BUENO, A.

McCRATE, A. J.

MEIRA, J. L.

RHYKERD, C. L.

SCHAFFERT, R. E.

TREVISAN, W. L.

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Genetic Variation in Sorghum bicolor (L.) Moench for Tolerance to*Levels of Exchangable Aluminum in Acid Soils of Brazil**Robert E. SchaffertAndrew J. McCrateWalter L. TrevisanfiJ.varoBuenoJosé Lyaio MeiraCharles L. RhykerdAluminum toxici ty is an irnportant growth limi ting facto r in manyacid soils. The problem in Brazil is particularly serious in stronglyacid subsoils that are difficult to lime. Acid subsoils with aluminum attoxí e levels r-educes root penetration and increases the probatrí l í ty- IJfinjury by drought (Foy, 1974-a)c.The "cerrado" constitutes one of the 0egetation types most widelydistributed in Brazil occupying more than two million square kilometersconcentrated principally in-the States of Goiás, Mato GrossO and MinasGerais (Cruz, 1972). The soils associated with "cerrado" ve[letation aregenerally acid, low in phosphdrus and high in toxic aluminum. Mendes(1972) summarized the resu1 ts of 1,200 soil samp1es of "cerrado"vegetation types from Minas Ger-aí.s, the Federal District, and Goiásana1yzed by the soi1s section of the Agricu1ture Research Institute ofthe Centra1-West (IPEACO) of the Ministry of Agriculture of Brazil. Of* Presented at the "Sorghum Workshop", University of Puerto Rico,Mayaguez, Puerto Rico, January 7-11, 1975.~* qtaff of the National Sorghum Project, EMBRAPA, Sete Lagoas, MinasGerais, Brazil.151these samples, 32.5 percent had a pH of less than 4.30 and an additional66.4 percent had a pH between 4.31 and 5.49. In addition 28.4 percent ofthe samples had exchangable aluminum levels between zero and 0.50 meg/100 g, 17.8 percent between 0.51 and 1.00 meg/l00 g, 11.3 percentbetween 1.01 and 1.50 meg/l00 g and 42.5 percent greater than 1.50 meg/100 g. Exchangable aluminum less than 0.3 meg/lOO g is considered to below whi1e values greater than 1.00 meg/lOO g are considered to be high.Df these same samples 72 percent had phospho~s 1evels considered to be10w or very 10w. Textural analysis indicated that 8~/oof the sampleswere either a sandy loam, cl.ay , sandy clay loam, or c1ay loam. The sesoils have a very low water ho1ding capacity. 8ecause of this low waterholding capac.í, ty and periods of one to two or more weeks without raincommonly occuring even during the rainy season, these soils areconsidered to be droughty.These "cerrado" soils frequently have a topography which makesthem suitab1e for mechanized agriculture and are located in geographicalareas with ádec-.ratre infrastructure for intensive agricul turaldeve1opment. The utilization of these soils for economic intensiveagriculture requires p1ant species and varieties which are moreefficient in phosphorus uti1ization and tolerant to toxic levels ofaluminum in the soil. Foy (1974a) reported that a wide range oftolerance exists between and within plant spací.ea,' Oifferences have beenreported in wheat, barley, alfalfa, rice, soybeans, and com (Foy, 1974aand C1ark and Brown, 1974). Varietal differences for this characteris~ic$have not been reported for sorghum.Sorghum has been envisioned by many scientists to have a future inthe "cerrado" of 8razil because os its drought to1erance. Considering152tn8 nature of the "cerrado" so11s, rainfall distribution, and cost oflime and fertilizer, a sorghum variety must be developed which hasgreeter tolerance to high levels of aluminum, a deeper rootsystem, andmore efficient phosphorus utilization.Ouring the 1973/74 agricu1bral year, Schaffert (1974) noted a widerange of drought to1erance in one rep1icated trial of experimentalsorghum hybrids during a period without rain during anthesis. A relativescale of one to five was used to record these observations where arating of one was given to plots with plants showing no visab1e stressand e rating of five was given to p10ts with p1ants near permanentwilting point. The trial was donducted on a typical "cerrado" soi1 nearSete Lagoas, Minas. Gerais, 8razi1 where three tons of lime had beenapplied prior to p1anting. The soil pH at the time the observations weremede was 4.8 with an average of 0.68 meg AI/IDO 9 and 24 ppm P. Theresu1ts are presented in Tab1es 1 and 2. An examination of the root..systems indicated a high correlation between rOot deve10pment anddrought to1erance. Foy (1974b) interpreted these data as variations into1erance to toxic 1eve1s of a1uminum in the soi1.Two experiments were conducted to veri fy if the differencesobserved were due to variation in tolerance to a1uminum +o=.city or someother factor. A virgin "cerrado" soil high in exchangab1e aluminum wasselected from IPEACO for greenhouse studies. Soi1 analysis resu1ts were:pH 4.6, 1.56 meg AI/100.g, 2 ppm and 0.06 meg K/100 g. The soi1 wasclassified as a c1ay. In the first exp8riment 48 two 1iter p1astic potswere fi11ed with the above soi1 after adding 100 ppm of N as ammoniumsu1fate, 100 ppm P as phosphoric acid and 100 ppm K as potassiumch1oride. A randomized complete b10ck design rep1icated four time was153TABLE 1. Production and drought resistance notes on experimental hybridsat 1PEACO (Sete Lagoas, Minas Gerais, Brpzil) for the 1973/74agricultural year.Treabnent Pedigree Production* Resistance to Drought**01 PU932242 x TX2536 2.0 1.502 PU932242 x TX2555 2.5 2.503 PU932242 x PU932204 3.0 3.004 PU932242 x TX2523 2.0 1..005 PU932242 x KS-2 3.0 3.506 1S8361 x TX2536 3.0 1.007 168361 x TX2555 2•.5 1..008 1S8361 x PU932204 4.0 3.009 1S8361 x TX2523 2.0 1.510 168361 x KS-6 4.0 3.011 160418 x TX2536 3.0 1.512 160418 x TX2555 2.5 1.513 160418 x PU032204 3.5 4.514 160418 x TX2523 2.5 3.515 160418 x KS-10 3.5 4.516 CK-60 x TX2536 2.0 1.517 CK-60 x TX2555 2.5 2•.518 CK-60. x PU932204 4.0 3.019 CK-60 x TX2523 3.0 2.520 Redlan x PU932204 3.0 3.521 Red1an x TX2523 2.5 4.022 Redlan x TX2540 3.0 2.523 KS-4 x TX2536 2.5 1.524 KS-5 x TX2536 2.5 1.525 KS-52 >{ TX2536 2.5 . 1.026 KS-51 x TX2536 3.0 1.027 KS-48 xTX2536 2.5 1.028 K~47 x TX2536 3.0 2.029 Ag 1001 2.5 1.530 RS-610 4.5 5.0* A r:e1ative scale 1 to 5 where 1 is high production and 5 is lowproduction. (RS-610 in an adjcent replicated trial produced 2.70 t/haand Ag 1001 produced 5.37 t/ha of dry grain under similiar conditions)** A re1ative scale of 1 to 5 where 1 = to1erance to drought and 5 =severe damage due to drought.154TABLE 2. Production and drought resistance notes averaged across malesl''l'tand females on experimental hybrids at 1PEACO (Sete Lagoas,Mi'nas Gerais, Brazil) for the 1973/74 agricul tural year.pedigree Type of line Number of hybrids Resistance t!3. Production* Drought**used ln average.PU932242 A 5 2.50 2.30158361 A 5 3.10 1.9019J418 A 5 3.00 3.10cK-60 A 4 -2.90 2.40Redlan A 3 2.80 3.33TX2536_,** R 10 2.60 1.35TX2536 R 4 2.50 1.48TX2555 R 4 2.88 2.38PU932204 R 5 3.50 3.40TX2523 R 5 2.40 2.50K5-2 R 1 3.00 3.50K5-6 R 1 4.00 3.00K5-10 R 1 3.50 4.50TX2540 R 1 3.00 2.50K5-4 'A 1 2.50 1.50K5-5 A 1 2.50 1.50K5-52 A 1 2.50 1.00K5-51 A i. 3.00 1.00KS-48 A 1 2.50 1.00KS-47 A 1 3.00 2.00* See notes for Table 1.** See notes for Table 1~.* Averaged over PU932242, 1S8361, 1S0418, CK-60.155used to study twelve sorghum varieties. Eight seeds were planted per poton October 9, 1974 and thinned to four plants per pot after germination.The varieties used were, 1S8361 S, Redlan S, PU9322D4, TX2536 , 1S8361 xPU9322D4, 1S8361 x TX2536, Redlan x PU932204, Redlan x TX2536, RS-610,Taylor-Evans Y-I01, Asgrow Oourado M and M35-1. Thirty days afterplanting the soil was removed from the roots by washing. Length of thelongest root, average length of the secondary roots, shoot length, dryroot weight and dry shoot weight were recorded for the four plants ineach pot.The data are presented in Table 3. Highly significant differenceswere obserVed for the five traitsstudied. Comparing the four lines,TX2536 did not have the characteristic dark brown discolored roots thatiscommonly associated with aluminum toxici ty (Foy, 1974a). PU932204 wassignificantly inferior to the otherlines in the study. PU932204 hadmore leaf discoloration resembling bronzing in rice that is caused byexcessaluminum ,in certain soils of Ceylon. TX2536 did not express thisbronzing.The hybrid combinations with PU932204 were inferior to TX2536 inIroot development but not shoot development. Heterosis was present foralI the traits studied with the hybrid superior to the mid-parent in alI.tbe .cases and superior tavbest parent in alI cases except secondary rootlength for the hybrid RedIan x pU9322D4. In hybrid combinations, 1S8361was slightly superior to RedIan in root and shoot weight but nearlyequa~ in root and shoot length. The failure to observe greater156differences was probably due to the extremely high leveI of aluminum inthis trial as was indicated by the second experimentoTaylor-Evans Y-IOl and Asgrow Dourado M, hybrids reported to havelABlE 3! Average root and shoot length and dry weight of 12 sorghumvarieties grown for 30 days in an acid "cer-rado" soil with"1.56 meg Al/I00 g.- Root Length Shoot Ory Shoot Dry root ivariety Longest Secondary Length Weight Weightan* cm* cm* g** g**-158361 8 18.7 9.5 26.2 0.:29 0.07Aedlan 8 20.3 12.5 25.1 0.28 0.11TX2536 18.2 11.9 19.6 0.21 0.08pU932204 7.7 5.0 18.5 0.:7 0.05168361 x TX2536 26.7 13.3 30.8 0.47 0.23168361 x PU932204 20.8 12.3 33.6 0.54 0.17Redlan x TX2536 " 26.4 13.4 30.6 0.43 0.20Redlan x PU932204 19.9 11.5 28.6 0.41 0.13Taylor-Evans Y-I0l 25.1 14.4 32.9 0.49 0.27Asgrow Dourado M 22.2 l3.1 30.2 0.46 0.21A~610 18.1 10.4 28.6 0.44 0.14M~l rr.o 6.6 25.5 0.32 0.08sx 1.34 1.11 1.28 0.029 0.016LSD.05 3.85 3.20 3.68 0.085 0.046* Average of four plants** Total weight of four plants.more drought tolerance in "cerrado" soils (Schaffert, 1974) were-superior to RS-610 reported to be highly suceptible to drought for the.tr-aí,ts observed. M35-1 was intennedia'te between the tolerant andlnontolerant lines in root development.A second greenhouse experiment was condUcted using the sarne soil-as the first experiment with six lime rates. The rates were- zero, 250,500, 1,000, 2,000,and 4,000 parts per million lime (8~/oCa2C03 and 20f0MgC03). These rates oorresponded to zero, 0.5, 1.0, 2.0, 4.0, and 8.0;tons per hectare of lime, respectively, The lime was mixed with the soUiand incubated for ten days prior to planting. One hundred ppm N, 100 ppm."J and 126 ppm K were applied as NH4N03 and KH2P04' Too com lines,OH40B and 8-57, and five sorghum varieties, PU932204, TX2536, IS836l xTX2536 , RS-610 and Taylor-Evans Y-lOl were planted on November 1, 1974 intv~ liter pots using a randomized complete block design with 3:replications. The pots were thinned to 4 plants per pot aftergermination. Twenty-five days after planting the soil was removed fromthe roots by washing with water. The data are currently being tabulated.and analyzed.The two comlines used in this experiment, OH40B and 8-57 havebeen reported by Clark (1974) to be suceptible and tolerant,respectively, to high levels of aluminum in the soil. The rootdevelopment of 8-57 was slightly superior to OH40B in the no limetreatment. The differences were greatly increased at the 250 ppm (0.5 tiha) lime treatment. The differences were less dramatic at the higherlime rates and appeared to disappear at the 2,000 and 4,000 ppm rates.Of the two sorghum lines, TX2536 and PU932204, in this experimentTX2536 had superior root development at the lower lime rates. The158greatest diff~rences were at 250 ppm (0.5 t/ha) and 500 ppm (1.0 t/ha)Df lime. The differences in rootdevelopment between the sorghumhybrids, 188361 x TX2.'336,Tayl.or--Evans Y-IOl and RS-610, were also thegreatest at 250 and 500 ppm lime. 188361 x TX2536 and Taylop-Evans Y-IOl\~re'similiar in root development and much greater than RS-610. Thedifferences in root development in sorghum lines and hybrids were lessdramatic at the higher lime rates and appeared to disappear at the2,000 and 4,000 ppm rates.Root development appeared to have"been slightly reduced at the4,000 ppm (8.0 t/ha) for both com and sorghum.80rghum was evaluated, using preliminary techniques, fortolerance to high exchangable aluminum in the soil. A large amount ofgenetic variation wa3 observed 'for root development indicating thatselection for tolerance to high exchangable aluminum should besuccessful. 188361 and TX2536 appeared to be tolerant to highexchangable aluminum and PU932204 was not tolerante These preliminarystudies are being fóllowed up with additional greenhouse and fieldstudies.References1. Clark, R.B. 1974. Personal communication.2. Clark, R.B. and J.C. Brown; 1974. Differential phosphorus uptakeby phosphorus-stressed com inbreds. Crop 8ci. 14:505-508.3. Cruz, J.M.A. 1972. Anais da 11 P,3união Brasileir.a de Cerrados. p.5-6.4. Foy, C.D. 1974. Effects- of aluminum on plant growth. p, 601-642. InThe plant root and its environment. ed. by E.W. Carson. UniversityPress of Virqinia, Charlottesville.1595. Foy, C.D. 1974. Persona1 communication.6. Mendes, J.F. 1972. Caracteristi.cas quimicas e fisicas de algunssolos sob cerrado. Anais da 11 Reunião Brasileira de Cerrados. P.51-62.7. Schaffert, R.E. Unpublished data.160

Genetic variation in Sorghum bicolor (L.) Moench for tolerance to high levels of exchangable aluminum in acid soils of Brazil.

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Genetic variation in Sorghum bicolor (L.) Moench for tolerance to high levels of exchangable aluminum in acid soils of Brazil.

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