Antitranspirants and their effect on crop

1. Assignment – 2
GUIDED BY
Dr. S.S Bhadauria
Submitted by
OMPRAKASH PARIHAR
Roll.no-20111109 (M.sc .previous )
Dept. of AGRONOMY
COA GWALIOR
Rajmata Vijayaraje Scindia Krishi Vishwa Vidyalaya
COLLEGE OF AGRICULTURE GWALIOR (M.P.)
Anti-transpirants and their effect on crops

2. Antitranspirants are the compounds or the substances
applied to the leaves of the plants for the purpose of
reducing water loss (transpiration) without causing a
momentous change in the various important processes of
the plant such as growth and photosynthesis.
 Antitranspirants are generally classified into four
distinct categories:-
 Stomatal closing type
 Filmformingtype
 Reflecting type
 Growth retardant

3. The scope of using antitranspirants includes
1. Under dryland area, to reduce water losses
through transpiration
2. In costly irrigation, for extending the
irrigation interval
3. In areas having poor quality of soil-water or
irrigation water, to reduce the uptake of salts
4. For reducing transplanting shock of nursery
plants.

4. There are four principles of transpiration
control:
1. By increasing leaf resistance to water vapour
transfer by application of materials, which tend to
close or cover stomata (e.g both stomatal closing
and film forming type of antitranspirants)
2 By reducing amount of energy absorbed by leaf
surface (e.g leaf reflectants).
3. By reducing top growth of plants (e.g growth
retardants)
4. By increasing air resistance to water vapour
transfer by shelter belts/windbreaks

5. Stomata closing type: Most of the transpiration occurs
through the stomata the leaf surface. Some fungicides like
Phenyl mercuric acetate (PMA) and herbicides like atrazine
in low concentration serve as antitranspirants by inducing
the stomatal closing.
PMA was found to decrease transpiration to greater degree
than the photosynthesis in a number of plants. Stomatal
opening is regulated by various sensors like, water, CO,light
and hormones. The opening is strongly controlled by hydro-
active mechanism, while other sensors are lıydro-passive
and is mediated through relative water content (RWC) of
guard cell chloroplast.

6. Film-forming type: Foliar spray of waxy or plastic
emulsions such as mobileaf. hexadeconol and silicone
produce an external physical barrier outside the stomatal
opening to retard the escape of water vapour through
stomatal opening.
The film so formed should have more resistance to the
passage of water than to that of carbon dioxide. Film type
antitranspirants, which provide selective type of
permeability barriers to water vapours and carbon
dioxide diffusion in the required directions, have not yet
been found so far.

7. Increasing leaf reflectance type: White reflecting
materials such as whitewash or kaolinite % spray form a
coating on the leaves and increase the leaf reflectance
(albedo). By Terecting the large amount of radiation,
Application of 5 per cent kaolin spray has been found to
reduce transpiration losses markedly.
Growth Retardants These chemicals reduce shoot
growth and increase root growth and thus enable the
plants to resist drought. They may also induce stomatal
closure. Cycocel is one such chemical uselul for
improving water status of the plant.

8. EFFECT OF ANTITRANSPIRANTS ON CROP
PRODUCTION:- Antitranspirants are used to reduce the
losses of water through transpiration, so that limited
amount of available soil moisture can be used for
completing the life cycle of crop plants.
Antitranspirants along with slowing the rate of
transpiration reduces the photosynthesis efficiency of crop
plant due to less uptake of carbon dioxide through
narrowed aperture of stomata, relatively less permeability
of carbon dioxide through the film and rise in leaf
temperature. Reduction in transpiration as well as
photosynthesis after treatment with antitranspirants is well
documented in the literature.

9. Limitations of antitranspirants :-
1. May reduce the rate of photosymthesis
2. May increase the leaf temperature by reducing
evaporative cooling
3. Interaction of climatic factors with
antitranspirants reduces their effectiveness for
longer duration
4. Marginal cost may be more than marginal
returns
5. May produce toxic effects on leaves.

10. Effects of antitranspirants in field crops
Antitranspirants in wheat In wheat cultivar DWD-1006,
irrigation,mulch and antitranspirant application were found to
improvise the growth, yield and yield contributing attributes and
cost of cultivation.
Five irrigations at different critical stages increased the various
growth parameters, mulched treatment provide highest total dry
matter production per plant and treatment with antitranspirant,
kaolin along with five irrigations were found to increase the dry
matter accumulation, grain yield and also offers highest gross
return and cost of cultivation (Brahma et al., 2007).
Antitranspirants in maize Antitranspirant application with
alachlor @ 20mg/litre in maize plants was reported to be most
effective in reducing the rate of transpiration and partially hindered
the stomatal opening

11. Antitranspirants in barley
Pre and post inoculation sprays of film- forming type of
antitranspirants viz., Nu- film P, emerald and vapor gard results in
greater decline in powdery mildew infection of barley seedlings,
significantly. For better results, mixture of 2% vapor gard along
with 1Mm alpha- difluoro methylornithine (DFMO) were found to
be the best against the fungus and applied before one day to
inoculation with the fungus (Walters, 1992).
Antitranspirants in soybean
Foliar application of antitranspirants, applied at 60 days after
planting i.e. at flowering stage and seed formation stage had very
positive effects in growth, yield and yield attributing traits of
soybean under limited irrigation, Antitranspirant, kaolin @6%
were found to be the most effective that significantly increased
the stem height, stem diameter, node number, number of pods,
number of seeds per plant,