Regarding cropping system interactions, allelopathy in cropping system and it includes multiple cropping system and legume interactions.

1. CROPPING SYSTEM INTERACTION
COMPETITIVE – COMPLEMENTRY – ALLELOPATHY
Thimmaiah M
1St Ph.D
Department of
Agronomy
UAHS, Shivamogga
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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).
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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
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4. Phyllosphere and Rhizosphere Interactions
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5. 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
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6. Kinds of Interactions
1. Competitive interaction
2. Non-competitive
3. Complementary
 Competitive interactions :
 One species may have greater ability to use factor and will gain at
the expense of the other and the limiting this is called as
competitive interaction or interference.
 In mixed crop communities, if the associated species are to share
their growth from a limited pool of recourses such as light, water
or nutrients, then it is non-competitive interaction or interference
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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 crop yield is
reduced by increasing competition.
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8. Competition functions
 Intra-Specific competition
Competition occurs between the same
species
 Inter-Specific competition
occurs between the different species
 Parabolic function
 Asymptotic function
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9. Response of asymptotic and Parabolic curves
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10. 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
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11. 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
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12. 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
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13. Intercropping v/s Monoculture
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14. 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.
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15. Interaction in Inter-Cropping
 Competition between the associated crops in mixed
crop communities has been discussed by Donald
(1963), Trenbath (1976) and Willey (1979).
 Competition for Solar Radiation:
 The taller crop in the intercropping systems intercepts
most of the solar radiation while shorter component
suffers.
 In Groundnut + Red gram intercropping system, light
interception is prolonged as red gram starts growing
after harvesting of groundnut.
 If the component crops have different growth durations
the peak demand for light occurs at different times. In
maize + green grams intercropping system, green gram
flowers in 35 days after sowing and is harvested 65
days after sowing, peak light demand for maize occurs
at 60 days after sowing when green gram is ready for1/28/2018 15

16.  The inclination of leaves greatly influences the
amount of light intercepted by the taller component
and the amount that is available to shorter
components. For example, one unit of LAI of
prostrate-leaved perennial rye grass (Trfolium
ripens) absorbed 50% of the incoming light where
as the some LAI of erect leaved perennial rye
grass (Lolium pereme) absorbed only 26%
(Breugham, 1958).
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17. 1/28/2018 17

18. Table1.Biological characters of maize in
monocropping and intercropping
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Maize+ Soybean
China Hanming et al,
2015

19.  Light interception in a sorghum (Sorghum bicolor)
based intercropping system was studied by Selvaraj
(1978).
 Light was measured in flux units from 45th-90th day
after sowing sorghum at 15 day interval.
 Light interception was expressed as percentages of
light on the top of the canopy of each crop.
 The red gram/sorghum intercropping system makes
better use of growth resources, particularly light, was
brought out by Willey et al. (1981).
 Under intercropping situations, the component crops
are grown in such a way that competition for light is
minimized (Okigbo, 1981); this can be achieved by
proper choice of crops and genotypes, the shorter
components being harvested sufficiently early so that
the later harvested component is not greatly affected.
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20.  Moisture and nutrients:
Competition for moisture and nutrients may result in
two types of effects on the less successful
components.
A) the roots to this component may grow less on the
sides towards plants of aggressive component.
B) plants affected by competition for soil factors may
have increased root/shoot ratio.
Among intercrops, sorghum and pearl millet are more
competitive in extracting nutrients. Generally the
intercrop stands remove greater amount of
nutrients than sole crop stands.
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21. Interactions on Insect pest
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22. Table 1. Seed yield of main crop and intercrops in
castor-based intercropping systems (kg ha-
1)
Tamil nadu Thanunathan et
al,2008
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23. 1/28/2018 23

24. Advantages of multi-storied cropping system
 Better use of growth resources including sunlight,
nutrient and water.
 Yield stability (suppress the growth of weeds).
 Ecological stability i.e. improved soil health and agro-
ecosystem. Flow of income during cropping periods.
 Other miscellaneous benefits like distribution of labour,
physical support of one crop to another and home
gardening leading to more food supply.
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25. Considering market price (per kg) of bitter gourd = Rs. 10, ridge gourd = Rs. 6,
bottle gourd = Rs. 5, Elephant foot yam = 15
Treatments
Yield (q/ha) Main Crop
Yield (q/ha) Companion
Crop
2014-15 2015-16 Mean 2014-15 2015-16 Mean
Sole Elephant Foot Yam
(cv. Gajendra)
373.55 378.60 376.07 - - - -
Elephant Foot Yam +
Bitter gourd
(cv. Hybrid US6214)
372.00 376.50 374.25 138.80 137.50 138.15
Elephant foot yam +
Ridge gourd
(cv. local)
362.00 362.65 362.32 147.30 147.97 147.64
Elephant foot yam +
Bottle gourd
(cv. Hybrid Mahima)
327.40 333.10 330.25 251.60 247.90 249.75
-
Table 2: Yield of elephant foot yam and companion crops under multi-
layer vegetable cropping system

26. NET INCOME
TOTAL
EFY 554000 --164765 389235
EFY+BITTERGAURD 699000 --(164765+28000) 506235
EFY+RIDGEGAURD 631200 --(164765+28000) 438435
EFY+BOTTLEGAURD 619500 --(164765+28000) 426735

27. Mechanism of yield advantage in intercropping
The most important index of biological advantage is the
 Relative yield total (RYT) : De wit and Land van Den Bergh (1965).
 Land equivalent ratio by Willey (1979).
 The mixture yield of a component crop expressed as a portion of
its yields as a sole crop from the same replacement series is the
relative yields of the crop and sum of relative yields of component
crop is called Relative yield total ( RYT).
 The total land area required under sole cropping to give the same
yields obtained in the intercropping is called Land equivalent ratio
(LER). Both the expressions (RYT and LER) are similar.
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28. Land Equivalent Ratio (LER)
 This is the most frequently used efficient indicator. LER
can be defined as the relative land area under sole crop
that would be required to produce the equivalent yield
under a mixed or an intercropping system at the same
level of management.
Where,
La and Lb are LER of crop a and crop b, respectively;
Yab = yield of crop an in intercropping,
Yba = yield of crop b in intercropping,
Yaa = yield of crop an in pure stand and
Ybb = yield of crop b in pure stand.
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29. 1/28/2018 29

30. Example: Let the yields of groundnut and red gram grown,
as pure crops are 1,200 and 1,000 kg/ha, respectively.
Let yields of these cops when grown, as intercrop be
1,000 and 600 kg/ha, respectively. The land equivalent
ratio of groundnut + red gram intercropping system is
LER of 1.43 indicates that a 43 percent yields advantage is
obtained when grown as intercrop compared to
growing as sole crops. In other words the sole crops
have to be grown in 1.43 ha to get the same yields level
that is obtained from 1.00 ha of intercropping.
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31. Relative Yields Total (RYT)
 The mixture yields of a component crop expressed as a
portion of its yields as a sole crop from the same
replacement series is the relative yield of crop and sum
of the relative yields of component crop is called
Relative Yields Total (RYT).
 Where ,
Yaa = yields of component a as sole crop
Ybb = yields of component b is a sole crop
Yab = yields of component a as intercrop in b
Yba = Yield of component b as intercrop in a.
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32. Example: in pasture mixture, Stylo and anjan grown in 1:1 ratio
with 50% sole crop population of both crops.
In I/C, mixture yield (50%) for Stylo and anjan is 6 and 4 tons/ha
of fodder, respectively.
The yield of these crops in sole stand with 100% plant
population is 10 and 8 tons/ ha of green fodder, respectively.
RYT = 12+8/10+8 = 20/18 = 1.11.
So RYT 1.11 indicates 11% extra fodder yields obtained by
mixture.
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33. Relative Crowding Coefficient (K or RCC)
 It is proposed by de Wit (1960).
 It is used in replacement series of intercropping. It
indicates whether a species or crop when grown in
mixed population has produced more or less yield
than expected in pure stand. In 50 : 50 mixture
Relative crowding coefficient can be defined as
 But when population differ from 50: 50 then,
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34. Where, K = coefficient of each crop species
 Yaa = Yield of pure stand of a
 Ybb = Yield of pure stand of b
 Yab = Mixture yield of a in combination with b
 Yba = Mixture yield of b in combination with a
 Zab = Sown proportion of a in mixture with b
 Zba = Sown proportion of b in mixture with a
 Kab = Values indicate the following
conclusions:
 K>1 = there is yield disadvantage
 K= 1 = there is no difference
 K< 1 = there is yield advantage in mixing
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35.  Crowding coefficient and LER give the yield
advantage but only LER give the magnitude of
advantage.
 Therefore LER is preferred to assess the
competition effects and yield advantage in
intercropping situations.
 The two main indices of dominance are the
aggressivity and competition index.
 Aggressivity is proposed by Mc Gihrist (1965). It
gives a simple measure of how much the relative
yield increase in species A is greater than that for
species B. It is an index of dominance.
 An aggressivity value Zero indicates that the
component species are equally competitive.
 A positive sign indicates the dominant species and1/28/2018 35

36.  competition index:
 It is proposed by Donald (1963).
 The basic process in the competition index is
the calculation of two equivalence factors.
 one each component species. It is the product
of two equivalent factors, one for each
component species. It is a measure to find out
the yield of various crops when grown together
as well as separately.
 It indicates the yield per plant of different crops
in mixture and their respective pure stand on
an unit area basis. If the yield of any crop
grown together is less than its respective yield
in pure stand then it is harmful association but
an increased yield means positive benefit.
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37. 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.
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38. 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 pulses
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40. Annidation 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.
 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
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41. 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.
 The taller component acts as wind barrier protecting
the short crop.
Eg. maize+ groundnut, onion + castor, turmeric + castor
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42. Overall Effects of Competition
 Three broad categories of competition can be
recognized:
1. Actual yield of each species is less than
expected. This is called mutual inhibition.
This is rare.
2. The yield of each species is greater than
expected. This is called mutual co-operation.
This cannot unusual.
3. One species yield is less and the other is
more than expected. This can be termed
compensation
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43. 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.
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
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44. 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 allelopathy:
Toxic substances may be converted into active
substances by some micro- organisms
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46.  Allelochemical produced from the leaves of
Eucalyptus globules drastically reduced the
germination of mustard (Brassica spp.) seed
sown underneath (Trenbath, 1976).
 Many plants exude organic substances from
their roots and some of these roots exudates
act as allelochemicals inhibiting the growth of
the neighboring species.
 Living roots of walnut (Juggles nigra),
cucumber (Curcumas sativa) and peach
(Prunes persia) are known to exude toxic
substances which inhibit the growth of the
plants growing near them.
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