Agronomists and Biotech Traits

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biotech traits

in maximizing

the potential o

The role o

ScienceScience

4 CSA News June 2011

by Madeline Fisher


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June 2011 CSA News 5

Fred Below already thinks cornis pretty perect. Just lookat its innate versatility and

responsiveness to management, saysthe ASA and CSSA member, and

its easy to see why its our highest-yielding crop.

But even perection can beimproved upon sometimes, andtoday genes rom other organismsare giving corn a boost. Since 1996,when genetically modied hybridsthat kill the European corn borer

by producing toxins rom the Btbacterium were introduced, theensuing bump in yield has broughtan estimated $7 billion to armersin ve states, according to a 2010report in Science. Below, a plant

physiologist at the University o Illi-nois in UrbanaChampaign, is evenmore excited about the Bt rootwormtrait, which combats rootworm in asimilar way. Not only is the pest the

most damaging one in his state, hesays, but the benets o healthier,longer-acting roots in corn could bevast.

To my mind, its sort o the

game-changer, Below says, be-cause all o a sudden, almost all theinvestment that the plant made inthe root system is protected.

Even though Below recognizesthe power o biotech traits, he isamong a growing group o research-ers who believe were putting toomany hopes and too much emphasison biotechnology today. A look atthe trend in ederal research dollarssays it all: Funding or elds like ge-nomics and molecular genetics hasskyrocketed in recent years, whilemoney or applied, agriculturalresearch has stagnated.

Some government ocials andseed companies have also madepredictions that echo those und-

ing trends, much to the dismay oagronomists. In one ot-quoted 2009research report in the journal PlantPhysiology, or example, the authorsestimate that biotechnology and

molecular marker-assisted breed-ing will make greater and greatercontributions to corn yield over thenext 20 yearsrom roughly 1 ton/acre now to nearly 10 times that by2030. Meanwhile, they predict thatagronomys impact will remain fatat just under 5 tons/acre, or 25% othe total yield by 2030.

Others (agronomists, not surpris-ingly) put agronomys contributionto yield gains closer to 50%. Butarguing percentages isnt really thepoint, Below says. It doesnt matter

i you have better biotech traits iyou dont take advantage o themand know how to manage them.Thats where the void is, really.Theres a huge void there.


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A More Balanced, Integrated

Approach to Enhance Yields

He and others around the countryare now calling or a return to a more

balanced and integrated approach toenhancing crop yields in the com-ing yearsone that brings to bear allthe ingenuity and technology we canmuster, including conventional breed-ing, novel tillage systems, innova-

tive machinery, advanced agronomicknowledge, and, yes, biotechnol-ogy. Ater all, this is how scientistsachieved the rst Green Revolutionand the tremendous yield gains o thepast 50 years: by deploying a wholeseries o innovations, including bettergenetics, irrigation, nitrogen ertilizer,integrated pest management, high-precision plantersthe list goes onand on.

There is no magic bullet, saysASA and SSSA Fellow Paul Fixeno the International Plant NutritionInstitute. I dont care i youre talkingabout genetics, or plant protectionproducts, or anything else. There is nosingle solution to the challenge thatagriculture is acing to an increasingextent as we look to the uture.

Most scientists agree that the

challenge o the uture is immense.The global population is predicted toplateau at around 9 billion people by2050a staggering number consider-ing that one in seven people todayare already hungry, according to theUnited Nations Food and AgricultureOrganization. At the same time, urbandevelopment and industrialization areexpected to consume more than 100million hectares o arable landanarea roughly three times greater thanthe current corn acreage in the UnitedStates. And we can orget about ex-

panding agriculture onto new lands,says ASA, CSSA, and SSSA Fellow

Ken Cassman, an agronomist at theUniversity o NebraskaLincoln. Mosto those let today are either marginalor agriculture, meaning they losenutrients and soil when armed orhigh yields, or theyre carbon-richecosystems, such as rainorests orsavanna, which release huge amountso greenhouse gases when plowed.

Add it all up, Cassman says, andthe bottom line is that average cropyields will need to increase exponen-tially by 1.3 to 1.4% per year over thenext 40 years, while production isheld to existing armlands. Annualincreases o this magnitude may notseem like much, and in act, globalmaize yields are growing at about this

rate. But rather than being exponen-tial, past yield gains in corn and othercrops have been linear, meaning thatthe relative rate o gain declines overtime as average yields rise, Cassmanexplains. From 1961 to 1990, or ex-ample, yields per hectare o soybeans,rice, and maize grew annually at rateso 2%, while rates or wheat were ashigh as 3%. Since 1990, though, thoserates have dropped below 1% or allcrops except corn.

The point is that current rates ogain are already below the rate o gainwere going to need i were goingto hold agriculture to existing arableland, he says.

The numbers are sobering enough,but Cassman has also seen thechallenges rsthand. In addition toworking on all the major crops inthe United States, he studied riceproduction throughout Asia or theInternational Rice Research Instituteduring the 1990s. He also witnessedthe conversion o virgin rainorestto cropland while stationed or a

time in the Amazon Basin. Throughthose experiences, he says that twothings became very clear. For one, theamount o land that can support high-yield agriculture is much smaller thanwe think, especially i we also hope toprotect carbon-rich areas like rain-

orests. And second, its veryhard to grow high-yield crops

consistently, he says.Very, very hard.

Pho

tocourtesyoftheUniversityofArkansasDivisionofAgriculture.


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What makes the task so dicult isthat yield is never determined simply

by genetics or any other single actor,although we seem to be orgetting thisin our excitement over biotechnologyand genomics, says ASA Fellow andPurdue University agronomist TonyVyn. Instead, yield always emergesrom complex interactions amongcrop genotype, the way that geno-type is managed in the eld, and themyriadand unpredictableenvi-ronmental conditions that can limitproduction, including rainall, pests,and nutrients. Enter the agronomist,whose job is to understand and bal-

ance all those actors. Ultimately, I

think the agronomist has to be theintegrator, Vyn says, who deciphersthe management approach that bestresolves the specic abiotic and bioticstress actors that limit yield or agiven genotype in a specic produc-tion environment.

Without that management exper-tise, new cultivars are like race carsequipped with powerul and highlyecient engines, but which neverreach top speed because they arenttaken out on the open road, says ASA

and CSSA Fellow Brett Carver, anOklahoma State University wheatbreeder. A new variety thats capableo yielding 60 bu/ac, or instance, willnever reach that potential i armerscontinue to grow it in a 30 bu/ac en-vironment. Youre never going to seethat race car go aster i you orce it todrive 25 miles per hour, Carver says.

High-Tech Management or

High-Tech Traits

Moreover, the main actor that putsthe brakes on yield shits constantly,adds Below. Its the law o the mini-mum: Identiying and removing onecritical limiting actor, such as disease,can allow armers to take a steporward in yielduntil they bump

up against the next limitation, say

lack o a micronutrient. This tradi-tional approach to raising yield works

ne in general,Below says; however,when the goal is to reacha whole new yield level, itsnot enough. Now, we need tomanage a bunch o things together,he says, which is precisely the idea

behind the high-technology pack-age o ve optimized managementpractices and inputs that he and hiscollaborators recently put together.

The package is expressly designed

to exploit new biotech traits in corn;specically, so-called triple-stack orsmart-stack genetically engineeredhybrids that simultaneously tolerateRoundup and ght corn borer androotworm. But true to his systems phi-losophy, Below combined the hybridswith our high-tech agronomic prac-tices that are known individually toenhance yield, such as planting cornat high densities and applying a oliarungicide at fowering to control leadisease and relieve plant stress.

In 2009 and 2010, his research teamthen examined the ability o the entire

Ultimately, I think the agronomist has to

be the integrator who deciphers the

management approach that best resolves

the specific abiotic and biotic stress

factors that limit yield for a given genotype

in a specific production environment.

PhotobyStephenAusmus(USDA-ARS).


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package to increase yields acrossmultiple sites in Illinois comparedwith a traditional management systemthat contained none o the high-techcomponents. To urther understandhow each individual actor contrib-uted to yield, they also employed anomission plot design, in which theyadded each practice one by one tothe traditional system or subtracted

them one at a time rom the high-techsystem.

They ound that while the rela-tive importance o each actor variedacross years and sites, the value o asingle component was always greaterwhen combined with the others in theull package than it was on its own.Although the results have yet to bepublished, they support Belows hy-pothesis that no single tool, no matterhow powerul, will get us where we

want to goand that includes biotech.Rather its the synergies now o

better genetics, better ertilizers, andprotection chemicals like ungicides,he says. All o those things multiplytogether.

In studies o the eects o plantpopulation number and nitrogenrate on corn yields and nitrogen useeciency, Vyn too, has ound that the

Bt rootworm trait cannot by itsel al-leviate the added nitrogen stress thatcorn plants experience when crowdedtogether at high densities. Thats notto say the trait has no value, he cau-tions. However, the results do suggestthere is no inherent yield advan-tage associated with Bt rootwormresistance, he says, that renders thegenotype suddenly more able to takeup nutrients, or example.

Farmers may see yields climb withthe trait, however, i theyre grow-

ing crops in areas where rootwormpressure is high (something that was

not the case in most o Vyns experi-ments). But protecting yield in thisway is not the same as pushing yield,Below says. For that, you need anintegrated, agronomic approach. Yes,youll get more yield with that traitalone it youre losing yield due to theinsect, he says, but youll not getmore yield than you would have in theabsence o the insect, unless you man-age the trait.

Intelligent Intensifcation

I we do learn to manage biotechtraits properly, Below is ully con-dent that we can push corn yieldsabove ambitious targets, such as 300

bu/acthe much talked about goalthat growers are aiming or by 2030.And, in act, entrants in the NationalCorn Growers Associations annualcorn yield contest are already hittingthat mark. But reaching those levelstoday also requires a no-holds-barred,throw-every-input-at-it approach. Thetrick in the uture will be to hit thesetargets without degrading the planetwith more ertilizers, pesticides, ero-sion, and greenhouse gas emissions.Now its about intelligent intensica-tion, Below says. Using the inputs

in the right way and the right place.

Fortunately many researchers arealready studying the impacts o agri-culture on the environment with aneye toward reducing armings oot-print, just as many others are workingon ways to increase productivity. Theproblem is that the two groups arentworking together to achieve bothgoals at the same time, Cassman says.Thus, or more than a decade he has

been calling or a strategy o ecologi-cal intensication that unites many

disciplinesincluding plant physiol-ogy, agroecology, and soil scienceinachieving consistently high yieldlevels while simultaneously workingtoward long-term agricultural sustain-ability.

For example, Vyn says, uturestudies o corn hybrids thatpossess drought tolerance

traits ideally will involvea range o scientists, in-

Pho

tocourtesyofUSDA-ARS.


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cluding crop physiologists who studyplant stress tolerance in the contexto interacting actors, such as plantdensity; meteorologists who look attranspiration and water use eciency;and soil scientists who examine car-

bon sequestration and trace gas emis-sions in rain-ed systems where yieldis being optimized with nutrients.

Fixen, or his part, calls this a sys-tems approachone that considers allo the interacting aspects o agricul-tural ecosystems and doesnt get toohung up on the magic bullets, such

as genomics or biotech. Its a mattero looking at all o the resources atour disposal, which are connected toagricultures ability to do what society

wants us to do, he says, and thenoptimizing the whole package.

What Will It Take to Get

There?

The remaining question is whatwill it take to get there? First andoremost, the scientists agree that weshould not only be producing manymore agronomic scientists overall, butmore critically, researchers who are

broadly trained to handle the com-

plexities o modern day agriculturalproblems and nd integrated solu-tions. Driven by trends in unding, ag-ricultural students today oten ocusinstead on narrow objectives, Fixensays, such as measuring greenhousegas emissions. Its a development thatworries him. We still need specialists,dont get me wrong, he says. Butwe also need people who can put allthe parts together to simultaneously

accomplish production and environ-mental objectives.

But achieving broad training o stu-dents requires money or this type oresearch, o course. And while Fixensees the USDA Agriculture and FoodResearch Initiatives (AFRIs) sup-port o large, regional, interdisciplin-

ary projects as a big step in the rightdirection, more unding is desperatelyneeded.

Thats why at an even moreundamental level, we must set the

proper goal, Cass-man says. The past 30years o abundant oodhave given us the luxury ochasing scientic questionsthat, although interesting and impor-tant, are likely never to bring to usthe same agricultural bounty in theuture. So its time now to ask or ashit in scientic priorities: specicallytoward those that will achieve a 70%increase in yields on existing arm-

lands while also dramatically reduc-ing agricultures negative environ-mental impacts.

I everyone demanded this kind oresearch along with evidence that itwas producing results, I guaranteeyou, we would see a dierent researchagenda, Cassman says. There wouldstill be some research on transgenicplants and genomicswe need thosetools, theres no question. It would

just be a smaller portion.

M. Fisher, CSA Newsmagazine leadwriter; [email protected]

We still need specialists, dont get mewrong. But we also need people who can

put all the parts together to simultaneously

accomplish production and environmental

objectives.

PhotoonoriginallysubmittedwithaCropSciencearticlebyNormanTaylor(2008;48:1-13).

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