- Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences
Fertility variation and its impact on seed crops in seed production areas and a natural stand of teak in southern India
Varghese, M.; Kamalakannan, R.; Nicodemus, A.; Lindgren, D.
Reproductive output and fertility variation in teak were evaluated in five study sites in Western Ghats region of southern India. In four seed production areas (SPA1-4)) and a natural population (NAT) plots with 100 trees were investigated. The 40-year-old seed production areas are located in high rainfall (>2,500 mm) sites in Kerala state and the natural stand is at a drier location in Tamil Nadu. Fruit production per tree was rather high in the natural stand (1500) and quite variable in the seed production areas. SPA 4, located far south from the other sites, had the highest fruit production (almost twice that in the other study sites), high relative population size (N-r = 0.5) and predicted low genetic drift in two consecutive years. Fecundity was very low in SPAs 2 & 3 (200 fruits per tree). Reproductive output was similar in successive years except SPA 1, where the fruit production in the first year was almost five times that in the second year. Fertility variation (computed as sibling coefficient, Psi) was in general higher in NAT and hence the relative population size was lower than in SPAs. The variation in female fertility in the natural stand was, somewhat surprisingly, similar to that in the seed production areas, while the male fertility variation was higher. In the seed production areas the male fertility variation was lower or similar to the female fertility variation. The fertility variation, Psi was on average around 3 and correspondingly the relative effective population size, N-r = 0.36 and the variance effective number around 60. Selection for tree diameter would improve predicted diversity of the seed crop as it was positively correlated with reproductive output and negatively correlated with fertility variation among trees.
sibling coefficient; genetic drift; population size; reproductive output; diversity
2008, Volume: 160, number: 1, pages: 131-141
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