Relationships Between Fruits And Seed Sizes, Germination And Early Seedling Growth Of Some Edible Plant Species In Southeastern Nigerian Rainforest

Abstract

Relationships between fruits and seeds sizes; seed germination and early seedling growth of seedlings of 25 plant species were studied at the University of Agriculture, Umudike, Nigeria. The destruction of Nigeria rainforest without an assured method of naturally regenerating it, has contributed to some edible plant species being either fewer per hectare or endangered in abandoned farmlands. Fruits of 25 plant species were collected from the rainforest at Umudike, Nigeria. For each plant species 100 fruits and seeds were selected for the study. All the fruits contained between 1 and 30 seeds. The length, width and weight of fruits and seeds of the plant species varied within and between plant species. The biggest fruits were those of Pentaclethra macrophylla with length ranging of between 435.22 and 508.52 mm while the biggest seeds were those of Plukernetia conophora each had length range of between 60.39 and 98.14 mm.. The length and width of each fruit and seed were measured using Digimatic Mitutoyo caliper. For each fruit and seeds, the weight was measured using electric weighing balance, Ohaus Corporation, Model Scout Prospu 402. Broadcast of 100 seeds of each plant species was done on germination boxes of size 30 x 60 cm, and watered twice daily. All the viable seeds germinated, however, mechanical dormancy was observed in the fruits of Spondias mombin, Tetrapleura tetraptera and Canarium schweinfurthii, whose seeds were covered by fibrous material. There was no co-relationship between seed size and germination rate because both small and big seeds started germination within the same week. The observed seedling types were Phanerocotylar -epigeal -reserve, (52.9%), Phanerocotylar -epigeal -foliaceous (20%) and Cryptocotylar -hypogeal -reserve (12.0 %), Phenerocotylar -hypogeal -reserve (8) and Cryptocotylar-epigeal-reserve (8%). There was a significant different in the growth rate of seedlings of the plant species. The rate of growth of 0.05 m per month of seedlings of Persea americana and Dacryodes edulis was comparatively high presumably because of the food stored in the seed. The rate of growth of 0.001 m per month of Dialium guineense seedlings was very poor presumably because of the relatively small quantity of food stored in the seed. Carpolobia lutea produced numerous branches exhibiting shrubby characteristics. It is recommended that fruits should be collected from different provenances and their proximate composition analysed. Fruits having desirable qualities should be genetically improved.