Response of flowering and seed production of sandalwood (Santalum album Linn., Santalaceae) to climate changes

摘要

Response of flowering and seed production to climatic changes was observed on sandalwood ex situ genetic conservation in Yogyakarta, Indonesia, in 2005 to 2010 flowering periods. To observe flowering phenology, each of 10 individual of 7 provenances were marked and the flowering phenology parameters were observed daily during the flowering period. To measure productivity parameters (Pollination Effectiveness, PE and Reproductive Success, RS), each of 10 individuals of 7 provenances were marked, and the flowers, fertilized flowers and mature seed were then counted. PE was measured by dividing Fertilized flower to Flower. RS was measured following the formula: RS = {Fruit/Flower) x {Seed/Ovule). Fluctuation on rainfall and temperature were observed during 2005 to 2010 flowering periods. The reduction on yearly rainfall was observed during 2006 to 2007. The elevated temperature increment until 31,06°C at the early of 2007 is the most extreme one. Prolonged rainy season recorded during 2008 to 2010 in which there were no dry month occured even in summer. Each of provenances still kept its flowering behavior similar to those expressed in their origin. Provenances of the same origin with similar genotypes performed similar flowering characters. Flowering asynchrony and plasticity observed among provenances. The value of PE and RS observed to be provenances specific, as well as seed abortion that was occurred at various developmental phases. Both flowering and seed production were strongly controlled by both genetic and climatic factors. Provenances with similar genotypes performed similar response to alteration of rainfall and temperature due to climate changes. Extreme temperature increment at early of 2007 led to shorter flowering period, higher flowering frequency, decrement of flower and fruit abundance, and higher seed abortion. In contrary, prolonged rainfall in 2010 affected to longer flowering period, later floral initiation, shorter stigma receptivity and pollen longevity, bigger size of reproductive organs and paler color of perigonium. Constantly, dry season always results to the highest production of flowers, pollinated flowers and mature fruits compared to those of rainy season.