Fig 1.
Mean monthly rainfall, relative humidity, and maximum and minimum temperatures during the field experiments.
Table 1.
Soil chemical characteristics for the field experimental sites in Years 1 and 2.
Table 2.
Chemical characteristics of soil used in the pot experiment.
Table 3.
Two-way ANOVA tables for the effects of NPK fertiliser application on leaf HCN levels from the pot experiment and on root HCN levels from the field experiments in Years 1 and 2.
Table 4.
HCN levels in leaves and roots of each variety in the pot and field experiments under the effects of increased NPK fertiliser application.
Fig 2.
Models of HCN responses to increased NPK fertiliser application for each cassava variety in the field experiments in Years 1 and 2.
Note that an ordinal scale was used to represent the fertiliser treatments and that; 0 = (N0P0K0), 1 = N1P1K1 and 2 = N2P2K2. Where; N0P0K0 = no fertiliser; N1P1K1 = 50 kg N + 10 kg P + 50 kg K /ha; N2P2K2 = 100 kg N + 25 kg P + 100 kg K /ha. Note that the sole K treatment (N0P0K1) has not been included in these analyses.
Fig 3.
Models of HCN responses to increased NPK fertiliser application for each cassava variety in the pot experiment.
Note that an ordinal scale was used to represent the fertiliser treatments and that; 0 = (N0P0K0), 1 = N1P1K1 and 2 = N2P2K2. Where; N0P0K0 = no fertiliser; N1P1K1 = 25 mg N + 5 mg P + 25 mg K /kg; N2P2K2 = 50 mg N + 13 mg P + 50 mg K /kg. Note that the sole K treatment (N0P0K1) has not been included in these analyses.
Table 5.
Correlations between the HCN levels in roots of each variety in Years 1 and 2.
Table 6.
Results of the multiple linear regression analysis showing relationships between nutrient concentrations in the YFEL’s and the root HCN levels of cassava varieties in the two field experiments.
Table 7.
Nutrient concentrations in the youngest fully expanded leaves of cassava varieties under each NPK treatment in Year 1.
Table 8.
Nutrient concentrations in the youngest fully expanded leaves of cassava varieties under each NPK treatment in Year 2.
Table 9.
Mean root dry matter contents, plant heights and stem diameters for each cassava variety at 11 MAP in Years 1 and 2.