I have to plan an investigation to find the effects on extracts made from tomato fruits on the germination and growth of cress seeds.
I can use fresh or dried tomato's- which would be better to use? with polar or non-polar solvents. How do i measure teh change in dry mass of teh seeds before and after germination has taken place if it does.
How would I carry out this investigation? I understand i have to mash up the tomatoes in order to get the extract but would i use the whole of the tomato or just parts of it? Then would i simply add the tomato mash to a solvant and then add to to cress seeds and see which seeds germinate and which do not?
If anyone could help then that would be much appricated.
Fresh tomatoes would be better - drying may affect the inhibitors. You can't measure CHANGE in dry mass, because measuring dry mass kills the seeds so it can only be done once - wet mass would have to be used (but that is a measure of growth, not germination). You should use the whole tomato unless you are investigating WHERE in the tomato a germination inhibitor might be. You would add the mash to water and use that to germinate the cress seeds (it might be useful to do a range of concentrations). You would record % germination of the cress seeds (unless you use exactly the same number of seeds each time, which can be tricky to count out (as you will need a lot of seeds).