|
Background
and Objective:
These trials were designed to evaluate the effects of three Rhizobia leguminosarum
inoculant formulations and three field histories on nodule formation and seed yield in
field pea. The field histories include: a one year pea rotation (1 y); a four year pea
rotation in 1998 (4 y); a five year pea rotation in 1999 (5 y); and no known history of
pea or lentil and concurrent inoculant use (nh). Two sites for each field history were
used in each of 1998 and 1999 for a total of 12 sites. The inoculant treatments consisted
of an untreated control, Self-stik peat inoculant, Rhizostick peat inoculant and a
granular inoculant.
Procedure and Project Activities:
1998 Locations
No history of Rhizobia inoculant use
Field 1: This trial was located at NE20-5-19W and had a four-year field history of
wheat, oats, wheat, and canola (1997, 1996, 1995 and 1994, respectively) with no previous
use of Rhizobia inoculant and a background soil Rhizobia content of 113 bacteria per gram
of soil.
Field 2: This trial was located at SE27-5-19W and had a four-year field history of
canola, oats, canola and wheat (1997, 1996, 1995 and 1994, respectively) with no previous
use of Rhizobia inoculant and a background soil Rhizobia content of 550 bacteria per gram
of soil.
Four year field rotation
Field 1: This trial was located at SE26-4-19W and had a four-year field history of
corn, canola, wheat, and field pea (1997, 1996, 1995 and 1994, respectively) and a
background soil Rhizobia content of 113 bacteria per gram of soil.
Field 2: This trial was located at NE20-5-19W and had a four-year field history of
wheat, oats, wheat, and field pea (1997, 1996, 1995 and 1994, respectively) and a
background soil Rhizobia content of 2180 bacteria per gram of soil.
One year field rotation
Field 1: This trial was located at NW22-5-19W and had a four-year field history of
field pea, wheat, canola, and wheat (1997, 1996, 1995 and 1994, respectively) and a
background soil Rhizobia content of 1130 bacteria per gram of soil.
Field 2: This trial was located at SE26-4-19W and had a four-year field history of
field pea, canola, wheat, and field pea (1997, 1996, 1995 and 1994, respectively) and a
background soil Rhizobia content of 565 bacteria per gram of soil.
1999 Locations
No history of Rhizobia inoculant use
Field 1: This trial was located at NE27-5-19W and had a five-year field history of
barley, canola, wheat, canola, and wheat (1998, 1997, 1996, 1995 and 1994, respectively)
with no previous use of Rhizobia inoculant.
Field 2: This trial was located at SE27-5-19W and had a five-year field history of
corn, canola, oats, canola and wheat (1998, 1997, 1996, 1995 and 1994, respectively) with
no previous use of Rhizobia inoculant.
Five year field rotation
Field 1: This trial was located at SE26-4-19W and had a five-year field history of fall
rye, wheat, canola, wheat, and field pea (1998, 1997, 1996, 1995 and 1994, respectively).
Field 2: This trial was located at NE20-5-19W and had a five-year field history of
canola, wheat, oats, wheat, and field pea (1998, 1997, 1996, 1995 and 1994, respectively).
One year field rotation
Field 1: This trial was located at SE27-5-19W and had a five-year field history of
lentil, canola, barley, canola, and wheat (1998, 1997, 1996, 1995 and 1994, respectively).
Field 2: This trial was located at SE15-5-19W and had a five-year field history of
field pea, wheat, lentil, wheat, and flax (1998, 1997, 1996, 1995 and 1994, respectively).
The field pea variety Carrera was used in 1998 and 1999. The Rhizobia inoculants
used were: Selfstik Legume Inoculant (MicroBio RhizoGen Corp); Rhizostick Inoculant
(Urbana Laboratories); Rhizoflo Granular Inoculant (Urbana Laboratories) in 1998; and
Nitragin Soil Implant + Granular Inoculant (LiphaTech) in 1999.
Field pea seed was inoculated on May 23, 1998. The seed was planted with a double disc
drill with an 8" row spacing and at a depth of 2" on May 23, 1998. The seeding
rate was 152 kg/ha (50 viable plants/square meter). Fertilizer (11-55-0) was applied with
the seed at a rate of 40 kg/ha of product. Emergence began on June 1, 1998, and an
emergence count was taken on June 13, 1998, 12 days after emergence (DAE). All plants in
four rows of 1-m length were counted and the total converted to number of plants per
square meter. Ten plants were sampled from each plot on June 22, 1998 (21 DAE) and five
plants were sampled from each plot at flowering, July 15, 1998 (44 DAE) and at
pre-harvest, August 19, 1998 (79 DAE). The nodules on each plant were counted and weighed
to determine the average number of nodules per plant and the average weight of nodules per
plant. Plots were harvested on August 26, 1998, and seed yields were calculated in kg/ha
at 16% moisture.
Field pea seed was inoculated on May 28, 1999. The seed was planted with a double disc
drill with an 8" row spacing and at a depth of 2" on May 28, 1999. The seeding
rate was 148 kg/ha (50 viable plants/square meter). Fertilizer (11-55-0) was applied with
the seed at a rate of 40 kg/ha of product. Emergence began on June 4, 1999, and an
emergence count was taken on June 16, 1999, 12 days after emergence (DAE). All plants in
four rows of 1-m length were counted and the total converted to number of plants per
square meter. Nodulation was not assessed in 1999. Plots were harvested on September 16,
1999, and seed yields were calculated in kg/ha at 16% moisture.
Results and Discussion:
Emergence
Plant emergence was higher in 1999 compared with 1998. Good soil moisture and warm soil
temperatures promoted good emergence in 1999. In 1998, cool, dry soil conditions in the
first 10 days after seeding affected germination and cool, wet soil conditions thereafter
promoted seedling disease development.
There were no significant differences in the emergence rate between inoculant
treatments within each field history.
In comparing field histories, the emergence rate in the 1 y rotation field was
significantly lower then in the 4 y rotation and no history fields in 1998. The higher
disease inoculum from the previous years’ crop residues in the 1 y rotation promoted
greater disease pressure in the 1 y rotation fields, which may have reduced the emergence.
This difference was not observed in 1999.
Nodulation
There were no significant differences between treatments in the number of nodules and
nodule weight per plant in the 4 y rotation fields and 1 y rotation fields. The presence
of the Rhizobia from the previous seeding of field pea in the 4 y and 1 y rotation fields
promoted an increase in the number of nodules per plant. The development of nodules from
the background Rhizobia overshadowed any differences that may have occurred between the
granular and peat inoculants and untreated control treatments in these fields. In the no
history fields, the granular treatment resulted in a significantly higher number of
nodules per plant at 21 and 44 DAE and a significantly greater weight of nodules per plant
at 44 DAE compared with the Rhizostick, Self-stik, and untreated control treatments. The
Rhizostick and Self-stik treatments resulted in an increase in the number of nodules and
weight of nodules per plant compared with the untreated control treatment in the no
history fields at 44 DAE. This could be attributed to the absence of commercial Rhizobia
and the ineffectiveness of indigenous occurring Rhizobia to produce nodules in field pea
in the no history fields.
At 44 DAE, the total nodule weight was significantly lower in the 1 y rotation fields
compared with the 4 y rotation fields even though the number of nodules were similar. The
higher level of root disease observed in the 1 y rotation field may have weakened the
surviving plants resulting in less energy available for nodule formation compared with the
4 y rotation fields.
Yields
Grain yields were significantly higher in 1999 compared with 1998. The weather
conditions in 1998 promoted the development of seedling and foliar diseases resulting in
lowered emergence and plant vigour. The fields under 1 y rotation were most severely
affected by disease in 1998.
The field history had more effect on grain yields than did the inoculant treatments. No
significant differences in grain yields were observed between inoculant treatments within
each field history. Rennie and Hynes (1993) suggest that significant yield increases of
6-7 bu/ac resulting from inoculant use occur when available nitrogen is less than 30
lb/ac. The estimated available nitrogen ranged from 44 to 81 lb/ac in this study. In
contrast, field histories had a noticeable effect on seed yield. Shorter rotations
resulted in lower seed yields.
A history of field pea in the crop rotation affects field pea growth in subsequent
years. Disease pressure was important in the poor performance in the 1 y rotation fields
in1998. Although diseases were not as apparent in 1999, they may have been a factor in the
lower yields in the 1 y rotation fields. The grain yields in the 4 y rotation fields were
slightly lower than the no history fields. Although the differences were not significant,
the lower yields may have resulted from some factors related to the previous crop. Soil
fertility and disease interactions were not assessed as they were beyond the scope of this
trial. These interactions may have affected pea yields.
Differences between inoculant treatments were minimal in this study. The granular
inoculant resulted in an increase in nodule formation and weight compared with the peat
inoculants and the untreated control treatments in the no history fields. In the 4 y and 1
y rotation fields, nodulation resulting from inoculant treatments were not discernible
from those resulting from background Rhizobia.
The field history strongly influenced the results. Yields were highest in the no
history fields and lowest in the one year rotation fields. These differences likely
resulted from a higher level of disease inoculant in the fields with more recent field pea
growth.
References:
Rennie, R.J. and R.K. Hynes. 1993. Scientific and legislative quality control of legume
inoculants for lentil and field pea. J. Prod. Agric. 6:569-574.
Acknowledgements:
This Project was made possible due to funding from the Governments of Manitoba and
Canada through the Canada-Manitoba Agri-Food Research and Development Initiative (ARDI)
and matching funds from Urbana Laboratories and Ag-Quest, Inc.
|
HomeContact
UsAbout
ManitobaDepartmentsLinksPrivacy 
