SEED, SEEDLING AND FRUIT MORPHOLOGY AND SEED GERMINATION OF Psidium sobralianum PLANTS OF THE SÃO FRANCISCO VALLEY, BRAZIL

Abstract

The Northeast region of Brazil has the second highest number of species of the Myrtaceae family. It is mostly covered by the Caatinga biome, which is very degraded, making it difficult to preserve species of this family. Thus, the objective of this work was to describe the seed, seedling, and fruit morphology, and seed germination of Psidium sobralianum Landrum & Proença plants of the São Francisco Valley, Brazil. The fruits were collected in an area of the Brazilian Agricultural Research Corporation (Embrapa Semiarid), in Petrolina PE, Brazil. The evaluations consisted of determinations of fruit shape, consistency, and number of seeds; seed form, cotyledons, hilum, hypocotyl-radicle axis, and embryo type; epicarp, mesocarp, endocarp, and seed staining; longitudinal, transversal, and ventral diameters of fruits and seeds; fruit, pulp, and seed fresh and dry masses; germination test; first count of germinated seeds; germination speed index; shoot and root lengths; shoot and root fresh and dry masses; and imbibition test. Psidium sobralianum has polyspermic, berry fruits, subclassified as solanidium, with persistent sepals and globular shape, consisting of epicarp, mesocarp, endocarp and seeds. The fruits have green with orange epicarp, pale-green mesocarp, and white endocarp. The seeds have a pilose and bony aspect, a pimentoid type of embryo, foliaceous cotyledons, presence of operculum and hilum, and pale-yellow tegument. The germination is epigeal phanerocotiledonar, with root protrusion from 26 days after sowing (DAS); it presents a short, glabrous, thick radicle, and a rounded, pale-green apex. The germination is slow, probably due to the mechanical barrier of the tegument, and stabilizes at 90 DAS.

Pre-germinative treatments and seed storage of Psidium cattleyanum Sabine morphotypes

“…The MGTs observed in this study are lower than those observed by Gentil et al (2018) for P. friedrichsthalianum seeds and those observed by Santos et al (2004) for P. cattleyanum seeds submitted to different temperatures. The germination of the species is slow probably due to the mechanical barrier of the tegument, as observed by Freitas et al (2018) for P. sobralianum, which may have been altered with the increase of imbibition time. According to Masetto et al (2014), the soaking of P. guinean seeds is effective for increasing germination, with a TMG higher than that found in the present study.…”

“…The yellow morphotype has a length of 3.67 mm (± 0.36 mm), a width of 2.81 mm (± 0.30 mm), and a thickness of 2.03 mm (± 0.27 mm). These values indicate that the seeds of P. cattleyanum are smaller than the seeds of other species of the same genus, such as P. sobralianum (length of 5.0 -7.0 mm) (FREITAS et al, 2018) and P. guajava (length of 2.70 -5.25 mm) (MISHRA et al, 2018). The size and shape of seeds are related to their dispersal strategy and are determinant for the establishment of seed or seedling banks.…”