The document discusses different types of interactions that can occur between crops grown in close proximity in cropping systems: 1. Competitive interactions occur when one crop uses limiting resources like water, nutrients, or light at the expense of the other crop. 2. Complementary interactions occur when one crop helps supply resources to the other crop, such as nitrogen fixation by legumes. 3. Allelopathic interactions can occur when one crop releases chemical toxins that inhibit the growth of the other crop. Successful intercropping requires minimizing competitive interactions and maximizing complementary effects between crop species.

1. CROPPING SYSTEMCROPPING SYSTEM
INTERACTION COMPETITIVE –INTERACTION COMPETITIVE –
COMPLEMENTRY –COMPLEMENTRY –
ALLELOPATHYALLELOPATHY

2. CROPPING SYSTEM- INTERACTION
In intensive cropping, when crops are grown
in association (intercropping or (sequential
cropping) interaction between different
component crop species occurs, which is
essentially a response of one species to the
environment as modified by the presence of
another species (commonly referred to as
interference or interaction).

3. Concept of competition in cropping
systems
• Interaction
The effect of presence of one plant on the
other plants environment
Types
Removal reactions
- competition
Additive reaction
- Allelopathy and Symbiosis

4. Competition in cropping systems
Inter cropping
• Solar radiation
• Water and
nutrients
• Allelopathy
Sequential cropping
• Change in soil
condition
• Shift in weed flora
• Incidence of pest
and diseases

5. The interaction may be
Competitive
Non-competitive
Complementary

6. COMPETITIVE INTERACTION
• One species may have greater ability to
use the limiting factor and will gain at
the expense of the other and this is
called as competitive interaction or
interference.

7. The concept of competition
The struggle between the individuals
within a population for available resources
Competition function
Any function or formulae that
represents the manner in which the
maximum plan yield is reduced by
increasing competition

8. Competition functions
• Intra-Specific competition
Competition occurs between the same species
• Inter-Specific competition
occurs between the different species
• Parabolic function
• Asymptotic function

9. Competitive relationship
1.Competition for growth resources
2.Mechanism of plant population stress
3.Effect of plant population on crop
4.Competition in intercropping and sequential
cropping

10. 1. Competition for growth resources
Competition for nutrients
Depends upon the root spacing of dominated
and aggressive crops
Competition for light
The growth duration of the component crops play
a major role
Competition for water
Depends on the Method of irrigation, RGR,
Earliness of water demand, Root extension-Lateral
and vertical growth

11. 2. Mechanisms of plant population stress
• Yield per plant linearly correlated with the
available space
• In close planting leaf surface per plant and
unit area is reduced
• Effect of rapid growth of weeds on plant
population-injurious
• The theory of injurious substances of the
rhizosphere

12. 3. Effect of plant population on growth
• Widely spaced crops have a circular root
distribution beneficial to crops
• Closely planted crops have un uniform root
spread
• Increased lodging in high plant density
• High plant density lead to seedling mortality
• Build up and spread of pest and diseases
more in HPD with out proper management

13. 4.Factors deciding optimum plant
density
• Plant size
• Tillering
• Lodging

14. Competition in intercropping and
sequential cropping
Important requirements for Successful
intercropping
 Different periods of peak nutrient demand
 Minimum competition for light
 The difference in maturity of component
crops should be at least 30 days

15. way of increase the light use efficiency
• Proper choice of crops
• Proper choice of Genotypes
• Adjustment of population density
• Proportion of each component in the mixture
• Planting pattern

16. Nutrient uptake kg/ha of maize and cow pea
Nutrient Sole crop Inter crop Total
Maize cowpe
a
Maize cowpea
N 185.0 101.0 163.0 40.0 203.0
P 3.97 1.55 3.89 1.30 4.93
K 176.0 54.20 156.0 37.0 193.0
S 157.0 89.0 142.0 62.40 205.0
(Singh et al.,2009)

17. • Roots of sunflower
Sunflower is not recommended for
cropping system approach especially in
sequential cropping
• Removal of sorghum stubbles with high C/N
ratio plays a major role in cropping system
productivity
(Reddy etal.,-2010)

18. • Solar energy use efficiency under rice based cropping system, the
efficiency ranged from 1.58 to 2.02 per cent in UP.
• Efficiency of solar energy use in cotton based cropping system at
Coimbatore from 0.82 to 1.77 per cent of PAR for the whole year,
• indicating that by proper choice of crops, the efficiency is doubled.
(Venugopal et al., 2005)

19. Non-competitive
• If the crops are grown in association and the
growth of either of the concerned species is
not affected, such type of interaction is
called non-competitive interaction or
interference.
• Or if these resources (growth factors) are
present in adequate quantities as a result of
which the growth of either of the concerned
species is not affected, then it is non-
competitive interaction or interference.

20. Complementary interaction
• If one species is able to help the other it is
known as complementary interaction. Or if the
component species are able to exploit to supply
of growth factors in different ways (temporal or
spatial) or if one species is able to help the other
in supply of factor.
• complementary interaction between space and
time called is annidations.
• legumes supplying part of N fixed by symbiosis
to non-legumes)
Eg. Maize intercrop with pulse

21. Annidations in Space
Certain crops require less light intensity and
high relative humidity . Such an altered micro
climate is provided when such crops are
grown in between tall growing components in
an intercropping system.
Eg. Turmeric/ Ginger / Black pepper in
coconut gardens.

22. Annidation in time
• When two crops of widely varying duration
are planted, their peak demands for light and
nutrients are likely to occur at different
periods, thus reducing competition.
• When early maturing crop is harvested it
become favorable for late maturing crop
• Eg. Sorghum+ Redgram, Groundnut+Redgram
and maize + greengram

23. Other Complementary Effect in
Intercropping Systems
• Presence of rhizosphere microflora and
mycorhiza associated with one of the crops
may lead to mobilization and availability of
nutrients which may benefit the associated
crop also.
• Similarly provision of physical support by a
tall crop to a climbing type of intercrop is
another example of complementary effect.
Eg. Coconut + Pepper, Sorghum + Lablab,
Maize+ Climbing Beans.

24. • The taller component acts as wind barrier
protecting the short crop as in maize+
groundnut, onion + castor, turmeric + castor

25. Allelopathy effect
• Allelopathy is referred as any direct or indirect
harmful effect that one plant has on another
through the relates of chemical substances or
toxins into the root environment.
• Some crops may be unsuitable as intercrops
because they secrete toxins into the soil which
will adversely affect the associated crops.

26. • Eg.Roots of cucumber, leaves of Eucalyptus
globules, decomposing residues of sunflower
are known to produce allelo chemicals,
affecting the growth of other crops. Such
crops must be avoided.

27. Types
• Allo inhibition : The chemical released by one
species may inhibit species of plants other
than the one releasing it
• Auto inhibition :inhibit more strongly plants
of the producer species itself
• Functional allelopathic :Toxic substances may
be converted into active substances by some
micro- organisms

28. For success in intercropping, the component
crops must
Differ in duration : a duration difference of 25% is
preferable, other evidences indicate that a
difference at least 32-40 days is necessary.
Differ in rooting pattern-peak nutrient and water
demand periods should occur at different times
should lead to more complementary effects.
should not leave any allelopathic effect
should not encourage the increased incidence of
any particular pest, disease or weed.

29. All our dreams can come true – if we have
the courage to pursue them.”
- Walt Disney