Here, the maximum correlation of NDVI is relatively low because reference yield
efficiency data indicates district statistical values, while NDVI is computed on the
observed cereal fields.
If the data is grouped with respect to the correlation rate of the yield efficiency and
the minimum covariance, then we get an example set of values listed in Table 7.2.
VPD6 and VPD12 denote VPD in the phenological stage 6 and summation of
VPD in phenological stage 1 and stage 2, respectively. ARF1234 is the accumulated
rainfall summation in stage 1, stage 2, stage 3, and stage 4. PTU56 is the summation
of PTU in stage 5 and stage 6. Tmin7 is the minimum temperature in phenological
stage 7.
When the values in Table 7.2 are used for the calculation of the regression
coefficients for yield efficiency (YE), then we get
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
2
3
4
5
6
7
Correlation to Yield Efficiency
Phenological stage
stage dur.
GDD
VPD
PTU
Tmin
RF
ET0
NDVI
Fig. 7.8 Variation of the correlations between the agrometeorological indices and the phenological
stage durations
Table 7.1 Phenological stage segmented parameters’ correlation to wheat yield efficiency
Stage 1
Stage 2
Stage 3
Stage 4
Stage 5
Stage 6
Stage 7
St.D.
À0.1970
À0.3093
0.3505
0.0517
À0.0913
0.2778
À0.1670
GDD
À0.5842
À0.4844
À0.2035
À0.0498
0.2678
0.5059
À0.0253
VPD
À0.6244
À0.5843
0.0952
À0.1566
0.1474
0.5566
À0.1802
PTU
À0.5919
À0.4851
À0.1661
À0.0081
0.3192
0.5288
0.0230
Tmin
À0.3057
À0.0125
À0.3547
0.0821
0.2985
0.2543
0.3102
RF
0.4559
0.3109
0.5418
0.3317
À0.1529
0.1423
0.1534
ET0
À0.5575
À0.4849
0.2285
0.1425
0.1834
0.5019
À0.2733
NDVI
0.3377
0.4322
0.4771
0.1588
0.1506
0.2588
0.0339
7 Data Fusion in Agricultural Information Systems
117
efficiency data indicates district statistical values, while NDVI is computed on the
observed cereal fields.
If the data is grouped with respect to the correlation rate of the yield efficiency and
the minimum covariance, then we get an example set of values listed in Table 7.2.
VPD6 and VPD12 denote VPD in the phenological stage 6 and summation of
VPD in phenological stage 1 and stage 2, respectively. ARF1234 is the accumulated
rainfall summation in stage 1, stage 2, stage 3, and stage 4. PTU56 is the summation
of PTU in stage 5 and stage 6. Tmin7 is the minimum temperature in phenological
stage 7.
When the values in Table 7.2 are used for the calculation of the regression
coefficients for yield efficiency (YE), then we get
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
2
3
4
5
6
7
Correlation to Yield Efficiency
Phenological stage
stage dur.
GDD
VPD
PTU
Tmin
RF
ET0
NDVI
Fig. 7.8 Variation of the correlations between the agrometeorological indices and the phenological
stage durations
Table 7.1 Phenological stage segmented parameters’ correlation to wheat yield efficiency
Stage 1
Stage 2
Stage 3
Stage 4
Stage 5
Stage 6
Stage 7
St.D.
À0.1970
À0.3093
0.3505
0.0517
À0.0913
0.2778
À0.1670
GDD
À0.5842
À0.4844
À0.2035
À0.0498
0.2678
0.5059
À0.0253
VPD
À0.6244
À0.5843
0.0952
À0.1566
0.1474
0.5566
À0.1802
PTU
À0.5919
À0.4851
À0.1661
À0.0081
0.3192
0.5288
0.0230
Tmin
À0.3057
À0.0125
À0.3547
0.0821
0.2985
0.2543
0.3102
RF
0.4559
0.3109
0.5418
0.3317
À0.1529
0.1423
0.1534
ET0
À0.5575
À0.4849
0.2285
0.1425
0.1834
0.5019
À0.2733
NDVI
0.3377
0.4322
0.4771
0.1588
0.1506
0.2588
0.0339
7 Data Fusion in Agricultural Information Systems
117