SEED VIABILITY, GERMINATION AND SEEDLING/FIELD EMERGENCE

In this laboratory we study three important quality characteristics (viability, germinability and seed emergence) of two types each of monocot and dicot seeds.  Furthermore, specifically we want to determine whether then planting medium affect the seed germination and seedling emergence.  Seed viability refers to whether the seed is living or not.  This is the potential ability of the seed to germinate.  Germinability is whether the seed is practically able to germinate under optimum conditions.  Seedling emergence is a resultant effect of the ability of the seed to germinate and the ability of the seedling to emerge from the medium (soil) in which the crop is seeded.  In a more practical context, farmers are interested in the actual rate of crop establishment at the field which is correlated to all these three aspects of seed quality, but usually different from all.  All these variables can be quantified as percentages.

Materials and Methods:
Pre-soaked seeds of selected moncot and dicot crops, tetrazolium, petri dishes, filter paper, trays with media to sow the seeds, blades, markers, label tags etc.

One of the experimental techniques you will adopt in this study is the representative/random sampling.  For investigating the three parameters (seed quality characteristics) of the total seed population in hand, you will only use a randomly drawn sample from the total seed lot for each parameter.  Record data separately for three parameters and seed types (crops).  Make sure you take unequal number of seeds for each sample taken for studying each parameter of a given crop (e.g.. 10 or 20 seeds).  You should not include broken seeds in the sample.

Seed Viability:  Cut each seed of the sample you extracted from the total seed lot through the germ/embryo.  Immediately place a drop of tetrazolium on the cut surface so that the reagent will touch the embryo.  Look for the color development (pink) and record the number of seeds that were viable within an hour of the treatment.

Seed germinability:  Place the seed sample on a wet filter paper lying on a petri dish.  Squirt water onto the filter paper to make sure that it will have sufficient water for the seeds to germinate.  Remember to place the seeds apart from one another and not to pour too much water (why?).  Place the dishes with seeds on a green house bench (or window sill).  Label your dishes with your group number or your initials.  Record the data during the next class (or two days ).

Seedling emergence:  Sow the seeds of the sample you drew from the main seed lot on the different media in trays (top soil, sand, vermiculite, and peat moss.  Place the seeds apart from one another and cover with a thin layer (1 cm) of the medium of the same tray.  Label the trays and place them on a green house bench.

Report:  Try to use a variety of presentation techniques in the results section.  Make sure you develop a discussion in which the results are interpreted, critically evaluated and reasoned out.  Present a concise account on how the observations must have been affected by the combined action of factors required for the expression of the seed quality parameter you studied.  Furthermore, include other factors that would have influenced these parameters.

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