Potato Tubers At Critical Water Stage

Considering how little water it has had, I was surprised to see tubers developing on stem branches (red) attached to the potted potato plant. Just shows how determined plants are to survive. Potato tubers are bulky short portions of underground stems.

True roots can also be seen. At this stage, these roots gather as much water as possible to support tuber growth. This is the critical stage in potato development, for water requirements. Limiting water at this stage will drastically reduce crop yield.

Potato Surface Roots Enter New Soil

A few new roots (green) have this week entered the new soil (above the red line) - two are visible on the surface. I have been careful only to wet the soil surface by lightly spraying clean water. I'm not sure what this means, other than surface roots seem to have a determining effect on new root growth and direction. Looks like the potato plant is now finished with. Might be best to discard it anyway, since there is always a danger of virus disease build-up which might affect future plantings.

Potato Update

After bringing potted potato plant back to wilting point to ensure the lower soil was dry enough, I added a layer damp soil to surface to see if surface roots could extract enough water for recovery. Because plant was still wilting one day later, I got nervous of plasmolysis and sprayed new soil with water so dampness went down about 6mm (1/4 inch). Plant started to recover.

If you remember, the last time I tried to damp just the surface, the result was the same. So it looks as if the tiny roots right beneath the surface (this doesn't seem likely) do not take in water and plant uses roots a little lower down (still in top 6 mm). Of course, it might just be that I didn't give roots long enough.

No sign yet of any roots growing into new soil. Will keep it damp and see what happens.

Surface Potato Roots Do Seem To Absorb Water

These wilting leaves on the potted potato plant indicate it is short of water. Good. I took the opportunity to test if the surface roots, described recently, will in fact take in water.

So, lightly sprayed surface with clean water . . . Nothing at first, even after 8 hours . . . But once water got down a quarter inch (6mm) or so, the plant did start to recover. I don't think much water got further down than this, but cannot be absolutely certain. Of course, I have no control. But it still gives some indication of the value of the surface roots in gathering rain showers.

Am letting plant reach wilting point again, then covering surface roots with damp garden soil to see what happens.