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Forage yields in the intercrops of pea with other cool season
annual legumes
Krstic, D.1, Mikic, A.2,
Cupina, B.1, Antanasovic, S.1,
Mihailovic, V.2, Eric, P.1 and Pejic, B.
University of Novi Sad, Faculty of Agriculture, Novi Sad, Serbia
2Institute of Field and Vegetable Crops, Novi Sad, Serbia
Introduction
Pea (Pisumsativum L.) is an economically important plant species worldwide, especially in temperate
regions. It is used in both human diets and animal feeding in the form of green forage, forage dry matter,
forage meal, silage, haylage, immature pods, immature grains, mature grains and straw (1) and also plays a
significant agronomic role through green manure and mulch. Pea is traditionally intercropped with
cereals in many regions of Europe and the world, but also as a companion crop in establishing a perennial
forage crop such as red clover (Trifolium pratense L.), alfalfa (Medicago sativa L.) or sainfoin (Onobrychis
viciifolia Scop.), where it acts as a bioherbicide (2).
Today, pea is one of the most important annual forage legumes in Serbia and other Balkan and South East
European countries. Recently, attempts have been made in Serbia to re-introduce neglected and
underutilized annual legume crops such as faba bean (Viciafaba L.) (3), grass pea (Lathyrus sativus L.) (4),
lentil (Lens culinaris Medik.) and bitter vetch (Vicia ervilia (L.) Willd.), as well as to introduce novel annual
legume crops such as white lupin (Lupinus albus L.) (5), that could serve as supplements in providing
animal husbandry with quality plant protein.
The aim of this study was to assess the possibility of
intercropping pea with other temperate annual legumes for
forage production.
Materials and methods
A small-plot trial was carried out during two pea growing
seasons, from the fall 2009 to the spring 2011 on a chernozem
soil at the Experimental Field of the Institute of Field and
Vegetable Crops at Rimski Sancevi near Novi Sad. Treatments
comprised several intercrop combinations of pea with other
cool season annual legumes, as well as the intercrop of pea
with contrasting leaf morphology. All treatments were
designed according to the four basic principles of the mutual
annual legume intercropping (6): 1) same time of sowing; 2)
similar growth habit; 3) similar cutting time; and 4)
combinations of crops with good standing ability (supporting
crop) with others that are susceptible to lodging (supported
crop). Seven treatments involving pea were included in the
trials: 1) fall-sown forage pea + faba bean, 2) fall-sown semi-
leafless dry pea + normal-leafed dry pea, 3) fall-sown semi-
leafless dry pea + bitter vetch, 4) spring-sown forage pea +
faba bean, 5) spring-sown forage pea + white lupin, 6) spring-
sown semi-leafless dry pea + normal-leafed dry pea and 7)
spring-sown semi-leafless dry pea + lentil (Figure 1). Each
component of the treatments was also included in the trial as
a pure stand.
Figure 1. Intercrops involving pea and other cool season
annual legumes 2010 and 2011 at Rimski Sancevi: (fall-
sowing) forage pea + faba bean (firstrow, left), semi-
leafless drypea + normal-leafed drypea (firstrow, righ t)
semi-leafless dry pea + bitter vetch (second row),
(spring-sown) forage pea + faba bean (third row, left),
forage pea + white lupin (third row, right), semi-leafless
drypea + normal-leafed drypea (fourth row, left) and
semi-leafless drypea + lentil (fourth row, right).
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All fall intercrops and sole crops were sown on 8 October 2009 and 15 October 2010, while all spring
intercrops were sown on 2 March 2010 and 6 March 2011. Plot size was 5 m2 and the experimental design
was a split-plot with three replicates. The seeding rates in sole crops were 75 viable seeds m-2 for fall- and
spring-sown faba bean and white lupin, 120 viable seeds m-2 for fall- and spring-sown forage and dry pea
and 180 viable seeds m-2 for bitter vetch and lentil. In all the intercrops, the seeding rates of each
component in its sole crop were reduced by 50%. No rhizobia or inorganic fertilizers were added and no
weed control was done. All the plots with sole crops were cut at the full bloom or early pod stage, while
the intercrops were cut when the first intercrop component reached the full bloom or early pod stage.
The green forage yield in all intercrops was measured immediately after cutting. The forage dry matter
yield in each was determined on the basis of forage dry matter proportion in the green forage samples
taken after the cutting and dried until constant mass at a room temperature. The reliability of green
forage yield in each intercrop was determined by calculating its Land Equivalent Ratio (LERGFY) as (6):
LERGFY = GFY(sg)ic / GFY(sg)sc + GFY(sd)K / GFY(sd)sc,
where GFY(sg)IC is the green forage yield of the supporting component in the intercrop, GFY(sg)SC is the
green forage yield of the supporting component in its sole crop, GFY(sd)IC is the green forage yield of the
supported component in the intercrop and GFY(sd)SC is the green forage yield of the supported
component in its sole crop. In an analogous way, the LER for forage dry matter yield (LERFDMY) was
calculated.
The results were analyzed using Statistica 8.0 software. Analysis of variance (ANOVA) was performed
and means were separated using Fisher's Least Significant Difference (LSD) test at P = 0.05.
Results and discussion
The seedling emergence in all the treatments was regular and provided the projected stand density.
Average green forage yields in the pure stands of fall-sown forage pea (46.1 t ha-1) and spring-sown faba
bean (45.6 t ha-1) were significantly higher compared to the other treatments, especially the spring-sown
normal leaf dry pea (27.9 t ha-1) and lentil (23.3 t ha-1) (Table 1). Among the fall-sown treatments, the
Table 1. A verage values ofggreen forage yield (t ha-1) and its Land Equivalent Ratio (LERGFY) in the intercrops
of pea with other cool season annual legumes for 2010 and 2011 at Rimski Sancevi_
Season
Treatment
Green forage yield
LERGFY
Supporting
crop
Supported
crop
Total
Fall
Faba bean
38.3
-
38.3
1.00
Fall
Forage pea
-
46.1
46.1
1.00
Fall
Faba bean + forage pea
16.5
32.0
48.5
1.12
Fall
Semi-leafless dry pea
33.5
-
33.5
1.00
Fall
Normal-leafed dry pea
-
29.6
29.6
1.00
Fall
Bitter vetch
-
35.6
35.6
1.00
Fall
Semi-leafless dry pea + normal-leafed dry pea
22.1
17.9
40.0
1.26
Fall
Semi-leafless dry pea + bitter vetch
24.1
22.5
46.6
1.35
Spring
Faba bean
45.6
-
45.6
1.00
Spring
White lupin
41.2
-
41.2
1.00
Spring
Forage pea
-
39.2
39.2
1.00
Spring
Faba bean + forage pea
19.2
23.4
42.6
1.02
Spring
White lupin + forage pea
17.3
26.9
44.2
1.11
Spring
Semi-leafless dry pea dry pea
30.1
-
30.1
1.00
Spring
Normal-leafed dry pea
-
27.9
27.9
1.00
Spring
Lentil
-
23.3
23.3
1.00
Spring
Semi-leafless dry pea + normal-leafed dry pea
17.4
15.6
33.0
1.14
Spring
Semi-leafless dry pea + lentil
19.5
14.8
34.3
1.28
LSD0.05
4.1
0.10
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average two-year green forage yield ranged from 40.0 t ha-1 in the intercrop of semi-leafless and normal-
leafed peas to 48.5 t ha-1 in the intercrop of faba bean and forage pea. In the spring-sown treatments, the
highest green forage yield was in the intercrop of white lupin and forage pea (44.2 t ha-1), while the
lowest green forage yield was in the intercrop of semi-leafless and normal-leafed peas (33.0 t ha-1).
The intercrops of semi-leafless pea, both fall-sown and spring-sown, had significantly higher two-year
average values than all other intercrops, especially 1.35 in the intercrop with bitter vetch and 1.28 in the
intercrop with lentil. In comparison to some other cool season annual legumes that also may play the role
of supported crop, such as grass pea, spring-sown forage pea had higher forage yields in the intercrops
with faba bean and white lupin, as well as much lower values of LERGFY when intercropped with both
(7).
Overall, the two-year average forage dry matter yield (Table 2) followed the same trend as the green
forage matter yield. Among the sole crop treatments, the average green forage yields in spring-sown faba
bean (13.2 t ha-1) were significantly higher compared to the other treatments, especially lentil (5.6 t ha-1).
In the fall-sown intercrops, the average two-year green forage yield ranged from 9.8 t ha-1 in the intercrop
of semi-leafless and normal-leafed peas to 12.5 t ha-1 in the intercrop of faba bean and forage pea. Among
the spring-sown intercrops, the intercrops of forage pea with faba bean and white lupin produced the
highest green forage yield (both 11.0 t ha- ), while the intercrop of semi-leafless and normal-leafed peas
produced the lowest green forage yield (7.7 t ha-1).
Table 2. Average values of forage dry matter yield (t ha-1) and its Land Equivalent Ratio (LERPDMY) in the intercrop of pea
with other cool season annual legumes for 2010 and 2011 at Rimski Sancevi._
Season
Treatment
Forage dry matter yield
LERFDMY
Supporting
crop
Supported
crop
Total
Fall
Faba bean
11.1
-
11.1
1.00
Fall
Forage pea
-
11.3
11.3
1.00
Fall
Faba bean + forage pea
4.6
7.8
12.5
1.11
Fall
Semi-leafless dry pea
8.5
-
8.5
1.00
Fall
Normal-leafed dry pea
-
7.3
7.3
1.00
Fall
Bitter vetch
-
8.9
8.9
1.00
Fall
Semi-leafless dry pea + normal-leafed dry pea
5.4
4.4
9.8
1.24
Fall
Semi-leafless dry pea + bitter vetch
5.9
5.6
11.5
1.32
Spring
Faba bean
13.2
-
13.2
1.00
Spring
White lupin
11.5
-
11.5
1.00
Spring
Forage pea
-
9.4
9.4
1.00
Spring
Faba bean + forage pea
5.4
5.6
11.0
1.00
Spring
White lupin + forage pea
4.5
6.5
11.0
1.08
Spring
Semi-leafless dry pea dry pea
7.2
-
7.2
1.00
Spring
Normal-leafed dry pea
-
6.6
6.6
1.00
Spring
Lentil
-
5.6
5.6
1.00
Spring
Semi-leafless dry pea + normal-leafed dry pea
4.0
3.7
7.7
1.11
Spring
Semi-leafless dry pea + lentil
4.5
3.6
8.0
1.26
LSD0.05
0.8
0.11
The intercrops of semi-leafless pea, both fall-sown and spring-sown, had significantly greater two-year
average values compared to the other intercrops, namely 1.32 in the intercrop with bitter vetch and 1.26
in the intercrop with lentil. In comparison to the results of other trials with mutual annual legume
intercrops, such as those including warm-season legumes such as soybean (Glycinemax (L.) Merr.) and
few Vigna species, the intercrops of pea with other cool season annual legumes had higher values of
LERFDMY (8).
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Conclusions
Depending on individual cases, intercropping various types of pea, such as forage pea and dry pea with
afila and normal leaves, with other cool season annual legumes may lead to higher forage yields and an
economical justification by high LER values and better utilization of natural resources. In comparison to
the traditional intercropping pea and other annual legumes with cereals for forage production, the
mutual intercropping of annual forage legumes provides farmers with high quality forage richer in
protein. Further research on the same subject will focus on forage quality aspects, such as the crude
protein and crude fiber content in forage dry matter and other less examined issues such as forage yield
components and crop physiology.
Acknowledgements
This research is a part of the project TR-31016 of the Ministry of Education and Science of the Republic of
Serbia.
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