Mustard seed practical

Discussion in 'Supporting Biology' started by clairelucas, Feb 8, 2018.

  1. Hi folks..
    wondered if anyone had any lovely tips on the required practical requiring white mustard /cress seeds. I tried in various containers -best growth in plastic egg box lids, probably as kept moist for longer in the initial germination BUT found even with apparent consistent watering got differing rates of growth, making a consistent class set x3 (for different conditions after germination) not possible. What am I doing wrong?
     
  2. Is this the AQA one testing for gravity/tropism? If so what we did is grow 10 seeds per group, so 1 petri dish with wet cotton wool per group. They used cress but this year we are using mustard as the cress seedlings were too fragile. They put their samples under a shoe box with a hole cut in it and then stood them on a side bench with the light entering the side of the hole for 3 - 4 days. We couldn't use lamps as a light source as ours are far to hot. Out of 7 classes , 6 had reasonable growth results - 1 failed as it was over a hot weekend and the seedlings dried out, couldn't be helped. If it isn't this practical, just ignore me! :):)
    ps. there may be issues with drying out but most times they were fine.
     
  3. That's the one.. Its the fact that the practical states the students should be supplied with already germinated seedlings, but at the different rates of growth, didn't manage to be consistent. Also found the day or two to germinate quite optimistic, but could be how cold my lab is.. window ledges in teaching labs directly over heaters, so dried out even quicker- don't want to have to water multiple times a day, and would be stuffed at weekends!
     
  4. Yes the mustard seedlings I have just grown took 6 days to be between 1 and 2 cm long for the start of the experiment (I was just trying as we hadn't used them before). We shall be doing this later on so I shall let you know if it turns out to be a disaster. I also think that AQA may have been talking about cress seeds for 2 to 3 day germination but if I remember rightly ours still took 4 to 5 days to get to a measurable length last year. It always gets me that they say to trial these practicals beforehand but it is not always possible.
     
    clairelucas likes this.
  5. I used white felt vs simple cotton wool (thin layer) and the felt gave more consistent height results , both in plastic petri dishes , although I know that growing them in the lids of the plastic petri dishes instead of using the bottom of the petri dish seems to make a difference in speed of growth. I have no idea why.
     
  6. If drying is a problem, you could try using a filter paper disc, with a tab cut that can dip down into a reservoir of water below, as a simple self-watering mechanism? e.g. balance the disc on top of a small upturned beaker, standing in a larger beaker of water?
     
    Casey and clairelucas like this.
  7. Shannon

    Shannon Shannon COMMITTEE

    Here, the teacher took them home over the holiday to get them growing. It is working apart from I sent her a 'dead' set of seeds.. Ours are by a window with two lamps on as students do not sit here.

    Petri dish and cotton wool seens to working well and cheap too! Using clean 2nd hand dishes and like supermarket cotton wool.

    Ill keep you guy updated on it;
     
    clairelucas likes this.
  8. To stop seeds drying out, this is a good idea. Just cut a bottle, use the bottom as a reservoir and the neck to grow the seeds Seeds.jpg (upside down - no top) as shown in picture.
     
  9. Like it alot!
     
    stelden likes this.
  10. Thanks for all your help-
    Now the teacher is doing recaps on this- does anyone have an example set of results she can use with her class, or know where we can get a set?
    Ours were pretty rubbish, better luck next time..
    Actually just found some excellent results on tes- so ignore this!
     
    Last edited: Apr 20, 2018