MATERIALS & METHODS the continuing preparation

This week continued as a week of preparation. I know it seems like the preparation phase just keeps going on and on. But, preparation is important and proper preparation is the only way we are able to truly reach and understand our findings once we reach our ultimate goal.

In our experiment our ultimate goal is to study the effects of allelopathy on the germination of seeds of plants of the lower Sonoran Desert. But, first we must determine the conditions under which our seeds will germinate, and how long it takes.  

Materials

Petri dishes (60 pre-labeled)

Paper towels

Seeds

Method

1.     Thoroughly wash hands, this will reduce contamination

2.     Cut the paper towels to fit the bottom of the labeled Petri dish, two for each Petri dish.

3.     Put one cut paper towel into the bottom of each Petri dish.

4.     Gently count and place seeds into Petri dish (# depends on species, but should be noted)

5.     Seeds should be counted twice.

6.     Moisten seeds with 5 mL of DI water

7.     Place lids on the Petri dishes

8.     Seal lids with paraffin, careful to assure no air can get into the Petri dish as this will alter growing conditions.

9.     Repeat the above procedure; prepare five Petri dishes for each species.

10.  Store the Petri dishes in an undisturbed area of the lab; note the room temperature.

11.  Check on the progress of germination at regular intervals

Next week I hope to have some germinating seedlings!

One of the seeds we are germinating is the Carnegiea gigantean or the Giant Saguaro. These slow growing majestic plants have come to symbolize the state of Arizona, and yet in the wild germination requires conditions that are not typical for Arizona. Evidence suggests that saguaro seeds germinate after a number of years of mild and wetter than average weather conditions. These conditions are estimated to occur “only a few times a century” and may evolutionarily be why these plants grow so slowly – only 1” in 15 years - and live beyond 200 years.

Growth Chart for the Saguaro

First year – reaches height of ½ inch

Fifteenth year – reaches height of 1 inch

40-50 years – reaches height of 10 feet and begins to flower

75 to 100 years – sprouts arm buds and reaches height of 12 to 20 feet

100 to 200 years – can reach heights of 60 feet and weigh upwards of 10 tons

 

Reference:

Dimmitt, Mark, "Cactaceae". A Natural History of the Sonoran Desert.  Arizona-Sonora Desert Museum Press, Tucson.