Structure and Function in Agroecosystem Design and Management - Chapter 19 pps

CHAPTER 19Effects of Climatic Change in Finland on Growth and Yield Formation of Wheat and Meadow Fescue Kaija Hakala CONTENTS Climatic Change.. 405 Effects of Simulated Climatic Change

CHAPTER 19

Effects of Climatic Change

in Finland on Growth and Yield Formation of Wheat and

Meadow Fescue Kaija Hakala

CONTENTS

Climatic Change 398

Climatic Change in Finland 398

Agriculture in Finland Today 399

Implications of Climatic Change for Finnish Agriculture 400

Effects of Climate Warming and Increased CO2Concentration on Growth and Yield of Wheat (Triticum aestivum L., cv Polkka) and Meadow Fescue (Festuca pratensis Hudson, cv Kalevi) — A Case Study 404

Simulation of Climatic Change 404

Determinations 405

Effects of Simulated Climatic Change on Photosynthesis and Rubisco Content of Wheat and Meadow Fescue 406

Effects of Climatic Change on Yield and Yield Quality of Wheat and Meadow Fescue 408

Wheat 408

Meadow Fescue 410

Conclusions 415

References 415

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CLIMATIC CHANGE

Short-wave solar radiation—part of UV-B, UV-A, visible light, and infrared tion—penetrates this layer The long-wave heat radiation from the Earth tothe atmosphere is, however, partly absorbed by the greenhouse gases TheEarth’s atmosphere is thereby warmed In this way, the temperatures on theEarth are high enough to maintain life in its present form

radia-Human activities are increasing the concentrations of greenhouse gases,

and through land use changes that release carbon bound in trees and soil The

addi-tion to this, the concentraaddi-tions of halogenated hydrocarbons, such as CFCs,have increased These are long-lived gases which will stay in the atmospherelong after their emissions have stopped They are very effective in absorbingthe long-wave heat radiation of the Earth On the other hand, they destroythe stratospheric ozone layer, which has an opposite effect on the radiationbalance The increase in the greenhouse gases caused by human activity isabout to lead to warming of the climate According to a report of theIntergovernmental Panel on Climate Change (IPCC, 1998), the mean annualtemperature on the Earth may increase by 1–3.5°C by 2100 At the same time,there may be big spatial and temporal changes in precipitation, and the meansea level may rise by 15–95 cm

CLIMATIC CHANGE IN FINLAND

A scenario of climate change in Finland (the central scenario, assumingcentral emissions and central climate sensitivity; Carter, 1996) states that the

4.4°C higher than now by the year 2100 According to the scenario, tion will increase by 11% and the sea level will rise 45.4 cm by 2100 Because

the temperature 1.2 and 2.4°C higher by 2020 and 2050, respectively (Carter,1996) While the average temperature will increase 0.4°C per decade, theincrease is greatest (0.6°C) in winter and smallest (0.3°C) during the growingseason

The increase in the mean temperature will also affect the length of thegrowing season According to the scenarios of Carter (1996, 1998), the grow-ing season would be 25 days longer than at present in southern Finland(Turku) and 23 days longer in northern Finland (Kajaani) by 2050 With anincrease in temperature of 4°C (approximately by the year 2100), the growingseason would be 48 days longer in southern Finland (Turku) and 37 days

longer in northern Finland (Kajaani) than at present (Tim Carter, personalcommunication) (Growing season is defined here so that it starts when theaverage daily temperature stays permanently above 5°C, and ends when thetemperature stays permanently below 5°C.) In 2050, with 2.4°C higher aver-age temperature, the growing season would start 10 days earlier in bothsouthern and northern Finland and end 15 and 13 days later than at present

in southern and northern Finland, respectively With 4°C higher temperature,the growing season would start 21 and 16 days earlier and end 27 and 21 dayslater than at present in southern and northern Finland, respectively (TimCarter, personal communication) The increase in growing season length may

be greater than when defined solely by the 5°C-threshold temperature Atpresent, even when the mean temperature has permanently risen over 5°C,the sowings of the spring cereals have to be delayed because of deep groundfrost, or because the ground is too wet and soft to carry heavy agriculturalmachinery In the warmer future climate, ground frost may be absent or meltearlier, and the ground may dry earlier because of shorter duration orabsence of snow cover

AGRICULTURE IN FINLAND TODAY

Agriculture in Finland is at present limited by low temperature and shortgrowing season In addition to this, late spring and early autumn frosts limitagriculture in areas where the average temperatures would be high enoughfor successful agriculture (Mela, 1996) Low temperatures may damage over-wintering crops, especially when the snow cover is thin during the winter

On the other hand, pathogens thriving under a thick snow cover also present

a major problem for overwintering crops Cultivation of spring-sown cereals,again, is often complicated by delay in sowing because of long duration ofsnow cover, ground frost, or too wet soil Because of late sowing (usually inearly May in southern Finland), the crops fail to benefit from the conditions

of high radiation in early spring In addition, the harvest of spring-sowncrops is often impeded by early autumn rain Because of the short growingseason, the varieties of spring-sown cereals cultivated in Finland are bred for

a short growing period The growing time and time for grain filling of thesevarieties are short, and they are thus less productive than varieties of cerealsbred for warmer climates, having slower growth rate and longer growingtime Despite the difficulties in cultivation of spring-sown cereals, they arenevertheless often preferred to autumn-sown cereals because of the unpre-dictable overwintering conditions

The area of Finland stretches from 60° to 70°N The great variation in tivation conditions in the different latitudes requires careful selection of cropsfor cultivation in the different areas The recommended cultivation area

cul-of many grass and potato varieties covers the whole cul-of Finland The

recommended cultivation area of cereals is, however, quite limited Thus,some barley and oats varieties can be cultivated up to the polar circle in thewest of Finland, where the Gulf of Bothnia warms the local climate.Otherwise, their cultivation is limited to areas south of 64°N Spring wheatand winter rye can be cultivated on areas south of 63°N, and winter wheat onareas between 61° and 62°N (Komulainen, 1998) The actual cultivation area

of spring wheat is depicted in Fig 19.1a

IMPLICATIONS OF CLIMATIC CHANGE FOR FINNISH

AGRICULTURE

Increase in growing season temperature and growing season length wouldexpand the cultivation area of crops With mean annual warming of 2.4°C (by

the year 2050), the regional suitability of spring wheat (Triticum aestivum) cv.

Ruso would shift 270 km north from the present baseline (calculated ity at present) in the west of Finland, and 460 km in the east (Figure 19.1c) The

suitabil-figures for spring barley (Hordeum vulgare, cv Arra) and oats (Avena sativa, cv.

Veli) would be 230 and 280 km north in the east and 340 and 500 km north inthe west, respectively Mean rate of shift to the north of these spring-sown cere-als by the year 2100 would be 45–58 km/decade (Carter et al., 1996)

However, when the growing season temperatures increase, the ment rate of the cereals increases (Saarikko and Carter, 1996) When this hap-pens between anthesis and yellow ripening, the time of grain filling becomesshorter This may lead to decreased yield because less time is available forcarbohydrate production through photosynthesis The effect of climatewarming on the duration of grain filling of spring barley (cv Pomo) is pre-sented in Figure 19.2, and the modeled effect on the yield in Figure 19.3

develop-In addition to the adverse effects on grain filling, increased temperaturesmay increase the occurrence of pests and pathogens in Finland For example,

a potato pest, potato cyst nematode (Globodera rostochiensis), may expand its

occurrence to Lappland, where it is not found at present (Carter et al., 1996).This and other pests and pathogens not known in Finland at present maycause yield losses of crop plants in the future warmer climate

also direct effects on plant growth Many investigations around the world

photosynthesis and biomass production (Cure and Acock, 1986).Experimental and modeling studies of Finnish crop plants have also shown

Carter et al., 1996; Hakala 1998a) An example of this is shown in Figure 19.2c.Yield loss caused by increased growing season temperatures (Figures 19.2aand b) is changed to yield gain with the projected concomitant increase of

Figure 19.1 (a) Actual cultivated area of spring wheat (Triticum aestivum) in 1990 as

a percentage of total arable land, (b) estimated probability of ful ripening (percent) for spring wheat cv Ruso under the baseline (1961 –1990) climate and (c) according to the climate change central scenario (Carter, 1996) with 2.4°C warming of climate Adopted from Carter et al., 1996.

success-Figure 19.2 Simulated change in duration of the phase heading to yellow ripeness

in barley (Hordeum vulgare) cv Pomo relative to the baseline climate

(1961 –1990) for the climate change central scenario (Carter, 1996) by (a) 2020 (1.2°C warming of climate), (b) 2050 (2.4°C warming), and (c)

2100 (4.4°C warming) Adopted from Carter et al., 1996.

Figure 19.3 Modeled grain yield (tn ha1) of barley (Hordeum vulgare) cv Pomo (a)

under the baseline climate (1961 –1990), (b) according to the climate change central scenario (Carter, 1996) by 2050 (with 2.4°C warming of climate), and (c) according to the central scenario of climate change by

EFFECTS OF CLIMATE WARMING AND INCREASED

CO 2 CONCENTRATION ON GROWTH AND YIELD OF

WHEAT (TRITICUM AESTIVUM L.,CV POLKKA) AND

MEADOW FESCUE (FESTUCA PRATENSIS HUDSON,

CV KALEVI)—A CASE STUDY Simulation of Climatic Change

Climatic change was simulated so that the temperatures were increased

during four growing seasons in 1992–1995 at Jokioinen, southern Finland

(60°49’ N, 23°30’ E) Spring wheat (Triticum aestivum L.) cv Polkka and meadow fescue (Festuca pratensis Hudson) cv Kalevi were grown under four

treatment regimes: (a) present-day conditions in the field; (b) conditions ofwarmer climate (temperatures 3°C above ambient); (c) conditions with

con-ditions of both warmer climate (temperatures 3°C above ambient) and higher

was based on the SILMU climate scenario developed for Finland (Carter,1996; central scenario), according to which, in about 100 years from now

the growing season temperatures 3°C higher than at present

To raise the temperatures above ambient (conditions of warmer climate),

(Hakala et al., 1996) The experimental field outside the greenhouse, senting the present-day conditions in the field (later referred to as the openfield), was covered at a height of 3–4 m with the same plastic film as was used

repre-in the construction of the greenhouse This resulted repre-in radiation conditionscomparable to those in the greenhouse The greenhouse temperatures wereregulated so that they were constantly 3°C higher than the temperatures in

experi-ments were conducted in open-top chambers (OTCs) The OTCs were big, 3

m in diameter, and 2 m high Each OTC was divided in half The northern halfwas occupied by the spring wheat stand, and the southern half used forexperiments with meadow fescue Four OTCs were set up in the greenhouse,and the same number in the open field In each location, two of the OTCs

replicates per treatment) In addition, two replicate plots similar to those withthe OTCs were sown in both temperature treatments, however with no OTC

on (open air plots) to study the chamber effect in the experiments (Hakala et

sown crops in 1992, 1993, and 1994, and after the beginning of the thermalgrowing season (before sowing of wheat) in 1995 The thermal growingseason was defined to begin after the average daily temperature of five

consecutive days had exceeded 5°C There was no CO2fumigation during thewinter.

The crops were sown 9–10 May in the open field, the normal sowing time

in the Jokioinen region To simulate the future conditions with average peratures 3°C higher than at present, and the growing season starting 2–3weeks earlier than at present (Tim Carter, personal communication), the cropswere sown about 3 weeks earlier inside the greenhouse than in the open field,

tem-as soon tem-as the thermal growing setem-ason had started in the greenhouse

The experiments were conducted on a heavy clay soil mixed with 1000

sea-sons 1994–1995, the clay-peat soil of the experimental site was replaced with

a lighter sandy loam soil brought from another field at Jokioinen During all

with a standard fertilizer (20% N, 6% P, 6% K), according to an analysis of thesoil nitrogen before sowing A detailed description of the soil and nutrientconditions is given in Hakala et al (1996) and Hakala and Mela (1996) Thecrops were sown directly in the field The sowing density of wheat was 600

exper-iment) For the same reason, the sowing density of wheat was lowered to 300

In 1992 and 1993, the meadow fescue canopies were cut at about monthlyintervals In 1994 and 1995, the cuttings were done each time the leaf areaindex (LAI) of the stand reached a value of 5, as measured with an automaticLAI meter (Licor, U.S.) Cutting according to LAI was adopted to make sure

accu-mulation of meadow fescue would not be affected by differences in thedegree of canopy closure An increase in the degree of canopy closure under

con-centration (Nijs et al., 1989) LAI 5 was chosen as the cutting LAI, becauseprevious investigations had shown that at this LAI the light interception ofthe sward is virtually complete, the net photosynthesis rate is at about maxi-mum, and the rate of dry matter accumulation of the sward has just reached

a steady maximum (Brougham, 1956; Robson, 1973a and b) It was assumed

depended on the rate of photosynthesis of the canopy Cutting according toLAI resulted in a different number of cuts being made in each treatment

Determinations

analysis system (ADC Co., England) The measurements were conductedthroughout the growing season, on sunny days, when the photon flux

density was not lower than 800 µmol photons m2s1 This photon flux sity was found to be close to light saturation for both wheat and meadow

ribulose-1,5-bisphosphate carboxylase-oxygenase (Rubisco) in the flag leaves of wheatand in the leaves of meadow fescue was measured in material collected in

1993 and 1994 The piece of the leaf where photosynthesis was measured wascut off after the measurement and immediately frozen in liquid nitrogen Theleaf pieces were kept in liquid nitrogen until the end of each measuringperiod and then stored at 80°C For determination of the content ofRubisco, the protein was separated by SDS-PAGE by the modified Laemmli(1970) method using 3.5% stacking gel and 13% separating gel Purifiedspinach Rubisco was used as standard The amount of Rubisco in the gelswas determined densitometrically after staining with 0.1% CoomassieBrilliant Blue R solution

Samples for the determination of biomass dry weight, leaf area, yield ponents, and nitrogen content of wheat and meadow fescue were collected inconnection with the cuts of meadow fescue and at anthesis and at harvest ofwheat The nitrogen content (% nitrogen of the dry weight) of the samples wasdetermined in 1992 with the Kjeldahl method using a Kjeltec System 1026Distilling Unit (Tecator AB, Sweden) Nitrogen content was not measured insamples collected in 1993 In 1994 and 1995, the nitrogen content was deter-mined with an automatic nitrogen analyzer, LECO FP-428 (LECO Corp., U.S.)

com-Effects of Simulated Climatic Change on Photosynthesis and Rubisco Content of Wheat and Meadow Fescue

(Schmitt and Edwards, 1981; Bowes, 1991; Sage, 1994; Nie et al., 1995; Rogers

et al., 1998) The reduction may be due to accumulation of carbohydrates inthe leaves in conditions where the sink for photosynthetic products is not inbalance with the source (photosynthesis) (Stitt, 1991) Reduction in the

sys-tem for the plants, while it allows them to invest the nitrogen released fromRubisco in processes limiting photosynthesis (e.g., light harvesting or elec-tron transport) and in growth (Sharkey, 1985; Stitt, 1991; Quick et al., 1992;Sage, 1994; Rogers et al., 1998) Rubisco makes up 50% of the total solubleprotein of plant leaves (Lawlor et al., 1989; Leegood, 1993) Therefore, a

content of crops Decrease in nitrogen content of grasses like meadow fescuemight decrease the nutritional value of their biomass as animal feed.Moreover, a considerable part of the nitrogen of wheat leaves is used as asource of nitrogen for the grain (Dalling et al., 1976; Waters et al., 1980;

Lawlor et al., 1989; Palta and Fillery, 1995) Therefore, a decrease in Rubiscoand thus protein content in the leaves of cereals might decrease the proteincontent of the grain and the baking quality of the flour milled from it.The photosynthetic activity of both wheat and meadow fescue increased

and in the present climate (ambient temperatures) (Hakala et al., 1999, Figure

meadow fescue The Rubisco content decreased in wheat under increased

Rubisco content not decreased in the flag leaves of wheat (Hakala, 1998a andb; Hakala et al., 1999) There was no change in Rubisco content connected with

a Wheat

b Meadow fescue

ambient temperatures

0 5 10

Figure 19.4 Mean rates of flag leaf photosynthesis of spring wheat (Triticum

aes-tivum L.) cv Polkka (a) and meadow fescue (Festuca pratensis Hudson)

tem-peratures) and in the simulated warmer climate (elevated tures) Combined data from all measurements in 1992 –1995.

meas-uring time are shown below the columns Bars on the columns indicate the standard error of mean Adopted from Hakala et al., 1999.