The Cairo bulletin., 1911-08-31
6R.AlN-soRGHUM CROP
Two Ways by Which It Can Be
Made Of Greater Value.
Most Useful In Regions Where Mols-
, ture 10 Often Controlling Factor
In Crop Production - Are
Drought Resistant.

y(By CARLETON r. BALL. Bureau Of
Plant Industry. U. 8. Department OF As-
i, riculture)
In general there are two ways by
which the grain-sorghum crops can be
made of greater value to the grower
The first Is by improving the yarie-
ties; the second. by finding more rap
ID and economical methods OF har.
vesting. Improved varieties can DO
obtained through selection OF present
sorts and by lettering the methods OF
growing them. More rapid and eco
nomical harvesting will come about
either through adapting the crops to
present machinery or through the In
vention OF new machines, or both.
There are Ave principal ways In
which Improvement may be made:
ID Increased drought resistance,
CD Increased earliness, (9) dwarfer
stature, a. greater productiveness.
and (5) increased machine harvest
Ing.
The grain sorghums are most use
ful In regions where moisture Is often
the controlling factor In crop pro
duction. Much good should therefore
be accomplished by increasing their
drought resistance, especially In the
areas of lighter rainfall. b4 49,.
No one knows exactly what drought
resistance is. 1t is probable that
what We call drought resistance 10
the effect of several different factors.
The most important OF these factors
are probably % increased ability to
prevent the loss OF water by transpf.
ration, l2) increased development OF
the root system, and 81 a possible
increase In power to extract water
from dry soil.
Differences In the power to control
Transportation are well-known and
readily observed facts. BY transpira-
ton Is meant the passing of water
from the tissues of the plant into the
air. In the processes OF their growth
all plants are constantly absorbing
water from the soil through their
,rootlets and allowing certain quaint
ties of this moisture to pass out into
the air through minute pores, called
stomata. This Is done In much the
same manner as water escapes
through the animal skin In the form
OF perspiration. In times OF drought
1t Is important that the plant lose as
little as possible of Its water supply
In this way. The plant best fitted to
prevent Transportation Is thus the most
drought resistant In .cacu, for in.
stance, this ability is highly perfect
ga. Corn Is much less drought resist,
Ant than the members OF the various
Groups OF sorghums. Corn IL IA dan!
yer when the leaves begin to curl,
knt sorghums often remain In this
Hondition for long time without per.
lhanent injury. a'tH,gls
The size and character OF the root
system Is probably a strong factor In \
drought resistance. The larger the
root system In proportion to tho plant
the better It can supply moisture. Tho
wider and deeper Its penetration. the
larger the area of soil from which 1t
draws moisture In times OF drought. |
a, deeply roofing plant may be able
W secure water when shallow root
systems lie wholly In dry soil. This
p entirely apart from possible dif. !
ferences in ability to secure moisture
from a given unit Of soil. Such differ
snces may exist. but the idea ID only !
q theory as yet. Unfortunately, the
character Of the root system cannot 1
be observed while making observa.
lions.