Water absorption and physiological responses of hog plum tree diaspores to storage
Abstract Hog plum tree seeds (Spondias mombin L.) have a complex dormancy mechanism, which causes slow germination and great unevenness. At present, there are no efficient methods to promote seed germination. The objective of the study was to evaluate the effect of storage on overcoming seed dormancy of this Anacardiaceae. Diaspores of two hog plum trees were used, identified as Mother plant 1 and Mother plant 2, established in Tomé-Açu city, PA. Initially, it was investigated whether the structures surrounding the seeds (internal mesocarp and endocarp) prevent water absorption. For this, the diaspores of the two mother plants were sown between blotting paper, with an adequate level of water and, periodically, in the total of 144 hours, the water content of the seeds was computed. The storage studies involved two experiments. In the first, diaspores from both mother plants with a water content of around 5.0% were stored in impermeable packages, for one year, under the following conditions: natural environment of Belém, PA (average temperature of 26.8 °C) and at temperatures of 6 ± 1 ° C and minus 18 ± 2 °. The germinative response of the stored diaspores was compared with those of non-stored diaspores. Prior to storage, selection was made on the diaspores, discarding the small ones. In the second experiment, the germinative response of the diaspores of the two mother plants, stored for zero, one, two, three, four, five and six months, under natural environment conditions of Belém, PA, was evaluated. It was observed that the structures that cover the seeds do not offer restrictions to the water absorption, thus discarding the hypothesis of physical dormancy, without, however, excluding the possibility of mechanical dormancy. The storage of diaspores for one year, regardless of the storage condition, did not affect the germination power of the seeds. On the other hand, responses of great magnitude, in terms of reducing the time required for germination, were obtained when the diaspores were stored under natural conditions and at minus 18±2 °C, indicating that dormancy is naturally overcome by storage . Overcoming dormancy was a little slower when the diaspores were stored at a temperature of 6±1 °C. It was found that the storage of diaspores in an environment with an average temperature of 26.8 °C for three months provides the overcoming dormancy of most of the seeds. The intensity of dormancy varied within and between mother plants.
