is a monocotyedonous grass with life span; summer annual but able to survive as
short-lived perennial in tropical grass and live in terrestrial habitat (shawn
steed). This yardgrass is a normal horticultural weed and annual turf. It grows
well in wet and compact soil, competes thrivingly with cool- season and warm-season
turf grasses especially with open and thin disturbed turf.
is considered as an oppresively intrusive weed due to it abundant and vigorous
growth of seed production (Holm et al. 1979). pH range from 10-5 will not
affect the seeds germination.. when the seeds are buried in the depth more than
7.6 cm or 3 inches, it will completely ceases(Chaujan and Johnson 2008; Odero
et aL. 2015) . Persistency of the seeds is due to abundant productions of seeds
and tolerance to close mowing. Goosegrass can grow up until 3 feets tall ( Uva
et. 1997) and reseeding to spread itself.
Hypogeal and epigeal
Multiple floret spikelets with 5 until 7 florets
that disarticulates above the glumes (glumes remain attached to plant) and
General shape : lanceolate
Normal size : 2.4 – 4(5) mm long
Color : straw colored
Texture :smooth, glabrous, papery
Distinguishing features : lemma strongly keeled
along mid-vein and with short stiff hairs, somewhat keeled along two lateral
veins, apex tapering to a point; callus blunt; awnless; rachilla short and
stout; palea slightly shorter than lemma, strongly keeled along two veins,
short stiff hairs along keels.
Not technically a caryopsis because the seed
coat is not fused to the pericarp.
General shape : ovoid to ellipsoid
Normal size : 2mm X 0.8-1.3mm wide
Color : straw yellow to light brown
Texture : smooth, glabrous, thin, and papery
At maturity the seed easily separates from the
General shape : ovate to squarish in outline,
dorsal side longitudinally ridged, ventral side +/- longitudinally grooved.
Normal size : 1-1.5mm long X 0.7 – 1.1mm wide
Colour : purplish – black
Texture : transversely ridged
Embryo : nearly 1/3 the length of the caryopsis
Endosperm : solid
Hilum : round and located in a basal depression
of a seed inaugurate with the water uptake and complete with the emergence of
the embryo, in many species radicle will appear first. Thenceforth, germination
is completed, and the seed is noticed as having germinated (sometimes termed
‘visible germination’), rather than germinating, and seedling growth is now
underway. Failure to pursue the definition has led to claims of molecular and cellular
too frequently events the occurring is during process of germination, when in
fact they are parts of growth of seedling. Thus, care must be taken to prescribe
clearly the germination time course for an appropriate sets of seeds under the surrounding
or conditions to which they are command.
to germinate in favorable times seeds enable themselves to be triggered. Those
seeds may look like dead, yet, in fact they are just experience dormant phase
in a life cycle of plant and they will germinate rapidly when times are right.
Some seeds wait days, some weeks and some many years until the conditions are
right. Few factors which will affect seed germination includes temperature, moisture
if the mature plants have good adaptation towards dry conditions, the seedlings
still need an ample moisture for seeds to grow. The presence of water triggered
seeds to germinate. Firstly, water is imbibed into the testa (seed coat) and either triggers germination by gradually
washes away the chemicals that inhibit germination which block the passage of
water towards the endosperm or directly reacting with the chemicals inside the
endosperm . Normally, these inhibitors are present in the seeds that need a
sustained period or amount of water for germination and to ensure that one
quick shower during dry season does not neither enhance nor trigger
than that, temperature also affects seed germination. Germination is triggered
when temperatures rise where the processess of chemical which enable the
embryonic leaf (hypocotyl) to grow up
are faster, the radicles to emerge down and formation of cotyledons in warmer
condtions. Besides, level of lights
important for germination. Many tiny seeds are naturally land on the surface of
the soil. Others are heavy and pass through the gut of animals. They will be
deposited in soil or droppings. Higher levels of light will trigger it, as the
plant knows, longer days mean better conditions.We are able to mimic factors
affecting germination using horticulture methods. It is used to trick the
seeds. Stratification is one of them, which horticulturalists use factors that
affect seed germination by placing the seeds in a cold environment like a refrigerator
for several weeks.
survival strategy that ensures the persistence of one species is called seed
dormancy. Dormancy is characterized as endogenous if it caused by the factors
within the embryo or exogenous if it caused by the factors outside the embryo.
Exogenous dormancy is further characterized as mechanical, chemical or
physical, meanwhile endogenous dormancy may be morphlogical or physiological. These combinations factors might
be responsible for dormancy in certain species (Jones and Nielson, 1992).
physical barrier intergrity varies by accession, species and year. It had been
demonstrated that, at the time seeds reaches it maturity, relative humidity
also affect dormancy (Quinlivan, 1970). Highly dormant seeds require
scarification to encourage or assure germination rates when planted. This study,
tested mechanical and chemical scarification techniques to discover which were
the most predictable yielded the best germination.
Classification of seef dormancy
(1977) found that,three levels of Physiological Dormancy: non-deep,
intermediate and deep and have their own characteristics. Majority of seeds
with PD have non-deep physiological dormancy. Addition, ?ve types of non-deep
physiological dormancy are recognized based on change of pattern in
physiological responses towards temperature during break of dormancy, (Figure
starting point 1.0 on the x-axis in Figure 4 is the fully dormant condition.
Values >0.0 to <1.0 represent the continuum of stages toward dormancy break in Types 1, 2 and 3. During the progression from dormancy to non-dormancy,the temperature range at which seeds can germinate gradually increases (y-axis): 1) Type 1 : low to high 2) Type 2 : high to low 3) Type 3 : medium to both high and low Furthermore, seeds with non-deep dormancy Types 1, 2 and 3, during progression of dormancy-break, its sensitivity to other factors, such as plant growth regulators will increases (Baskin and Baskin, 1998). On the contrary, limited knowledges of seeds with Types 5 and 4 proposed that they do not exhibit a distinct continuum of changes during break of dormancy (Figure 2.3). Alternately, seeds show up to proceed from the dormant state (1.0) to the non-dormant state (0.0) without undergo the continuum of states exhibited by seeds with Types 1, 2 and 3. At least, with regards to widening of their temperature responses for germination. Hence, during dormancy-break, Type 4 seeds gain the ability to germinate only at high temperatures, and gain the ability to germinate only at low temperatures are those seeds with Type 5. 2) Morphological dormancy The seeds with morphological dormancy (MD), its embryo is small or under developed and differentiated, i.e. hypocotyl–radicle and cotyledon(s) can be distinguished (Baskin and Baskin, 1998). Embryos in seeds with MD are not physiologically dormant and do not require a pre-treatment of dormancy-breaking in order to germinate; thus, they simply need times to grow to full size and then germinate where radicle protrusion occur. The period of dormancy is the time elapsed between radicle emergence and incubation of fresh seeds. Under convenient conditions, embryos infreshly matured seeds begin to elongate within a period of a few days to 1-2 weeks, and the seeds will germinate within 30 days. 3) Morphophysiological dormancy Seeds with this kind of dormancy require a pre-treatment of dormancy-breaking because they. Seeds with morphophysiological dormancy (MPD), embryo growth or emergence of radicle required a substantially longer period of time compare to seeds with MD. Physical dormancy Physical dormancy (PY) is caused by one or more water-impermeable layers of palisade cells in the fruit or seed coat (Baskin et al., 2000). Occasionally, under both arti?cial and natural (except mechanical scari?cation) conditions for dormancy break in seeds with PY, had been assumed to involve the formation of an opening known as water gap in a particular anatomical structures on the seeds coat, through which water moves direct to the embryo (Baskin et al., 2000). However, researcher Morrison et al. (1998) have conferred evidence that, in some taxanomy of Fabaceae, break of dormancy by heating may occur through the disruptions of the seed coat in one region(s) other than the strophiole (lens). Chemical or mechanical scari?cation also promote germination with non-deep physiological dormancy seeds. Thus, it is common for any investigator to report about the seeds of particular taxon have physical (water-impermeable seed-coat) dormancy, when in fact, it is not the case. Lack of water uptake was not documented by examining imbibition in non-scari?ed versus scari?ed seeds, and more seeds of plant taxa not known to have PY (see Baskin et al., 2000). Break of dormancy by scari?cation in seeds with non-deep PD appears to relate with weakening (lowering the resistance for penetration of radicle) the layer that cover the embryo, thus, its help the radicles to penetrate. Contrast to wild-type tomato intact seeds (Lycopersiconesculentum cv. Moneymaker), detipped seeds (endosperm removal plus layers of testa opposing the radicle) germinated in polyethylene glycol (PEG) solutions that had more negative by c. 0.5 MPa osmotic potential (Groot and Karssen, 1992) 4) Combinational dormancy Occur in seeds with (PY + PD), the seeds or fruit coat is impermeable to water, plus, the embryo is physiologically dormant. The physiological components appear to be at the non-deep level in all of the examples with which we are familiar (Baskin and Baskin, 1998). Freshly matured embryos seeds of some winter annuals, e.g. Geranium, Geraniaceae and Trifolium, Fabaceae, have some conditional dormancy and will come out of dormancy (after-ripen) in a dry storage or in the ?eld within few weeks after maturity, although the seed coat remains impermeable towards water (Baskin and Baskin, 1998). Embryos in such genera like Ceanothus (Rhamnaceae) and Cercis (Fabaceae) have more deeply dormant (yet still non-deep). Thus, it require cold strati?cation for several weeks. Altogether, seed dormancy is a typical quantitative genetic traits, involving many genes, substantially in?uenced by the environment during development of seeds, and exhibiting continuous or non-discrete phenotypic variations. Moreover, it is controlled by nuclear genes and maternal effects in some genotypes and species. Interactions of epistatic may occur among loci (Li and Foley, 1997; Van der Schaaret al., 1997; Foley and Fennimore, 1998; Koornneef etal., 2000; Foley, 2001). Van der Schaar et al. (1997) mentioned that 'Of the traits with wide genetic variations in nature, seed dormancy is presumably one of the most complicated'.