Variations of Weeds Seeds of Species Belonging to Poaceae on the Basis of Germination, Production and Morphological Characteristics

Aims: Seed characters are very helpful for identification of a large number of species or genera. In many cases, morphological characteristics, germination and production of seeds, can be used to distinguish species and varieties.

Methodology: Study it thoroughly in the laboratory where researchers often observe it by naked eyes, in addition to the reliance on references and researches concerning describing seeds to make the study effective and successful it must be conducted carefully with continual vigilance because of the smallness of some seeds so we use magnifying glass, the optical microscope and pocket lamp to see the different external parts of seeds. Germination of seeds was carried out in laboratory under different temperature (5°C, 10°C, 15°C, 20°C, 25°C, 30°C). Production of abundant small seeds is a common adaptation that ensures a high probability of dispersal and re-infestation. Eight characteristics were used to identify eight species of seeds which belong to Poaceae family. The morphological characteristics in which the study was based on are: shape, color, size (length, breadth), solidity, brightness, surface, appendages, weight per 100 seeds. Considerable differences were noticed between the various species of weeds seeds.

Results: The seeds of the family have great variation in their seed mass and size, considered one of the important factors affecting germination percentage and production rate. Germination percentages ranged from 80% to 100%, depending on the species and temperature. The highest germination percentages were reached at alternating temperatures (05°C/30°C). Studies on seed production potential in Bromus sterilis, Bromus rubens, Bromus lanceolatus and Bromus madritensis showed that each plant produces an average of 3700±637, 5000±592, 3000±380 and 4500±426 seeds respectively. Lolium rigidum produces 950±304 seeds /plant whereas Lolium multiflorum produces 900±258 seeds/Plant. One isolated Avena sterilis plant can produce over 235±14 seeds. Thus Avena alba produced 64±15 seeds per plant. Each weeds species shows morphological characteristics different from the plant or other species, these morphological characteristics are not restricted to the external form of the plant only but it can be on level of different other parts of plant like fruit and seed.

Conclusion: The study showed that the seeds morphological characteristics can be helpful in identification of species. The ability to produce seeds with big capacity of germination is, most probably, a mechanism by which species of Poaceae as other weed species adapts to new environmental situations and ensures its survival by facilitating the dispersal of its seeds in time and space.