Fig. 1. Effect of compaction pressure on the soil dry bulk density.
rate was 72.6 meaning that in 362 out 1320 pots 27.4 were empty that is having no
emerged plants. The frequency of empty pots, averaged over genotypes for soil water content,
was 62 under high initial water content condi- tion and 38 for the low water content. The
corresponding frequencies for sandy loam and clay loam soil types were 42 and 58, respec-
tively. These frequency estimates indicated a wa- ter content and soil type effect on emergence. In
the same manner a compaction pressure effect Fig. 2 was indicating that compaction pressure
higher than 125 kPa resulted in 3 – 9 increase of empty pots.
Variable genotypes, empty pots, showed the expected response with the inbreeds being affected
more severely due to inbreeding depression Fig. 3. Besides this expected response some differ-
ences were evident within the group of outcrossed genotypes indicating possible genotypic differ-
ences. Main effects were highly significant for all variables and some interaction effects, as well
Table 2. In spite of some interaction effects and especially those for the root diameter being sig-
nificant, interaction effects generally contributed no more than 3.5 to the total variance for each
main effect. This means that the average main effects could be considered disregarding interac-
tions Table 3.
Time to shoot emergence was affected by the factors studied, as well Tables 2 and 3. Com-
Fig. 2. Frequency histogram of empty pots versus compaction pressure.
3. Results
The soil compaction effect on soil dry bulk density is shown in Fig. 1. The overall emergence
Fig. 3. Empty pots frequency averaged over soil type, water content and compaction pressure.
Table 2 Analysis of variance for the sugar beet growth parameters
a
Plant dry matter Root dry matter
Root diameter Plant height
Root length Main effects
Water content WC Pressure P
Soil S Variety V
Interactions WC×P
ns WC×S
ns WC×V
ns ns
ns P×S
P×V ns
ns S×V
ns ns
ns WC×P×S
ns ns
WC×P×V ns
ns ns
ns ns
WC×S×V ns
WC×S×P×V ns
a
ns, not significant effect. Effect significant at P = 0.05. Effect significant at P = 0.01.
paction pressures 1 – 125 kPa did not seem to affect time to emergence but when the pressure
exceeded a threshold point of 200 kPa the emer- gence time increased linearly. Concerning the
genotypic response, although the average geno- typic effect did not show differences Table 3, the
clustering of genotypes in groups indicated geno- typic differences which were in the range of about
2 days data not shown showing that genotypes could be grouped in fast and slow emerging.
These differences could not be clearly attributed to inbreeding versus outcrossing effects, since
some of the differences could be attributed to fruit shape genotype 782 being multigerm and some
other to hybrid vigor P104. Also the slow emerging genotypes included an inbred line 031
and a hybrid variety Rizor whereas all other genotypes ranged between fast and slow. Vari-
ables related to performance like plant height, aerial dry matter and root traits diameter, length
were affected by soil water, compaction pressure and soil type. Genotypic differences were ob-
served, as well. The average plant height was significantly lower 87 vs. 138 mm under high soil
water and in the sandy loam soil type Table 3. The same holds true for the compaction pressure
effect. Thus compaction pressure from 1 to 125 kPa resulted in higher plants as compared to
pressures higher than 200 kPa Table 3. Concerning plant height averaged over factors,
genotypes showed a different response. Three groups were evident as confirmed by data pre-
sented in Table 3. The inbred group genotypes 031, 002 and 009 as expected, had the smaller
height, the hybrid one genotypes P104, S-582 and 782 the larger, whereas the remaining genotypes
were of intermediate height. The soil water con- tent had a significant effect on dry matter pro-
duced by the aerial part of plants Table 2. Increased initial soil water resulted in a substan-
tial reduction 0.41 vs. 0.79 g whereas the com- paction pressure resulted in a detrimental effect in
the same direction. Thus, pressures from 0 to 125 kPa did not seem to influence the dry matter
production whereas beyond the threshold point of 200 kPa that dry matter showed a linear decrease
Table 3.
Genotypic differences in dry matter production, averaged over all factors, were evident, as ex-
pected. Thus inbreds genotypes 031, 002 and 009 had the lowest dry matter production due appar-
ently to inbreeding depression. In the same man- ner root traits were affected by all factors studied
Tables 2 and 3. Trends were in the same direc-
T .A
. Gemtos
et al
. Europ
. J
. Agronomy
12 2000
201 –
209
Table 3 Performance of each parameter studied under the conditions tested
Time to emergence Average main
Plant dry matter Final plant height
Root dry matter Diameter at soil level
Root length mean mm
mean g mean mm
mean g mean days
mean mm effects
Initial soil water content 3.68 9 0.10
52.2 9 1.25 0.17 9 0.007
0.79 9 0.04 138 9 3.02
Low 4.7 9 0.11
2.48 9 0.10 7.0 9 0.15
33.6 9 1.25 87 9 3.02
0.41 9 0.04 0.09 9 0.007
High Soil compaction pressure
kPa 53.3 9 2.34
1 4.1 9 0.21
142 9 5.65 0.73 9 0.06
0.17 9 0.014 3.82 9 0.19
53.2 9 2.34 0.86 9 0.06
4.15 9 0.19 0.19 9 0.014
150 9 5.65 50
4.3 9 0.20 3.76 9 0.19
4.1 9 0.21 48.8 9 2.34
137 9 5.65 0.76 9 0.06
0.16 9 0.014 125
0.14 9 0.014 3.0 9 0.19
42.9 9 2.34 4.8 9 0.22
200 91 9 5.65
0.55 9 0.06 280
36.6 9 2.34 6.8 9 0.22
103 9 5.65 0.55 9 0.06
0.11 9 0.014 2.57 9 0.19
38.9 9 2.34 340
2.54 9 0.19 7.9 9 0.24
0.88 9 0.014 96 9 5.65
0.41 9 0.06 400
26.8 9 2.34 8.8 9 0.24
70 9 5.65 0.28 9 0.06
0.04 9 0.014 1.71 9 0.19
Soil type 0.17 9 0.007
3.75 9 0.10 48.5 9 1.25
Clay loam 123 9 3.02
5.6 9 0.11 0.80 9 0.08
37.4 9 1.25 102 9 3.02
2.41 9 0.10 0.09 9 0.007
0.40 9 0.08 Sandy loam
6.0 9 0.12 Genotype
24.8 9 2.99 031
6.5 9 0.30 74 9 7.09
0.27 9 0.09 0.07 9 0.017
1.75 9 0.24 26.4 9 2.99
0.07 9 0.017 1.79 9 0.24
0.23 9 0.09 002
60 9 7.09 6.2 9 0.29
0.08 9 0.017 2.05 9 0.24
32.2 9 2.99 92 9 7.09
009 0.34 9 0.09
5.8 9 0.29 59.7 9 2.99
P104 4.92 9 0.24
0.26 9 0.017 5.1 9 0.25
1.20 9 0.09 159 9 7.09
3.69 9 0.24 5.5 9 0.26
51.3 9 2.99 136 9 7.09
0.69 9 0.09 0.15 9 0.017
S-562 5.3 9 0.25
3.29 9 0.24 52.9 9 2.99
141 9 7.09 0.70 9 0.09
782 0.14 9 0.017
45.0 9 2.99 0.65 9 0.09
3.35 9 0.24 0.14 9 0.017
115 9 7.09 Vergina
6.1 9 0.27 2.77 9 0.24
6.4 9 0.27 39.7 9 2.99
99 9 7.09 0.44 9 0.09
0.99 9 0.017 Rizor
0.12 9 0.017 3.24 9 0.24
41.9 9 2.99 6.1 9 0.26
765 117 9 7.09
0.74 9 0.09 0.15 9 0.017
3.61 9 0.24 52.1 9 2.99
5.5 9 0.25 T1594
131 9 7.09 0.76 9 0.09
46.1 9 2.99 5.5 9 0.26
3.39 9 0.24 0.13 9 0.017
A1991 0.66 9 0.09
116 9 7.09
tion as those observed for the above ground dry matter production. High initial soil water and the
high compaction pressure resulted in the same detrimental effects whereas the genotypic differ-
ences were observed in the same manner as previ- ously. Root diameter at soil level Tables 2 and 3
was larger under low soil water, and clay loam soil type whereas low compaction pressures 0 –
125 kPa resulted in larger diameter as compared to high pressure. Genotypes reacted in different
manner indicating genetic effects Table 3. Thus inbreds genotypes 031, 002 and 009 had the
smaller diameter, hybrid P104 the largest and all other genotypes intermediate. Finally, root length
was affected by soil water content and com- paction pressure, but not by soil type Tables 2
and 3. High initial soil water with high com- paction pressure resulted in decreased root length,
whereas the genotypic differences observed for all other traits were evident, for the root length as
well. Thus inbreds genotypes 031, 002 and 009 had the smaller root length as compared to the
other genotypes.
4. Discussion
