Leaf and canopy traits for heat
resistance in field pea
Rosalind Bueckert, Yunfei Jiang and Tom Warkentin,
Crop Physiology & Pulse Breeding, Dept Plant Sciences
& Crop Development Center, Univ SK
+1 (306) 966-8826 [email protected]
Tamworth, 2016
Seriously, in Canada, heat stress?
Node 3 aborted = 2 flowers lost
Node 2 = 1 flower/pod lost
Node 1 = 1 flower/pod lost
4 out of 6 pods lost
The obnoxious side of heat stress
-
Pea is a heat wimp
28⁰C for 5 days
32⁰C for 1-2 days
-Drought increases sensitivity
- Heat burns on wet leaves
- Flower bud development
no flowers, small flowers = less pollen & ovules
- Open flowers, small pods:
abort, seeds abort at ends of pod
LESS FLOWERS, PODS,
SEEDS, YIELD
PAM spectacular
Potential canopy traits for cooling
Yuma Arizona, 2012
Pea Association Mapping Panel
94 cultivars
E. and W. Europe, Australia, N. America
Early and late seeding, irrigated
Late : flowering after 14 April
heat > 28 to 41 ⁰C
• 20% cultivars flower and set pods at 36 to 41 ⁰C
• Retained 40- 50% of pods
PAM collection has diverse canopy traits
Leaf greenness, flower color, leaf type, canopy habit
Best performers in Arizona: entire and semi-leafless
Which canopy traits are associated with keeping pea cool?
Methods
PAM in field, micro plots
•2012 yield, nodes, pods
•2013 yield, leaf size, habit, leaf wax, pigments
•2015 as 2013 plus spectral sensing
Subset of PAM 2013-2016, yield plots
Vegetation index data like NDVI
Entire leaf
Stipules + 2 or 3
sets of leaflets
Semi-leafless
(Afila)
Stipules + more
tendrils
Traits:
Indeterminacy
Canopy habit
Leaf type
Leaf color
Node number, reproductive nodes
(Continued flowering)
Vining vs upright
Entire vs semi-leafless (Afila)
Leaflet/stipules, petioles/tendrils
Scanned area
Main stem diameter
Wax cuticle (potassium dichromate/acid)
Chlorophyll (green)
Carotenoids (yellow/orange)
Anthocyanins (red/blue)
Flower color Red, pink, cream vs white
Instruments
*SPAD meter (greenness)
*Spectral reflectance (wax, radiation load,
15+ vegetation indices NDVI, PRI, etc)
*Continuously logged NDVI and PRI
*Infrared canopy temperature, thermistors
(in expanding leaf and flower node)
__________________
Green NDVI
PRI
GRVI
Red/Green
ARVI, WBI
Green normalized difference vegetation index (narrow band)
Photochemical reflectance index
Green ratio vegetation index
Red green ratio
Atmospherically resistant vegetation index, Water band index
6 apps to a cool canopy or more yield in heat
App 1
Upright canopy
Hottest part of a plant is the top
Flowers are at the top
1 to 3 °C warmer than air 10am-4pm
Pods, lodged & diseased canopies
warmer than air temperature
-Semi-leafless trait
-Indeterminate (19 nodes, 8+ reproductive)
but not too vining (23+)
App 2
Leaf type/shape and wax
-Semi-leafless trait
-Entire leaf cultivars can be heat resistant (Naparnyk)
Wax reflects heat, frosty bloom = cooler leaf temperature
Wet & shiny wax absorbs heat, warmer
Amount of cuticle wax is linked to leaf & petiole size
Entire = large leaf surface from stipules + leaflets,
more and thicker wax
Semi-leafless = less leaf area, more petioles and tendrils,
thicker wax on petioles, not stipules
App 3
Flower color
No specific flower color is associated with cooler canopies
White flowered 0.5°C cooler 1/3 times
No specific flower color is associated with more yield overall
Best performers both white
(Arizona)
and red flowered (SK 2015)
App 4
Pigments
GREEN chlorophyll pigments remarkably stable
Higher pigment concentration in petioles
Color chemistry in lab expensive and insensitive
• SPAD meter and vegetation indices better
• NDVI, red/green ratio
ORANGE carotenoid pigments stable
Lab chemistry method is like chlorophyll
• PRI index is better
RED anthocyanin pigments stable, chemistry useless
• Petioles, with less green, are better tissue
App 4 cont.
Pigments
Avoid chemistry. Use an instrument.
Role of individual cultivar’s pigments- needs more physiology
App 5
Genetic group
PAM has 7 genetic groups,
3 broader groups
Average values mask individual genotype performance
Group 1 (18 Canada, 2 USA)
Highest yielding, coolest canopy
19 nodes, 8 reproductive, narrow stem, darkest green
Group 2 (all regions)
Lowest yielding, warmest canopy, largest leaves,
most & thickest leaf wax, least and thinnest petiole wax
Some good heat tolerant genotypes
Group 3 (most regions)
Intermediate.
App 6
Plant features
Indeterminate – more flowering nodes,
can afford to lose more flowers and recover
19+ nodes, 8+ reproductive nodes
Small seeded cultivars- retain more ovules and seeds in pods
seed size 225-250 mg, 6+ seeds per pod
Take home message for farmers
•
•
•
•
Keep pea canopy upright (semi-leafless)
Use a small seeded cultivar
Indeterminate - long flowering duration
Protect top of canopy from disease
Santa’s toy list
• SPAD meter (greenness)
• Spectral imaging (300 to 1100 nm)
NDVI and green indices, PRI, WBI, ARVI
• Infra-red thermometers
-small ear thermometer ($55) for top of plant
-IR thermometer for above canopy temperatures
Questions? Comments?
Instruments & measurements: Jason Denis, Brandon Louie, Zhifa Wang, Yunfei Jiang,
Endale Tafesse, Steve Ryu, Rong Xiang, Yong Liu, Jannatul Ferdose, Donna Lindsay,
Prabhath Lokurruge.
Genotyping & mapping: Marwan, Rob Stonehouse, Yunfei Jiang.
Investigators and collaborators: Art Davis, Bunyamin Ta’ran, Phil Davies.
Funding from Western Grains Research Foundation, Saskatchewan Pulse Growers,
Agricultural Development Fund of SK, NSERC-CRD, CDC Pea Breeding royalties.