Genetic and Environmental Effects on Dough Mixing Characteristicsand Agronomic Performance of Diverse Hard Red Winter Wheat Genotypes

Cereal Chem. ~()(5):51 ~523 Wlwat (hilil'/ilil (/('slil'llll/ I .. ) genotypes with short mixing times usually have low lllixing toiel'ance values. which make them more ,ensitive to overmixing in commercial bread production. In thi, ,tudy. we evaluated the genotypic and environmental elTects on agronol11ic performance and end-u.se quality of 27 experimental genotypes (hereaner reJ'crred to a, Illixlllg tolerant genotypes) which were identified in an initial ,creen ;f' having short Illixing tinle, and good mixing tolerances to I) determine whether genotypes identified in a preliminary end-usc quality ,creen ilS lines with usuilily long tolerance, but ,horl mixing timcs were due to their genotype (C;), the environment (I~). or C; x h: and a, these resulh were ulllisual. 2) determine whether or not our initial screen predicts end-usc quality. and 1) deterillinc the stability of both agronomic ilnd end-usc quality traih. The 27 gcnotypes and five check cultivar, wcrc grown in a ramlomiled completc block design with two I'cplicates in nine cnvironmcnts in 1')')7 and I ')')~. ;\11 plots werc harvested I'or grain yield. The harvested grain I'rolll the I'irst replicate and I'andolll genotypes I'rom the sceond replicate were nlicronlilled to Dough mixing properties arc very important in breadmaking, and noms milled from dirferent wheat (,/I'iliculII oe.l{il'lIl11 L.) cullivars can vary widely in the work and energy input required I'or optimum dough development. The rundamental reasons for these dilTerences arc not rully understood. however it is believed that protein content and interactions arc involved in the dillerences betwcen cultivars (Bushuk 199~). Bread doughs should be mixed to thc point or optimulll gluten development to produce good hread. More or less mixing causes improper dough developlllent. which produces an inferior quality bread (Doerry 1995). An important ractor alTecting dough quality is the dough mixing timc. Dough mixing time rcrers to the amount or time required to llli).. tlte ill~rcdicllts to fUrill duugh. \vhich dctCrlllillCS tile energy consumed by dough mixCl's. To reduce cnergy costs, bakers would like short mixing noms. llowever, nours with short mixing time orten have low mixing tolerance values, which means they can be readily overtllixed. Overmixing occurs when the ingredients arc added or doughs arc mixed beyond the optimal mixing time. ()vermixing rirst results in dough breakdown and products made rl'Onl overmixed doughs arc inferior (13ushuk 199~), even when the best liour is used (Paredes-Lope!. and l:3ushuk 19~3). The practical advantage or a wheat cultivar that is milled to make a nour with a shorter dough mixing peak time (an indication or optinlUlll dough development and stability) but with good mixing tolerance (an indicator or the resistance or a dough to overtnixing) i.s that Ie" labor. time. and energy arc needed in the bakery to develop thc optimum dough, and that the resultant dough is tolerant or overmixing, thus improving consistency or the rinal product. In a preliminary screening or wheat germplasm within the Nebraska breeding progral1l in 19()6, a nUl1lber or genotypes were identi ried that had shorter mixing times relative to mixing tolerI ('Olllrihuli()l1 or the lJlli\cr:-.ity or :--.lchraska i\~ricllltllr{\l Research Division as .I()lIl'Il,i1 Snics Pap"1 No. Il(J2~. .~ ])q)(\rlllll'111 or Agrollomy 8:. IlorticLlhLlre_ lJniversity or Nebraska, Lincoln, NE. j ('()rrl'~polJ(lilll2 author: ph<ll'Il/,igcrl (o)ulll.cdu. I lISI1;\-;\RS, tlni"cr,ily oj' Nebraska. Lincoln. NI:. -., I kp<lrllllclll or Biollll'try, lJlli\Tr~ily or Nehraska, Lincolll, NL. Publication no. C-2003-0723-05R. @ 2003 American Association of Cereal Chemists, Inc. 518 CEREAL CHEMISTRY produce nour sample, for evaluation of nom yield. protein content. and mixograph mixing time ami mixing tolerance valucs. Seed diameter. thou,and kernel weight, and kernel hardness were also measured in three environments. Environmcnt. C;, ami C; x I~ interaction elTects (mainly changes in magnitude) were ~igniric~1I11 !"or most agrolloll1ic ~\l1d end-usc quality parameters. Our initi;i1 screen. which had identificd 27 genotypes. was partially elTective in identifying genotypes that have shorter mixing time value, compared with their mixing tolerance values. We identil'ied four genotypes (15';;) I'ronl tire mixing tolerant genotypes that Irad a good mixing tolerance value and relatively shorter mixing time, as did the released clIllivms 'Agate' and 'Scout 66'. I [owever. Illixing characteristics values 01' all genotypes 1'cI1 within the acceptable linlits. indicating our screen cllectively identified genotypes with acceptable lIuality. Mixing tolerant genotypes. whiclr had been i(kntificd as having short mixing tillle scores and long mixing tolerance scol'es. were considered stahle acr()~.'-, envirOIllllents. anee values. Mixing time is scored as time (min) to peak dough development. Mixing tolerance is scored on a (),7 scale (Nebraska Wheat Quality Lab, Lincoln, NE), taking into account hoth curve width after peak development and the angle 01' departure (Baen!.iger et al 200 I). While mixing time and mixing tolerance arc measured in dirrerent units, the numerical values (not units) for mixing time in winter wheat tend to correlate with those or mixing tolerance, and it is very rare that the nunlerical value ror mixing tolerance is greater than the numerical value ror mixing time. Historically. winter wheat cultivars with good mixing tolerance values have very strong, long mixing time characteristics (Baen!.iger et al 200 I). As this was a preliminary screen rrom one c"viro","c"t, the short 'llixillg tillle charactcristic coupled with the good mixing tolerance value could have been due to the environment (E) as well as the genotypes (G). Though impossible to measure in one environment, it is known that end-usc quality characteristics arc influenced by genotypic and environmental factors and their interactions (C x E) (Peterson et al 1(92). [<or many quality characteristics, environmental variances were generally larger than those due to genetics (Graybosch et al 19(6). The objectives or this study were to I) deteJ'lnille whether ge11Otypes identified in a preliminary end-lise quality screen as having mixing time values smaller than mixing tolerance values were due to G, E, or G x Ii: and as these results were unusual 2) determine whether or not our initial screen predicts end-usc quality; and 3) determine the stability or both agronomic and end-usc quality