Dormancy Breaking and Storage Behavior of Garcinia cowa Roxb. (Guttiferae) Seeds: Implications for Ecological Function and Germplasm Conservation

Abstract

Abstract:The dormancy breaking and storage behavior of Garcinia cowa Roxb. seeds were investigated. The seeds of G. cowa had 8-11 months dormancy in their natural habitat. Seeds were matured and dispersed at the end of the rainy season (mid-late August to late September) and were scatter-hoarded by rodents as food for winter after the seeds had fallen to the ground. Seedlings often emerged in the forest during the rainy season (May to August) the following year. Intact seeds of G. cowa failed to germinate after being sown at 30 °C for 120 d and the mean germination time (MGT) of seeds cultured in a shade (50% sunlight) nursery was 252 d. The most effective method of breaking dormancy was to remove the seed coat totally, which reduced the MGT to 13 d at 30 °C. Germination was also promoted by partial removal of the seed coat (excising the hilum and exposing the radicle) and chemical scarification (immersion in 1% H 2 O 2 for 1 d). Unscarified seeds take up water rapidly in the first 96 h, but water was absorbed by the outside seed coat, without penetrating through it. The moisture content (MC) of G. cowa seeds was high (50% in fresh weight) at shedding. The seeds could tolerate desiccation to some extent, until the MC reached approximately 40%; below that, the viability decreases rapidly and all seeds died at approximately 17% of MC. Seed viability decreased rapidly when seeds were chilled at 4 °C; germination was 2% after storage for 1 week. Even stored at 10 °C, seeds began to be damaged after 4 weeks. Seed storage for 1 yr revealed that in both dry (relative humidity (35 ± 5)%) and moist (wet sand) storage conditions, seed viability declined, but germination percentages for seeds stored under moist conditions are better than for seed stored under dry conditions. Because of their low tolerance to desiccation, marked chilling sensitivity and relatively short lifespan, G. cowa seeds should be classified into the tropical recalcitrant category. The ecological implications of dormant recalcitrant seeds and cues on storing recalcitrant seeds were discussed.

Garcinia Kola Heckel Seeds Dormancy-Breaking

“…Seed coat removal therefore affected positively dormancy-breaking by reducing the mean germination time of 46 days. Comparable result was obtained for Garcinia cowa seeds where the total removal of seed coat was revealed as the most effective dormancy-breaking treatment [7]. Germination occurred also quite early for coated seeds placed in banana false trunk and coated seeds soaked in pineapple juice.…”

“…Comparable results were obtained for Garcinia cowa, a tropical recalcitrant seed. Below 40% of moisture content, seeds viability decreased rapidly and all seeds died at approximately 17% of moisture content [7]. Dried seeds used in the experiment were responsible of poor seed germination and germination spread.…”

“…The failure of seeds germination may be due to embryo death or deep seed dormancy. The test of ungerminated seeds viability is usually performed by using tetrazolium chloride [7,9]. The high proportion of ungerminated seeds may be a consequence of a high proportion of dead seeds; however the non-implementation of the tetrazolium chloride test limits this hypothesis.…”

“…Previous studies investigated on Garcinia kola Heckel and Garcinia cowa Roxb. seeds germination [7,11]. Both studies were carried out in laboratory conditions and part of the outcomes couldn't be implemented by small farmers.…”

Técnicas para superação da dormência de sementes de guanandi

“…Sementes recalcitrantes são liberadas da planta mãe com alto teor de água, quase com a umidade necessária para iniciar a germinação. Liu et al (2005) trabalharam com Garcinia cowa, uma espécie recalcitrante que apresenta envoltórios semelhantes ao do guanandi, e constataram baixa absorção de água das sementes até o início da germinação, principalmente quando estas estavam livres do revestimento restritivo. Limas et al (2007) observaram o mesmo comportamento em sementes de ucuúba, espécie recalcitrante, que ganhou menos de 5% de água após 72 horas de hidratação.…”