Variation and Relationships among Agronomic Traits in Durum Wheat [Triticum turgidum (L.) Thell. ssp. turgidum conv. durum (Desf.) MacKey] under South Mediterranean Growth Conditions: Stepwise and Path Analyses
Table 6
Full and stepwise regression models and direct and indirect effects of independent variables on grain yield.
Full regression model
b
t
Prob
R2 mult
Constant
41.742 ± 47.85
0.872
0.392
—
DHE
−0.630 ± 0.39
−1.613
0.121
—
BIO
0.328 ± 0.04
9.382
0.000
—
SN
0.126 ± 0.12
1.065
0.299
—
PHT
0.071 ± 0.08
0.903
0.376
—
HI
0.934 ± 0.13
7.049
0.000
—
CHL
−0.013 ± 0.01
−1.140
0.267
—
CT
0.173 ± 0.41
0.419
0.679
0.9458
Stepwise regression model
Variables available: BIO, SN, PHT, HI, CHL, and CT
β
b ± SEb
t
a
R2 mult
BIO
0.999
0.361 ± 0.012
31.22
—
—
HI
0.528
1.271 ± 0.077
16.49
−46.954
0.949
Variables available: SN, PHT, HI, CHL, and CT
SN
0.769
1.033 ± 0.104
9.95
—
—
CHL
−0.287
−0.061 ± −0.016
3.75
—
—
PHT
0.231
0.319 ± 0.0140
2.79
26.08
0.683
Path analysis
Variable
DHE
BIO
SN
PHT
HI
CHL
CT
Direct effect
−0.014
0.918
0.068
0.050
0.490
−0.033
−0.010
Indirect effects
−0.325
−0.082
0.690
0.257
−0.271
−0.146
−0.177
ri/j
−0.339
0.836
0.758
0.307
0.219
−0.179
−0.187
DHE = days to head, BIO = aboveground biomass, SN = spike number, GY = grain yield, Yeco = economical yield, PHT = plant height, STW = straw yield, HI = harvest index, CHL = chlorophyll content, and CT = canopy temperature.
