1.- c ?T7A245.7 % i 3 0.1423 l i 3-1423 L November 1982 Maize Dwarf Mosaic Virus: * .~\- , ' Q '\ *1. “H igle—% and D0ub|e—Cr0ss Hybrids .' 5 .*- J: ' F ; ‘ ». i». a‘ _ w. ,4 1;... ect of Strain A on Corn lnbreds, [Blank Page in Origaal Bulletin] m‘- m" "*1; MAIZE DWARF MOSAIC VIRUS: EFFECT OF STRAIN A on conu INBREDS, SINGLE- AND oouste-cnoss HYBRIDS R. W. Toler, A.J. Bockholt and F. G. Alston* *Respectively, Professor, Department of Plant Sciences, Associate Professor, and Graduate Research Assistant, Department of Soil and Crop Science, Texas Agricultural Experiment Station, College Station. KEY WORDS: Maize dwarf mosaic virus / resistance / corn / hybrid mechanisms CONTENTS SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 MATERIALS AND METHODS . . . . . . . . . . . . . . . . . . . . . . . 2 RESULTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Days to Silk . . . . . . . . . . . . . . . . . . . . . . . . . 5 Plant Height . . . . . . . . . . . . . . . . . . . . . . . . . 5 Ear Height . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Disease Ratings . . . . . . . . . . . . . . . . . . . . . . . . 7 Yield . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Shelling Percent . . . . . . . . . . . . . . . . . . . . . . . 8 Test Weights . . . . . . . . . . . . . . . . . . . . . . . . . 8 DISCUSSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 LITERATURE CITED . . . . . . . . . . . . . . . . . . . . . . . . . 11 TABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 SUMMARY Five Texas corn double crosses, the single-cross parents, and the inbreds used to make the single crosses were studied for their reaction to inoculation of maize dwarf mosaic virus strain A (MDMV). Character- istics studied included: days to silk, plant height, ear height, disease ratings, yield, shelling percent and test weights. Significant differences occurred between inoculated diseased vs. uninoculated healthy single crosses and double-cross hybrids due to the effects of susceptible inbred lines. No significant differences occurred with the crosses among the resistant lines. MDMV caused differences among hybrid entries for each characteristic considered. All entries generally showed the same disease symptoms, to different degrees. Maize dwarf mosaic virus delayed maturity, reduced plant and ear heights, and reduced yields. There was no effect on shelling pecent, test weights, ear length, or seed set. when three susceptible inbred lines were in a double-cross hybrid, MDMV significantly affected the performance of the hybrid. MAIZE DWARF MOSAIC VIRUS: EFFECT OF STRAIN A ON CORN INBREDS, SINGLE- AND DOUBLE-CROSS HYBRIDS R. W. Toler, A.J. Bockholt and F. G. Alston INTRODUCTION Maize dwarf mosaic virus strain A (MDMV) is the most widespread virus attacking corn, bringing damage to all areas where corn is grown (2,6,7). The disease causes characteristic stunting and mottling in stricken plants but symptom expression varies greatly by genotype. The most promisi-ng means of MDMV control is through host resistance (1). Hybrids and inbred lines of corn have been screened for their reaction to MDMV in Arkansas, Ohio, Georgia, Missouri, and Tennessee (3, 4, 9, ll, 16, 17). Several Texas inbred lines were screened in Illinois, and two lines showed a high degree of tolerance (12). Virus rating systems have been developed to compare the degree of tolerance of hybrids and inbred lines (15). Zuber et al. (16, 17) rated corn strains in 1967 and 1968 in Missouri; however, only in 1968 was a Texas inbred (Tx 601) rated (17). Tx 601 was found to be highly tolerant by Dale and York (5) in 1967-rated inbred lines and single crosses developed from the most tolerant inbreds. Tx 602 was entered in the screening and also rated high in tolerance to MDMV. Studies on inheriting tolerance to MDMV were conducted with inbred lines in Missouri and Tennessee (10,12). By crossing a tolerant inbred line, an intermediate degree of tolerance resulted. Studies in Missouri conducted by Loesch and Zuber (12) indicated that tolerance was con- trolled by more than one gene, and the progeny responded differently to aheterogeneous virus population. Josephson, Hilty, and Arnold (10) in Tennessee found that tolerance to MDMV could be transferred to a susceptible inbred by backcrossing. Also, Zuber et al. (unpublished data) reported on a study of methods to predict MDMV reactions in double crosses which differ in the number of tolerant or susceptible inbreds. This study was designed to determine the effects of MDMV {ion yield and agronomic characteristics and to assess the effects of susceptible inbred lines or single crosses on the performance of double crosses which differ in the number of tolerant or susceptible inbreds. MATERIALS AND METHODS These studies included five Texas single crosses and the single-cross parents as well as the inbreds used to make the single crosses (Table 1). The inbreds included resistant and susceptible lines. The tests were planted on chips or clay loam with 448 kg of l7-ll-6 fertilizer applied per hectare at planting and 336 kg of ammonium nitrate per hectare appliedat the five-leaf stage of growth. A randomized split-plot design with three replications was employed. Each plot consisted of six rows 6.1 m x by 102 cm and replications of a single variety at a density of 32,310 plants per hectare. One half of each plot (three rows) was inoculated, and the other half served as the control. Plants were inoculated in the three-leaf stage of growth with an artist's airbrush (13) using 7.06 kg/cmz pressure a flow rate of l0 ml/min and a leaf distance of 2.5 cm. Inoculum consisted of infected sorghum sudan hybrid homogenized in a Waring blender with equal volume of phosphate buffer pH 7.5 with one percent 600 mesh carborundum added after filtering. The inoculum was refrigerated until used. Data were collected on stand, symptoms, days to silk, plant height, ear height, root lodging and plant breakage, disease incidence, yield, shelling percent, seed set, and test weight. Days to silk was determined by calculating the number of days from planting to the time 50 percent of the prlants iri a plcrt showed silk. Plant height was measured from the ground level to the tip of the tassel after vegetative growth had stopped. Ear height was measured from the ground level to the base of the upper ear. Plants were rated visually during the boot stage for disease symptoms and stunting according to the following scale: S Virus rating 1 = No apparent infection of plant. 2 = Mottling in whorl of plant only. 3 = Mottling of entire plant. 4 = Chlorosis of entire plant. 5 = Discoloration of plant other than chlorosis. 6 = Severe chlorosis, mottling, or discoloration of plant. Stunting 1 = No apparent stunting of plant. 2 = Slight stunting of plant. 3 = Stunting of plant with reduced ear size. 4 = Stunting of plant with no ear present. 5 = Death of plant. Data were collected from the middle rows of the inoculated and uninoculated plots to reduce border effects. Stand counts were taken ‘to correct yield per plot. Root lodging and plant breakage were taken before harvest to determine standability. Plants that were leaning nuare ‘than degrees from an erect position were considered lodged. Any plant with the stalk broken below the upper ear was considered broken. Yield was determined by converting the shelled corn weight per plot into hectoliters of shelled corn per hectare. Shelling percent was deternrined by dividing the shelled corn weight by the ear corn weight and con- verting to percent. Test weights were taken on a standard test weight scalee for" the hybrid test and for the plots of the inbred test that had sufficient shelled corn to make a measurement. Ear length and ear width measurements, and seed set ratings were 'taken (H1 the lrybrid test only. Ear length was measured in cm from tip to butt. Ear width was measured in cm through the middle of the ear. Seed set was rated visually at the time of harvest, according to the following scale: Seed set rating 1. No apparent effect of MDMV — 95 to l00 percent. 2. Slight reduction in seed set - 75 to 95 percent. 3. Severe reduction in seed set - 25 to 75 percent. 4. Very poor seed set - Less than 25 percent. Analysis of variance was computed for days to silk, yalant tnaight, ear- height, yield, shelling percent, ear length, ear width, and seed set in hybrid tests. The appropriate F-tests were used to indicate significant differ- ences with varieties considered as the main plot and the treatment (irnacularted vs. uninoculated) as the sub-plot. If the F-test indicated significance, the means were then separated with Duncan's Multiple Rauwge Test. Data were collected on the inbred lines in an attempt to determine if MDMV effects on yield and other agronomic characteristics of corn hybrid could be predicted from inbred line response. RESULTS Days to Silk The analysis of variance for days to silk showed highly significant differences among mean, squares of varieties, treatment, and interaction between treatment and varieties (Table 2). The MDMV-infected plots were delayed at maturity on an average of 2.0 days. All but one of the inbred lines (Tx 585, a highly virus-tolerant inbred) had delayed maturity, ranging from 5.3 days for Tx 441 to 0.3 days for Tx 127C. The inbred lines K 55, K 64, TX 441, Tx 303, TX 325, and TX 508 were all significantly delayed at maturity by the virus. MDMV caused a significant delay in maturity among hybrids (Table 3). The average delay in days to silk in the inoculated plots was 1.2 days. The effects of single crosses on double crosses are also shown in Table 3. The double cross Tx 28A was delayed in maturity by inoculation with MDMV; however, only one parent, TX 303 X (Tx 325, was delayed by the effects of MDMV. Texas 40 also showed a significant difference between x inoculated and uninoculated treatments as did the parental TX 303 X Tx 508. Tx 34 and Tx 30 showed no significant differences between inocu- lated and uninoculated plots, but both parents (Tx 203 X Tx 303 and Tx 601 x TX s02; Tx 303 x 325 and TX 1730 x Tx 203, respectively) showed a significant difference between inoculated and control. Plant Height 4 Differences in the effect of MDMV on plant height were observed among the inbred lines (Table 4). Average plant height of the inocu- lated inbreds was reduced 9.4 cm. Also, the mean square of interaction between treatment and inbreds showed a significant difference. Duncan's Multiple Range Test indicated that K 55, K 64, Tx 303, and Tx 325 were significantly reduced in plant height by MDMV, with Tx 303 reduced the most (27.8 cm). Plant height of Tx 585, Tx 601, and Tx 602 was not reduced, indicating a high degree of tolerance to the virus. Tx 127C also showed a high degree of tolerance against stunting. Analysis of variance was highly significant for the effect pf MDMV on plant height of hybrids tested (Table 5). The treatment effect was highly significant as was the mean square 0f the interaction between MDMV treatment and hybrids. Two double crosses, Tx 17w and Tx 40, and three single crosses, K 55 X K 64, Tx 303 X Tx 325, and Tx 303 X Tx 508, showed significant height reductions when inoculated with MDMV. A reduction in plantheight of 14.5 cm for the three single crosses was significant while a reduction of 3.56 cm or less in single crosses was not significant. Degree of effect of singlecrosses on plant height of double-cross hybrids is also shown in Table 5. Tx 17 w and Tx 40 were reduced 18.6 cm or more in height compared to 5.2 cm for the other double crosses. Only one parental single cross, however, for Tx 17w and Tx 40 (K 55 X K 64 and Tx 303 X Tx 508, respectively) showed a signifi- cant reduction in plant height betweentvirus-inoculated and control. Significant reduction in plant height occurred between inoculated and control for inbreds Tx 303 and Tx 325 (Table 4), but neither Tx 28A nor Tx 30 showed a reduction in height (Table 5). However, crosses involving Tx 303 generally were affected more by the virus than crosses involving the other inbred lines. Ear Height MDMV significantly reduced ear heights for the inoculatd inbred plots (Table 6). The average drop was 5.99 cm. Again, the inbred lines K 55, K 64, Tx 61M, Tx 441, Tx 303, and Tx 325 were affected significantly. Tx 508, Tx 585, and Tx 127C, however, all showed a high degree of tolerance. Ear height of double crosses was not affected by MDMV when only one or two inbreds were susceptible, but if three susceptible inbreds were used, MDMV significantly reduced ear height (Table 7). Tx 17w showed a significant reduction, but only. one of its parental single crosses, K 55 X K 64, was susceptible. Three of the parental inbreds for Tx 17w (K 55. K 64, and Tx 61M) all had significant reduction in ear height due to MDMV inoculation. The ear height of Tx 28A was significantly reduced, but neither of its parental single crosses was significantly reduced. Three of its parental inbred lines, however (Tx 441, Tx 303, and Tx 325), were affected significantly. Disease ratings Stunting ratings verified the results of the plant heights previously discussed. The virus reduced plant height of all inbred lines except ix 58s, Tx s01, and Tx s02 (Table s). No inbred line was totally resistant to MDMV, but degree of tolerance varied, with Tx 601, Tx e02, ix 58s and Tx 173p the mast tolerant. Inbred lines K s5, |< s4, Tx 508, Tx 61M, Tx 303, Tx 441, and Tx 325 were most affected by MDMV. All the single crosses and Texas hybrids showed at least a mottling of the whorl, and all hybrid entries showed stunting at the boot stage (Table 9). K 55 X K 64, Tx 303 X Tx 508, and Tx 17W showed mottling of the entire plant. when the final plant height was measured, Tx 30 and Tx 601 X Tx 602 showed a slight increase in plant height of the inocu- lated rows. The difference, however, was not significant. Yield MDMV reduced yields of all susceptible inbred lines. Yields ranged from 31.83 hectoliters/hectare (hl/ha) for the control plots of Tx 61M to 5.08 hl/ha for the infected plots of TX 602 (Table 10). Uninoculated plots had an average yield of 11.82 hl/ha, and the uninoculated plots had a mean ‘yield of 17.58 hl/ha for the inbreds. An average difference of 5.76 hl/ha per acre was obtained between inoculated and uninoculated plots. Yields of single- and double-cross hybrids ranged from 84.66 hl/ha for Tx 303 X Tx 508 to 29.11 hl/ha for Tx 601 X Tx 6.02 (Table 11). The mean yield of inoculated plots was 61.30 hl/ha, and for the uninocu- lated plots 67.70 hl/ha. Four single crosses yielded below the overall mean of the inoculated and uninoculated treatments. The five Texas double-cross hybrids yielded above the overall mean yield, except for inoculated plots of Tx 17w. The only entry that was significantly reduced in yield was Tx 303 X Tx 508which had a difference of 27.45) hl/ha between the inoculated and uninoculated treatments. Shelling Percent None of the inbred lines were significantly reduced in shelling percent by the effect of MDMV (Table 12). A range for shelling percent from 84.2% for both the inoculated and the uninoculated plots of Tx 303 to 54.8% for the uninoculated plots of Tx 601 was observed. Inbred lines K 64, Tx 303, and Tx 601 either were not affected or were increased in shelling percent for the inoculated plots, but not signifi- cantly. MDMV did not significantly lower the shelling percentages of the hybrids (Table 13). A range from 87.43% for the uninoculated plots Tx 303 X Tx 325 to 73.17% for the inoculated plots of K 55 X K 64 was obtained. The arc sin was used to make the analysis of variance, converting percentages to angles. Shelling percent of only one entry, K 55 X K 64, was significantly decreased by the effects of MDMV. Test weights For the inbreds, test weight was not determined due to missing data caused by some plots producing insufficient shelled corn to perform the test. Maize dwarf mosaic virus did not significantly reduce the test weights of hybrids. A range of 75.70 kg/hl for the uninoculated plots of Tx 17w to 67.4 kg/hl for the uninoculated plot by Tx 127 X Tx 441 was obtained (Table 14). The test weights of Tx 28A and Tx 173D X Tx 203 were significantly increased by inoculation. DISCUSSION Data obtained in the tests indicated MDMV caused differences among hybrid entries for each characteristic considered. MDMV delayed maturity, reduced plant and ear heights, and reduced yields. The effect of MDMV on susceptible inbred lines could be seen in they single crosses and double-cross hybrids by a significant difference between the inoculated vs. uninoculated groups. with the crosses among the resistant lines, nosignificant differences occurred. All the entries generally showed the same disease symptoms, to different degrees. Tx 601 and Tx 602 are sister lines selected from yellow Tuxpan, both having late maturity, which may explain their low yields. No consistent effect of the susceptible or tolerant single cross on the performance of the double-cross hybrid could be determined from this study. The effect of having one or two susceptible inbred lines in a double-cross hybrid did not generally affect the susceptibility of the hybrid. However, when three susceptible inbred lines were in adouble-cross hybrid, MDMV affected the performance of the hybrid. Differences could not be seen on the effect of susceptible single crosses on the performance of the double—crosshybrid. Maize dwarf mosaic virus causes substantial economic losses in corn production . At present, the main factor of control is the tolerance of the hybrids grown. The data from this study contributes to information 10a needed to detelop resistant or highly-tolerant hybrids available that are adapted to the growing areas of Texas. 10. 11. 12. 13. 14. 15. 11 LITERATURE CITED anci R. N. Toler. 1968. Texas Agri. Exp. Sta. Effects of maize dwarf PR-2509, 6 pp. Bockholt, A. J. mosaic on grain sorghum. Dale, J. L. 1964. virus from corn in Arkansas. Isolation of a mechanically transmissible Plant Dis. Reptr. 48:661-663. Dale, w]. L., and \J. 0. ‘York. 1967. Maize dwarf mosaic virus ratings of corn hybrids and inbreds tested in Arkansas lfl 1966. Ark. Agri. Exp. Sta. Mimeograph series 153. ' Maize dwarf mosaic virus Ark. Dale, J. L., and J. o. York. 1967. ratings of corn hybrids and inbreds in Arkansas lfl 1967. Agri. Exp. Sta. Mimeograph series 163, 5 pp. lDale, J. L., and J. 0. York. 1967. Maize dwarf mosaic resistance in corn. Ark. Farm Research. 17:12. ~ liobbs, 1)., and W. Toler. 1966. Plant Disease Views and Reviews. Texas Agri. Ext. Serv. Special edition. Janson, F. and C. Ellett. 1963. A new corn disease in Ohio. Plant Dis. Reptr. 47:1107-1108. J&flSCHl, F., E. Williams, W. R. Findley, E. J. Dollinger and C. W. Ellett. 1965. Maize dwarf mosaic: new corn virus disease in Ohio. OHTC) Agri. lixpt. Sta. Ext. Bull. 460 and Res. Circ. 137C Josephson, L. M., and J. W. Hilty. 1965. Remfifioncfi mum strains to virus disease in Tennessee in 1965. USDA Crops Res. Div. Agri. Res. Serv., coop. with Tenn. Agri. Exp. Sta. Josephson, L. M., J. w. Hilty and J. Arnold. 1967. Inheritance of tolerance of corn inbreds to the maize dwarf mosaic virus. 1967. Agron. Abstr., Amer. Soc. of Agron. Kuhn, (I. W. 1968. Univ. of Ga., Coll. of Agri. Exp. Sta. Corn viruses in Georgia. Res. Rept. 23. Loescfli, P. .]., Jr. and M. S. Zuber. 1967. An inheritance study of resistance to maize dwarf mosaic virus on corn (Zea mays L.). Agron. Jour. 59:423-426. Tkaler, F2. W. and T. T. Hebert. 1965. Transmission of soil-borne oat mosaic virus increased by artist's airbrush. Plant Dis. Reptr. 49:553-555. Toler, w., C. D. Hobbs, and A. J. Bockholt. 1967. Identifi-‘ cation, transmission and distribution of maize dwarf nnosaicz in Texas. Plant Dis. Reptr. 51:777-781. Nil liams, L“ E., and L. J. Alexander. 1965. Maize dwarf mosaic, a new corn disease. Phytopathology 55:802-804. 12 16. Zuber, M. S., A. J. Keaster, and P. J. Loesch, Jr., 1968. Virus ratings of strains in Missouri, 1967. Univ. of Mo., C011. Agri. Exp. Stat., Spec. Rept. 100. 17. Zuber, M. S., A. J. Keaster, A. G. weir, C. F. Stark, and P. J. Loesch. Jr. 1968. Virus ratings of corn strains in Missouri. 1968. Univ. of Mo., C011. Agri. Exp. Sta. Spec. Rept. 102a 13 Tab1e 1. Inbreds and hybrids test for effect of MDMV. Hybrid Sing1e Cross Inbred Tx 303 TX 303 x TX 325==:::j:::::::: TX 325 Tx 3 ”fl_’____,,Jx 173D X 1730 x TX 20 x 203 Tx 127C TX 127c x TX 441<=:I::::::::: Tx 441 Tx 28A 2 TX 303 X 303 x TX 32s‘=:::I:::::::; x 325 Tx 203 TX 203 x TX 303<=:::::::::: TX 303 Tx 34 Tx 601 X 501 x TX 602—=:::::::::::l Tx 602 x 127C TX 127c x TX 441==::iI::::::f Tx 441 Tx 40 TX 303 X 303 x TX 50a~=::II::::::: Tx 508 K 55 55 x K 54==:::III::::::::; K 54 Tx 17H: Tx 61M TX 61M x TX 585=::::j:::::::T x 585 14 Table 2. Summary of mean days to siik for the plots inoculated with MDMV and the uninoculated plots for the inbred test. Inbred Days to Si1k* Lines Inocuiated Uninocudated K 55 77.3 g g 74.l** K 64 78.8 efg 75.7 h** Tx 61M 79.8 def 79.2 def Tx 585 78.3 efg 78.4 efg TX 1270 8 74.8 h 74.5 n Tx 441 83.2 bc 77.9 de** Tx 1730 79.3 def 78.2 efg Tx 203 78.8 efg 78.0 fg Tx 303 84.1 bc 79.3 def** TX 325 85.0 5 80.8 d** Tx 508 83.0 c 79.7 def** Tx 601 84.8 bc 84.2 bc TX 502 91.1 8 90.0 8 * Duncan's Mu1tip1e Range Test - any two means having any one of the same ietters are not significant. ** Indicates significant difference between the inoculated and uninocuiated treatments of the inbred lines. 15 Table 3. Summary of mean days to silk for the plots inoculated with MDMV and the uninoculated plots for the hybrid test. Days to Silk* Varieties Inoculated Uninoculated K 55 x K364 69.7 nop 09.0 p Tx 17w 69.3 op 69.6 op Tx 61M X Tx 585 70.8 klmn 70.3 lmno TX 1730 X TX 203 72.0 ghij 70.8 klmn** TX 30 72.2 ghij 71.1 jklm TX 303 X TX 325 77.3 C e 75.6 d** TX 28A 72.6 gh 71.3 ljk1** TX 1270 X TX 441 72.7 fgh 71.7 hljk TX 40 71.4 ljkl 70 .0 mn0** Tx 303 x Tx 500 75.2 a 72.1 ghij** TX 203 X TX 303 73.7 Ef 72.3 ghi** Tx 34 73.0 e 73.0 efg TX 501 X TX 502 81.7 ~80.4 b** * Duncan's Multiple Range Test - any two means having any one of the same letters are not significant. ** Indicates significance between the inoculated and uninoculated treatments of the single crosses or Texas hybrids. 16 Table 4. Summary of mean plant heights for the plots inoculated with MDMV and the uninoculated plots for the inbred test. Inbred Plant Heights (Cm.)* Lines Inoculated 061666016166 K 55 123.4 k 139.2 ij** K 64 130.ijk 2 146.4 hi** Tx 61M 155.9 fgh 165.1 efg Tx 585 151.1 ghi 149.0 ghi Tx 1270 149.8 ghi 149.9 ghi Tx 441 188.2 cd 201.9 abc Tx 173D 170.0 ef 177.5 de TX 203 162.6 fgh 169.3 ef Tx 303 185.1 d 212.9 ab** Tx 325 122.7 k 2 145.0 hi** Tx 508 157.8 fgh 167.4 ef Tx 601 215.1 a 212.9 ab Tx 602 201.3 66 4 200.7 66 * Duncan's Multiple Range Test - any two means having any one of the same letters are not significant. ** Indicates significance between the inoculated and uninoculated treatments of the inbred lines. 17 Table 5. Sunmary of mean plant heights for the plots inoculated with MDMV and the uninoculated plots for the hybrid tests. Plant Height (Cm.)* Varieties Inoculated Uninoculated X 55 X K 64 189.2 k 206.2 j** Tx 17w 211.7 j 232.1 ghi** Tx 61M X Tx 585 223.6 j 230.0 hi Tx 1730 X Tx 203 228.9 hi 229.1 hi Tx 30 248.2 cde 245.9 cdef Tx 303 X Tx 325 231.1 hi 245.1 cdefg** Tx 28A 250.6 bcd 261.8 ab Tx 127C X Tx 441 235.0 efghi 235.4 efghi Tx 40 237.4 efgh 255.3 bc** Tx 303 X Tx 508 203.0 238.5 defgh** Tx 203 X Tx 303 234.1 fghi 2 245.0 cdefg Tx 34 266.7 a 273.5 a Tx 601 X Tx 602 251.2 bcd 251.1 bcd * Duncan's Multiple Range Test - any same letters are not significant. two means having any one of the ** Indicates significance between the inoculated and uninoculated treatments of the single crosses or Texas hybrids. 18 Table 6. Summary of mean ear heights for the plots inoculated with MDMV and the uninoculated plots for the inbred test. Inbred Ear Height (Cm.)* Lines Inoculated Unihoculated K 55 32.28 l 42.95 k** K 64 38.71 kl 48.54 j** Tx 61M 57.48 gh 65.74 ef** Tx 585 62.59 de 65.61 ef Tx 127C 51.08 ij 48.54 j Tx 441 60.50 fgh 72.64 cd** Tx 173D 60.73 fgf 61.98 fg Tx 203 56.39 ghi 59.11 gh Tx 303 57.56 gh 74.40 c** Tx 325 ~ 42.32 kll 57.51 gh** Tx 508 56.95 gh 55.70 hi Tx 601 81.03 b 84.68 b Tx 602 95.89 a 97.03 a * Duncan's Multiple Range Test - any two means having any one of the same letters are not significant. ** Indicates significance between the inoculated and uninoculated treatments of the inbred lines. 19 Table 7. Summary of mean ear heights for the plots inoculatd with MDMV and the uninoculated plots for the hybrid test. Ear Height (Cm)* Varieties Inoculated Uninoculated K 55 X K 64 65.91 o 79.86 n** Tx 17w 84.46 mn 94.03 jkl** Tx 61M X Tx 585 93.68 jkl 37.02 jkl Tx 173D X Tx 203 101.27 hi 99.11 ij Tx 30 108.53 efg 112.52 cdef Tx 303 X Tx 325 92.00 kl 98.48 ijk Tx 28A 106.63 fgh 114.25 cde** Tx 127C X Tx 441 90.68 lm 87.10 lm Tx 127C X Tx 441 90.68 lm 87.10 lm Tx 40 109.47 defg 116.15 bcd Tx 303 X Tx 508 84.10 mni 108.07 ifg** Tx 203 X Tx 303 99.11 ij 104.67 ghi Tx 34 119.20 abc 123.04 ab iTx 601 X Tx 602 123.55 a 124.16 a * Duncan's Multiple Range Test - any two means having any one of the same letters are not significant. ** Indicates significance between the inoculated and uninoculated treatments of the single crosses or Texas hybrids. 20 Table 8. Summary of MDMV ratings at boot stage with only inoculatd plots rated for the inbred test. Inbred Virus Stunting Lines Rating* Rating** 1-5 1§5 K 55 4.0 2 7 K 64 5.0 2.0 Tx 61M 3.7 2.0 Tx 585 2.0 1.0 Tx 127C 2.3 2.0 Tx 441 2.3 2 7 Tx 173D 2.0 1.7 Tx 203 2.7 2.0 Tx 303 3.0 2.3 Tx 325 2.3 2.3 Tx 508 3.7 2.3 Tx 601 1.7 1.0 Tx 602 2.0 1.0 * 1 = No apparent infection of plant. 2 = Mottling in whorl of plant only. 3 = Mottling entire plant. 4 = Chlorosis of entire plant. 5 = Discoloration of plant other than chlorosis. 6 = Severe chlorosis, mottling or discoloration of plant. ** Stuntin , I ' No apparent stunting of plant. Slight stunting of plant. Stunting of plant with reduced ear size. Stunting of plant with no ear present. Death of plant. U'I->OOI\) ll ll ll ll l 21 Table 9. Summary of virus ratings at boot stage on the hybrid test for inoculated split-plot only. Means at Boot Stage Varieties Virus Rating* Stunting** K 55 X K364 3.0 2.7 Tx 17w 2.7 2.0 Tx 61M X Tx 585 2.0 1.3 Tx 1730 X Tx 203 2.0 2.0 Tx 30 2.0 2.3 Tx 303 X Tx 325 2.0 2.0 Tx 28A 2.0 2.3 Tx 127C X Tx 441 2.0 1 7 Tx 40 2.0 g2.3 Tx 303 X Tx 508 S 3.0 3.0 Tx 203 X Tx 303 2.0 2.7 Tx 34 2.0 1.7 Tx 601 X Tx 602 2.0 1.3 * 1 = No apparent infection of plant. 2 = Mottling in whorl of plant only. 3 = Mottling entire plant. 4 = Chlorosis of entire plant. 5 = Discoloration of plant othr than chlorosis. 6 = Severe chlorosis, mottling or discoloration of plant. ** Stuntin I " No apparent stunting of plant. Slight stunting of plant. Stunting of plant with reduced ear size. Stunting of plant with no ear present. Death of plant. UW-POOIU ll ll ll ll I 22 Table 10. Summary of mean yields in shelled bushels for the plots inoculated with MDMV and the uninoculated plots for the inbred test. Inbred Yield (Hectoliters/Hectarel Lines E Inoculated Uninoculated K 55 8.12 hijk 21.67 cd** K 64 7.79 ijk 17.28 def** Tx 61M 20.32 cde 31.83 a** Tx 585 24.62 DC‘ 23.71 bcd TX 127c _ 13.89 efghi I 15.24 defg TX 441 - 7.11 jk 12.87 fghij Tx 173D 16.94 def 24.04 bc** Tx 203 11.17 fghijk 13.55 efghij TX 303 14.90 defgh 29.47 ab** Tx 325 5.14 k 9.60 ghijk TX 508 5.43 k 11.17 fghijk TX 501 13.21 fghij 12.53 fghij Tx 602 I 5.08 k 5.56 k * Duncan's Multiple Range Test - any two means having any one of the same letters are not significant. ** Indicates significance between the inoculated and uninoculated treatments for the inbred test. 23 Table 11. Summary of mean yields for plots inoculated with MDMV and the uninoculated plots for the hybrid test. Yield (Hectoliters/Hectare) Varieties Inoculated Uninoculated K 55 X K864 51.81 gh 64.00 defgh Tx 17w 59.93 defgh 75.52 abcd Tx 61M X Tx 585 65.39 cdefg 67.05 bcdefg Tx 1730 X Tx 203 65.45 cdefg 8 73.20 abcde Tx 30 68.38 bcdef 70.42 abcdef Tx 303 X Tx 325 48.41 h 56.89 fgh Tx 28A 71.81 abcdef 70.88 abcdef Tx 127C X Tx 441 58.23 efgh 62.52 Tx 40 82.98 ab 80.24 abc Tx 303 X Tx 508 57.21 efgh ' 84.66 a** Tx 203 X Tx 303 71.02 abcdef 71.17 abcdef Tx 34 66.73 cdefg 74.88 abcd Tx 601 X Tx 602 30.13 i 29.11 i "k Duncan's Multiple Range Test - any two means having any one of the same letters are not significant. ** Indicates significance between the inoculated and uninoculatd treatments of the single crosses of Texas hybrids. 24 Table 12. ‘Summary of mean shelling percent for the plots inoculated with MDMV and the uninoculated plots for the inbred test. Shelling Percent* Inbred Lines Inoculated dninoculated K 55 67.2 abcd 69.0 abcd K 64 76.7 abc 75.9 abcd Tx 61M 76.0 abc 78.3 abc Tx 585 78.0 abc 80.5 ab Tx 127c 72.1 abcd 75.1 abcd Tx 441 59.3 cd 70.9 abcd Tx 1730 74.5 abcd 76.7 abc Tx 203 73.8 abcd 79.4 abc Tx 303 84.2 a 84.2 a TX 325 3 51.9 bcd 75.0 abcd Tx 508 59.0 cd 60.8 bcd Tx 601 61.7 bcd 54.8 d Tx 602 64.2 abcd 67.5 abcd * Duncan's Multiple Range Test - any two means having any one of the same letters are not significant. 25 Table 13. Summary of mean shelling percents and test weights for the plots inoculated with MDMV and the uninoculated plots of the hybrid test. Shelling Percent* Varieties Inoculated Uninoculated K 55 X K 64 73.17 e 80.43 cd** Tx 17w 82.70 abcd 82.90 abcd Tx 61M X Tx 585 81.10 bcd 84.57 abc M Tx 1730 X Tx 203 81.17 bcd 76.83 de Tx 30 84.90 abc 83.20 abc Tx 303 X Tx 325 85.90 ab 87.43 a Tx 28A 84.20 abc 84.53 abc Tx 127C X Tx 441 82.80 abcd 82.40 abcd Tx 40 85.90 ab 82.80 abcd 1Tx 303 X Tx 508 81.70 bcd 85.33 abc Tx 203 X Tx 303 85.17 abc 85.27 abc Tx 34 81.17 bcd 85.80 abc Tx 601 X Tx 602 86.13 ab 84.30 abc ** Duncan's Multiple Range Test - any two means having any one of the same letters are not significant. ‘ Indicates significance between the inoculated and uninoculated treatments of the single crosses or Texas hybrids. Table 14. 26 Sunmary of mean test weights for the plots inoculated with MDMV and the uninoculated plots of the hybrid test. Test weight (Kg/hl)* Varieties Inoculated Uninoculated K s5 x K 64 75.4 a 74.5 ab." Tx 17w 74.7 abc 75.7 a Tx 61M X Tx 585 74.9 ab 75.4 a Tx 1730 X Tx 203 75.6 af 73.9 bcde** Tx 30 72.7 efg 73.1 de Tx 303 X Tx 325 71.1 hijk 70.5 ijk Tx 28A 71.4 hij 70.2 k** Tx 127C X Tx 441 68.0 l 67.4 l Tx 40 70.3 jk 70.8 hijk TX 303 X Tx 508 72.9 efr 72.0 fgh Tx 203 X Tx 303 74.5 abc 74.5 abc Tx 34 73.6 cde 74.9 ab** Tx 601 X Tx 602 71.7 ghi 74.1 bcd** * 'k'k Duncan's Multiple Range Test - any two means having any one of the same letters are not significant. Indicates significance between the inoculated and uninoculated treatments of the single crosses or Texas hybrids. 4.11.1 [Blank Page in Original Bulletin] 7 4-. K‘ m", ; l; : 7. ,- . _» \. Mention of a trademark or a proprietary product does not constitute a guarantee or a warranty of the product by The Texas Agricultural Experiment Station and docs not imply its approval to the exclusion of other products that also may be suitable. 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