the functional trait, genetic variations and drought tolerance of six teak provenances contributing valuable information for breeding programs and sustainable forest management. The multidisciplinary approach integrating physiological, biochemical, and genomic analyses offers a comprehensive framework for understanding and improving teak cultivation, ensuring sustainable production in the face of environmental challenges.