Effect of intercropping (sorghum/cowpea), Bradyrhizobium, Nitrogen and Phosphorus fertilizers on Growth of Cowpea under rainfed conditions

Ekhlas Mohamedzein Musa Mohamedzein¹

Faculty of Agriculture, University of Sinnar, Sudan.

HNSJ, 2022, 3(6); https://doi.org/10.53796/hnsj3612

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Published at 01/06/2022 Accepted at 05/05/2022

Abstract

Afield experiment was carried out at the experimental field of Faculty of Agriculture (Abu Naama) – University of Sinnar for two successive seasons to study the effect of intercropping, Bradyrhizobium, N and P fertilizers on growth of cowpea. The experimental layout was arranged in split- split plot design with six replicates. Parameters studied are nodule numbers, nodules dry weight, plant height and shoot and root dry weight. The results showed that intercropping significantly increased number and dry weight of nodules; Bradyrhizobium inoculation, N and P fertilizers significantly increased number and dry weight of nodules, plant height, shoot and root dry weight in two seasons compared with the control.

Key Words: Bradyrhizobium; Nitrogen; Phosphorus; intercropping;, cowpea; rainfed.

عنوان البحث

تأثير الزراعة البينية والتلقيح ببكتيريا العقد الجذرية (Bradyrhizoium) والتسميد النتروجيني والفسفوري علي نمو اللوبيا حلو

اخلاص محمد زين موسى محمد زين¹

¹ كلية الزراعة، جامعة سنار، السودان.

HNSJ, 2022, 3(6); https://doi.org/10.53796/hnsj3612

تاريخ النشر: 01/06/2022م تاريخ القبول: 17/05/2022م

المستخلص

أجريت تجربة حقلية بالمزرعة التجريبية لكلية الزراعة (أبونعامة) – جامعة سنار لموسميين متتالين لدراسة تأثير الزراعة البينية والتلقيح ببكتيريا العقد الجذرية (Bradyrhizoium) والتسميد النتروجيني والفسفوري علي نمو اللوبيا حلو. أظهرت نتائج الدراسة أن الزراعة البينية أدت إلي زيادة معنوية في عدد العقد الجذرية ووزنها الجاف في الموسمين، كما أن التلقيح ببكتيريا العقد الجذرية (Bradyrhizoium) والتسميد النتروجيني والفسفوري أدي إلي زيادة معنوية في عدد العقد الجذرية ووزنها الجاف وطول النبات والوزن الجاف للساق والجذور في الموسمين مقارنة بالشاهد.

Introduction

Intercropping legumes and non legumes is an agriculture practice of cultivating two or more crops on the same place of land at the same time. It is commonly practiced in many parts of the world in order to increase the productivity per unit area of the land (Bhupinder et al., 2003).

Cowpea (Vigna unguiculata L. Walps) is an important grain legume throughout the tropics and subtropics, covering Africa, Asia and Central and South America. It provides a cheap source of plant protein for the poor people in the third world. In Sudan cowpea is grown widely as a subsistence crop in Kordofan, Darfur and Central and Southern regions as a rainfed crop. In addition to the value of cowpea, as a leguminous plant, that can fixing atmospheric nitrogen and improving soil nitrogen, cowpea is also drought and shade tolerant, therefore, it compatible as an intercrop with many crops (IITA, 1997).

The inoculation the inoculums to the seedling) enhance nodule numbers, their effectiveness, the growth and yield of soybean (Salih, 2002), hyacinth bean (Obied, 2003), fenugreek (Abdelgani, 1997) and groundnut (Mohamedzein, 1996).

Application of nitrogen fertilizer as a starter dose enhanced the nodulation then the growth and yield of legumes (Abu Naib, 1982; Mahdi et al., 1983; Karrar, 1984), also phosphate is known to improve rhizobial growth and vigor resulting in greater colonization, root infection and nodulation (Mahdi and Mustafa, 2005). The main objective of this study is to determine the effect of inoculation with Bradyrhizobium strain, intercropping, nitrogen of legumes by locally or introduced Bradyrhizobium or Rhizobium strains (either by dressing the seeds at sowing or by adding

and phosphorus fertilizers on growth of cowpea under rainfed conditions.

Materials and Methods:

Afield experiment was carried out at the experimental field of Faculty of Agriculture (Abu Naama)- University of Sinnar (Latitude 12◦ 44 N and Longitude 34◦ 7 E) for two successive seasons (2014and 2015). The soil of the experimental site is characterized by 11.5% sand, 19.6% silt. 68.9% clay, pH=8.1, Ece= 0.9, N= 0.06% and P=5.3%.

Sorghum (Sorghum biocolor L. Monech) seed of variety tabat were obtained from the Sudanese Arabian company, cowpea (Vigna unguiculata L. Walps) seeds were obtained from the local market of Abu Naama, and Bradyrhizobium strain was obtained from Environment and Natural Resources Research Institute, National Centre for Research.

The experimental site was prepared by ploughing, harrowing, then leveling and ridging. The land was divided into plots, each of 4X6 m, 70 cm between ridges, and six north- south ridges per plot. P and N fertilizers were added at sowing. The experiment was arranged in split split plot design with six replicates. The following treatments were assigned to main plots:

1- Uninoculated (Control)

2- Inoculated with Bradyrhizobium strain.

The following cropping systems were assigned to the sub plots:

1- Cowpea (monocropping system)

2- Cowpea/sorghum (intercropping system)

3- Sorghum (monocropping system)

The following fertilizers were assigned to the sub sub plots:

1- No fertilizers (control)

2- 20 Kg N/ha

3- 50 Kg P/ha

At sowing seeds of cowpea were wetted using 40% gum Arabic solution and mixed thoroughly with the charcoal based inoculums of Bradyrhizobium, inoculated seeds were left to dry for few minutes in shade. Five seeds of inoculated or uninoculated cowpea in conjunction with sorghum were sown by hand on the ridges in holes 30 cm apart, which were later thinned to three plants per hole for both crops. The crops were grown in alternate, single rows. The plots were irrigated immediately after sowing. There after rainfall was the main source of irrigation.

Three samples from each plot were taken at 4, 6, 8 and 10 weeks after sowing. The parameters which were measured are nodules number, plant height, dry weight of nodules, shoot and root (determined after drying in an oven at 70°C for 48 hours).

Each sample was analyzed in triplicate. The data were subjected to analysis of variance and means were separated by the Duncan´s multiple range test with probability of P≤ 0.05.

Results:

Nodules number, nodules dry weight and plant height of cowpea significantly (p≤0.05) increases by Bradyrhizobium inoculation and intercropping compared to control in two seasons, also significantly (p≤0.05) increased by application of nitrogen or phosphorus fertilizers compared with control or with Bradyrhizobium inoculation alone in two seasons (Tables 1 &2; 3&4 and 5&6).

Shoot dry weight and root dry weight significantly (p≤0.05) increased by Bradyrhizobium inoculation, nitrogen and phosphorus fertilizers compared with control (Tables 7&8 and 9&10).

Table 1: Effect of intercropping (sorghum/cowpea), inoculation, N and P on nodules number of cowpea (nodule/plant) in season 2014

Treatment Time (weeks after sowing)

4 6 8 10

Monocropping system

Control 10.6^a 14.3^a 21.7^a 11.5^a

20 Kg N/ha 21.7^b 30.8^c 48.7^cd 20.7^c

50 Kg P/ha 20.8 ^b 31.1^cd 49.2^cd 21.2 ^c

TAL 169 21.3 ^b 30.6^c 45.3^cd 20.6 ^c

TAL 169+ 20 Kg N/ha 21.8 ^b 33.7^cde 52.3^de 21.3 ^c

TAL 169+ 50 Kg P/ha 22.1 ^b 33.8^cde 54.0 ^de 21.0 ^c

Mean 19.7 29.1 45.2 19.3

Intercropping system

Control 11.2^a 17.8 ^b 27.2 ^b 16.1^b

20 Kg N/ha 21.4 ^b 31.0^cd 50.6^d 20.7 ^c

50 Kg P/ha 22.8 ^b 31.4^cd 51.8^cd 21.3 ^c

TAL 169 22.3 ^b 31.0^cd 47.8^cd 20.9 ^c

TAL 169+ 20 Kg N/ha 22.5 ^b 35.1^e 57.3^e 21.7 ^c

TAL 169+ 50 Kg P/ha 22.8 ^b 34.9^de 58.7 ^e 22.6 ^c

Mean 20.5 30.2 48.9 20.6

LSD (5%) treatments 2.6 3.2 4.1 3.1

LSD (5%) means 0.4 0.5 0.7 0.5

Table 2: Effect of intercropping (sorghum/cowpea), inoculation, N and P on nodules number of cowpea (nodule/plant) in season 2015

Treatment Time (weeks after sowing)

4 6 8 10

Monocropping system

Control 10.7^a 17.3^a 25.7^a 9.8 ^a

20 Kg N/ha 21.3^bc 31.3^c 40.2 ^b 17.8^bc

50 Kg P/ha 21.1^bc 31.6^cd 41.3^bc 19.4 ^c

TAL 169 19.7^b 30.1^cd 42.2^bc 19.4 ^c

TAL 169+ 20 Kg N/ha 21.7^bc 41.7^d 54.3 ^d 20.5 ^c

TAL 169+ 50 Kg P/ha 21.5^bc 41.2 ^d 49.0^cd 19.2 ^c

Mean 19.3 32.4 42.1 17.7

Intercropping system

Control 11.7 ^a 22.3 ^b 29.7 ^a 15.3 ^b

20 Kg N/ha 23.2 ^c 32.6^cd 40.3^bc 20.5 ^c

50 Kg P/ha 23.6^cd 32.7^cd 47.2^cd 20.7 ^c

TAL 169 22.3^bc 32.6^cd 45.5 ^c 20.1 ^c

TAL 169+ 20 Kg N/ha 29.4 ^d 43.2 ^d 53.8 ^d 21.1 ^c

TAL 169+ 50 Kg P/ha 28.3 ^d 43.4 ^d 54.7 ^d 20.8 ^c

Mean 23.1 34.5 45.2 19.8

LSD (5%) treatments 3.0 2.7 4.2 3.6

LSD (5%) means 0.5 0.5 0.7 0.6

Table 3: Effect of intercropping (sorghum/cowpea), inoculation, N and P on nodules dry weight of cowpea (g/plant) in season 2014

Treatment Time (weeks after sowing)

4 6 8 10

Monocropping system

Control 15.22^a 36.11^a 88.89^a 47.17^ab

20 Kg N/ha 66.67^ef 112.22^c 507.68^bc 97.11^c

50 Kg P/ha 62.61^e 148.89 ^d 570.22^c 108.33^cd

TAL 169 50.39^d 131.67^cd 491.06^bc 117.56^de

TAL 169+ 20 Kg N/ha 50.56^cd 316.50^h 707.10^d 193.28^f

TAL 169+ 50 Kg P/ha 99.39^g 340.00 ^h 746.11 ^d 238.55^g

Mean 57.47 180.90 518.51 133.67

Intercropping system

Control 22.28^ab 38.89^ab 155.22^ab 41.72 ^a

20 Kg N/ha 28.22^b 128.89^cd 414.00^b 75.06^b

50 Kg P/ha 71.67^ef 182.22 ^e 493.17^bc 85.72^bc

TAL 169 39.17^c 77.82 ^b 493.17^bc 115.61^d

TAL 169+ 20 Kg N/ha 46.94^cd 221.67^f 593.67^cd 122.22^de

TAL 169+ 50 Kg P/ha 85.56 ^f 246.06^g 617.89^cd 132.45^e

Mean 48.97 149.26 461.19 95.46

LSD (5%) treatments 8.70 23.92 87.12 14.37

LSD (5%) means 1.45 3.99 14.52 2.40

Table 4: Effect of intercropping (sorghum/cowpea), inoculation, N and P on nodules dry weight of cowpea (g/plant) in season 2015

Treatment Time (weeks after sowing)

4 6 8 10

Monocropping system

Control 21.36^a 14.56^a 127.05^a 57.21^a

20 Kg N/ha 53.69^cd 158.35^c 503.32^de 348.52^g

50 Kg P/ha 62.25^d 167.31^cd 593.60^e 117.60^bc

TAL 169 40.33^b 239.59^d 763.94^f 172.10^cd

TAL 169+ 20 Kg N/ha 76.74^e 337.48^e 684.32^f 299.79^f

TAL 169+ 50 Kg P/ha 104.37^f 368.00^f 648.36^ef 237.89^e

Mean 56.96 218.38 553.52 205.52

Intercropping system

Control 24.64^ab 44.00^a 268.33^b 69.55^ab

20 Kg N/ha 50.55^c 143.15^bc 386.19^cd 100.00^b

50 Kg P/ha 62.46^de 174.92^cd 437.45^cd 110.25^bc

TAL 169 40.95^bc 134.14^b 491.40^d 206.70^de

TAL 169+ 20 Kg N/ha 46.56^bc 179.96^cd 361.10^c 184.50^d

TAL 169+ 50 Kg P/ha 85.13^ef 240.09^de 543.17^de 150.15^c

Mean 47.55 151.21 455.57 136.86

LSD (5%) treatments 6.94 20.27 83.13 30.42

LSD (5%) means 1.16 3.38 13.86 5.07

Table 5: Effect of intercropping (sorghum/cowpea), inoculation, N and P on plant height of cowpea (cm/plant) in season 2014

Treatment Time (weeks after sowing)

4 6 8 10

Monocropping system

Control 21.28^a 35.88^a 53.72^a 90.93^a

20 Kg N/ha 27.06^bcd 49.17^bc 59.22^bc 105.67^b

50 Kg P/ha 28.38^bcd 52.14^bcde 70.00^d 121.95^d

TAL 169 25.75^b 50.64^bcd 68.00^cd 106.33^bc

TAL 169+ 20 Kg N/ha 28.09^bcd 52.08^bcde 59.22^bc 114.78^cd

TAL 169+ 50 Kg P/ha 29.92^bcd 55.83^d 78.89^e 124.72^d

Mean 29.92 49.29 65.03 110.73

Intercropping system

Control 26.70^bc 53.30^de 60.17^bc 98.06^ab

20 Kg N/ha 27.31^bcd 55.58^ef 59.00^b 111.28^bcd

50 Kg P/ha 30.53^cd 56.77^f 70.39^de 116.39^cd

TAL 169 27.42^bcd 48.55^b 54.84^ab 110.00^bcd

TAL 169+ 20 Kg N/ha 27.61^bcd 51.23^bcd 59.89^bc 115.06^cd

TAL 169+ 50 Kg P/ha 32.00^d 52.82^cde 67.47^c 124.11^d

Mean 28.59 53.05 61.21 112.48

LSD (5%) treatments 3.90 3.54 2.40 13.74

LSD (5%) means 0.65 0.59 3.40 2.29

Table 6: Effect of intercropping (sorghum/cowpea), inoculation, N and P on plant height of cowpea (cm/plant) in season 2015

Treatment Time (weeks after sowing)

4 6 8 10

Monocropping system

Control 22.56^a 37.00^a 62.25^a 95.89^a

20 Kg N/ha 24.17^ab 53.39^bcd 66.61^ab 112.84^bc

50 Kg P/ha 27.14^cd 56.00^bcde 90.45^cdef 128.61^cd

TAL 169 25.64^bc 55.67^bcd 82.94^cd 112.94^bc

TAL 169+ 20 Kg N/ha 27.08^cd 57.72^cde 94.55^defg 119.61^cd

TAL 169+ 50 Kg P/ha 30.38^e 63.06^d 105.28^g 131.39^d

Mean 26.24 53.81 84.18 116.88

Intercropping system

Control 23.30 ^a 47.83^bc 77.95^bc 103.33^ab

20 Kg N/ha 27.25^cd 59.00^de 86.72^cde 116.95^bcd

50 Kg P/ha 26.78^cd 68.67^e 97.50^defg 121.33^cd

TAL 169 23.55^a 47.22^b 94.44^defg 115.84^bcd

TAL 169+ 20 Kg N/ha 26.28^cd 54.89^bcd 101.71^efg 121.06^cd

TAL 169+ 50 Kg P/ha 27.83 ^d 63.28^de 103.72^fg 129.94^d

Mean 25.38 57.07 93.58 118.08

LSD (5%) treatments 1.80 8.90 13.78 15.82

LSD (5%) means 0.30 1.48 2.30 2.64

Table 7: Effect of intercropping (sorghum/cowpea), inoculation, N and P on shoot dry weight of cowpea (g/plant) in season 2014

Treatment Time (weeks after sowing)

4 6 8 10

Monocropping system

Control 1.28^a 5.78^a 9.08^a 29.09^a

20 Kg N/ha 1.63^bc 7.03^ab 12.61^ab 52.29^b

50 Kg P/ha 1.93^d 10.82^d 16.92^c 62.08^cd

TAL 169 1.34^ab 6.75^ab 14.09^bc 57.31^bc

TAL 169+ 20 Kg N/ha 1.73^bc 7.90^abc 15.47^bc 63.26^cd

TAL 169+ 50 Kg P/ha 1.61^b 9.60^cd 17.27^e 62.94^cd

Mean 1.59 7.98 14.24 54.49

Intercropping system

Control 1.34^ab 5.89^a 9.99^a 32.07^a

20 Kg N/ha 1.87^cd 6.12^ab 12.16^ab 64.32^d

50 Kg P/ha 1.95^d 7.27^abc 15.21^bc 65.01^d

TAL 169 1.40^ab 7.04^ab 14.05^abc 61.01^cd

TAL 169+ 20 Kg N/ha 1.85^cd 7.90^abc 16.32 ^c 66.03^d

TAL 169+ 50 Kg P/ha 1.86^cd 8.31^bc 17.20 ^c 66.25^d

Mean 1.17 7.17 14.15 59.11

LSD (5%) treatments 0.16 2.04 3.20 6.16

LSD (5%) means 0.03 0.34 0.53 1.03

Table 8: Effect of intercropping (sorghum/cowpea), inoculation, N and P on shoot dry weight of cowpea (nodule/plant) in season 2015

Treatment Time (weeks after sowing)

4 6 8 10

Monocropping system

Control 1.44^a 5.67^ab 8.36^a 30.07^a

20 Kg N/ha 2.10^b 6.35^abc 9.19^b 57.31^bcd

50 Kg P/ha 2.94^cd 9.95^d 9.55^bcd 67.00^d

TAL 169 2.50^bc 5.74^abc 9.57^bcd 52.41^bc

TAL 169+ 20 Kg N/ha 2.88^cd 7.47^bcd 9.98^de 66.36^d

TAL 169+ 50 Kg P/ha 3.12^cd 8.73^cd 10.16^e 66.11^d

Mean 2.49 7.32 9.47 57.21

Intercropping system

Control 1.58^ab 4.30^abc 8.56^a 38.70^a

20 Kg N/ha 2.33^bc 5.09^ab 9.40^bc 54.08^bcd

50 Kg P/ha 2.40^bc 6.09^abc 9.75^cde 57.18^bcd

TAL 169 2.57^bc 4.01^a 9.80^cde 51.11^b

TAL 169+ 20 Kg N/ha 3.27^d 4.93^abc 10.12^e 62.70^bcd

TAL 169+ 50 Kg P/ha 3.52^e 5.93^abc 10.19^e 63.02^cd

Mean 2.61 5.06 9.64 54.46

LSD (5%) treatments 0.56 2.38 0.42 10.30

LSD (5%) means 0.09 0.40 0.07 1.72

Table 9: Effect of intercropping (sorghum/cowpea), inoculation, N and P on root dry weight of cowpea (g/plant) in season 2014

Treatment Time (weeks after sowing)

4 6 8 10

Monocropping system

Control 0.23^a 0.93^a 1.16^a 2.44^a

20 Kg N/ha 0.33^cde 1.10^abc 1.87^bcd 3.95^b

50 Kg P/ha 0.34^de 1.39^de 2.01^bcde 4.03^b

TAL 169 0.26^ab 1.20^bcde 1.74^bc 3.81^b

TAL 169+ 20 Kg N/ha 0.32^cde 1.27^bcde 1.94^bcd 3.84^b

TAL 169+ 50 Kg P/ha 0.31^cd 1.32^cde 2.08^bcd 3.90^b

Mean 0.30 1.20 1.80 3.66^b

Intercropping system

Control 0.25^ab 0.94^ab 1.69^b 2.68^a

20 Kg N/ha 0.31^cd 1.04^ab 1.89^bcd 3.82^b

50 Kg P/ha 0.35^e 1.12^abcd 1.95^bcd 3.76^b

TAL 169 0.27^b 1.19^bcde 1.84^bcd 3.70^b

TAL 169+ 20 Kg N/ha 0.30^bc 1.33^cde 2.12^cd 3.88^b

TAL 169+ 50 Kg P/ha 0.34^de 1.46 ^e 2.21^d 3.92^b

Mean 0.30 1.18 1.95 3.63

LSD (5%) treatments 0.04 0.22 0.30 0.44

LSD (5%) means 0.01 0.04 0.05 0.07

Table 10: Effect of intercropping (sorghum/cowpea), inoculation, N and P on root dry weight of cowpea (nodule/plant) in season 2015

Treatment Time (weeks after sowing)

4 6 8 10

Monocropping system

Control 0.40^a 0.98^a 1.57^a 2.57^a

20 Kg N/ha 0.60^bc 1.15^abc 1.69^ab 4.00^b

50 Kg P/ha 0.74^c 1.45^de 2.13^abcd 4.08^b

TAL 169 0.60^bc 1.25^bcde 2.23^cd 3.86^b

TAL 169+ 20 Kg N/ha 0.59^bc 1.33^bcde 2.40^cd 3.90^b

TAL 169+ 50 Kg P/ha 0.69^bc 1.37^cde 2.41^cd 3.95^b

Mean 0.60^bc 1.26 2.07 3.95

Intercropping system

Control 0.56^abc 0.99^a 1.59^a 2.73^a

20 Kg N/ha 0.57^bc 1.09^ab 1.81^abc 3.87^b

50 Kg P/ha 0.66^bc 1.16^abcd 2.21^bcd 3.81^b

TAL 169 0.55^ab 1.24^bcde 2.32^cd 3.75^b

TAL 169+ 20 Kg N/ha 0.59^bc 1.38^cde 2.41^cd 3.95^b

TAL 169+ 50 Kg P/ha 0.66^bc 1.50^e 2.62^d 3.97^b

Mean 0.60 1.23 2.16 3.68

LSD (5%) treatments 0.16 0.22 0.56 0.44

LSD (5%) means 0.03 0.04 0.09 0.07

Discussion:

Nodules number of cowpea significantly increased by Bradyrhizobium inoculation (Pahwa and Yadava, 2002; Kishan et al., 2001; Fenning and Danso, 2001), by Bradyrhizobium inoculation and starter dose of nitrogen (Babo and Mishra, 2001) and by Bradyrhizobium inoculation and phosphorus fertilizer application (Mand et al., 1991).

The increment of nodules dry weight by Bradyrhizobium inoculation was reported for soybean and hyacinth bean (Obied, 2003), soybean (Salih, 2002), faba bean (Ahmed, 2000) and fenugreek (Abdelgani, 1997), and by Bradyrhizobium inoculation and application of nitrogen and phosphorus fertilizers for groundnut (Mohamedzein, 1996).

The increment of nodules number and nodules dry weight by intercropping may be due to execration of organic compounds by companion cereals e.g. carbohydrates needed by bacteria.

The increment of plant height, shoot dry weight and root dry weight by Bradyrhizobium inoculation were for soybean and hyacinth bean (Obied, 2003), soybean (Salih,2002), by Bradyrhizobium inoculation nitrogen and phosphorus fertilizers for cowpea (Babo and Mishra, 2001), for groundnut (Mohamedzein, 1996).

Inoculation, nitrogen and phosphorus fertilizers increased the fixation, which in turn enhances growth and consequently plant height, shoot dry weight and root dry weight of cowpea.

References:

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Abu Naib, S.A. (1982). Studies on root nodule bacteria of some leguminous plants and inoculums production in the Sudan. M. Sc. (Agric.) Thesis, University of Khartoum.

Ahmed, T.H.M. (2000). Effect of fungicides and Rhizobium inoculation on symbiotic properties, yield and seed quality of faba bean. Ph. D. (Agric.) Thesis, University of Khartoum.

Babo, R. and Mishra, S.K. (2001). Growth and pod production of cowpea (Vigna sinensis Savi) as affected by inoculation, nitrogen and phosphorus. Annals of Agricultural Research, 21 (1): 104-106.

Bhupinder, S.; Kalidindi, U.; Singh,B. and Usha, K. (2003). Nodulation and symbiotic nitrogen fixation of cowpea genotypes as affected by fertilizer nitrogen. Journal of plant Nutrition, 26 (2): 463-473.

Fenning, J.O. and Danso, S.K.A. (2001). Response of cowpea to inoculation with indigenous Bradyrhizobium strains. Tropical Science, 41 (4): 172-176.

IITA, (1997). International Institute of Tropical Agriculture. Ibadan, Nigeria. Annual report.

Karrar, K.I.M. (1984). Studies on grain legume responses to Rhizobium inoculation in Khartoum Province and Toker Delta. M. Sc. (Agric.) Thesis, University of Khartoum.

Kishan, S.; Rathore, S.V.S.; Ganeshamurthy, A.N.; Singh, D.R. and Swaroop, K. (2001). A study on pod, shoot, yield and dry matter production of vegetable cowpea (Vigna unguiculata Walp.) as affected by phosphorus, potash and Rhizobium. Vegetable Science, 28 (2): 190-191.

Mahdi, A.A.; Mukhtar, N.O. and Mohamed, G.E. (1983). Microbiology research in Sudan. pp. 101-104. In Faba Bean in the Nile Valley. Saxena. M.C. and Stewart.

Mahdi, A.A. and Mustafa, E.M.A. (2005). Response of Guar to Bradyrhizobium inoculation and to nitrogen and phosphate fertilization. University of Khartoum, Journal of Agricultural Sciences, 13 (1): 97-110.

Mand, S.; Dahiya, B.N. and Lakshminarayana, K. (1991). Nodulation, nitrogen fixation and biomass yield by slow and fast growing cowpea rhizobial in guar under different environments. Annals of Biology, 7 (1): 31-37.

Mohammedzein, E.M.M. (1996). Effects of Bradyrhizobium and Vesicular Arbuscular Mycorrhizal (VAM) inoculation on symbiotic properties, yield and seed quality of groundnut. M. Sc. (Agric.) Thesis, University of Khartoum.

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