Variability in plant – microbe interaction between
Lupinus
lines and
Bradyrhizobium
strains
Keith O. Robinson
a, Desta A. Beyene
b, Peter van Berkum
c, Regina Knight-Mason
a,
Harbans L. Bhardwaj
d,*
aDepartment of Life Sciences,Virginia State Uni6ersity,Petersburg,VA23806,USA
bUni
6ersity of Maryland,College Park,MD20742, USA
cUSDA-ARS,Belts
6ille Agricultural Research Center,Belts6ille,MD20705,USA
dAgricultural Research Station,Virginia State Uni
6ersity,PO Box9061,Petersburg,VA23806, USA
Received 13 March 2000; received in revised form 18 July 2000; accepted 19 July 2000
Abstract
Even though lupin (Lupinus albus L.) is known to potentially fix 150 – 200 kg/ha nitrogen for the use of a succeeding crop, precise information about lupin×Bradyrhizobiumstrain interaction under the climatic conditions prevalent in the mid-Atlantic region of the United States is unknown. We conducted two greenhouse experiments with the objective of characterizing this symbiotic relationship and to evaluate potential interaction between Bradyrhizobium strains and lupin lines. In the first experiment, performance of 60 bradyrhizobial strains was evaluated by inoculating three lupin cultivars and using combined score, which consisted of an arithmetic total of plant vigor, nodulation scores from crown root, nodulation scores from fibrous roots, shoot dry weight, and root dry weight. In the second experiment, performance of 80 lupin lines was evaluated by inoculating with three selectedBradyrhizobialstrains and using the combined score, which consisted of an arithmetic total of plant vigor, acetylene reduction activity, nodule number per plant, nodule weight per plant, and dry shoot weight. Significant variation existed for all traits in both experiments except for nodule number in the second experiment. Significant Bradyrhizobial strain by lupin line interaction existed for nodulation score, shoot and root dry weights, and the combined scores. Comparison of relative ranks indicated that nodulation effectiveness was dependent on specific strain and lupin line combinations. It was concluded that specific
Bradyrhizobialstrain and lupin line combinations would need to be identified for successful utilization of lupin’s capability to fix atmospheric nitrogen for use in low-input and sustainable agriculture. © 2000 Elsevier Science Ireland Ltd. All rights reserved.
Keywords:Nitrogen fixation; Legumes; Sustainable crop production
www.elsevier.com/locate/plantsci
1. Introduction
There is renewed interest in lupin (
Lupinus albus
L.) as a crop for use in sustainable and
environ-ment-friendly agriculture because of its high
po-tential for biological nitrogen fixation, which may
contribute 150 – 200 kg nitrogen per ha for use by
the succeeding crops [1 – 3] and its potential in
providing nutritious food and feed (32 – 38%
protein). The nitrogen-fixation potential of lupin
makes it suited ideally to low-input sustainable
and environment friendly agriculture because
min-eral nitrogen fertilizer may not be needed for crop
production. Lupin, being a legume, benefits
poten-tially from a nitrogen-fixing symbiosis with soil
bacteria. These soil bacteria belong usually to the
genus
Bradyrhizobium
[4,5].
Contribution of Virginia State University and US Department of Agriculture. Journal Article No. 219. The use of trade names or vendors does not imply approval to the exclusion of other products or vendors that may also be suitable.
* Corresponding author. Tel.: +1-804-5246723; fax: + 1-804-5245950.
E-mail address:[email protected] (H.L. Bhardwaj).
Several species of lupin have potential in
agri-culture and within each species there is significant
genetic diversity [6]. The different traits within
lupin have not been explored to identify cultivars
or lines, which are most suitable for crop
produc-tion in the mid-Atlantic region of the USA. The
identification of suitable cultivars and lines is
im-portant because the potential benefit from
nitro-gen fixation may be influenced by the plant
genotype and bradyrhizobial strain interaction [7].
Therefore, our objective was to evaluate the
inter-action between
Bradyrhizobium
strains and lupin
lines for nodulation and plant performance.
2. Material and methods
2.1.
Plant material
These studies were conducted with three
culti-vars (
L
.
albus
cv Lunoble,
Lupinus angustifolius
cv
Gungurru, and
Lupinus luteus
cv Juno) in the first
experiment and 80 lines of
L
.
albus
in the second
experiment (Table 4).
2.2.
Bradyrhizobial material
In the first experiment, we used 60 strains of
Bradyrhizobium
(Table 3) whereas the second
ex-periment was conducted
with three selected
bradyrhizobial strains (USDA 3044, 3051, and
4114). These strains were obtained from the
Na-tional
Rhizobium
Culture Collection, maintained
by US Department of Agriculture in Beltsville,
MD. The bradyrhizobial strains were grown in 10
ml modified arabinose-gluconate (MAG) broth [8]
at room temperature to a density of approximately
10
9cells per ml before they were used as liquid
inoculants at the time of sowing.
2.3.
Experimental conditions
[image:2.612.26.530.399.520.2]The first experiment was arranged as a factorial
design of the three lupin cultivars and the 60
bradyrhizobial strains and was conducted in a
greenhouse with supplemental lighting at the
Beltsville Agricultural Research Center, USDA,
Beltsville, MD. Lupin seeds were sterilized by
Table 1
Analysis of variance (mean squares) for lupin plant characteristics following inoculation of three lupin cultivars with 60
Bradyrhizobium lupinistrainsa
Source Plant vigor Nodulation score Dry weight Combined score
Crown Roots Shoot Root
0.91** 7.59** 3.31**
Strain (S) 0.52** 0.06 8.53**
22.20**
Cultivars (C) 6.71** 62.07** 11.68** 0.77** 153.59**
0.88**
S×C 0.22 1.03** 0.23* 0.05** 3.13*
2.26 0.03
0.18 0.55
Error 0.25 0.49
Mean 2.54 2.57 2.36 1.27 0.36 9.10
0.03 0.06 0.05 0.03
S.E. 0.01 0.09
a*, **, Significant at 5 and 1% levels, respectively. If the strain–line interaction was significant, the significance of strains and
cultivars was obtained by using strain–line interaction mean square as the error term.
Table 2
Analysis of variance for lupin plant characteristics following inoculation of 80 lupin lines with threeBradyrhizobiumstrainsa
Source of variation Acetylene reduction activity Plant vigor Nodule Plant weight Combined score
Number Weight
59.53* 0.60*** 24.59
Lines 0.001* 0.20*** 133.61**
248.98*** 1008.60***
Strains 3.09*** 159.22*** 0.003* 3.63***
90.77 0.10
0.001 19.49
Error 44.56 0.35
6.08 2.20 4.17 0.058 0.94 13.45
Mean
0.46 0.04 0.002 0.03 0.68
S.E. 0.04
[image:2.612.30.531.586.698.2]Table 3
Overall performance of 60 Bradyrhizobium strains, based on combined score, and relative rank when used to inoculate three selected lupin cultivarsa
Number Strain Combined scoreb
Gungurruc Junod Lunoblee Mean
8.1 (19) 11.2 (13)
1 USDA 3040 7.5 (58) 8.9
8.0 (20) 10.5 (26)
2 USDA 3041 8.2 (49) 8.9
8.4 (12) 9.6 (37)
USDA 3042 8.6 (44)
3 8.9
4 USDA 3043 7.3 (34) 8.6 (48) 8.5 (46) 8.1
11.1 (1) 12.8 (1)
USDA 3044 9.2 (29)
5 11.0
8.2 (15) 11.3 (10)
6 USDA 3045 10.9 (6) 10.1
9.2 (8) 11.2 (12)
USDA 3046 11.2 (2)
7 10.5
USDA 3047a
8 10.2 (4) 9.7 (35) 8.4 (47) 9.4
10.4 (2) 11.8 (6)
USDA 3048 9.3 (27)
9 10.5
USDA 3049
10 8.2 (16) 11.3 (11) 10.4 (12) 10.0
7.6 (26)
11 USDA 3051 11.6 (9) 11.1 (4) 10.1
6.8 (39) 8.0 (53)
USDA 3052 7.3 (59)
12 7.3
7.3 (35) 11.7 (7)
13 USDA 3053 9.5 (20) 9.5
5.5 (50) 5.9 (60)
USDA 3054 7.9 (55)
14 6.4
10.1 (5) 9.9 (30)
15 USDA 3054a 10.1 (15) 10.0
8.2 (17) 10.8 (20)
USDA 3055 10.6 (10)
16 9.9
7.1 (37) 8.6 (49)
17 USDA 3057a 8.7 (42) 8.1
9.6 (6) 11.6 (8)
USDA 3058 10.5 (11)
18 10.6
USDA 3059
19 6.4 (42) 12.6 (2) 9.7 (18) 9.6
6.1 (45) 12.2 (5)
USDA 3060 10.8 (8)
20 9.7
7.5 (30) 11.0 (18)
21 USDA 3061 9.5 (21) 9.3
5.9 (48) 8.1 (52)
USDA 3062 8.1 (50)
22 7.4
USDA 3063
23 5.4 (51) 9.9 (33) 7.6 (57) 7.6
5.7 (49) 9.9 (32)
USDA 3063a 8.0 (52)
24 7.9
USDA 3505
25 8.6 (11) 11.0 (16) 9.1 (33) 9.6
26 USDA 3510 9.3 (7) 10.5 (25) 8.6 (43) 9.5
– (.)f 9.9 (34)
USDA 3514 9.3 (28)
27 9.6
– (.)f 10.1 (29)
28 USDA 3644 9.1 (35) 9.6
7.9 (22) 11.0 (17)
USDA 3709 10.4 (13)
29 9.8
6.0 (47) 6.9 (59)
30 USDA 3710 7.9 (54) 6.9
7.8 (24) 9.9 (31)
USDA 3711 9.2 (31)
31 9.0
4.3 (52) 7.3 (57)
32 USDA 3712 8.1 (51) 6.6
– (.)f 9.4 (39)
USDA 3714 9.1 (36)
33 9.3
USDA 3926
34 8.0 (21) 9.0 (45) 7.9 (53) 8.3
6.1 (46) 7.7 (55)
USDA 3927 8.6 (45)
35 7.5
9.0 ( 9) 12.3 (3)
36 USDA 3928 10.3 (14) 10.5
– (.)f 12.3 (4)
USDA 3930 9.2 (30)
37 10.7
USDA 3931
38 7.5 (31) 8.8 (47) 8.8 (41) 8.4
– (.)f 9.1 (43)
USDA 3932 8.9 (40)
39 9.0
USDA 3935
40 7.6 (27) 6.9 (58) 6.1 (60) 6.9
USDA 3937
41 8.2 (18) 10.8 (21) 9.9 (17) 9.6
7.6 (28) 10.7 (23)
USDA 3943 9.1 (34)
42 9.1
7.6 (29) 10.2 (28)
43 USDA 4105 9.5 (23) 9.1
6.5 (41) 9.2 (42)
USDA 4106 8.4 (48)
44 8.0
USDA 4107
45 8.7 (10) 9.2 (41) 10.8 (9) 9.6
8.4 (13) 9.4 (38)
USDA 4108 9.5 (24)
46 9.1
USDA 4109
47 7.4 (33) 10.8 (22) 11.2 (3) 9.8
6.3 (43) 8.9 (46)
48 USDA 4110 9.7 (19) 8.3
7.5 (32) 11.1 (14)
USDA 4111 8.9 (38)
49 9.2
7.8 (25) 8.5 (50)
50 USDA 4112 9.2 (32) 8.5
7.3 (36) 9.7 (36)
USDA 4113 11.4 (1)
51 9.5
USDA 4114
52 – (.)f 11.1 (15) 9.0 (37) 10.5
6.2 (44) 10.6 (24)
USDA 4115 8.9 (39)
Table 3 (Continued)
Number Strain Combined scoreb
Gungurruc Junod Lunoblee Mean
54 USDA 4116 10.3 (3) 9.2 (40) 10.0 (16) 9.8
7.9 (23) 7.7 (54) 10.9 (7)
55 USDA 4117 8.8
– (.)f 9.1 (44)
USDA 4118 9.4 (25)
56 9.3
USDA 4119
57 – (.)f 7.6 (56) 11.0 (5) 9.5
8.3 (14) 8.4 (51)
58 USDA 4120 9.4 (26) 8.7
7.0 (38) 10.3 (27)
USDA 4121 9.5 (52)
59 8.9
USDA 4122
60 6.8 (40) 10.9 (19) 7.8 (56) 8.5
7.8
Mean 9.9 9.3 9.1
aLSD (5%) for comparing lupin cultivars, 0.40; LSD (5%) for comparing Bradyrhizobium strain averaged over three lupin cultivars, 1.81; LSD (5%) for comparingBradyrhizobiumstrains within Gungurru, 3.13; LSD (5%) for comparingBradyrhizobium
strains within Juno, 2.87; LSD (5%) for comparingBradyrhizobiumstrains within Lunoble, 2.19.
bAn unweighted total of plant vigor score, score based on nodulation on the crown of the root, score based on nodulation on
fibrous roots, root dry weight, and stem dry weight. cL.angustifolius.
dL.luteus. eL.albus.
fThe plants did not survive.
soaking for 5 min in 1% bleach and then were
rinsed five times with sterile distilled water. These
surface-sterilized seeds were held at room
tempera-ture between sterile paper towels moistened with
sterile distilled water until they germinated. The
germinated seeds were planted in furrows in
auto-claved vermiculite, which had been placed in
20-cm sterilized plastic pots and had been moistened
with full strength N-free plant nutrient solution
[9]. Each germinated seed was inoculated with 0.5
ml of a bradyrhizobial suspension. Each lupin
line
×
bradyrhizobial strain combination was
repli-cated three times. The pots were watered with
sterile distilled water as needed. The second
exper-iment, a factorial design of three bradyrhizobial
strains (USDA 3044, 3051, 4114) and 80 lines of
L
.
albus
, was also conducted in a greenhouse with
supplemental lighting at the Beltsville Agricultural
Research Center. The protocols used in the second
experiment were similar to those used in the first.
2.4.
Data collection and analysis
In the first experiment, the plants were grown
for 52 days before they were turned out of the pots
and the vermiculite was washed off the roots.
Each plant was assigned a vigor score from 1 to 3
with 1, poor; 2, intermediate; and 3, vigorous
plant growth. A nodulation score was also
as-signed separately to each plant based on nodules
at the crown of each root and those located on the
fibrous roots with 1, no nodulation; 2, a few small
nodules; 3, many small nodules; 4, a few large
nodules; and 5, many large nodules. Shoot and
root dry weights were also recorded.
In the second experiment, the plants were grown
for 54 days before harvesting. After harvesting,
each plant was given a vigor score and nodulation
score similar to that for the first experiment. The
numbers of nodules, nodule dry weight, and shoot
dry weight were recorded. The acetylene reduction
activity (ARA) as described by [10] was used to
compare nitrogenase activities by the strain and
lupin line combinations. The nodulated roots were
separated from shoots at the cotyledonary nodes
and were enclosed quickly in 250 ml mason jars
and incubated with 10% acetylene for 15 min
before collecting 0.5 ml gas samples for
determina-tions of ethylene as described by [11].
[image:4.612.29.527.65.203.2]Table 4
Performance of 80 lupin lines, based on combined score, and relative rank when inoculated with three selectedBradyrhizobium
strainsa
Number Line Combined scorea
USDA3044 USDA3051 USDA4114 Mean
2.74 (70) 21.94 (2)
1 PI-168891 25.12 (12) 16.60
2.72 (71) 11.01 (29)
2 PI-170528 17.16 (36) 10.29
38.81 (7) 11.69 (25)
PI-179361 22.38 (18)
3 24.29
4 PI-232924 36.15 (8) 09.65 (38) 18.40 (33) 21.40
43.91 (5) 17.75 (10)
PI-237719 28.90 (4)
5 30.19
15.86 (30) 19.03 (6)
6 PI-243335 28.58 (5) 21.16
3.33 (64) 18.26 (8)
PI-244572 27.79 (9)
7 16.46
PI-250094
8 57.41 (2) 17.69 (11) 39.03 (1) 38.04
32.45 (11) 17.92 (9)
PI-250572 23.48 (15)
9 24.62
PI-251559
10 3.27 (67) 18.62 (7) 23.32 (16) 15.07
2.06 (76)
11 PI-255375 14.10 (19) 28.53 (6) 14.90
3.57 (63) 17.62 (12)
PI-255471 26.99 (11)
12 16.06
5.24 (60) 09.90 (37)
13 PI-287241 12.32 (48) 09.15
9.24 (50) 10.88 (30)
PI-289160 21.34 (20)
14 13.82
8.40 (53) 10.23 (35)
15 PI-316610 24.67 (13) 14.43
12.25 (41) 12.88 (22)
PI-368911 20.06 (23)
16 15.06
20.35 (20) 14.32 (18)
17 PI-368914 16.22 (39) 16.96
13.30 (39) 16.03 (15)
PI-368915 22.83 (17)
18 17.39
PI-381322
19 16.18 (29) 13.09 (21) 30.60 (2) 19.95
15.41 (33) 10.06 (36)
PI-386098 19.49 (26)
20 14.98
15.04 (35) 10.26 (34)
21 PI-434855 19.17 (29) 14.83
18.04 (25) 05.77 (54)
PI-434856 06.26 (66)
22 10.02
PI-457921
23 79.96 (1) 06.89 (47) 06.56 (63) 31.14
13.29 (40) 05.43 (56)
PI-457923 06.47 (64)
24 08.40
PI-457924
25 47.09 (4) 23.72 (1) 12.34 (47) 27.71
26 PI-457926 34.12 (9) 1.52 (77) 04.81 (71) 13.48
48.56 (3) 7.16 (45)
PI-457927 15.77 (40)
27 23.83
1.96 (77) 13.58 (20)
28 PI-457928 04.58 (73) 06.70
39.71 (6) 7.57 (43)
PI-457929 16.48 (38)
29 21.25
1.57 (80) 16.50 (13)
30 PI-457930 19.46 (27) 12.51
24.52 (13) 10.69 (33)
PI-457931 18.98 (30)
31 18.06
17.52 (27) 1.47 (78)
32 PI-457932 11.71 (49) 10.23
10.12 (47) 6.25 (51)
PI-457933 23.95 (14)
33 13.44
PI-457934
34 18.85 (23) 8.79 (40) 28.20 (7) 18.61
24.30 (14) 4.09 (60)
PI-457935 09.33 (54)
35 12.57
10.25 (45) 14.80 (17)
36 PI-457936 27.22 (10) 17.43
20.89 (19) 3.43 (64)
PI-457937 21.97 (19)
37 15.43
PI-457938
38 33.22 (10) 3.41 (66) 13.79 (44) 16.81
13.68 (37) 6.85 (48)
PI-457939 20.26 (22)
39 13.59
PI-457940
40 16.82 (28) 4.46 (59) 30.21 (3) 17.16
PI-457941
41 21.25 (18) 19.97 (4) 13.00 (46) 18.07
8.00 (54) 12.38 (24)
PI-457942 19.56 (25)
42 13.31
23.10 (16) 3.89 (62)
43 PI-457944 28.08 (8) 18.36
15.06 (34) 3.29 (68)
PI-457945 19.41 (28)
44 12.59
PI-457946
45 23.88 (15) 5.35 (57) 20.96 (21) 16.73
15.54 (32) 11.47 (26)
PI-457947 14.94 (42)
46 13.98
PI-457948
47 18.17 (24) 12.54 (23) 05.25 (69) 11.99
10.13 (46) 10.81 (31)
48 PI-457950 14.11 (43) 11.68
8.64 (52) 11.08 (28)
PI-457951 07.42 (60)
49 09.05
9.75 (48) 4.09 (61)
50 PI-457952 04.00 (76) 05.94
10.39 (44) 6.92 (46)
PI-457953 08.95 (55)
51 08.76
PI-457954
52 31.34 (12) 1.86 (72) 07.78 (59) 13.66
5.59 (59) 1.60 (75)
PI-457955 04.06 (75)
Table 4 (Continued)
Combined scorea
Number Line
USDA3044 USDA3051 USDA4114 Mean
21.46 (17) 1.60 (74) 01.65 (80)
54 PI-457956 08.24
2.09 (75) 3.33 (67)
PI-457959 05.45 (68)
55 03.62
PI-467348
56 4.11 (62) 1.53 (76) 17.20 (35) 07.61
PI-467349
57 19.76 (21) 3.03 (69) 18.79 (31) 13.86
3.29 (65) 1.62 (73)
PI-467350 08.26 (57)
58 04.39
7.32 (56) 16.38 (14) 08.87 (56)
59 PI-468127 10.86
4.77 (61) 1.42 (79)
PI-468128 01.82 (79)
60 02.67
PI-468129
61 18.90 (22) 1.31 (80) 10.44 (51) 10.21
PI-469095
62 18.03 (26) 20.95 (3) 10.17 (52) 16.38
9.19 (51) 6.12 (53)
PI-469096 10.55 (50)
63 08.62
9.68 (49) 15.46 (16)
64 PI-476370 02.17 (78) 09.10
13.43 (38) 6.61 (49)
PI-476371 16.49 (37)
65 12.17
PI-476372
66 5.72 (58) 6.15 (52) 18.44 (32) 10.10
PI-476373
67 11.55 (43) 2.86 (70) 18.04 (34) 10.82
14.10 (36) 4.65 (58)
PI-476374 04.39 (74)
68 07.71
69 PI-476375 6.17 (57) 2.31 (71) 07.86 (58) 05.44
15.80 (31) 8.87 (39)
PI-481545 15.14 (41)
70 13.27
PI-481546
71 2.55 (72) 5.49 (55) 03.46 (77) 03.83
PI-481547
72 11.63 (42) 8.29 (41) 06.27 (65) 08.73
3.20 (68) 10.77 (32)
PI-481548 04.72 (72)
73 06.23
PI-481549
74 1.92 (79) 19.73 (5) 07.35 (62) 09.67
3.29 (66) 11.15 (27)
PI-481550 10.14 (53)
75 08.20
7.50 (55) 3.48 (63)
76 PI-481551 5.86 (67) 05.61
2.19 (74) 7.61 (42)
PI-481552 07.42 (61)
77 05.74
1.96 (78) 6.50 (50) 05.04 (70) 04.50
78 PI-481553
2.52 (73) 3.42 (65)
Lycayne 09.79 (24)
79 08.57
LUNABLE
80 2.83 (69) 7.55 (44) 13.55 (45) 07.98
Mean 15.72 9.36 15.27 13.45
aLSD (5%) for comparing lupin line means, 15.36; LSD (5%) for comparing bacterial strain means, 2.98.
an example, for the combination of Gungurru
with strain 3040, the values for plant vigor score,
nodulation scores from crown root, nodulation
scores from fibrous roots, shoot dry weight in
grams, and root dry weight in grams for
replica-tion 2 were, 2, 3, 2, 0.332, and 0.850 g,
respec-tively, thus, leading to a combined score of 8.182
(2+
3
+
2
+
0.332
+
0.850
=
8.182). In the second
experiment, the combined score consisted also of
an arithmetic total of plant vigor score (value
from 1 to 3), ARA (The amount of ethylene
expressed as
m
mol per jar per h), nodule number
per plant, nodule weight per plant in grams, and
dry shoot weight in grams.
All data on individual variables and combined
scores were analyzed using generalized linear
model procedure in SAS [12].
3. Results and discussion
3.1.
E
6
aluation of bradyrhizobial strains
Due to differential plant survival in the first
experiment, data were available only for 52
bradyrhizobial strains with Gungurru (
L
.
angusti
[image:6.612.32.527.62.423.2]cultivars for root dry weight and bradyrhizobial
strains was not significant (Table 1) except for root
dry weight for bradyrhizobial strains (Table 2).
Based on the combined score (Table 3), Juno was
most efficient lupin cultivar for nodulation with a
mean score of 9.9, followed by Lunoble with a mean
score of 9.3. Within Juno, the score varied from 5.9
(USDA 3054) to 12.8 (USDA 3044). Within
Luno-ble, the score varied from 6.1 (USDA 3935) to 11.4
(USDA 4113). Within Gungurru, the score varied
from 4.3 (USDA 3712) to 11.1 (USDA 3044). The
combined score averaged over three lupin cultivars
varied from 6.4 (USDA 3054) to 11.0 (USDA 3044).
Based on the combined analysis, which included
all strains and three lupin cultivars and used strain –
lupin cultivar interaction mean squares as the error
term, the most efficient five strains of
Bradyrhizo
-bium
were, USDA 3044, USDA 3930, USDA 3058,
USDA 4114, and USDA 3048. The five least
efficient strains of
Bradyrhizobium
were, USDA
3054, USDA 3712, USDA 3935, USDA 3710, and
USDA 3052.
3.2.
E
6
aluation of lupin lines
Significant variation existed among lupin lines
and bradyrhizobial strains for all the variables
tested except for nodule number in an evaluation of
80 lupin lines inoculated with three strains of
Bradyrhizobium
(Table 4). It was not possible to
estimate line – strain interaction or to derive the
error variance because of lack of replications.
Therefore, the line – strain mean squares were used
as the error term.
The combined scores for 80 lupin lines varied
from 2.7 to 38.0 (Table 4). The highest ranking five
lupin lines were, PI-250094, PI-457921, PI-237719,
PI-457924, and PI-250572. The combined score of
these five lines varied from 38.0 to 24.6 whereas the
mean combined scores for Lunoble and Lycayne
were 8.3 indicating that these five lines potentially
are desirable over the current lupin cultivars under
conditions of nitrogen fixation and might be useful
as parents in a breeding program. However, the
data were obtained in a greenhouse study and
similar evaluations under field conditions would be
needed.
3.3.
Bradyrhizobial strain and lupin line specifity
Results of both experiments indicated specificity
between
Bradyrhizobium
strains and lupin lines. In
the first experiment (Table 3), the strain USDA 3040
had a combined score of 8.1 (ranked 19), 11.2
(ranked 13), and 7.5 (ranked 58), for Gungurru,
Juno, and Lunoble cultivars, respectively. Similarly,
the combined score for USDA 3044 also varied
depending upon the lupin line. In this case, the
combined scores were 11.1 and 12.8 when evaluated
with Gungurru (ranked 1) and with Juno (ranked
1), respectively, but only 9.2 (ranked 29) with
Lunoble. In the second experiment, lupin line
PI-250094 had the highest mean score of 38.04. This
lupin line had a combined score of 57.41 (ranked 2),
17.69 (ranked 11), and 39.03 (ranked 1) when
evaluated with USDA 3044, 3051, and 4114,
respec-tively. The lupin line PI-457921 had a combined
score of 79.97 (ranked 1), 6.89 (ranked 47), and 6.56
(ranked 63) when evaluated with USDA 3044, 3051,
and 4114, respectively. In general, it was not
uncom-mon for the combined score to fluctuate depending
upon the combination of bradyrhizobial strain and
lupin line (Table 4). In the majority of cases, the
lupin lines nodulated satisfactorily with most
bradyrhizobial strains. The combined score of
PI-237719 line was 43.91 (ranked 5), 17.75 (ranked 10),
and 28.90 (ranked 4) when evaluated with USDA
3044, 3051, and 4114, respectively. Similar results
were also obtained with PI-250094.
some lupin cultivars might be chosen as a
reason-able choice in a field situation where inoculant is
not controlled, but a different choice might be
made where both the host and bacteria could be
specified. Therefore, we conclude that if the
resur-gence of lupin as a nitrogen-fixing component in
sustainable crop production is to be successful,
specific lupin cultivar and bradyrhizobial strain
combinations need to be identified. These results
also imply that breeding programs to develop high
yielding lupin cultivars, adapted to the
mid-At-lantic region, should use the most suitable
bradyrhizobial strain as inoculant to precisely
de-termine lupin productivity for sustainable crop
production systems.
Acknowledgements
Assistance of Charles Simon (USDA-ARS,
Pull-man, Washington, USA), and Blaine Schatz
(Car-rington Research Extension Center, North Dakota
State University, Carrington, ND) for providing
seeds and technical assistance is acknowledged
gratefully. Major author acknowledges the
finan-cial support from M.S. to Ph.D. program of
Vir-ginia
State
University
and
resources
of
Agricultural Research Station, Virginia State
University.
References
[1] E. van Santen, D.W. Reeves, G.L. Mullins, White lupin, a potential new crop for Alabama. Alabama Agriculture Expansion Station, Highlights Agric. Res. 40 (1994) 15. [2] D.W. Reeves, Experiences and prospects for lupin in the South and Southeast, in: Prospects for Lupin in North America, Proceedings of the Symposium Sponsored by the Center for Alternative Plant and Animal Products, University of Minnessota, St. Paul, MN, March 21 – 22, 1991, pp. 23 – 30.
[3] D.W. Reeves, J.T. Touchton, R.C. Kingery, The use of lupin in sustainable agriculture systems in the Southern Coastal Plain, in: Abstracts of Technical Papers, No. 17, Southern Branch ASA, Little Rock, AR, February 3 – 7, 1990, p. 9.
[4] P.J. Bottomley, H.H. Cheng, S.R. Strain, Genetic struc-ture and symbiotic characteristics of a Bradyrhizobium
population recovered from a pasture soil, Appl. Environ. Microbiol. 60 (1994) 1754 – 1761.
[5] L.L. Barrera, M.E. Trujillo, M. Goodfellow, F.J. Garcia, G. Davila, P. van Berkum, E. Martinez-Romero, Genetic diversity of bradyrhizobia nodulatingLupinusspp., Int. J. Syst. Bacteriol. 47 (1997) 1086 – 1091.
[6] L.A. Field, D.H. Putnam, Crop description, growth and development, in: R.A. Meronuck, M. Harvey, D.H. Putnam (Eds.), Lupin Production and Utilization Guide, Center for Alternative Plant and Animal Products, Uni-versity of Minnesota, St. Paul, MN, 1993, pp. 3 – 4. [7] B. Lagacherie, M. Bours, J.J. Giraud, G. Somer,
Interac-tion between Rhizobium lupini strains and species or cultivars of lupin (Lupinus albus, Lupinus luteus and
Lupinus mutabilis), Agron. Sci. Prod. Veg. Environ. Paris 3 (1983) 809 – 815.
[8] P. van Berkum, Evidence for a third uptake hydrogenase phenotype among the soybean bradyrhizobia, Appl. En-viron. Microbiol. 56 (1990) 3835 – 3841.
[9] D.O. Norris, Techniques used in the work with Rhizo
-bium. Commonwealth Bureau of Pasteures and Field
Crops, Hurley Berkshire Bull. 47 (1964) 186 – 198. [10] R.W.F. Hardy, R.D. Holsten, E.K. Jackson, R.G. Burns,
The acetylene – ethylene assay for N2-fixation: laboratory and field evaluation, Plant Physiol. 43 (1968) 1185 – 1207. [11] P. van Berkum, C. Sloger, Immediate acetylene reduction by excised grass roots not previously pre-incubated at low oxygen tensions, Plant Physiol. 64 (1979) 739 – 743. [12] SAS, SAS System for Windows, SAS Institute Inc., Cary,
NC, 1994.
[13] J.E. Harper, Soil and symbiotic nitrogen requirements for optimum soybean production, Crop Sci. 14 (1974) 255 – 260.
[14] S.L. Neuhausen, P.H. Graham, J.H. Orf, Genetic varia-tion for dinitrogen fixavaria-tion in soybean of maturity group OO and O, Crop Sci. 28 (1988) 769 – 772.
[15] T.R. Sinclair, A.R. Soffes, K. Hinson, S.L. Albrecht, P.L. Pfahler, Genotypic variation in soybean nodule number and weight, Crop Sci. 31 (1991) 301 – 304.
[16] M.L. Ferrey, P.H. Graham, M.P. Russelle, Nodulation efficiency ofBradyrhizobium japonicumstrains with geno-types of soybean varying in the ability to restrict nodula-tion, Can. J. Microbiol. 40 (1994) 456 – 460.
[17] D.L. Pazdernik, P.H. Graham, C.P. Vance, J.H. Orf, Host genetic variation in the early nodulation and dinitrogen fixation of soybean, Crop Sci. 36 (1996) 1102 – 1107. [18] K.K. Ayisi, D.H. Putnam, C.P. Vance, P.H. Graham,
Bradyrhizobiuminoculation and nitrogen fertilizer effects on seed yield and protein of white lupin, Agron. J. 84 (1992) 857 – 861.
