EMBOSSED COLORED MULCHES
PLASTIC MULCH FOR EARLIER CROPS
The use of the traditional black and
clear plastic mulches is a well documented case. The use of colored
mulches and their benefits is just beginning to emerge. An article dated
August 15, 1991 in the Washington Post noted scientists are discovering
that colored mulches could have a profound effect on plant size, yield,
earliness of harvest and potentially flavor.
It’s all connected to the way plants
“read” light, the way light is reflected and how light waves signal plants
to act in certain ways, according to Michael Kasperbauer, research plant
physiologist at the USDA’S Costal Plains Research Center in Florence, SC
and Patrick Hunt, soil scientist at the center.
“Visible light,” Kasperbauer explained,
“is that part of the spectrum between 400 and 700 nanometers. We see
different shades of red from 600 to 700 nanometers.” (A nanometer is a
measure of wavelength.) Plants, he continued, “see” another red, called
far-red, which is just beyond human vision. It occurs on the spectrum
scale at a wavelength of about 720 to 750 nanometers.
In nature, green leaves absorb red and
reflect far-red, so when a plant “sees” a high proportion of far-red it
reacts as if there were competing plants present. It springs into a
survival mode, rather like that produced by adrenalin pumping when fear
strikes a human. Since plants can’t flee for their lives, instead they
grow taller and put out leaves that are thin and contain extra chlorophyll
and proteins to use light more efficiency.
What all this means to the gardener
standing there scratching his head at his fear-struck tomatoes is bigger,
healthier plants with greater yields that ripen earlier. Even more
intriguing, said Hunt, is that this stimulus-response mechanism can be
fine-tuned to produce a specific result at a certain time.
The important thing is that we will be
able to keep all of the good water conservation and weed control benefits
of mulch, plus the added benefit of using reflected light to improve the
amount and quality of plant products at little extra cost.
The green mulch is widely used on peppers, cantaloupes, watermelons and
other vine crops. Green acts like clear in warming the soil but at the
same preventing weeds, mostly broad-leaf and a few grasses, like the black
mulch. Depending on weather conditions, using green plastic results in a
five to ten day earlier crop harvest than black mulch. There is also an
increase in yields.
According to researchers at Cornell and Clemson universities when
tomatoes are grown on red mulch they have higher yields, stronger stems
and ripen earlier. Research has also found that red mulch reduces nematode
damage. The plant responds to the high proportion of reflected far-red
from the red mulch by growing taller and putting out more leaves.
White on black mulch is used to help cool the soil for mid to late summer
planting of crops for the fall of which would benefit from the cooler soil
temperature. Lettuce, broccoli cauliflower, and other cole crops benefit
from this mulch. This mulch increases yields and reduces aphid