Effect of planting date choice on the vulnerability of

winter wheat to climate change: Case study of cool

temperate, northwestern provinces of Iran

Ali Akbar Rasouli

, Behrouz Sari Sarraf

, Gholamali Kamali

and Shahrokh Fateh

Professor of Climatology Department, Faculty of Geography and Planning, University of Tabriz, Tabriz, Iran

and Department of Environmental Sciences, Macquarie University, Sydney, Australia

Professor of Climatology Department, Faculty of Geography and Planning, University of Tabriz, Tabriz, Iran

Faculty Member of Meteorological Department, Faculty of Basic Science, Azad University, Science and

Research Branch, Tehran, Iran

I.R. of Iran Meteorological Organization, Tehran, Iran

ABSTRACT

In this study, vulnerability to trend in length of 4 phonological stages (Initial, Anthesis, Maturity and Harvest) and

total length of crop season (LCS) as a measure of climate change has been studied in 27 stations situated in 6 cool

temperate provinces of north western Iran. Time series data for 25 years period between1989-90 to 2014-15 based on

8 scenarios for planting (sowing) date are studied to assess the effect of climate change on each station. The results

show that late planting causes less vulnerability (except in Nahavand and Zarrineh stations) but also shorter crop

season which is unfavorable. The Anthesis and Initial stages are most affected but Maturity and Harvest stages seem

to be indifferent to climate change. Correct management training and disposal of hospital wastes should be one of

the operational objectives of hospital managers and this important issue should be included in planning courses for

staff of all hospitals.

KEY WORDS: IRAN, WINTER WHEAT, GROWING DEGREE DAYS, PHENOLOGY, CLIMATE CHANGE, PLANTING DAT5E

172

ARTICLE INFORMATION:

*Corresponding Author: fateh4582@gmail.com

Received 30

Dec, 2016

Accepted after revision 12

March, 2017

BBRC Print ISSN: 0974-6455

Online ISSN: 2321-4007

Thomson Reuters ISI ESC and Crossref Indexed Journal

NAAS Journal Score 2017: 4.31 Cosmos IF : 4.006

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Online Contents Available at: http//www.bbrc.in/

Biosci. Biotech. Res. Comm. Special Issue No 1:172-180 (2017)

Ali Akbar Rasouli et al.

BIOSCIENCE BIOTECHNOLOGY RESEARCH COMMUNICATIONS EFFECT OF PLANTING DATE CHOICE ON THE VULNERABILITY OF WINTER WHEAT TO CLIMATE CHANGE 173

INTRODUCTION

Winter Wheat is one of the strategic agricultural prod-

ucts of Iran. This variety of wheat has the best yield and

quality in north-western provinces of country, includ-

ing West and East Azerbaijan, Ardabil, Zanjan, Kord-

estan and Hamedan. Despite the fact that the mentioned

region has the area of 17578000 acres or nearly 16.3%

of the country area, the area under cultivation of win-

ter wheat in these provinces consist about 40% of total

wheat cultivating farms in the country or about 2411000

acres. This implies that the region is prone of cultivating

wheat (and also other agricultural products) about 2.3

times more than other parts of country.

Another fact that veri es this is fraction of area under

cultivation of wheat per total province area. Among 31

Iranian provinces, ranking of this statistic shows that all

the provinces in selected area rank below 10, including

 rst rank in country, Hamedan Province with 21.2% of

its area under cultivation of wheat, Second rank Arda-

bil Province with 20.0%, rank 4 Kordestanprovince with

18.4%, rank 6 Zanjan provinces with 14.1% and  nally,

rank 9 and 10 East and West Azerbaijan provinces with

9.7% and 9.6% respectively.

Although the most important source of impact on

yield of wheat, especially in dry farming, is adequate

and timely precipitation, the climate change and global

warming plays an undeniable role on long-term trends

and attitudes toward choice of new places for building

farms to answer the consistently increasing demand for

this strategic product.

Choice of planting date is also a key factor and is

studied to assess its impact on yield of many crops,

specially wheat and maize. (Gomez-Macpherson and

Richards,1995; Radmehr et al., 2003; Turner, 2004).

For example Epplin et al. (2000) showed that a 3-week

change in planting date of winter wheat, from 1 to 21

September is associated with an expected 44% increase

in grain yield but the foliage yield drops 68%.

Tsimba et al. (2013) studied the effect of planting

date on maize phonological stages in cool temperate

sites across New Zealand. They showed that emergence-

anthesis duration was longest for the earliest plantings,

averaging 890°Cd vs. 830°Cd for the latest plantedcrops.

Conversely, grain  lling duration was shortest for the

earliest or latest plantings (1220°Cd) vs. 1270°Cd for

optimum plantingdates.

Roshan et al. (2013) studied present and future cli-

mate projections over the region ofwheat production

over Iran. Observedclimate (temperature and degree

day) changes during theperiod (1951–2009) is discussed

andprojected futurechanges up to 2100 based on the

MAGICC/SCENGEN 5.3compound model was utilized.

It was concluded that the wheat growthperiod will be

negatively affected due to the increase ofthe tempera-

ture. The growth period is expected to be shorterby 21.3,

22.3, 23.9, 26.7, and 32.3 days for the northern,western,

central, southern, and eastern regions by the year

2050.

Andarzian et al. (2014) studied 4 stations in Khuz-

estan province, Iran to determine optimum sowing date

using Cropping System Model (CSM)-CERES-Wheat

model. Themodel was run for 8 sowing dates starting on

25 October and repeated every 10 days until 5 January.

They assessed the performance of model based on dif-

ferent statistics anthesis date, maturity date, grain yield

and biomass compared to observed data.

Waha et al. (2012) studied management measures for

adaption to impacts of climate change in Sub-Saha-

ran Africa, including dual cropping system of maize-

groundnut and choice of optimal planting date. They

suggested that even though cropping system modi -

cation can reduce negative impacts of climate change,

but it requires knowledge, labor, enough time for soil

preparation and market and also adds up the risk of fac-

ing non rainy seasons. Instead, farmers can adapt sow-

ing date to the start of the mainrainy season, which has

showed good results in Northern provinces of South

Africa nad Cameron.

Dobor et al. (2016) strived to develop a mechanism

to optimal choice of planting date. PD data from 294

agricultural enterprises in Hungary during the period

from 2001 to2010 were used to validate the PD methods.

Effect of climate change on the timing of PD was evalu-

atedusing an ensemble of 10 climate change projections.

Their analysis predicts a shift to earlier PDs for maize

(approx. 12 days) and laterPD for winter wheat (approx.

17 days) for the 2071–2100 period. The results indicated

that maize PDsshould be changed according to the ear-

lier start of the growing season in spring. In contrast,

currentlyused PDs should be preserved for winter wheat

to avoid climate change related yield loss. Proposed PD

estimation methods performed better than other eight

tested methods.

In a Mediterranean type environment the correct

choice ofsowing date and cultivar are critical determi-

nants of yield (Connoret al., 1992). Sowing date may

normally occur within a ‘sowingwindow’ starting with

the  rst signi cant rainfall after summerand closing

when a sowing date would be too late to achieve area-

sonable yield. It is general practice in most Mediterrane-

anenvironments to sow at the beginning of the rainfall

season inautumn if the frost risk for anthesis is low with

such an earlysowing date. The advantages of this prac-

tice have been widelyshown through  eld experiments

and crop simulation models(Stapper and Harris, 1989;

Shackley and Anderson, 1995; Henget al., 2007; Asseng

et al., 2008).

Ali Akbar Rasouli et al.

174 EFFECT OF PLANTING DATE CHOICE ON THE VULNERABILITY OF WINTER WHEAT TO CLIMATE CHANGE BIOSCIENCE BIOTECHNOLOGY RESEARCH COMMUNICATIONS

Early sowing dates increase theinterception of solar

radiance of a crop, allowing it to accumulatemore dry

matter (Stapper and Harris, 1989), and avoid terminal-

drought at the end of the growing season. This prac-

tice isconsidered less feasible where frost risk during

later winter/earlyspring is too high (Connor et al., 1992;

Anderson et al., 1995), but ifappropriate cultivars are

available, the risk of frost damage can beminimized

(Stapper and Fischer, 1990).

In this article, adaptable planting date strategy is

studied over cool temperate region of north-western

Iran, affected by Mediterranean weather systems, using

8 scenarios beginning from 26 September, each with 7

days lag. The trend in four phenological stages beside

total Length of Crop Season (LCS) as a measure of inten-

sity of the effect of climate is calculated in 27 stations

in the region.

MATERIALS ANDMETHODS

The  eld statistics shows us that almost 90% of farms in

north-western Iran are planted in the  rst two months

of autumn from 22 September to 20 November. As the

meteorological conditions vary with yearly date, correct

choice of planting date is a key factor to avoid threats

in different growing stages of the plants and reach

best quality and quantity of product. In this article, 27

synoptic stations with complete data series available

for 25 years from agricultural year 1989-90 to 2014-

15 are studied. To show the effect of choice of planting

date, 8 scenarios, each one with 7days additional lag,

are designed for planting date, beginning from 26 Sep-

tember every year. Four reference phenological stages

are selected based on GDD received in each stage in

each year and the length of stage is calculated. A trends

analysis is performed on each stage for each scenario.

The absolute shift of trend in each stage and total trend

existing in sum of length of stages as Length of Crop

Season (LCS) is described as statistics showing vulner-

ability to climate change and summarized to show its

behavior spatially and temporally.

The duration of the length of crop season (LCS) and

of the crop development phases was simulated using the

concept of growing degree days (GDD,°C day−1) adopt-

ing the approach described inRaes et al. (2012):

Where and are maximum and minimum air

temperature,respectively, and T

base

refers to the base tem-

perature, considered equal to zero for winter wheat. The

GDD required for achieving initial stage of growing of

wheat is considered 400

C, for Anthesis stage equal to

1250

C, for Maturity stage 1900

C and  nally the Har-

vest stage 2150

C, summing up from the planting date.

Calculating lengths of different stages for 27 selected

stations in 25 years of studying period considering 8

different scenarios for planting date,results in 17024

 gures. After that, statistics including mean, standard

deviation, coef cient of variation of lengths of each

period and trend (

C/year) and Pearson product moment

are calculated for 648 states in 4 different stages of 8

mentioned scenarios.The Length of Crop Season is the

sum of lengths of 4 stages of growth mentioned.

So the total trend observed in LCS is also equal to sum

of trends observed in each growing stage. Dependency

of Lengths of each period besides the total LCS is stud-

ied. Whether the trend of the length of each period is

related to selection of planting date is determined as the

measure of effect of date of planting scenario choice on

vulnerability to climate change.

RESULTS AND DISCUSSION

Assuming choice of a speci c scenario and averaging

resulted LCSs for each station, we observe a possible.

FIGURE 1. The area of study and 27

stations selected

(1)

(2)

Ali Akbar Rasouli et al.

BIOSCIENCE BIOTECHNOLOGY RESEARCH COMMUNICATIONS EFFECT OF PLANTING DATE CHOICE ON THE VULNERABILITY OF WINTER WHEAT TO CLIMATE CHANGE 175

FIGURE 2. LCS and its trend according to

Scenario 1

FIGURE 3. LCS and its trend according to

Scenaio 2

FIGURE 4. LCS and its trend according to

Scenario 3

FIGURE 5. LCS and its trend according to

Scenario 4

Ali Akbar Rasouli et al.

176 EFFECT OF PLANTING DATE CHOICE ON THE VULNERABILITY OF WINTER WHEAT TO CLIMATE CHANGE BIOSCIENCE BIOTECHNOLOGY RESEARCH COMMUNICATIONS

FIGURE 6. LCS and its trend according to

Scenario 5

FIGURE 7. LCS and its trend according to

Scenario 6

FIGURE 8. LCS and its trend according to

Scenario 7

FIGURE 9. LCS and its trend according to

Scenario 8

Ali Akbar Rasouli et al.

BIOSCIENCE BIOTECHNOLOGY RESEARCH COMMUNICATIONS EFFECT OF PLANTING DATE CHOICE ON THE VULNERABILITY OF WINTER WHEAT TO CLIMATE CHANGE 177

CHART 1. Change of observed trend in LCS with

changed scenario of planting date in 27 selected

stations

CHART 2. Length of mean crop season according

to each scenario on 27 selected stations

CHART 3. As in Chart 1 for initial stage

Whether or not the trend is meaningful can be tested

statistically but is beyond the scope of this article. Here

we classify trends below -2days/year as classi ed as

“Large negative trend” implying rapid (and even obvi-

ous) shrinking of LCS period. Other trends below -1

are classi ed as Medium Negative, below 0 as “Small

negative’, below +0.7 as “small positive” and below

1.6 as “Medium positive”. The more negative the trend,

the more shrinking of LCS which inherently results in

CHART 4. As in Chart 2 for initial stage

CHART 5. As in Chart 1 for Anthesis stage

CHART 6. As in Chart 2 for Antesis stage

CHART 7. As in Chart 1 for Maturity stage

Ali Akbar Rasouli et al.

178 EFFECT OF PLANTING DATE CHOICE ON THE VULNERABILITY OF WINTER WHEAT TO CLIMATE CHANGE BIOSCIENCE BIOTECHNOLOGY RESEARCH COMMUNICATIONS

CHART 8. As in chart 2 for Maturity stage

CHART 9. As in Chart 1 for Harvest Stage

CHART 10. As in Chart 2 for Harvest Stage

less available sun hours and less quality and yield. This

can be avoided by better choice of planting date if this

selection results in smaller absolute observed trend and

therefore, more stable conditions climatically.

The obvious shortening of LCS with adding lag to

planting date scenario which is aunfavorable result,

despite the other obvious  nding that the trends are

damped when adding to planting date lag scenario

which seems to be a favorable one.

As the chart 1 shows, all stations face positive change

in trend of LCS when adding to scenario date. Ardebil

station is least affected and Sahand station the most.

Nahavand station has positive trend and reaches the

maximum value. Also Zarrineh station showed a shift

from negative to positive trend on scenario4 (planting

on 17October). Almost all other stations move toward

zero trend when choosing scenario 5 to 8. Also the mean

observed LCS is lowered between 15 days in Parsabad

station to 35 days in Zarrineh station when postponing

the planting date.

This result is the sum of effect on phonological grow-

ing stages. Similar analysis on stages is performed and

results are depicted on charts.

Initial stage of growth shows completely different

results for different stations. Nahavand station shows a

constant increase with adding to lag scenario. It moves

from -0.5 negative trend to +1.5 days/year. For Sarab,

Khalkhal and Zarrineh stations, trend becomes large

negative in  rst scenarios and diminishes in scenarios 5

to 8. Sardasht, Ardebil and Piranshahr stations show a

constant move toward large negative trends. The other

stations, begin from zero trend, reach a maximum posi-

tive trend on scenario4 (17 October) and continue to

medium negative trends on scenarios 5 to 8.

Also the mean observed Length of initial stage is

added between 50 (in Parsabad station) to 110 days

(in Zarrineh station) when postponing the planting

date.

Trend existing in the length of Anthesis stage also

shows different behavior in different stations. Some of

stations, very cold in climate, show a peak in  rst plant-

ing scenarios like Zarrineh, Khalkhal, Sarab. They reach

near zero trend in this stage for last scenarios of plant-

ing. Some other stations like Sardasht, Ardebil, Piran-

shahr and Maragheh reach their peak in last scenarios

showing a maximum positive trend there, meaning

sharp elongation of length ofanthesis stage if planting is

postponed a lot. Others show a minimum trend on sce-

nario 4 and reach near zero trend on last stages. Among

these, Sahand station shows maximum descent, obvi-

ously more than other stations. Totally, adding to trend

for all stations when selecting late planting scenario can

be con rmed visually. Also the mean observed Length

of Anthesis stage lowered between 40 days in Parsabad

station to 120 days in Zarrineh, Bijarand Takabstation

when postponing the planting date.

The mean observed Length of Maturity stage low-

ers between 30 days in Parsabad station to 5 days in

Zarrineh station when postponing the planting date.

Sahand station shows a peak on scenario 3 but returns

to normal situation on last scenarios. It can be said that

except Ardebil station that remains indifferent to selec-

tion of planting scenario, all stations converge to about

Ali Akbar Rasouli et al.

BIOSCIENCE BIOTECHNOLOGY RESEARCH COMMUNICATIONS EFFECT OF PLANTING DATE CHOICE ON THE VULNERABILITY OF WINTER WHEAT TO CLIMATE CHANGE 179

32 days in late scenarios and totally, less vulnerability

is observed to planting date selection. The same condi-

tion is obvious in trends chart with maximum descent

of trend in Parsabad and Sardasht stations and near zero

trend in late scenarios.

The mean observed Length of Harvest stage lowers

between 4 days in Parsabad station to 5 days in Zarrineh

and Takab stations when postponing the planting date.

Sahand station shows a different sharply descending

behavior but returns to normal situation on last sce-

narios. It can be said that except Ardebil station that

remains indifferent to selection of planting scenario, all

stations converge to about 11 days in late scenarios and

totally, less vulnerability is observed to planting date

selection. The same condition is obvious in trends chart

with maximum descent of trend in Parsabad and Ascent

in Maragheh and Zarrineh stations and near zero trend

in late scenarios.

CONCLUSION

In this article, 27 stations in 6 north-western provinces

of Iran, which are prone of cultivating winter wheat, are

studied. The magnitude of observed trend in 4 pheno-

logical stages (Initial, Anthesis, Maturity and Harvest)

are calculated based on required Growing Degree Days

on 25 years period from Crop Season of year 1989-90 to

2014-15 according to 8 planting date scenarios begin-

ning from 26 September with 7 days lag between sce-

narios.

The results show that Anthesis stage is most vulner-

able to climate change. Initial stage is in second rank

and the last stages of maturity and harvest seems to be

indifferent to planting date choice. The trend in total

Length of Crop Serason (LCS) becomes more positive

when postponing planting date. This implies diminish-

ing of negative trend in case of planting on 26 Sep-

tember, except of Nahavand station that faces a posi-

tive trend in late planting scenarios and Zarrineh station

that shift sign of trend on scenario 4. Even though this

 nding shows more stable conditions if late plant-

ing is chosen, obvious decrease in total crop length

season for all stations, which is negative in the sense

that it means shorter photoperiod, less quality/quan-

tity product and also adding the risk of facing frost in

Anthesis stage, planting in October is suggested to be

better.

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