Online Resource 1 Means and standard deviations of results from media type experiment (Figure 2)

Measurement / Media / Seed Line / Mean / SD
Length / Difco / DR5 / 32.549 / 1.816
UB / 27.948 / 3.125
Agarose / DR5 / 11.019 / 1.658
UB / 9.605 / 1.349
Phytagel / DR5 / 33.895 / 2.414
UB / 31.665 / 3.028
Skewing / Difco / DR5 / 0.286 / 0.081
(HGI) / UB / 0.511 / 0.084
Agarose / DR5 / 0.087 / 0.124
UB / -0.01 / 0.177
Phytagel / DR5 / 0.043 / 0.058
UB / 0.067 / 0.072
Waving / Difco / DR5 / 0.912 / 0.019
(STR) / UB / 0.821 / 0.098
Agarose / DR5 / 0.963 / 0.017
UB / 0.91 / 0.044
Phytagel / DR5 / 0.98 / 0.009
UB / 0.975 / 0.022
Waving / Difco / DR5 / 0.98 / 0.174
(WD) / UB / 0.656 / 0.141
Agarose / DR5 / 1.678 / 0.768
UB / 1.222 / 0.488
Phytagel / DR5 / 0.815 / 0.398
UB / 0.865 / 0.37

Online Resource 2 Means and standard deviations of results from media hardness quantification tests (Figure 3)

Media / Avg. Force (N) / SD
0.5% Phytagel / 0.572 / 0.025
1.0% Phytagel / 1.512 / 0.030
1.2% Phytagel / 1.680 / 0.049
1.5% Phytagel / 2.213 / 0.068
0.8% Difco Agar / 0.169 / 0.010
1.0% Difco Agar / 0.349 / 0.015
1.5% Difco Agar / 0.977 / 0.070
0.5% Agarose / 0.389 / 0.004
1.0% Agarose / 1.009 / 0.161

Online Resource 3 Coefficients and significance for regression curves of media hardness, DR5 and UB genotypes, all of which were significant (p < 0.05). General equation y=ax3+bx2+cx+d.

Genotype / Coefficient/
Statistic / L / HGI / STR / WD
DR5 / a / --- / -0.020 / 0.924 / ---
b / 13.238 / 0.757 / -3.350 / -0.390
c / -34.933 / -0.828 / 3.940 / 0.856
d / 42.985 / 0.334 / 2.093 / -0.342
Res. Std. Err. / 10.410 / 0.121 / 0.622 / 0.569
F-stat / 24.570 / 8.356 / 20.610 / 5.462
DF / 2, 231 / 3, 230 / 3, 230 / 2, 231
Adj. R2 / 0.168 / 0.087 / 0.202 / 0.037
UB / a / --- / -5.731 / 0.823 / ---
b / 6.883 / 2.239 / -2.772 / ---
c / -21.429 / -2.531 / 3.316 / 0.280
d / 37.929 / 0.863 / 1.512 / -0.647
Res. Std. Err. / 11.140 / 0.211 / 0.870 / 0.569
F-stat / 9.172 / 20.350 / 16.800 / 12.420
DF / 2, 160 / 3, 159 / 3, 159 / 1, 161
Adj. R2 / 0.092 / 0.264 / 0.226 / 0.066

Online Resource 4 Correlation between media hardness and root skewing with regression curves separated by media type for DR5 roots. Points represent means (average n = 26) and error bars represent 95% confidence interval. Complete statistics and significance values are found in Table S5. Straightness data were logit transformed to produce a normal distribution. WD data were log transformed to produce a normal distribution. A) Length of primary root. Root length decreased as H increased. Regression curve equations: LDifco = -9.092(H) + 34.495, R2= 0.501; LAgarose = -4.913(H) + 15.974, R2 = 0.354; LPhytagel = -6.948(H) + 40.060, R2 = 0.284. B) Horizontal growth index. Difco agar resulted in decreasing HGI as H increased, but the remaining media types resulted in increasing HGI as H increased. Regression curve equations: HGIDifco = -0.036(H) + 0.279, R2= -0.010; HGIAgarose = 0.062(H) + 0.025, R2 = 0.002; HGIPhytagel = 0.053(H) – 0.002, R2 = 0.102. C) Straightness of primary root. STR increased as H increased, but at different rates, depending on the media type. Regression curve equations: logit(STRDifco) = 0.474(H) + 2.307, R2 = 0.233; logit(STRAgarose) = 0.689(H) + 2.654, R2 = 0.093; logit(STRPhytagel) = 0.176(H) + 3.709, R2 = 0.032. D) Root wave density. WD tended to increase as H increased for Difco agar and agarose, but decreased as H increased for Phytagel. Regression curve equations: ln(WDDifco) = 0.242(H) - 0.079, R2 = 0.111; ln(WDAgarose) = 0.444(H) - 0.047, R2 = 0.030; ln(WDPhytagel) = -0.013(H) - 0.187, R2 = -0.008

Online Resource 5 Coefficients and significance for regression curves of media hardness in UB, general equation y=ax2+bx+c. All coefficients are significant (p < 0.05)

Genotype / Coefficient/
Statistic / L / HGI / STR / WD
Difco Agar / a / 0.000 / 0.000 / 0.000 / 0.000
b / -9.636 / -0.142 / -0.054 / 0.574
c / 32.110 / 0.583 / 1.562 / -0.655
Res. Std. Err. / 3.759 / 0.085 / 0.542 / 0.231
F-stat / 27.280 / 11.490 / 0.041 / 25.740
DF / 1, 29 / 1, 29 / 1, 29 / 1, 29
Adj. R2 / 0.467 / 0.259 / -0.033 / 0.452
p-value / < 0.001 / 0.002 / n.s. / < 0.001
Agarose / a / 0.000 / 0.000 / 0.000 / 0.000
b / -2.651 / -0.182 / -0.046 / 0.720
c / 12.279 / 0.173 / 2.470 / -0.613
Res. Std. Err. / 2.405 / 0.170 / 0.503 / 0.472
F-stat / 3.684 / 3.447 / 0.026 / 7.053
DF / 1, 37 / 1, 37 / 1, 37 / 1, 37
Adj. R2 / 0.066 / 0.061 / -0.026 / 0.137
p-value / n.s. / n.s. / n.s. / 0.012
Phytagel / a / 0.000 / -0.133 / 0.000 / 0.000
b / -9.909 / 0.445 / 0.448 / 0.384
c / 43.491 / -0.280 / 2.951 / -0.980
Res. Std. Err. / 5.992 / 0.128 / 0.669 / 0.570
F-stat / 102.300 / 15.630 / 16.750 / 16.970
DF / 1, 91 / 2, 90 / 1, 91 / 1, 91
Adj. R2 / 0.524 / 0.241 / 0.146 / 0.148
p-value / < 0.001 / < 0.001 / < 0.001 / < 0.001

Online Resource 6 Coefficients and significance for regression curves of media hardness in DR5, general equation y=ax+b. All coefficients are significant (p < 0.05)

Genotype / Coefficient/
Statistic / L / HGI / STR / WD
Difco Agar / a / -9.092 / -0.036 / 0.474 / 0.242
b / 34.495 / 0.279 / 2.307 / -0.079
Res. Std. Err. / 3.288 / 0.093 / 0.302 / 0.226
F-stat / 34.140 / 0.669 / 11.010 / 5.104
DF / 1, 32 / 1, 32 / 1, 32 / 1, 32
Adj. R2 / 0.501 / -0.010 / 0.233 / 0.111
p-value / < 0.001 / n.s. / 0.002 / 0.031
Agarose / a / -4.913 / 0.062 / 0.689 / 0.444
b / 15.974 / 0.025 / 2.654 / -0.047
Res. Std. Err. / 1.594 / 0.123 / 0.491 / 0.514
F-stat / 41.540 / 1.112 / 8.615 / 3.267
DF / 1, 73 / 1, 73 / 1, 73 / 1, 73
Adj. R2 / 0.354 / 0.002 / 0.093 / 0.030
p-value / < 0.001 / n.s. / 0.004 / n.s.
Phytagel / a / -6.948 / 0.053 / 0.176 / -0.013
b / 40.060 / -0.002 / 3.709 / -0.187
Res. Std. Err. / 6.647 / 0.092 / 0.526 / 0.584
F-stat / 50.160 / 15.150 / 5.152 / 0.022
DF / 1, 123 / 1, 123 / 1, 123 / 1, 123
Adj. R2 / 0.284 / 0.102 / 0.032 / -0.008
p-value / < 0.001 / < 0.001 / 0.025 / n.s.

Online Resource 7 ANOVA statistics for media arrangement experiment (Figure 6)

Measurement / Variable / F value and degrees of freedom / p-value
Length
(L) / Seed lines / F1, 419 = / 199.977 / p < 0.001
Media / F2, 419 = / 7.824 / p < 0.001
Interaction / F2, 419 = / 2.929 / n.s.
Skewing
(HGI) / Seed lines / F1, 419 = / 1.168 / n.s.
Media / F2, 419 = / 4.992 / p = 0.007
Interaction / F2, 419 = / 1.789 / n.s.
Waving
(STR) / Seed lines / F1, 419 = / 19.744 / p < 0.001
Media / F2, 419 = / 21.015 / p < 0.001
Interaction / F2, 419 = / 2.519 / n.s.
Waving
(WD) / Seed lines / F1, 419 = / 2.751 / n.s.
Media / F2, 419 = / 2.628 / n.s.
Interaction / F2, 419 = / 1.741 / n.s.

Online Resource 8.Means and standard deviations of results from media arrangement experiment (Figure 6)

Measurement / Media / Seed Line / Mean / SD
Length
(L, mm) / Holes / DR5 / 24.326 / 4.563
UB / 32.161 / 5.677
Layer / DR5 / 27.536 / 4.152
UB / 33.165 / 5.493
Surface / DR5 / 25.680 / 5.081
UB / 34.722 / 7.870
Skewing
(HGI, %) / Holes / DR5 / 1.216 / 11.136
UB / 1.488 / 11.334
Layer / DR5 / 0.119 / 7.815
UB / -0.311 / 9.808
Surface / DR5 / 2.350 / 7.919
UB / 6.557 / 8.989
Waving
(STR, %) / Holes / DR5 / 97.109 / 2.649
UB / 96.659 / 2.536
Layer / DR5 / 98.444 / 0.914
UB / 98.235 / 1.065
Surface / DR5 / 98.397 / 0.859
UB / 97.310 / 1.607
Waving
(WD, waves/mm) / Holes / DR5 / 0.826 / 0.983
UB / 0.584 / 0.410
Layer / DR5 / 0.586 / 0.241
UB / 0.540 / 0.152
Surface / DR5 / 0.517 / 0.193
UB / 0.506 / 0.154

Online Resource 9Root morphometric data from all altered media tests, average n = 22.

Line / Media / Length / SD
Length / HGI / SD
HGI / STR / SD
STR / WD / SD
WD
DR5 / 0.8% Difco / 32.250 / 3.003 / 0.261 / 0.095 / 0.919 / 0.021 / 1.005 / 0.212
UB / 0.8% Difco / 30.989 / 4.463 / 0.572 / 0.065 / 0.796 / 0.089 / 0.588 / 0.156
DR5 / 1.0% Difco / 32.549 / 1.816 / 0.286 / 0.081 / 0.912 / 0.019 / 0.980 / 0.174
UB / 1.0% Difco / 27.948 / 3.125 / 0.511 / 0.084 / 0.821 / 0.098 / 0.656 / 0.141
DR5 / 1.5% Difco / 25.423 / 3.804 / 0.240 / 0.090 / 0.939 / 0.018 / 1.219 / 0.344
UB / 1.5% Difco / 22.805 / 3.095 / 0.447 / 0.090 / 0.814 / 0.035 / 0.924 / 0.170
DR5 / 0.5% Agarose / 14.063 / 1.171 / 0.049 / 0.117 / 0.941 / 0.032 / 1.276 / 0.613
UB / 0.5% Agarose / 11.248 / 4.038 / 0.103 / 0.141 / 0.914 / 0.039 / 0.814 / 0.414
DR5 / 1.0% Agarose / 11.019 / 1.658 / 0.087 / 0.124 / 0.963 / 0.017 / 1.861 / 0.918
UB / 1.0% Agarose / 9.605 / 1.349 / -0.010 / 0.177 / 0.910 / 0.044 / 1.182 / 0.530
DR5 / 0.5% Phytagel / 36.176 / 7.003 / 0.027 / 0.096 / 0.975 / 0.014 / 0.994 / 0.606
UB / 0.5% Phytagel / 37.888 / 7.791 / -0.068 / 0.172 / 0.951 / 0.043 / 0.542 / 0.304
DR5 / 1.0% Phytagel / 33.895 / 2.414 / 0.043 / 0.058 / 0.980 / 0.009 / 0.815 / 0.398
UB / 1.0% Phytagel / 31.665 / 3.028 / 0.067 / 0.072 / 0.975 / 0.022 / 0.865 / 0.370
DR5 / 1.2% Phytagel / 20.931 / 2.265 / 0.146 / 0.088 / 0.976 / 0.011 / 1.060 / 0.647
UB / 1.2% Phytagel / 20.263 / 1.570 / 0.130 / 0.115 / 0.961 / 0.016 / 0.553 / 0.329
DR5 / 1.5% Phytagel / 27.836 / 2.637 / 0.088 / 0.060 / 0.985 / 0.006 / 0.874 / 0.335
UB / 1.5% Phytagel / 23.242 / 1.930 / 0.052 / 0.074 / 0.981 / 0.006 / 1.071 / 0.417

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