Genetic variation in carbon isotope discrimination-based water use efficiency of teak (Tectona grandis L. f.) and its association with growth and wood quality traits

Teak ( Tectona grandis L. f.) is one of the most preferred tropical timber species for afforestation, reforestation, and commercial plantation in the world. In the event of global warming caused by projected climate change, water-use-efficient teak planting stock would become essential for breeding and plantation activities. To characterize and to evaluate the association of water-use efficiency (WUE) with other growth and wood quality traits, we measured height, girth at breast height (GBH), wood density (WD), and carbon isotope discrimination (CID) values of 162 teak plus trees in a national teak germplasm bank (NTGB). The genetic diversity and structure of these accessions were also confirmed through 21 microsatellite markers for confirmation of their representation of teak meta-population in India. Results indicate 30.43% variation in average height (11.17 ± 3.40 m), 25.51% variation in GBH (67.18 ± 17.14 cm), and 7.48% variation in WD (789.24 ± 59.04 kg/m 3 ) among the accessions. The accessions exhibited a significantly high level of genetic polymorphism (88.74%) with a moderate level of Shannon’s diversity index (0.53) and comparatively low heterozygosity (0.27). No significant correlation was found between height and GBH with the CID values. This confirms that the measurement of growth and wood quality traits in teak alone is not helpful to tree breeders for indirect selection of water-use efficient trees. Rather, assessment of more specific traits related to growth, wood quality, and WUE of teak in different locales will be required to improve the teak germplasm in India.