-1 INVESTIGATING HEAT TOLERANT TRAITS IN PEA … Presentation Author: anonymous Created Date:...
1
RATIONALE Field pea is a major grain legume crop in western Canada. However, pea cultivars are heat sensitive and readily abort flowers and young pods in air temperatures above 30 °C, resulting in reduced and unstable yield from year to year. Our goal is to improve pea heat tolerance through a combination of phenology, pollen viability and canopy traits. In 2010 to 2012, 12 cultivars were grown in the field in two soil zones at a normal and late seeding date to investigate yield formation. Daily maximum temperatures >29 °C caused abortion of flowers and young pods. Yield losses were greater in the later seeded plots where flowering was displaced into warmer temperatures. In 2013 we mapped pod yield at specific nodes in controlled heat in the growth chamber. We also measured pollen viability on a subset of five cultivars from one field site (2012), noting abnormal pollen tube germination in vitro at temperatures > 30 °C. Heat tolerant cultivars achieved greater pod retention through early flowering, and a longer flowering duration. An overview of our findings and future strategies to screen genotypes for other heat tolerant traits is below. INVESTIGATING HEAT TOLERANT TRAITS IN PEA CULTIVARS Rosalind A. Bueckert, Tom Warkentin, Dept. of Plant Sciences & CDC, Univ. Saskatchewan [email protected] (306)-966-8826 CONCLUSIONS Heat stress in pea reduces time spent in reproduction. Heat causes abortion of flowers, pods and seed. Seed size is also reduced. Pollen viability in vitro is reduced by heat. Genotypic variation is apparent in heat sensitivity and tolerance. FUTURE RESEARCH We are in the process of characterizing heat tolerance through early flowering and flower duration via Recombinant Inbred Lines. We are also looking at pollen biology to find pea genotypes that can pollinate better under high temperature. We also plan to look at vegetative traits such as leaf type, leaf size, tendril and petiole thickness, leaf color, pigment and wax (cuticle) to help in transpirational responses and canopy cooling. Time spent in reproductive growth is reduced by warm temperature. The higher the mean maximum temperature, the less days spent in reproductive growth, and yield is reduced. At Saskatoon, the dryland site, 25.5°C or higher reduced reproduction to 35 days or less. Irrigation (Outlook) ameliorates heat stress and more days are spent in reproductive growth. HEAT REDUCES TIME SPENT IN REPRODUCTION Mean daily maximum temperature in reproduction ( o C) 20 21 22 23 24 25 26 27 28 29 30 Reproductive phase (days) 20 25 30 35 40 45 50 55 60 Outlook 2000 2003 2005 2006 2007 2008 2009 Mean daily maximum temperature in reproduction ( o C ) 20 21 22 23 24 25 26 27 28 29 30 Reproductive phase (days) 20 25 30 35 40 45 50 55 60 HEAT REDUCES YIELD IN LATE SEEDED PEA POLLEN TUBES BECOME LONGER AND THINNER POLLEN GRAINS ARE SMALLER WITH LESS VIGOR HEAT MAKES FLOWERS AND PODS FALL OFF Number of days above 28 o C 10 12 14 16 18 20 22 24 26 28 30 Yield (kg ha -1 ) 1000 2000 3000 4000 5000 6000 7000 2000 2003 2005 2006 2007 2008 2009 Saskatoon The more days , say 20 + in a season with maximum temperatures above 28°C, the less yield for dryland pea. Flowering node Node with set baby pods Oldest node with two pea pods Developing node flower buds 25 μm Germinating pollen Vn- Vegetative nucleus Gn- Generative nucleus (gives rise to 2 sperm nuclei) Pt- Pollen tube Cp- Callose plug Percentage germination (%) * 25 o C 35 o C 25 o C 35 o C *** * * Length Width Area Dimension of pollen grain (μm) 25 o C 35 o C Dimension of pollen tube (μm) Length Width Area *** *** Distal and proximal (basal) positions Proximal dominant, distal likely to abort Aborted fraction of all potential pods in 2011, two seeding dates Cultivar Alaska Carneval Centennial Cooper Cutlass Delta Eclipse Golden Kaspa Meadow Sage Striker Aborted fraction (%) 0 10 20 30 40 50 60 70 80 90 100 Early Late Pea yield in 2011, Early and Late seeding Cultivar Alaska Carneval Centennial Cooper Cutlass Delta Eclipse Golden Kaspa Meadow Sage Striker Yield kg ha -1 0 1000 2000 3000 4000 5000 Early Late DURATION OF HEAT REDUCES YIELD Four hours incubation of pollen in vitro from cv. Alaska at 25 o C and 35 o C. Non viable and heat treated pollen is smaller than normal viable pollen. Pollen germination is reduced by heat, and pollen tube germination in 35 o C results in longer, thinner abnormal tubes. FUTURE RESEARCH – COOLING THE CANOPY PS051011 Rocket Superscout CDC_Treasure Naparnyk CDC_Golden SW_Marquis Rally Aragorn Pod number per plant 0 2 4 6 8 10 12 14 16 Pea under irrigation in Arizona (30 to 40°C) can still set pods and fill seed when irrigated. Out of 94 cultivars, 24 were able to set 6 or more pods from normal (grey bars) and late (cyan - hot) seeding-date trials. Naparnyk was able to produce most pods in this hot environment, and this cultivar was indeterminate, with normal leaves. In addition to timing of flowering date and duration of flowering (phenology), various canopy traits likely reduce heat stress by maintaining cool leaves. Treatment Pod weight (g) Pea weight (g) Pea number Failed pollination Aborted sites % of funiculi Failed peas % of set peas Temp 25 C 0.79 a 0.67 a 3.16 a 2.95 a 52.2 a 9.1 a 34 C 0.69 b 0.60 b 3.10 a 2.90 a 51.9 a 10.8 a Node 1 1.14 a 0.99 a 4.55 a 1.80 d 34.4 d 9.6 a 2 0.88 b 0.76 b 3.77 b 2.35 c 42.7 c 11.3 a 3 0.65 c 0.55 c 2.83 c 3.00 b 54.8 b 12.2 a 4 0.29 d 0.23 d 1.36 d 4.55 a 76.4 a 6.8 a Pod position proximal 0.98 a 0.84 a 4.05 a 1.98 b 38.4 b 13.8 a distal 0.50 b 0.44 b 2.20 b 3.87 a 65.8 a 6.1 b Node 1 25 C 1.07 a 0.88 a 4.77 a 1.71 a 32.4 a 6.9 a 34 C 0.90 b 0.10 b 4.33 a 1.88 a 36.4 a 10.4 a Pea in three days of controlled heat (ramped from 18 to 34°C for 6 hours) reduces pod weight and pea weight. Nodes were treated with heat just as the flowers of node 1 opened. Heat also reduced the distal pod weight. Measurements were made 20 days after heat treatment started. Mean of 3 reps and 10 cultivars. Note that node position and pod position within a node also have developmental responses. Funding from Agriculture Development Fund of Saskatchewan, Western Grains Research Foundation, Saskatchewan Pulse Growers Association and the NSERC-CRD program. We thank Jannatul Ferdose for pollen measurements and Donna Lindsay for measurements from the growth chamber study. HEAT REDUCES POD WEIGHT AND SEED WEIGHT PER POD Gn Vn Pt Cp Pt distal proximal 25 o C 25 o C 35 o C 35 o C
Transcript of -1 INVESTIGATING HEAT TOLERANT TRAITS IN PEA … Presentation Author: anonymous Created Date:...
RATIONALE
Field pea is a major grain legume crop in western Canada.
However, pea cultivars are heat sensitive and readily abort
flowers and young pods in air temperatures above 30 °C,
resulting in reduced and unstable yield from year to year.
Our goal is to improve pea heat tolerance through a
combination of phenology, pollen viability and canopy
traits.
In 2010 to 2012, 12 cultivars were grown in the field in two
soil zones at a normal and late seeding date to investigate
yield formation. Daily maximum temperatures >29 °C
caused abortion of flowers and young pods. Yield losses
were greater in the later seeded plots where flowering was
displaced into warmer temperatures.
In 2013 we mapped pod yield at specific nodes in controlled
heat in the growth chamber. We also measured pollen
viability on a subset of five cultivars from one field site
(2012), noting abnormal pollen tube germination in vitro at
temperatures > 30 °C.
Heat tolerant cultivars achieved greater pod retention
through early flowering, and a longer flowering duration.
An overview of our findings and future strategies to screen
genotypes for other heat tolerant traits is below.
INVESTIGATING HEAT TOLERANT TRAITS IN PEA CULTIVARS Rosalind A. Bueckert, Tom Warkentin, Dept. of Plant Sciences & CDC, Univ. Saskatchewan [email protected] (306)-966-8826
CONCLUSIONS Heat stress in pea reduces time spent in reproduction. Heat causes abortion of flowers, pods
and seed. Seed size is also reduced. Pollen viability in vitro is reduced by heat. Genotypic
variation is apparent in heat sensitivity and tolerance.
FUTURE RESEARCH We are in the process of characterizing heat tolerance through early flowering and flower
duration via Recombinant Inbred Lines. We are also looking at pollen biology to find pea
genotypes that can pollinate better under high temperature. We also plan to look at
vegetative traits such as leaf type, leaf size, tendril and petiole thickness, leaf color, pigment
and wax (cuticle) to help in transpirational responses and canopy cooling.
Time spent in reproductive growth is reduced by warm
temperature. The higher the mean maximum temperature,
the less days spent in reproductive growth, and yield is
reduced.
At Saskatoon, the dryland site, 25.5°C or higher reduced
reproduction to 35 days or less.
Irrigation (Outlook) ameliorates heat stress and more days
are spent in reproductive growth.
HEAT REDUCES TIME SPENT IN REPRODUCTION
Mean daily maximum temperature in reproduction (oC)
20 21 22 23 24 25 26 27 28 29 30
Re
pro
du
cti
ve
ph
as
e (
da
ys
)
20
25
30
35
40
45
50
55
60
Saskatoon Outlook 2000
2003
2005
2006
2007
2008
2009
Mean daily maximum temperature in reproduction (oC )
20 21 22 23 24 25 26 27 28 29 30
Rep
rod
ucti
ve p
hase (
days
)
20
25
30
35
40
45
50
55
60
HEAT REDUCES YIELD IN LATE SEEDED PEA
POLLEN TUBES BECOME LONGER AND THINNER POLLEN GRAINS ARE SMALLER WITH LESS VIGOR
HEAT MAKES FLOWERS AND PODS FALL OFF
Number of days above 28 oC
10 12 14 16 18 20 22 24 26 28 30
Yie
ld (
kg
ha
-1)
1000
2000
3000
4000
5000
6000
7000
2000
2003
2005
2006
2007
2008
2009
Saskatoon
The more days , say 20 + in a season with maximum
temperatures above 28°C, the less yield for dryland pea.
Flowering node
Node with set baby pods
Oldest node with two pea pods
Developing node flower buds
25 µm
Germinating pollen
Vn- Vegetative
nucleus
Gn- Generative
nucleus
(gives rise to 2
sperm nuclei)
Pt- Pollen tube
Cp- Callose plug
Perc
en
tag
e g
erm
inati
on
(%
)
*
25oC 35oC
25oC
35oC
*** *
*
Length Width Area
Dim
en
sio
n o
f p
ollen
gra
in (
µm
)
25oC
35oC
Dim
en
sio
n o
f p
ollen
tu
be (
µm
)
Length Width Area
***
***
Distal and proximal (basal) positions Proximal dominant, distal likely to abort
Aborted fraction of all potential pods in 2011, two seeding dates
Cultivar
Alaska
Carneval
Centennial
Cooper
Cutlass
Delta
Eclipse
Golden
Kaspa
Meadow
Sage
Striker
Ab
ort
ed
fra
ctio
n (
%)
0
10
20
30
40
50
60
70
80
90
100
Early
Late
Pea yield in 2011, Early and Late seeding
Cultivar
Alaska
Carneva
l
Centenn
ial
Cooper
Cutlass
Delta
Eclips
e
Golde
n
Kaspa
Meado
w
Sage
Strike
r
Yie
ld
kg
ha
-1
0
1000
2000
3000
4000
5000
Early
Late
DURATION OF HEAT REDUCES YIELD
Four hours incubation of pollen in vitro from cv. Alaska at 25oC
and 35oC. Non viable and heat treated pollen is smaller than
normal viable pollen. Pollen germination is reduced by heat,
and pollen tube germination in 35oC results in longer, thinner
abnormal tubes.
FUTURE RESEARCH – COOLING THE CANOPY
Cultivar
PS05
1011
Roc
ket
Supe
rsco
ut
CD
C_T
reas
ure
Nap
arny
kC
DC
_Gol
den
SW_M
arqu
isR
ally
A
rago
rn
Po
d n
um
be
r p
er
pla
nt
0
2
4
6
8
10
12
14
16
Pea under irrigation in Arizona (30 to 40°C) can still set
pods and fill seed when irrigated. Out of 94 cultivars,
24 were able to set 6 or more pods from normal (grey
bars) and late (cyan - hot) seeding-date trials.
Naparnyk was able to produce most pods in this hot
environment, and this cultivar was indeterminate, with
normal leaves. In addition to timing of flowering date and
duration of flowering (phenology), various canopy traits
likely reduce heat stress by maintaining cool leaves.
Treatment Pod weight
(g)
Pea
weight
(g)
Pea
number
Failed
pollination
Aborted sites
% of funiculi
Failed peas
% of set peas
Temp 25 C 0.79 a 0.67 a 3.16 a 2.95 a 52.2 a 9.1 a
34 C 0.69 b 0.60 b 3.10 a 2.90 a 51.9 a 10.8 a
Node 1 1.14 a 0.99 a 4.55 a 1.80 d 34.4 d 9.6 a
2 0.88 b 0.76 b 3.77 b 2.35 c 42.7 c 11.3 a
3 0.65 c 0.55 c 2.83 c 3.00 b 54.8 b 12.2 a
4 0.29 d 0.23 d 1.36 d 4.55 a 76.4 a 6.8 a
Pod position
proximal 0.98 a 0.84 a 4.05 a 1.98 b 38.4 b 13.8 a
distal 0.50 b 0.44 b 2.20 b 3.87 a 65.8 a 6.1 b
Node 1 25 C 1.07 a 0.88 a 4.77 a 1.71 a 32.4 a 6.9 a
34 C 0.90 b 0.10 b 4.33 a 1.88 a 36.4 a 10.4 a
Pea in three days of controlled heat (ramped from 18 to 34°C for 6 hours) reduces pod
weight and pea weight. Nodes were treated with heat just as the flowers of node 1
opened. Heat also reduced the distal pod weight. Measurements were made 20 days
after heat treatment started. Mean of 3 reps and 10 cultivars. Note that node position
and pod position within a node also have developmental responses.
Funding from Agriculture Development Fund of Saskatchewan, Western Grains Research
Foundation, Saskatchewan Pulse Growers Association and the NSERC-CRD program.
We thank Jannatul Ferdose for pollen measurements and Donna Lindsay for measurements
from the growth chamber study.
HEAT REDUCES POD WEIGHT AND SEED WEIGHT PER POD
Gn
Vn
Pt
Cp
Pt
distal
proximal
25oC 25oC 35oC 35oC
