AUGUST 10, 1903. - 
THE EFFECT OF LIGHT ON 
PLANTS. 
By James MarttHew. 
” 
“Light is, except warmth,’ wrote Lind- 
ley, “the most powerful stimulus that can 
bo employed to excite the vital actions of 
plants, and its energy is in proportion to 
its intensity.” 
Tts chemical action is various. Under 
its influence there is a constant exhalation 
of oxygen from jplants bly day and an 
inhalation of-carbolic acid. When dark- 
ness comes the action is reversed. The 
_stronger the light the greater will. be the 
outflow of oxygen, and the purer will, 
therefore, be the air for human use. 
Ceteris paribus, a sunny and dry, land 
should be healthier and cheerier than a 
cloudy and rainy one. The nations of 
Southern Europe are at least brighter 
spirited than the Northern. The sun- 
light on constantly marshy land only draws 
up miasma. : 
Tt is light that sets going in the spring- 
time young buds.. At the point nearest 
to the light—the tips of branches—the 
leaf-buds first show. With increasing 
force of light growth advances; dulness 
or diffused light checks. With a strong, 
well-rooted plant, development is con- 
tinuous; but when, as in the case of cut- 
tings, there is no root formed, the 
strengthening light excites too great ra- 
pidity of growth, there is no forthcoming 
supply of sap in the stem to maintain the 
young leaves, and they are burned off. 
Hence the necessity for placing cuttings 
and young and tender plants in shade, viz., 
diffused light, and also for covering over 
temporarily ‘newly transplanted trees or 
plants until they acquire foothold. 
Perhaps the most obvious effect of light 
is to give color. Plants and children rear- 
ed in cellars are of sickly hue. Plants grown 
in the dark are colorless. 
sent up by a seed is almost without color, 
but as it creeps into the light its faint 
green tinge deepens. Asa rule, roots are 
colorless, but there there are exceptions, as 
the carrot and beet. But let a potato or 
carrot peep above ground, and every por- 
tion exposed will speedily tinge green. 
The upper surface of leaves is darker than 
the under from looking upwards. The 
most intense and delicate tinting of petals 
ia only possible in the brightest sunlight. 
It is in equatorial lands that the most. gor- 
geous flowers are to be found. Sumatra is 
the home of the Rafflesia Arnoldi, the lar- 
gest flower in the world. Towards the 
Poles tints shade off into dull greys. - 
Another result of exposure to light is 
flavor. As the sap rises in the stem it 
gets thickened by evaporation, the light 
also acts chemically upon it, and it is con- 
verted into organizable matter. It is from 
this that flower buds are formed, and from 
The first shoot > 
THE AUSTRALIAN GARDENER. 
the flower buds fruit. In the fruit itself 
the action of light is direct. The flavor 
of fruits is caused mainly by the propor- 
tion of acid and sugar and essential oils. 
The noticeable taste of most fruits in the 
first stage is acidity. It is the sunlight 
that changes sourness into sweetness, and 
gives to each fruit its peculiar and essen- 
tial flavor. According to the intensity of » 
light will be the speed, and thoroughness 
with which the change is effected. In dif- 
’ fused light fruit will not ripen well and all . 
round. Fruit on low branches, or leaf 
covered, ripens often only on one side. 
Peaches are said not to-be able to mature 
fruit in greenhouses where light is diffused. 
The best and most fruit in our gardens will 
be nearest to the light—at the tips of the 
branches. : . 
1. Healthiness—The intensity of its 
sunlight will cause free elimination of oxy- 
gen from foliage. No doubt the mallee 
leaves, with their rich, pure odorousness 
are being rapidly burned, but in place of 
them every year will see a variety and den- 
sity of foliage round the settlement. The 
. bright and dry air should be unfavorable 
too to some kinds of blight. 
2. Activity of Plants.—Few things 
strike one more than the readiness with 
which cuttings root. No doubt the virgin 
soil has to do with this result. But with- 
out leaves you can have no.roots, and it is 
the light that calls forth the leaves. .The 
intensity of the light is, however, against 
the successful raising of annuals in the 
open. 
3. Color—The perfectness and softness 
of the tints of our flowers is a marvel. 
Gladioli, Verbenas, Roses, Pinks, Picotees 
cannot be surpassed. The blossom is 
rapid, endures only. a very short time, and 
is gone. Flower culture for Melbourne sale 
may become an industry. Then there is the 
coloring of our fruits. The appearance of 
our apples, pears, oranges, lemons will af- 
fect their value. In oursteady and bright 
sunlight our fruits should be finely and 
thoroughly tinted. Tomatoes ripen toa 
very perfect redness through and through. 
Tt will be a point, too,.if-we can with our 
advantages dry grapes and prunes with an 
attractive look. ' 
4, Fineness of Flavor.—I regard this as 
of more importance than any of the pre- 
ceding. It is taste, after all, more than 
show that guides the demand. Ifa fruit 
ripens under equal and steady conditions 
it is likely to be better than if exposed ‘to 
uncertain and lengthened ones. With 
strong, equal, direct sunlight most of our 
fruits, with careful irrigation, should 
acquire a flavor all their own. With care- 
ful irrigation there should be avoided that 
surface burning of some kinds of fruits*that 
destroys look and firmness and good.-taste. 
Altogether the brightness and force of 
our sunlight, though it may imply care- 
ful rearing of young stuff—as cuttings 
and annuals—and involve possible misses 
in transplanting and budding, neverthe- 
less will bring benefits outreaching far its 
possible drawbacks—The “Mildura Culti- 
vator,” 
TI 
BULBS AND COLD STORAGE. 
A discovery of the 20th century is that 
almost all bulbs, be they Lilies, Irises, 
Hyacinths or Snowdrops, Tulips or Nar- 
cissi, are controllable by a certain range 
of the thermometer. The 19th century 
was, responsible for forcing, but many 
bulbs wete injured; others did not , 
respond to it, or even perished of it. On 
the other-hand, frost killed bulbs, the 
term hardy being only comparative in this 
respect. The old method was to regard 
a bulb absolutely quiescent from the 
fading of the flower to the season for 
starting a fresh year of growth. But to- 
day the gardener learned that if on the 
completion of one year’s flowering he 
places the bulb in a definite temperature, 
he can practically control the date of 
flowering in the next. Assume, for in- 
stance, that the ground temperature 
averages 50 degrees from August to 
March, and a given bulb flowers in July, 
by ~ putting the bulb in a temperature 
averaging 40 degrees for the quiescent 
months it will flower in September in- 
stead of July without any dwarfing its 
growth. Of course, the matter is not 
quite so simple as in this brief note would 
appear. We only aim at giving the drift 
of what may be called the “cold storage of 
bulbs.” —“Graphic,” 
TABLE DECORATING. 
All plants employed for tabie decoration 
should have pieces of some close-growing 
greenery, such as Selaginella Kraussiana 
in its various forms, dibbled in the surface 
of the-soil wherein they are growing. If 
thiy is done when the yvuug seedling or 
rooted cutting is put into its pot, by the 
time it is fit to take its place on the table 
the Selaginella will have grown into a 
beautiful green, yellow, or silver carpeting 
for it. Many people place this green cover- 
ing over the soil only when using the 
plants, but it has not then so graceful or 
- natural an appearance as when established 
and growing. 
. A. person who has much table decoration 
to carry out will do well to always keep a 
few pans of Selaginella growing ready for 
emergencies.- Shallow pans, such as are 
supplied with orchid pots, are the ones 
to use, and they should contain but the 
thinnest layer of leafy, sandy soil, so that 
it and the greenery can be transferred with 
little disturbance to pots wherein their ser- 
vices are required. 
_ Sphagnum Moss, and many of the varie- 
ties in the woodland, make useful substi- 
tutes for Selaginella, but are scarcely se 
well suited for growing on the surface soil 
of the pots, as many of them form tufts 
not sufficiently pervious to air, , 
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