Annual Fertility Variation in Clonal Seed Orchards of Teak (Tectona grandis L.f.) and its Impact on Seed Crop

Abstract

Fertility variation was studied in two clonal seed orchards (CSO) of teak in four consecutive years (2003-2006). Both orchards were raised in 1976 with grafts of phenotypes selected for growth and form. The seed orchards of CSO I (Topslip, Tamil Nadu State) and CSO II (Walayar, Kerala State) have 15 and 20 clones, respectively, with 13 common clones. The proportion of flowering ramets was generally low ranging from 16 to 53% across years. The best fruit yield during the study period was around 18 kg ha-1 in CSO I and 17 kg ha-1 in CSO II. Highly significant clonal variation and clone by year and clone by site interactions were observed for fertility traits. The clonal contribution was more skewed in poor flowering years than in abundant flowering years and in CSO II than in CSO I. Broad sense heritability for flower and fruit production per tree was low to moderate (0.16 to 0.55). Flower and fruit production by individual ramets in successive years were positively correlated. Correlations between reproductive and growth traits were generally low, but correlation was strong between flowering and fruiting. Fertility variation and group coancestry were higher in poor flowering years than in abundant years and in CSO II than CSO I. Restricting seed collection to abundant flowering years, adjusting ramet number to balance contribution of clones and mixing of seeds from successive years are suggested to reduce relatedness among orchard progeny. The usefulness of low input breeding options for teak like seed production areas are also discussed.

Impact of fertility variation on genetic diversity and phenotypic traits in second generation seed production areas and clonal seed orchards of Eucalyptus camaldulensis

“…The situation can be quite alarming if fertility is skewed in a clonal stand as seen in CSO 2. Difference in fecundity and gene diversity was reported in teak CSOs (Ψ, 8.3 vs 1.7) across sites (Varghese et al, 2006) and between years (Nicodemus et al, 2009) in southern India.…”

Genetic diversity and forest reproductive material - from seed source selection to planting

“…A large variability in fertility is observed between and within populations (Kang et al 2003), among clones (El-Kassaby et al 1989, Bilir et al 2002, Nicodemus et al 2009, Ertekin 2010, Li et al 2011, and between years (Machanska et al 2013). This variability was greater in the stands than in SO (Kang et al 2003), in years of low yield (El-Kassaby et al 1989) and in younger populations (Kang et al 2003).…”

Discovery of SNPs in lignin biosynthesis genes (CAD1, MYB1 and MYB2) and their association with wood density in teak

“…The species is distributed in a wide range of natural and man-made forests and possesses virtually all of the genetic properties necessary for an association genetic approach. For instance, the species shows a substantial amount of genetic diversity (Nicodemus et al 2005 (Vaishnav and Ansari 2019) and loosely structured population (Nicodemus et al 2005;Ansari et al 2012;Vaishnaw et al 2015;Vaishnav and Ansari 2019). One of the potential limitations of AM is to yield high number of false-positive association (Type I error).…”