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Re: Swords losing chlorophyll
John Fritch wrote:
> I'm having a problem with some sword plants. Some of the older, longest
> leaves look like the chlorophyll is draining out of them, leaving just a
> lacy skeleton of veins and capillaries. I think the same thing is beginning
> to happen to some more recently added Sagittaria subulata. The newer
> shorter leaves look all right.
It sounds like you might have a couple things going on.
Sword plants are usually grown emersed by commercial nurseries. The
first thing that happens when you plant them under water is that they go
through some changes. The emersed leaf blades are oval or cordate
(heart-shaped) and carried on petioles that are longer than the leaf
blade. The submersed leaves are normally smaller (to start with), with
shorter petioles and more pointed (lanceolate) leaves. This is true for
the three of four species that are usually called "amazon swords".
There are other Echinodorus species that retain more oval leaves under
water. Most of those plants get big.
Your plants may just be adapting to submersed growth and losing their
older leaves. This same thing can be said for your Saggitaria; they,
too may have been grown emersed.
Yellowing older leaves and dying older leaves (especially dying back
from the tip of the leaf) can also indicate a nitrogen shortage. You
can check if this is the case by measuring the nitrate concentration in
you tank. You should have a few ppm of nitrate. Ammonia and nitrite
(which are also sources of plant-available nitrogen) should be
unmeasurable in an established tank.
Echinodorus and Saggitaria both respond well to Jobes spikes cut into
pieces and pushed into the substrate in their root zones. That would
provide your plants with more of the nitrogen, phosphorus and potassium
that they need in relatively large proportions.