Published January 19, 2017
Note
Automated Rainout Shelter’s Design
for Well-Defined Water Stress Field Phenotyping
of Crop Plants
Surya Kant,* Emily Thoday-Kennedy, Sameer Joshi, Jignesh Vakani, Jess Hughes, Lancelot Maphosa,
Andy Sadler, Meri Menidis, Anthony Slater, and German Spangenberg
ABSTRACT
Field phenotyping to identify water stresstolerant crop genotypes is challenging due to
uncertainty in the timing of rainfall. Rainout
shelters offer a way of establishing controlled
water stress environments by excluding
untimely rain events. Here, we present a
detailed description of custom-designed
rainout shelters. These shelters are fully
automated and portable. The rainout shelters
were constructed from steel arch frames and
polyethylene cladding, which move on plastic
road barriers. The three connected shelters,
each 20 ´ 10 m, are rain sensor activated,
solar powered and equipped with a motion
sensor camera for remote monitoring. These
rainout shelters have proven to be effective
tools for field water stress phenotyping.
S. Kant, E. Thoday-Kennedy, S. Joshi, J. Vakani, J. Hughes, L. Maphosa,
Agriculture Victoria, Grains Innovation Park, 110 Natimuk Road,
Horsham, VIC 3400, Australia; A. Sadler, Argosee Greenhouse Technology
Pty Ltd., 6 Laurence Road, Walliston, WA 6076, Australia; M. Menidis,
A. Slater, G. Spangenberg, Agriculture Victoria, AgriBio, Centre for
AgriBioscience, 5 Ring Rd, Bundoora, VIC 3083, Australia. Received 15
Aug. 2016. Accepted 11 Sept. 2016. *Corresponding author: (surya.kant@
ecodev.vic.gov.au). Assigned to Associate Editor Jose Rotundo.
W
ater limitation is a major abiotic stress, hindering crop
production in the majority of the world’s agricultural
regions (Passioura, 2007; Zhang et al., 2015). Water stress results
in altered plant development, yield, and quality and occurs when
water supply (rainfall or irrigation plus stored soil moisture) does
not meet plant water demands. Consequently, the ultimate impact
is dependent on the duration and severity of the stress event, as
well as the developmental stage of the plants (Fischer and Maurer,
1978; Choudhury and Kumar, 1980; Singh and Malik, 1983;
Dolferus et al., 2011). Therefore, as significant yield and quality
losses are encountered under water stress, breeding for improved
tolerance to water stress in crop varieties is vital.
The development of tools to enable precise phenotyping under
natural field conditions is key for breeding stress-tolerant crops.
While phenotyping for water stress responses in a controlled environment glasshouse is relatively easier, the results can potentially
be unreproducible in the field due to differences in factors such as
planting density, soil volume, and moisture content (Passioura, 2006,
2012). Changing rainfall patterns and the erratic prevalence of water
stress events pose considerable difficulties in replicating exact water
stress conditions during field experiments. To allow for reliable scientific results during water stress-tolerance field studies, regulation
of water reaching the plants is important. Experimental approaches
for controlling rainfall during field experiments include managed
Published in Crop Sci. 57:327–331 (2017).
doi: 10.2135/cropsci2016.08.0677
© Crop Science Society of America | 5585 Guilford Rd., Madison, WI 53711 USA
This is an open access article distributed under the CC BY-NC-ND license
(http://creativecommons.org/licenses/by-nc-nd/4.0/).
crop science, vol. 57, january– february 2017 www.crops.org327
environment facilities, such as rainout shelters, to exclude
untimely rain events. Rainout shelters can range from simple
fixed structures to complex retractable designs. Fixed shelters have a stationary frame or roof and permanently cover
vegetation and experimental plots for the entire duration
of the research (Clark and Reddell, 1990; Reynolds et al.,
1999; Svejcar et al., 1999; Yahdjian and Sala, 2002; English
et al., 2005; Heisler-White et al., 2009). In contrast, retractable rainout shelter designs incorporate a permanent frame or
footings with a moveable shelter roof to allow plants exposure to open field conditions, except during rain events. The
earlier retractable designs featured shed-like shelters, which
ran on ground-based rail systems (Bruce and Shuman, 1962;
Horton, 1962; Hiler, 1969; Stansell et al., 1976; Legg et al.,
1978; Upchurch et al., 1983; Ries and Zachmeier, 1985)
or elevated rail systems (Dubetz et al., 1968; Arkin et al.,
1976; Foale et al., 1979; Maw and Stansell, 1986). Retractable shelters have since evolved to incorporate designs based
on polytunnels (DaCosta and Huang, 2006; Misson et al.,
2011; de Guevara et al., 2015). While fixed and retractable
rainout shelters are typically used in field crop research, other
specialized shelter designs have also been reported, such as
curtain-type shelters (Beier et al., 2004), hand-operated
designs (Bittman et al., 1987; Chauhan et al., 1997), and
unique, semiportable, retractable shelters (Kvien and Branch,
1988; Hatfield et al., 1990; Parra et al., 2012). While many
of the previously published designs were suitable for their
intended purpose, no design contained all of the features
we desired when designing our new rainout shelters. The
required features for the shelters included:
rainout shelters’ structures and parts were manufactured
and supplied by Argosee Greenhouse Technology.
Base Foundation and Frame Structure
To allow for portability of the rail system and foundations,
the rails were mounted off the ground on plastic road barriers (1500 ´ 500/200 (base/top) ´ 770 mm) (Fig. 1A and
1B, Supplemental Fig. 1) that acted as foundations when
filled with water and were transportable when empty. Each
barrier weighs about 19 kg empty and 250 kg when filled
with water. Full portability of the whole rainout shelter
system was demonstrated in both 2015 and 2016, when
the system was successfully dismantled, relocated to a new
experimental site, and reassembled in working order.
The mobile roof structure was based on a polytunnel
design. Nine identical 180° galvanized steel arches were
braced together and mounted in the rail system on castor
wheels (four per arch). The external height of each arch
peak was 4.2 m from ground level with an internal clearance of 2 m (Fig. 1C, Supplemental Fig. 1 and 2). Each set
(i) a lightweight, robust design to allow the structures to
be portable while maintaining durability in all weather
conditions, especially high winds
(ii) automatic deployment by a rain sensor to guarantee
that no rainfall events are missed
(iii) a self-contained, onsite, renewable energy power
supply to ensure that all power is generated onsite,
limiting potential failures and problems with no mains
power infrastructure
(iv) full drainage for runoff to ensure that a complete
water stress environment is maintained
(v) easy portability to allow for crop rotation and to comply
with regulations when used in transgenic experiments.
The design and features of this customized, unique rainout shelter are described in the following sections.
Automated, retractable,
and portable rainout shelter
Three portable, retractable rainout shelters were conceptualized and designed by the Plant Phenomics group
(Horsham, Agriculture Victoria, DEDJTR) and Argosee
Greenhouse Technology (Walliston, WA, Australia). The
328
Fig. 1. Architectural design and layout of rainout shelters and
components. (A) and (B) interlocked plastic road barriers used
as foundations for rainout shelters with dimensions, (C) the basic
individual arch design on foundations with distances from ground
level, (D) the layout of one rainout shelter showing the nine arch
framework on the full length foundations with dimensions, and (E)
layout of three adjacent rainout shelters (1, 2, and 3).
www.crops.org
crop science, vol. 57, january– february 2017 of braced arches was clad with a polyethylene sheet that
covered down to the foundations, with shade cloth hung
at the north and south openings to prevent nonvertical
rainfall from entering. The whole rainout shelter system
was designed to withstand a high wind load (up to 153
km h−1) with minimal movement. Further information
on design, assembly, and technical specifications are presented in Fig. 1 and in Supplemental Figs. 1 and 2.
Proper rainwater drainage from the shelters is crucial
to avoid spillage into the experimental plots. Rainwater runoff from the roof was directed into gutters that
diverted rainwater into downpipes. These were plumbed
underground at both ends of each shelter and resurfaced
20 m away from the shelters to ensure a water stress environment under the shelters.
The rainout shelters were installed adjacent to each
other at the Plant Breeding Centre, Horsham, VIC, Australia, (36°43¢ S, 142°06¢ E) in May 2014 (Fig. 2) and (36°44¢
S, 142°06¢ E) in May 2015 to facilitate prebreeding water
stress tolerance research in field crops, particularly wheat.
Mechanical and Electrical Control
While moving from parked to covering the experimental
area, the shelter structures need to move smoothly to avoid
overloading the motors and to ensure that all three shelters
operate in unison. For this, 750 W motor assemblies were
installed on each shelter to move the shelters along the
rail system. Electrical limit switches were installed at each
end of the shelters to stop the motors once the shelters
had reached their final position, covering the experimental plots or parked. Each electric motor was connected to a
master control panel that controlled the operation system
(manual or rain-sensor automation), forward movement,
and reversing. To prevent activation by dew or fog, the
rain sensor was set to activate when small water droplets were present, triggering the movement of the shelters
from parked to covering the experimental area. The
rainout shelters were able to move from parked to their
final position over the experimental area in less than 2
min (although travelling speed is adjustable), in which
time negligible rainfall can reach the plants. To facilitate
germination and plant establishment during initial crop
growth, the rainout shelters can be left on manual mode
until sufficient growth has occurred. Then, the operational system can be switched to automatic.
To ensure the rainout shelters were self-contained,
efficient, and sustainable, power for the motors was supplied by a portable solar system with battery storage. The
solar system installed consisted of six 200 W solar panels,
a maximum power point tracking solar charge controller,
and four industrial batteries, each 6 V with 400 A hr. This
allowed all the necessary power to be generated on site
from a renewable resource.
To confirm complete automation of the rainout shelter
system, a motion sensor surveillance camera was installed,
featuring a web platform that allowed for remote monitoring and image capture. This means that shelters could
be monitored remotely from an electronic device with
internet connection, which allowed for real-time monitoring and fault notification without the need to visit the
shelter location. The camera was set to capture five images
over the 2-min shelter movement sequence. An additional
function allowed for instant image capture at any time
point through connected remote devices.
Layout of Rainout Shelters
and Experimental Plots
Each shelter measures 20 ´ 10 m, covering an experimental area of 200 m 2 to the north, with an additional 22
´ 10 m south of the experimental area for the parking of
the shelter (Fig. 1D). Each rainout shelter accommodated
42 experimental plots (plot size: 2 ´ 1 m) with 0.5-m
Fig. 2. Automated rainout shelters installed at the experimental site. Shelters are in the parked position south of the experimental wheat
plots at the Plant Breeding Centre, Horsham, VIC.
crop science, vol. 57, january– february 2017 www.crops.org329
pathways in between (Supplemental Fig. 3). Shelters were
orientated north–south, to maximize crop exposure to
sunlight and prevent shading from the shelter roof when
parked. The three rainout shelters were installed adjacent
to each other, with the middle shelter sharing foundations
with the shelters on either side (Fig. 1E and 2).
While the rainout shelter design incorporates a
full drainage system, accidental runoff or rain blow (in
north or south) were still a concern. To ensure that
potential runoff does not reach the experimental plots,
border plots were planted around the experimental
plots with a buffer variety (Supplemental Fig. 3). To
capture blown-in moisture, both the north and south
ends of each range were planted with small border plots
(1 ´ 1 m), while continuous border plots (20 ´ 0.3
m) were hand-sown along the road barrier foundations,
in case of any water droplets from the gutter system
(Supplemental Fig. 3).
This rainout shelter design incorporates all of the
required features in a robust, self-contained, portable
design that could be easily adapted in other locations.
ConcluSIONS
Rainout shelters have been used in agricultural and
ecosystem research for over 50 yr. Despite numerous
shelter designs in the literature, several major limitations were yet to be fully addressed, such as portability
and a self-contained power system. The novel rainout
shelter described in this article presented a design that
is fully portable due to the unique, plastic road barrier
foundations and is still completely robust and practical.
This design also featured a fully contained and portable solar system and a full drainage system, as well
as a surveillance camera for remote web-based monitoring and image capture. With rainout shelter designs
constantly evolving, we propose that this novel rainout
shelter design can become a basis for new shelter designs
with full portability and integrated technology. Rainout shelters are vital phenotyping tools in water stress
research as the need for field validation of traits and the
understanding of crop responses to different agroecological conditions becomes crucial for the breeding of
water stress tolerant crop varieties.
Conflict of Interest
The authors declare that there is no conflict of interest.
Supplemental Material Available
Supplemental material for this article is available online.
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