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Chapter 14

Sorghum Genetic Enhancement for ClimateChange AdaptationBelum V.S. Reddy, A. Ashok Kumar, Sampangiramireddy Ramesh, and Pulluru S. Reddy

Introduction

Sorghum [Sorghum bicolor (L.) Moench] is thefifth most important cereal crop and is the dietarystaple of more than 500 million people in over90 countries, primarily in the developing world.It is grown on 47 m ha in 104 countries in Africa,Asia, Oceania, and the Americas (Table 14.1).The United States, Nigeria, India, Mexico, Su-dan, China, and Argentina are the major sorghumproducers globally (http://faostat.fao.org/site/567/default.aspx#ancor, accessed February 11,2010). Sorghum grain is mostly used directlyfor food (55%) and is consumed in the form ofporridges (thick or thin) and flat breads; how-ever, sorghum is also an important feed grain(33%), especially in Australia and the Americas.Stover (crop residue after grain harvest) is animportant source of dry matter to both milch anddraft animals in mixed crop-livestock systems.Sorghum is also an effective source of greenfodder due to its quick growth and high yieldand quality. Of late, sorghum with sugar-richjuicy stalks (called sweet sorghum) is emergingas an important biofuel crop. Thus, sorghum is

a unique crop with multiple uses as food, feed,fodder, fuel, and fiber.

Yield and quality of sorghum is influencedby a wide array of biotic and abiotic con-straints. Significant biotic constraints include theinsects, such as shoot fly, stem borer, midge,head bug, aphid, army worms, and locusts, andthe diseases, such as grain mold, charcoal rot,downy mildew, anthracnose, rust, and leaf blight.Striga (Striga asiatica, Striga densiflora, Strigahermonthica) is a devastating parasitic weedfound in many regions of Africa and India.Abiotic constraints include: problematic soils,drought, and temperature extremes. Climatic andedaphic changes including variable precipita-tion, higher soil and air temperatures, and in-creased soil alkalinity and acidity driven byincreasing anthropogenic activities are becom-ing major global concerns threatening sorghumproduction.

This chapter examines the implications ofclimate change for major sorghum-growing ar-eas and production. Inherent characteristics ofsorghum to cope with climate change effects,the genetic options to mitigate climate change

Crop Adaptation to Climate Change, First Edition. Edited by Shyam S. Yadav, Robert J. Redden, Jerry L. Hatfield,Hermann Lotze-Campen and Anthony E. Hall.c© 2011 John Wiley & Sons, Ltd. Published 2011 by John Wiley & Sons, Ltd.

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SORGHUM GENETIC ENHANCEMENT FOR CLIMATE CHANGE ADAPTATION 327

Table 14.1. Sorghum area, production, and productivityin 2007 for countries with substantial area.

Area Production Yield(m ha) (m t) (t ha−1)

World 46.9 63.4 1.4Africa 29.5 26.1 0.9Americas 6.5 24.6 3.8Asia 10.1 10.8 1.1Europe 0.2 0.7 3.6Oceania 0.6 1.3 2.1Sudan 9.0 5.8 0.7India 8.5 7.2 0.8Nigeria 7.8 9.1 1.2Niger 2.8 1.0 0.3USA 2.7 12.6 4.6Mexico 1.8 6.2 3.5Burkina Faso 1.6 1.6 1.0Ethiopia 1.5 2.2 1.5Mali 1.1 0.9 0.8

Source: http://faostat.fao.org/site/567/default.aspx#ancor.

effects and future strategies for genetic improve-ment are discussed.

Climate change impacts onsorghum production

Global warming due to climate change will affectgrain and stover yields in crops, more so in trop-ical Africa and Asia where sorghum is a majorfood crop. Most climate change models predictrises in air and soil temperatures and sea levels,and increased frequencies of extreme weatherevents leading to unprecedented changes in agri-cultural production in the years to come (IPCC2007). Although both developed and develop-ing countries will be affected, developing coun-tries with little adaptive capacity and limited re-sources are more vulnerable to climate changeeffects. Desertification, shortages of fresh wa-ter, soil erosion, increased salinity, changed pestand disease scenarios, and biodiversity loss aresome of the factors that adversely affect agricul-tural productivity. Detailed implications of cli-mate change effects, resilience of populations,and coping mechanisms are not fully understoodin most countries in the semiarid tropics (SAT) of

Asia and Africa (Dar 2007; Cooper et al. 2008),which are traditional sorghum belts.

Predicted climate change effectson crop growth and yield in majorsorghum growing areas

The world climate is continuing to change atrates that are projected to be unprecedented inrecent human history. Global average surfacetemperature increased by about 0.6◦C duringthe twentieth century (IPCC 2007). Accordingto the Fourth Assessment Report (IPCC 2007),most of the observed increase in the global av-erage temperature since the mid-twentieth cen-tury has been attributed to the observed increasein anthropogenic greenhouse gas concentrations.The Intergovernmental Panel on Climate Change(IPCC) climate models predict an increase inglobal average surface temperature of between1.4◦C and 5.8◦C from 2001 to 2100, the rangedepending largely on the scale of fossil fuel burn-ing between now and then and on the differentmodels used. At the lower range of tempera-ture rise (1–3◦C), global food production mightactually increase, but above this range, it wouldprobably decrease (IPCC 2007). However, broadtrends will be overshadowed by local differ-ences, as the impacts of climate change are likelyto be highly spatially variable (Cooper et al.2008). Table 14.2 describes predicted changes in

Table 14.2. Predicted changes in temperature and rainfallin the major sorghum growing areas (based on regionalpredictions for A1B scenario for the end of the twenty-firstcentury).

Region Season

Temperatureresponse

(◦C)

Precipitationresponse

(%)

East Africa Oct–Dec +3.1 +11Mar–May +3.2 +6

Southern Africa Oct–Mar +3.1 −10West Africa Jul–Oct +3.2 +2South Asia Jun–Feb +3.3 +11

Source: IPCC 2007.



328 CROP ADAPTATION TO CLIMATE CHANGE

temperature and rainfall in major sorghum-growing areas.

Disaggregated effects of predictedchanges in temperatures andrainfall on sorghum yields

Preliminary cropping simulations exercises wereconducted at ICRISAT to assess the impacts ofclimate change on sorghum yields in SAT areasof Africa and Asia. The following four scenarioswere examined: potential grain yield with currentcropping constrained only by climate; percentchange in yield with current climate modified forpredicted changes in rainfall; percent change inyield with current climate modified for predictedchanges in temperature; and percent change inyield with current climate modified for pre-dicted changes in both temperature and rainfall(Table 14.3).

Initial simulations predicted that for any givenclimate change scenario, the impact of climatechange could vary both in nature and in mag-nitude from location to location, from crop tocrop, from cultivar to cultivar, and from sea-son to season. In general, the sorghum matu-rity period of current varieties decreases withincreased temperatures. Climate change effectsin terms of high temperatures and erratic rainfallmay drastically reduce sorghum yields in SouthAsia, Southern Africa, and West Africa (Cooperet al. 2008; Table 14.3).

The impact of climate change on insectpests will be felt in terms of increased produc-tion losses and reduced efficacy of management

strategies (Chakraborty et al. 2000). For all insectspecies, higher temperatures below the species’upper lethal limit could result in faster develop-ment rates, leading to rapid increase of pest pop-ulations as the time to reproductive maturity is re-duced. For example, an increase of 1◦C and 2◦Cin daily maxima and minima will cause codlingmoth (Cydia pomonella) to become active about10–20 days earlier than expected. Overwinter-ing of pests will increase as a result of climatechange, producing larger spring populations as abase for a build-up in numbers in the followingseason. There will be increased dispersal of air-borne pest species in response to atmosphericdisturbances. Many insects are migratory andtherefore may be well adapted to exploit new op-portunities by moving rapidly into those areas,which becomes increasingly favorable as a resultof climate change (Hill and Dymock 1989). Allthese possibilities have a significant bearing oncrop productivity.

Characteristics of sorghumthat help in coping withclimate change

Sorghum is a C4 plant with an extensive andfibrous root system enabling it to draw mois-ture from deep layers of soil. Sorghum requiresless moisture for growth compared to other ma-jor cereal crops; for example, in some studies,sorghum required 332 kg of water per kg of ac-cumulated dry matter, whereas maize required368 kg of water, barley required 434 kg, andwheat required 514 kg. Sorghum has the capacity

Table 14.3. Disaggregated effects of climate change on sorghum yields.

RegionPotential grainyield (kg ha−1)

Rainfalleffect on yield

Temperatureeffect on yield

Climate changeeffect on yield

East Africa short rains 3244 +10% +11% +21%East Africa long rains 2232 +6% +42% +48%Southern Africa 2753 −6% −16% −22%West Africa 1896 +6% −20% −14%South Asia 2800 +1% −38% −37%

Source: Cooper et al. 2008.




to survive some dry periods and resume growthupon receipt of rain (House 1985). Sorghum alsowithstands wet extremes better than many othercereal crops, especially maize. Sorghum contin-ues to grow, though not well, in flooded condi-tions; maize, by contrast, will die. Sorghum pro-duces grain even when temperatures are high.Inflorescence development and seed-set are nor-mal at temperatures of 40–43◦C and at 15–30%relative humidity, if soil moisture is available.Sorghum is not as tolerant of cool weather assome maize cultivars. Sorghum grows slowly be-low 20◦C, but germination and growth will occurin some varieties at temperature as low as 12◦C(House 1985).

Climate change adaptation andgenetic options

Climate change being a threat multiplier, suit-able strategies need to be urgently integratedinto national and regional sorghum improve-ment programs. Some of the adaptation strate-gies to address climate change impacts includedevelopment of better weather forecasting sys-tems, crop husbandry technologies and pest fore-casting and pest management technologies, andchanges in land use and water management sys-tems. Mitigation strategies may also include de-velopment of technologies to achieve improvedinput use efficiencies (such as fertilizer micro-dosing and need-based application of pesticidesfor pest management) but these involve recur-ring costs. Genetic management is considered asthe most cost-effective and eco-friendly optionto mitigate the adverse impact of climate changeon sorghum production. Unlike other adaptationstrategies, genetic options do not involve recur-ring costs. Genetic options should focus on rede-ployment of trait-specific germplasm and breed-ing for plant defense traits.

Redeployment of germplasm

Climate change will cause changes in the lengthof the growing period (LGP) in some regions.

The LGP is defined as the number of days inany given rainfall season, when there is suffi-cient water stored in the soil profile to supportcrop growth. The impact of climate change onthe likely change in the average LGP acrossAfrica has been comprehensively mapped byICRISAT using the General Circulation ModelHadCM3.B1 for the period 2000–2050 (Cooperet al. 2009). The study showed that the extentof global SAT areas will be changed through (1)SAT areas being “lost” from their driest mar-gins and become arid zones due to LGPs becom-ing too short or (2) SAT areas being “gained”on their wetter margins from subhumid regionsthrough the reduction in the current LGPs inthose zones. It means sorghum could be grown innew areas of the currently humid tropics wheresorghum is not grown at present. Large-scaleadaptation studies will be required to under-stand soil and climate conditions, pest scenar-ios, cropping systems, consumptions patterns,and markets in the new areas. International agri-cultural research centers (IARCs), agriculturalresearch institutes (ARIs), and national agricul-tural research system (NARS) with large reser-voirs of sorghum germplasm, breeding material,and commercial cultivars could play a significantrole in deploying suitable germplasm to the newareas. Several trait-specific, non-milo, and high-yielding female lines developed at ICRISAT, in arange of plant heights and maturities can be uti-lized in producing the hybrids that are of valueto different agroecological zones (Table 14.4).Development of crop cultivars with a maturityduration that matches the prevailing LGP will beone of the best strategies to cope with changesin LGP. Retargeting of traits of local importanceshould be undertaken by the NARS with the helpof other partners.

Drought tolerance

Four growth stages in sorghum have been con-sidered as vulnerable to drought: germinationand seedling emergence, postemergence or earlyseedling stage, midseason or preflowering, and




Table 14.4. Details of the sorghum trait-specific (milo) and non-milo A-/B-pairs developed atICRISAT-Patancheru.

S. No. ICSA numbers Traits Total lines

1 1–103 High yielding 77∗2 88,001–88,026 High yielding 15∗3 89,001–89,004 High yielding 44 90,001–90,004 High yielding 45 91,001–91,010 High yielding 106 94,001–94,012 High yielding 127 201–259 Downy mildew resistant 598 260–295 Anthracnose resistant 369 296–328 Leaf blight resistant 33

10 329–350 Rust resistant 2211 351–408 Grain mold resistant 5812 409–436 Shoot fly resistant (rainy) 2813 437–463 Shoot fly resistant (postrainy) 2714 464–474 Stem borer resistant (rainy) 1115 475–487 Stem borer resistant (postrainy) 1316 488–545 Midge resistant 5817 546–565 Head bug resistant 2018 566–599 Striga resistant 3419 600–614 Acid soil tolerant lines 1520 615–637 Early maturity lines 2321 638–670 Durra (large grain) lines 3322 671–687 Tillering and stay-green lines 1723 688–738 Non-milo (A2) cytoplasmic lines 5124 739–755 Non-milo (A3) cytoplasmic lines 1725 756–767 Non-milo (A4) cytoplasmic lines 12

Total 689

Source: Reddy et al. 2006.∗The number of lines being maintained.

terminal or postflowering. Terminal drought isthe most limiting factor for sorghum productionworldwide. In sub-Saharan Africa, drought atboth seedling establishment and terminal stagesis very common. In India, sorghum is grown dur-ing both rainy and postrainy seasons. The vari-able moisture availability at both prefloweringand postflowering stages during the rainy seasoncan have severe impact on grain and biomassyield. Climatic variability and associated geno-type × environment interactions do not permitclear definition of target environments. Opportu-nities to make progress in breeding for droughttolerance occur both in understanding the envi-ronmental control of crop growth and in devel-oping simplified approaches to modeling effectsof climate change (Bidinger et al. 1996).

Drought and/or heat stress at the seedlingstage often results in poor emergence, plantdeath, and reduced plant stands. Severe preflow-ering drought stress results in drastic reductionin grain yield. Postflowering drought stress toler-ance is indicated when plants remain green andfill grain normally. A stay-green trait has beenassociated with postflowering drought tolerancein sorghum. Genotypes with the stay-green traitare also reported to be resistant to lodging andcharcoal rot (Reddy et al. 2007; Fig. 14.1).

Genetic enhancement of sorghum for droughttolerance would stabilize productivity and con-tribute to sustainability of production systemsin drought-prone environments. The extent ofgrain yield losses due to drought stress de-pends on the stage of the crop and the timing,




Fig. 14.1. Expression of stay-green trait (in sorghum) under receding soil moisture conditions in a vertisol (Photo courtesy:C Tom Hash, Santosh Deshpande, and Vincent Vadez, ICRISAT).

duration, and severity of drought stress. Sorghumresponses to moisture stress at all four growthstages have been well characterized. Variationin these responses has been observed and foundto be heritable (Reddy et al. 2009). Since thephenotypic responses of genotypes differing indrought tolerance can be masked if drought oc-curs at more than one stage, screening techniqueshave been developed to identify drought-tolerantgenotypes at each of the growth stages, sepa-rately (Reddy 1986; Blum et al. 1989; Muchowet al. 1996; Haussmann et al. 1998; Borrell et al.2000a, 2000b; Harris et al. 2007). Of the sev-eral mechanisms to circumvent drought stressin sorghum, drought escape (related to shortermaturity durations), drought avoidance (main-tenance of higher leaf water potential, LWP),and drought tolerance (related to greater osmotic

adjustment, OA) are important and have beenwell characterized (Reddy et al. 2009). However,LWP and OA did not correlate well enough withgrain yield in field conditions to merit selectionbased on them; in addition, screening techniquesdeveloped based on LWP and OA were not costeffective in sorghum breeding. Empirical screen-ing based on imposing drought at various growthstages and measuring plant morphological andyield responses was the most effective approach.Long mesocotyl in seedling establishment andrecovery from midseason stress after release byrains are important traits that can be easily de-ployed in lines. The stay-green trait has beenwell exploited to enhance postflowering droughttolerance in sorghum (Reddy et al. 2009).

At ICRISAT, growth-stage-specific breedingfor drought tolerance, which involves alternate




seasons of screening in specific drought andwell-watered environments, has been used tobreed sorghum that can yield well in bothhigh-yield-potential environments as well as indrought-prone environments (Reddy et al. 2009).Since hybrids have exhibited relatively betterperformance than open pollinated cultivars forgrain yield under water-limited environments,hybrid cultivar development (including their par-ents) should be given strategic importance for en-hancing sorghum production in water-scarce en-vironments (Reddy et al. 2009). The progress inenhancing drought tolerance in sorghum throughconventional approaches is limited by the quanti-tative inheritance of drought tolerance and yieldcoupled with the complexity of the timing, sever-ity, and duration of drought. Biotechnology ap-pears to offer promising tools, such as marker-assisted selection, for genetic enhancement ofdrought tolerance in sorghum. Four stable andmajor QTLs were identified for the stay-greentrait and are being introgressed through marker-assisted selection (MAS) into elite genetic back-grounds at ICRISAT, QDPI, Purdue University,and Texas A&M University (Reddy et al. 2009).

Integration of the sorghum genetic map de-veloped from QTL information with the physicalmap will greatly facilitate the map-based cloningand precise dissection of complex traits such asdrought tolerance in sorghum. Sorghum has acompact genome size (2n = 20) and can be anexcellent model for identifying genes involved indrought tolerance to facilitate their use in othercrops. Paterson et al. (2009) reported that with re-spect to withstanding drought, sorghum has fourcopies of a regulatory gene that activates a keygene family that is present in a wide variety ofplants. Sorghum also has several genes for pro-teins called expansins, which may be involvedin helping sorghum to recover from droughts.In addition, it has 328 cytochrome P450 genes,which may help plants respond to drought stress,whereas rice has only 228 of these genes.

Some of the drought-tolerant sources identi-fied in sorghum at ICRISAT include Ajabsido,B35, BTx623, BTx642, BTx3197, El Mota,

Table 14.5. Sorghum germplasm and breeding linestolerant to drought at specific growth stages,ICRISAT-Patancheru, India.

Growth stage Tolerant sources/improved lines

Seedling emergence IS 4405, IS 4663, IS 17595 andIS 1037, VZM1-B and 2077 B,IS 2877, IS 1045, D 38061, D38093, D 38060, ICSV 88050,ICSV 88065, and SPV 354

Early seedling ICSB 3, ICSB 6, ICSB 11 andICSB 37, ICSB 54, and ICSB88001

Midseason DKV 1, DKV 3, DKV 7, DJ1195, ICSV 272, ICSV 273,ICSV 295, ICSV 378, ICSV 572,ICSB 58, and ICSB 196

Terminal drought E 36-1, DJ 1195, DKV 3, DKV 4,DKV 17, DKV 18, and ICSB 17

Source: ICRISAT 1982; Reddy et al. 2004a.

E36Xr16 8/1, Gadambalia, IS12568, IS22380,IS12543C, IS2403C, IS3462C, CSM-63,IS11549C, IS12553C, IS12555C, IS12558C,IS17459C, IS3071C, IS6705C, IS8263C,ICSV 272, Koro Kollo, KS19, P898012,P954035, QL10, QL27, QL36, QL41, SC414-12E, Segaolane, TAM422, Tx430, Tx432,Tx2536, Tx2737, Tx2908, Tx7000, and Tx7078(www.icrisat.org). ICRISAT has identified linesthat are tolerant to drought at various growthstages (Table 14.5). Drought tolerance of M35-1, a highly popular postrainy season adaptedlandrace in India, has been amply demonstrated(Seetharama et al. 1982).

Heat tolerance

Sorghum flowers and sets seed under high tem-peratures (up to 43◦C) provided soil moisture isavailable (House 1985). In many regions of theworld, sorghum production encounters heat anddrought stress concurrently, thus initial efforts inbreeding for temperature stress emphasized heattolerance. Jordan and Sullivan (1982) reportedheat and drought tolerance to be unique and in-dependent traits. Despite the level of adaptation




of sorghum in the SAT, seedling establishmentis still a major problem. Failure of seedling es-tablishment due to heat stress is one of the keyfactors that limits yields and affects stability ofproduction (Peacock 1982).

Understanding the genetic control of heattolerance in sorghum is a prerequisite forformulating an appropriate breeding program.Thomas and Miller (1979) reported that sorghumseedlings respond differently when exposed tovarying temperatures, and genetic variation forthermal tolerance in sorghum has been shown toexist in certain lines that are capable of emergingat soil temperature of about 55◦C. Peacock et al.(1993) and Howarth (1989) discussed the needfor greater diversity in sorghum seedling toler-ance to heat in superior genotypes, as this willimprove crop establishment in the SAT. Geneticvariability for heat tolerance among the geno-types at the seedling stage was demonstrated byWilson et al. (1982). Using screening techniquessuch as the leaf disc method (Jordan and Sulli-van 1982) and leaf firing ratings by ICRISATbreeders, genetic variability past the seedlingstage was demonstrated and positive correlationswere found between grain yield and heat toler-ance, thus making breeding for heat tolerance aviable option. Genetic variability for heat toler-ance in sorghum was also reported by other re-searchers (Sullivan and Blum 1970; Jordan andSullivan 1982; Seetharama et al. 1982).

Khizzah et al. (1993) studied four sorghumparental lines RTx430, BTx3197, RTx7000, andB35 and their F1s and F2 progenies during theirreproductive phases to assess the genetic ba-sis of heat tolerance in sorghum. They reportedthat parents were more heat tolerant comparedto their F1s and the heat tolerance is associatedwith two genes with a simple additive modeland epistatic interaction. Khizzah et al. (1993)also stated that cultivars with good late-seasondrought tolerance were also heat tolerant, sug-gesting a possible relationship between droughtand heat responses. Low to high heritability ofheat tolerance found in sorghum suggests thefeasibility of genetic enhancement of this trait.

B35 and BTx3197 could be used as sourcesfor heat tolerance in sorghum improvement pro-grams (Khizzah et al. 1993). The importance ofadditive gene effects over dominance effects forheat tolerance index was reported by Setimelaet al. (2007). Further studies are needed to betterunderstand the inheritance of heat tolerance insorghum.

Selection for heat tolerance in sorghum hashad limited success as (1) laboratory techniquesto screen for heat tolerance have not been ef-fective in increasing heat tolerance expressed infield conditions and (2) field screening for heattolerance is difficult to manage and is often con-founded with drought tolerance (Rooney 2004).

Resistance to pests and diseases

Sorghum is affected by an array of insects anddiseases worldwide. Genetic options for shoot flyresistance and grain mold tolerance in sorghumare discussed because of their global importance.

Shoot fly resistance

Among the insects, shoot fly (Atherigona soc-cata) is a major grain-yield-limiting insect pestthat causes damage when sowing is delayed inthe rainy or postrainy seasons. Shoot fly infesta-tion is high when sorghum sowings are periodicdue to erratic rainfall, which is common in theSAT. Greater incidence of shoot fly incidence isexpected with the predicted increases in tempera-ture due to climate change. Agronomic practices,synthetic insecticides, and host plant resistancehave been employed for shoot fly managementto minimize losses. Host plant resistance canplay a major role in minimizing the extent oflosses and is compatible with other tactics ofpest management, including bio-control mea-sures. ICRISAT contributed to development andrefinement of the interlard fish meal techniqueand no-choice-cage technique for screening forresistance against shoot fly and several resistantlines with desirable genetic backgrounds have




been identified (ICSV 702, ICSV 705, ICSV708, PS 21318, PS 30715-1, and PS 35805)as well as other sources (IS 18551) (Sharmaet al. 1992). Interestingly, some of these linesturned out to be sweet sorghums with higherBrix%, juice volume, and stalk yield. Followinga trait-based pedigree breeding approach, alarge number of shoot-fly-resistant seed parentsfor both rainy season (ICSA/B 409 to ICSA/B436) and postrainy season (ICSA/B 437 toICSA/B 463) adaptations were developed(Reddy et al. 2004b; http://test1.icrisat.org/gt-ci/Newsletters/ISMN_Specialissue/Text/ISMN-47_SpecialIssue_text.pdf, Accessed February17, 2010). More recently, additional sources ofresistance viz., IS 923, IS 1057, IS 1071, IS1082, IS 1096, IS 2394, IS 4663, IS 5072, IS18369, IS 4664, IS 5470, and IS 5636 are beingused in the development of shoot-fly-resistanthybrid parents. In a B-line development pro-gram, the shoot fly resistance levels in theadvanced lines (BC7s and BC9s) was high, withlow shoot dead hearts % (33–46%) comparedto the susceptible check 296B (59% SFDH)and significantly higher grain yield (up to 10%)compared to 296B (4.11 t ha−1) (Table 14.6).

Table 14.6. Performance of advanced sorghum B-linesfor agronomic traits and shoot fly resistance in 2008 rainyseason at ICRISAT-Patancheru, India.

Genotype

Days to50%

flowering

Plantheight

(m)

Shootfly deadhearts(%)

Grainyield

(t ha−1)

SP 97041 68 1.5 33 4.50SP 97029 70 1.4 38 3.51ABT 1007 68 1.6 39 4.52SP 97033 70 1.6 40 3.57SP 97035 69 2.1 45 6.09SP 97037 68 1.5 46 5.33

ControlsIS 18551 72 3.0 31 2.57296B 70 1.5 59 4.11Swarna 69 1.8 44 4.86Mean 69 1.73 46.02 4.28CV (%) 2.95 21.33 53.93 14.00CD (5%) 3.47 0.63 42.02 1.00

New B-lines with high grain yield and shoot flyresistance were identified during the 2008 rainyseason at ICRISAT-Patancheru. Marker-assistedbackcrossing has been attempted at ICRISAT-Patancheru to transfer five putative QTLs fromthe donor parent IS 18551 into the genetic back-grounds of elite shoot-fly-susceptible B-linesBTx623 and 296B, and the introgression linesare being evaluated (Tom Hash, unpublished).

Considering the potential risk of using a sin-gle source of CMS for developing hybrids, sev-eral A-lines based on diverse alternative CMSsources—A2, A3, A4 (M), A4 (VZM), and A4

(G)—have been developed. Conclusive stud-ies have been conducted at ICRISAT to estab-lish the suitability of hybrids based on CMSsources other than A1, the widely used CMS sys-tem. Evaluation of hybrids developed involvingisonuclear alloplasmic A-lines (A1, A2, A3, A4

(M), A4 (G), and A4 (VZM) cytoplasms) each insix nuclear genetic backgrounds (ICSA 11, ICSA37, ICSA 38, ICSA 42, ICSA 88001, and ICSA88004) for 2 years indicated no significant dif-ferences between the cytoplasms for shoot fly re-sistance in rainy and postrainy seasons (SanjanaReddy, ICRISAT–Patancheru, unpublished).

In the shoot fly resistance improvement pro-gram at ICRISAT in 2009 rainy season, 11 elitesweet sorghum hybrids with 11–42% less, 12 ad-vanced hybrids with 5–14% less, 10 B-lines with5–51% less, and 24 R-lines showed 5–52% lessshoot fly dead hearts than the control (SSV 84:88–93% dead hearts) (Sharma HC, unpublished).

Grain mold resistance

Grain mold (caused by a complex of Fusar-ium and many other pathogenic and saprophyticfungi) is a major disease of sorghum causedby a complex of fungi that affects grain pro-duction and quality. The disease is particularlyimportant in the case of improved, short- andmedium-duration sorghum cultivars, such as theimproved/released cultivars that mature duringthe rainy season in humid, tropical, and subtrop-ical climates. With increase in temperature and




more intensive rains due to climate change, moldinfection is expected to be more severe than atpresent. Photoperiod-sensitive cultivars that ma-ture after the rains (or at the end of rainy sea-son) often escape grain mold infection. Sorghumcultivars with the white grain pericarp (used asfood in India) are particularly more vulnerableto grain mold than those with brown or red grainpericarps. Both greenhouse and field screeningtechniques have been standardized by ICRISATand NARS partners for effective screening forgrain mold resistance, and new sources of resis-tance have been identified for use in breedingprograms (Thakur et al. 2006). A total of 156grain mold tolerant/resistant lines were identi-fied by screening 13,000 photoperiod-insensitivesorghum germplasm lines (Bandyopadhyay et al.1988). Resistance has been found mostly incolored grain sorghums with and without tan-nins and also in a few white-grain sorghums(Thakur et al. 2006; Bandyopadhyay et al. 1988,1998). Using the grain-mold-resistant white-

grained germplasm sources, a couple of hybridparents and varieties were developed. PVK 801is one such variety developed by MarathwadaAgricultural University (MAU), India, in part-nership with ICRISAT. PVK 801 is quite pop-ular in the rainy season in India. Studies onICRISAT-developed B-lines in multilocation tri-als by the Indian national program showed that11 entries (ICSB 355, -376, -377, -383, -388, GM3, ICSB 355-1-10, -393-7-1, -401-4-2, -403-4-1,and SGMR 33-1-8-3-2) have stable grain moldresistance across five locations, with mean pan-icle grain mold rating (PGMR) = 2.0 (PGMRrepresents the percentage of grain molded ona panicle, recorded on a 1–9 scale, where 1 =highly resistant and 9 = highly susceptible) dur-ing 2006−07 (http://nrcjowar.ap.nic.in/aicsip06/reports/pathology.pdf, accessed December 12,2009). Recent studies at ICRISAT-Patancheruindicated that it is possible to breed grain-mold-resistant hybrids with grain yields comparable topopular high grain yielding hybrids. Table 14.7

Table 14.7. Performance of selected advanced sorghum B-lines for grain mold tolerance and agronomictraits in 2008 rainy season at ICRISAT-Patancheru, India.

GenotypeDays to 50%

floweringPlant height

(m)Panicle grain moldrating (PGMR)2

Grain yield(t ha−1)

SP 97047 71 1.9 6.0 5.13SP 97051 71 1.8 6.0 4.79SP 97045 70 1.9 6.7 6.37SP 97065 69 1.7 6.7 5.19SP 97067 73 1.7 7.0 4.94SP 97053 68 1.8 7.0 3.81SP 97055 71 2.0 7.0 5.24SP 97057 70 1.8 7.0 5.68SP 97069 70 1.6 7.0 3.57SP 97073 73 1.5 7.0 5.14SP 97059 72 1.6 7.3 3.58

ControlsBulk Y (susceptible check) 50 1.3 9.0 5.54296 B (susceptible check) 71 1.4 9.0 4.52IS 14384 (resistant check) 72 3.1 2.0 6.58Mean 69.50 1.75 6.98 4.95CV (%) 1.94 7.57 7.74 9.44CD (5%) 2.23 0.22 0.88 0.77

Source: Ashok Kumar, ICRISAT (Unpublished).PGMR represents the percentage of grain molded on a panicle, recorded on a 1–9 scale, where 1, highlyresistant; 9, highly susceptible.




depicts the grain mold tolerance and agronomictraits of some of the recently developed sorghumB-lines. In addition to these efforts, SSR marker-based diversity assessment of grain mold resis-tance sources has been conducted and identifica-tion of QTLs for grain mold resistance is under-way at ICRISAT-Patancheru and Indian nationalprograms.

Increased grain microdensity

Malnutrition due to micronutrient deficiency (Feand Zn) is alarming in Southeast Asia includ-ing India, especially in preschool children andpregnant women. The intensity of micronutri-ent malnutrition is high in the SAT, the homefor millions of resource-poor people. The peo-ple of SAT depend upon sorghum along withother food staples for their calorie and micronu-trient requirement. Droughts and water scarcitydiminish dietary diversity and reduce overallfood consumption and this may lead to malnu-trition (http://www.fao.org/docrep/010/ai799e/ai799e00.HTM, accessed February 17, 2010).Biofortification, i.e., development and deploy-ment of micronutrient-dense sorghum cultivarsusing the best conventional plant breeding meth-ods complemented by biotechnology tools, hasbeen recognized as an effective strategy to mit-igate dietary micronutrient deficiency. Researchefforts at ICRISAT and elsewhere showed thatthere is considerable genetic variability and highheritability for grain Fe and Zn contents, andit is possible to genetically enhance the grainmicronutrient content (Fe and Zn) in sorghum(Reddy et al. 2005; Ashok Kumar et al. 2009).Studies at ICRISAT identified promising Fe-and Zn-rich donors in the sorghum core col-lection for use in developing Fe- and Zn-richcultivars (Ashok Kumar et al. 2009). Signifi-cant positive correlation was observed betweengrain Fe and Zn contents (r = 0.75). Fiveaccessions—IS 5427, IS 5514, IS 55, IS 3760,and IS 3283—with high grain Fe (>50 mg kg−1)and high Zn (>37 mg kg−1) contents can be uti-lized to increase the diversity and micronutrient

density of sorghum hybrid parents in the future(Table 14.8). PVK 801 is a high yielding, grain-mold-tolerant ICRISAT-MAU partnership vari-ety possessing high grain Fe (>50 ppm) and Zn(>35 ppm) contents.

The way forward

Climate change will modify the LGP acrossthe regions of interest, but this can be miti-gated by the retargeting and redeployment ofexisting germplasm. Predicted temperature in-creases, through their effect on increasing rate ofcrop development, will have greater negative im-pact on crop production than the relatively small(+/− 10%) changes in rainfall that are pre-dicted to occur. Yield gap analyses at ICRISATand elsewhere have shown that the negative im-pacts of climate change can be largely mitigatedthrough greater adoption of improved crop, soiland water management innovations by farm-ers, and better targeted crop improvement ap-proaches by farmers, more explicitly focused onadaptation to climate change. The impact of cli-mate change on yields under low input agricul-ture is likely to be minimal as other factors willcontinue to provide the overriding constraintsto crop growth and yield. The adoption of cur-rently recommended improved crop, soil, water,and pest management practices, even under cli-mate change, will result in substantially higheryields than farmers are currently obtaining un-der low input systems. Adoption of heat tolerantvarieties could result in complete mitigation ofclimate change effects that result from temper-ature increases. Owing to the evolutionary ad-vantages, its genetic resources and progress ingenetic advancement, sorghum is in a uniqueposition to cope with climate change. Develop-ment of medium to long duration cultivars withheat and drought tolerance, resistance to pestsand diseases, and higher micronutrient densityin high- yielding backgrounds is the key for fu-ture sorghum improvement programs. Tappingalternate markets like sweet sorghum for biofueland fodder, grain for poultry feed and starch and



Tab

le14

.8.

Mea

npe

rfor

man

ceof

sele

cted

sorg

hum

germ

plas

mlin

esev

alua

ted

for

grai

nFe

and

Zn

cont

ents

atIC

RIS

AT-

Pata

nche

ru,d

urin

gth

e20

07an

d20

08po

stra

iny

seas

ons.

ISN

o./

pedi

gree

Rac

eO

rigi

nD

ays

to50

%flo

wer

ing

Plan

the

ight

(m)

Glu

me

cove

rage

(%)

Gra

inyi

eld

(tha

−1)

Gra

insi

ze(g

100−

1)

Iron

(mg

kg−1

)R

ank

Zin

c(m

gkg

−1)

5427

Dur

raIn

dia

652.

054

2.0

2.75

60.5

156

.855

14G

uine

a-bi

colo

rIn

dia

681.

771

1.4

2.97

56.2

244

.655

Dur

ra-c

auda

tum

US

711.

075

1.3

2.64

54.1

338

.337

60C

auda

tum

-bic

olor

USS

R68

1.9

672.

22.

2352

.84

37.1

3283

Bic

olor

US

661.

871

1.9

2.70

50.2

542

.017

580

Cau

datu

mN

iger

ia66

1.9

791.

62.

0949

.96

40.5

1595

2G

uine

aC

amer

oon

812.

438

2.5

3.35

49.3

741

.338

13D

urra

Indi

a79

2.2

831.

41.

7349

.28

38.1

1526

6C

auda

tum

Cam

eroo

n70

1.4

542.

72.

6548

.69

43.6

2939

Kafi

rU

S69

2.0

633.

63.

9448

.410

37.2

4159

Dur

raIn

dia

651.

950

1.5

3.30

47.6

1137

.639

29K

afir-

durr

aU

S75

2.0

792.

22.

0947

.612

39.5

3443

Gui

nea-

caud

atum

Suda

n68

1.7

633.

33.

4747

.413

39.3

3925

Dur

ra-c

auda

tum

US

782.

067

2.4

1.95

47.2

1438

.554

60D

urra

-bic

olor

Indi

a66

1.5

791.

42.

6846

.915

46.4

1245

2C

auda

tum

-bic

olor

Suda

n64

1.9

793.

24.

3446

.816

33.2

2801

Cau

datu

mZ

imba

bwe

711.

871

2.3

3.11

45.5

1745

.025

36K

afir-

caud

atum

US

721.

883

2.3

2.36

45.2

1837

.054

29D

urra

Indi

a66

1.7

792.

82.

9944

.419

30.0

356

Dur

raU

S84

1.1

462.

22.

7144

.220

32.9

2265

Dur

ra-b

icol

orSu

dan

752.

271

1.8

1.69

44.2

2140

.912

695

Bic

olor

Sout

hA

fric

a68

1.9

100

2.8

2.58

44.1

2238

.955

38D

urra

Indi

a65

1.4

331.

72.

2243

.923

36.9

5476

Dur

raIn

dia

691.

575

2.1

2.69

40.8

2435

.516

337

Cau

datu

mC

amer

oon

801.

738

2.4

3.03

40.5

2534

.058

53G

uine

a-du

rra

Indi

a65

1.7

292.

45.

9140

.526

31.5

1431

8B

icol

orSw

azila

nd79

2.1

792.

22.

2539

.329

38.0

1067

4D

urra

-cau

datu

mC

hina

652.

146

1.9

4.04

38.5

3037

.622

215

Dur

ra-b

icol

orU

SSR

802.

171

2.9

2.39

26.3

3121

.4

337




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