Symptoms of calcium deficiency are more pronounced and
appear earlier in most plants than do those of other elements.
Unlike the other nutrients whose deficiency symptoms first be-
come clearly defined on stalks and leaves, the first signs of
calcium deficiency are mirrored in lack of root growth. The
small roots growing from the seed disintegrate. The seedling
makes a tuft of leaves which at first appear greener than nor-
mal. Eventually, they lose their color and the plant dies pre-
maturely. Small additions of calcium to the nutrient solution
have marked corrective effects.
Because lack of calcium curtails root development, a higher
ratio of leaves and stalk to total weight of plant is obtained. It
is with lack of calcium and nitrogen that the greatest extremes
in the ratio of roots to tops are obtained. The former produces
the least and the latter the largest amount of roots in relation
to leaves and stalks.
Lack of calcium does not have such a pronounced harmful
effect upon rice as it does on other crops. Rice requires little
calcium for growth and contains only a small amount of it at
maturity. The element seems to play some special part in the
synthesis of proteins, for crops high in proteins are also high
Absorption of excess calcium, is possible under unfavorable
cultural conditions. When these happen, the plants usually find
it hard to avail themselves of iron but absorb nitrogen in larger
quantities than are needed. For this reason a calcium excess may be found associated with conditions which cause the foliage
to be either a lighter or a darker green than is normal.
No species have yet been found which can reproduce from
the amount of calcium contained in their seed alone, though
there is a possibility that certain species of rice might.