The nice thing about it is that a huge percentage of home gardeners grow tomatoes, and it shows some nice clear examples of various problems on the same species so it's easy to compare.
I figured Tomatoes might be a good indicator of my system's health, and could give me a clue to my capsicum leaf on the last post. As a result of my research, I think my problem with the capsicum is just about the abuse I put them through when they were little seedlings. All the leaves that have fallen off where the ones that were already there as seedlings.
The only problem with tomatoes as an indicator species, is I dont know if tomatoes need stacks of a given trace element or only a little.
So I was wondering about some indicator plants that might be worth planting in a bigger system that would start to fall over at the first sign of a problem. ie plants that were very intolerant to a specific deficiency.
I used to have some pot plants and one (I think it was called a chocolate flower) had a very long stalk that would stand straight up when all was well, but take a bit of a nap and lie on the ground when it was the slightest bit thirsty. I'd water it and it would spring back to standing upright. The result was, I would always know when to water my little mobile garden. As long as I maintained my mental distance from my thoughtless torture of the chocolate flower, the rest of my garden never went thirsty.
So I thought I might plant some indicator species that fell over at the merest whiff of a particular deficiency.
I dont know what they are, but I thought I'd plant them.
120 Things in 20 years, sometimes more than just vague open ended research proposals.