STEM BORING OF SOYBEAN BY DECTES TEXANUS (COLEOPTERA: CERAMBYCIDAE) AND THE NATURE OF ITS IMPACT ON YIELD - Soybean and Wheat Crops: Growth, Fertilization, and Yield - page 118

difference ( F = 0.890; df = 1,205; P = 0.347). In 2006, there were no significant differences
between infested and uninfested plants for any component of yield.
Among uninfested plants in 2005, stem diameter was linearly correlated with stem weight
( F = 31.08; df = 101; P < 0.001; r 2 = 0.235), with pod number ( F = 27.96; df = 101; P <
0.001; r 2 = 0.217) and with total seed weight ( F = 49.63; df = 101; P < 0.001; r 2 = 0.329).
Similarly, stem weight was linearly correlated with pod number ( F = 48.20; df = 101; P <
0.001; r 2 = 0.323) and total seed weight ( F = 98.87; df = 101; P < 0.001; r 2 = 0.495) and pod
number was correlated with total seed weight ( F = 83.70; df = 101; P < 0.001; r 2 = 0.453).
Among infested plants, stem diameter was linearly correlated with stem weight ( F = 42.92; df
= 102; P < 0.001; r 2 = 0.296), with pod number ( F = 39.63; df = 102; P < 0.001; r 2 = 0.280)
and with total seed weight ( F = 46.71; df = 102; P < 0.001; r 2 = 0.314) and stem weight with
pod number ( F = 59.18; df = 102; P < 0.001; r 2 = 0.367) and with total seed weight ( F =
65.65; df = 102; P < 0.001; r 2 = 0.392) and pod number with total seed weight ( F = 172.14; df
= 102; P < 0.001; r 2 = 0.628).
Since there were no significant differences between infested and uninfested plants in
2006, data were pooled for regression analyses. Once again, stem diameter was linearly
correlated with stem weight ( F = 92.73; df = 121; P < 0.001; r 2 = 0.434), pod number ( F =
81.90; df = 121; P < 0.001; r 2 = 0.404) and seed weight ( F = 57.45; df = 121; P < 0.001; r 2 =
0.322) and stem weight with pod number ( F = 133.68; df = 121; P < 0.001; r 2 = 0.525) and
total seed weight ( F = 106.77; df = 121; P < 0.001; r 2 = 0.469) and pod number with total
seed weight ( F = 418.07; df = 121; P < 0.001; r 2 = 0.776).
Among infested plants, tunnel length displayed no relationship with pod number ( F =
0.81; df = 102; P = 0.371) in 2005 but was positively correlated with total seed weight ( F =
4.06; df = 102; P = 0.047), although no significant variation was explained (r 2 = 0.038). In
2006, neither pod number ( F = 0.98; df = 62; P = 0.326) nor total seed weight ( F = 1.25; df =
62; P = 0.267) displayed any relationship with tunnel length.
Table 1. Mean (± SEM) values of various yield components (dry weights) for soybean
plants with (Infested) and without (Control) larvae of Dectes texanus in two years
Treatment Stem diameter
(mm)

Stem weight
(gm)

Pod number Tunnel length

(mm)

Seed weight
(gm)

2005

Control 5.69 ± 0.10a 4.99 ± 0.13a 40.35 ± 1.07a --- 7.96 ± 0.25b

Infested 5.94 ± 0.08a 5.24 ± 0.13a 43.09 ± 1.14a 36.89 ± 1.13 8.72 ± 0.27a

F 1, 205

3. 74 1.83 3.07 N/A 4.30

P

0.053 0.178 0.081 N/A 0.039

2006
Control 8.14 ± 0.19a 7.47 ± 0.32a 54.64 ± 2.33a --- 21.31 ± 0.93a
Infested 7.82 ± 0.19a 7.67 ± 0.38a 52.54 ± 2.28a 21.62 ± 1.25 20.11 ± 0.93a
F 1,121 1.36 0.16 0.41 N/A 0.82
P 0.246 0.693 0.523 N/A 0.367
Values bearing the same letters were not significantly different (ANOVA, α > 0.05) between Infested
and Control plants within years.