A report card on the N -fixation of field pea in southern Australia

A report card on the N2-fixation of field
pea in southern Australia
Liz Farquharson, Ross Ballard , Nigel Charman (SARDI)
and Matthew Denton (University of Adelaide)
GRDC Project DAS00128 Optimising Nitrogen fixation in grain legumes, Southern Region
A report card on the N2-fixation of field pea in southern Australia
Field pea is grown on more than 250,000 ha in southern Australia
Good
Satisfactory
Poor
N2 fixation in field pea
benchmark: 20 kg N/t sh DM
(Unkovich et al. 2010)
Nodulation @ 10 weeks
post sowing
Response to inoculation
when soil rhizobia present
Data is from field trials conducted in SA and Vic (2011-2015)
17 x inoculation response trials with Kaspa field pea
7 x trials with 15 genotypes of field pea
Comments
Good
Satisfactory
Poor
N2 fixation field pea
benchmark: 20 kg N/t shoot DM
Relationship between pea DM production and fixed N/ha
Many instances where below 20 kg fixed N/t shoot DM
Comments
Variable. Room for some
Improvement.
Good
Satisfactory
Poor
Nodulation @10 weeks
Relationship between pea early nodulation and N2 fixation
Comments
All cultivars nodulate with soil
rhizobia.
Below par at some acid sites.
30
25
Fixed N (kg/tDM)
20
15
10
5
0
0
50
100
Total Nodules per plant (@10wks)
150
Guide: Above 50 nodules per plant at 10 weeks post sowing
increases chances of achieving benchmark N2 fix (20 kg fix N/t
shoot DM)
Good
Satisfactory
Poor
Comments
Can we improve nodulation and N2 fixation where
rhizobia backgrounds exist ?
Response to Inoculation when
soil rhizobia present.
Nodulation of Kaspa field pea @ 17 sites – no inoculation
160
Nodule number per plant
140
Not inoculated
120
100
Nodulation is lower
than expected at
some sites with high
numbers of rhizobia.
80
60
40
20
0
1
10
100
1000
10000
100000
Number of rhizobia per gram of soil before sowing (Most Probable Number + 1)
Good
Satisfactory
Poor
Comments
Factors other than
rhizobia number may be
limiting.
Response to inoculation when
soil rhizobia present.
Negligible response of Kaspa field pea nodulation to inoculation with high rates of
Rhizobium strain WSM1455 @ 17 sites
160
Nodule number per plant
140
Not inoculated
120
Inoculated with WSM 1455
100
80
60
Responsive
site
40
20
0
1
10
100
1000
10000
100000
Number of rhizobia per gram of soil before sowing (Most Probable Number + 1)
Good
Satisfactory
Poor
Comments
Factors other than rhizobia
number may be limiting.
pH, soil N, herbicides?
Response to inoculation when
soil rhizobia present.
Little response of Kaspa field pea to inoculation with high rates of Rhizobium strain WSM1455 @
17 unbiased sites
5
Ndfa %
Site Mean
72.0
WSM1455 (% of Nil)
103
76.0
99
4
Yield t/ha
Parameter
Nodule Number PP
(R2 = 0.26,
P <0.01)
3
2
Max Biomass gram
PP
15.0
105*
1
Shoot N %
2.0
103
0
Grain yield t/ha
2.4
102
Grain N %
3.5
104**
Fixed shoot N kg/ha
93.0
107
0
20
40
60
80
100
Nodule number per plant
Nodule number per plant (@10 wks) was positively correlated
with crop yield indicating there may still be some potential for
improvement.
120
140
160
How do you improve N2-fixation of field pea?
Better rhizobia for very acid soils
Relationship between pea DM production and fixed N(shoot) per ha
Pea symbiosis
performed poorly at
low pH (4.7) site
Rhizobia with putative
acid tolerance for field
pea and faba bean being
developed and tested.
(Murdoch University,
DAFWA, SARDI)
Cultivar variation
• On average 16-21 kg N2 fixed per t shoot DM
Nitrogen fixation of field pea cultivars
Fixed N( kgN/tDM)
25
(average across 7 sites)
lsd=1.6
20
15
10
5
N2 fixation index for field pea to be released in 2017.
OZP1208
OZP1101
PBA Hayman
OZP0903
OZP1104
PBA Gunyah
Cultivars vary in their N2 fixation capacity.
PBA Twilight
Kaspa
PBA Oura
Morgan
Wharton
Parafield
PBA Pearl
PBA Percy
PBA Coogee
0
Managing Soil N
Effect of Mineral N at sowing
on Field pea
57
51**
No N applied
+ 30 units N
18
Total nodules per plant
.
15**
N fixed shoots (kg /t DM)
Soil mineral N
added at sowing
reduced nodulation
and N2 fixation of
field pea
Other factors………..
•
•
•
•
•
Herbicides
Seed applied chemicals
Time of Sowing
Nutrition (P, Zn,Mn)
Manage Disease and Weeds
A report card on the N2-fixation of field pea in southern Australia
Good
Satisfactory
Poor
N2 Fixation in field pea
Benchmark: 20 kg N/t sh DM
Variable. Room for
Improvement.
Nodulation @ 10 weeks
All cultivars nodulate
well with soil rhizobia.
Below par at some
sites.
Response to Inoculation
when soil rhizobia present
Factors other than
rhizobia number may
be limiting.
pH, soil N, herbicides?
Acknowledgements and Thanks
Larn McMurray and Clare Agronomy Group (SARDI)
Jason Brand (DPI Vic)
Maarten Ryder (University of Adelaide)
PBA Pea Breeders
Ronald Yates (DAFWA/Murdoch University)

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