TABLE 5.
Integrated effect of biochar and nitrogen application on rapeseed photosynthesis and transpiration rates during 2019–2020 and 2020–2021.
| Biochar | Nitrogen | Photosynthesis (umol CO2 m–2) |
Transpiration (mmol H2O m–2 s–1) |
||||||
| 2019–2020 |
2020–2021 |
2019–2020 |
2020–2021 |
||||||
| Seedling | Flowering | Seedling | Flowering | Seedling | Flowering | Seedling | Flowering | ||
| B0 | N0 | 7.39 g | 15.15 h | 8.67 i | 16.27 f | 2.47 cd | 3.08 g | 3.33 g | 4.06 ef |
| N75 | 9.27 ef | 16.84 gh | 12.69 fg | 20.60 e | 2.52 cd | 3.85 efg | 3.51 fg | 4.52 cdef | |
| N225 | 16.34 a | 22.04 e | 18.23 cd | 26.67 bcd | 3.60 ab | 4.78 de | 4.70 bcde | 6.23 ab | |
| N450 | 12.76 d | 19.41 f | 15.93 de | 24.72 d | 3.04 bc | 4.39 ef | 3.82 efg | 5.49 abcde | |
| B15 | N0 | 7.59 fg | 16.47 gh | 11.33 gh | 19.08 ef | 2.53 cd | 3.81 efg | 3.73 efg | 5.58 abcd |
| N75 | 9.62 e | 21.86 e | 15.04 ef | 21.18 e | 2.70 cd | 4.75 de | 4.34 cdef | 5.89 abc | |
| N225 | 16.55 a | 25.88 bc | 22.07 b | 27.27 bcd | 3.87 a | 5.93 ab | 4.95 abcd | 6.58 a | |
| N450 | 14.00 cd | 23.78 cde | 22.63 b | 29.87 abc | 3.50 ab | 4.85 bcde | 5.04 abc | 6.68 a | |
| B30 | N0 | 8.24 efg | 16.65 gh | 10.84 ghi | 18.07 ef | 2.48 de | 3.77 efg | 3.76 efg | 4.75 bcdef |
| N75 | 8.55 efg | 17.83 fg | 15.01 ef | 24.75 d | 2.50 cd | 4.33 ef | 3.98 defg | 5.70 abc | |
| N225 | 16.09 ab | 24.75 bcd | 25.93 a | 28.86 abc | 4.04 a | 5.60 abcd | 5.79 a | 5.86 abc | |
| N450 | 14.39 bcd | 28.35 a | 26.21 a | 31.97 a | 3.92 a | 6.03 a | 5.81 a | 6.80 a | |
| B60 | N0 | 7.37 g | 16.00 gh | 9.52 hi | 18.73 ef | 2.27 d | 3.45 fg | 3.37 fg | 3.39 f |
| N75 | 8.66 efg | 15.87 gh | 10.73 ghi | 20.85 e | 2.30 d | 3.95 efg | 3.54 fg | 4.01 ef | |
| N225 | 15.74 abc | 23.60 de | 18.79 c | 26.36 cd | 3.66 ab | 4.82 cde | 5.08 abc | 4.15 def | |
| N450 | 15.12 abc | 26.50 ab | 23.90 ab | 29.15 ab | 3.78 a | 5.89 abc | 5.34 ab | 4.90 bcde | |
| F-values and significance level | |||||||||
| Biochar | 0.44 ns | 19.76*** | 28.94*** | 7.54** | 1.55 ns | 4.70** | 5.83** | 12.38*** | |
| Nitrogen | 159.74*** | 123.75*** | 170.82*** | 75.08*** | 35.23*** | 21.00*** | 21.79*** | 7.08** | |
| Biochar × Nitrogen | 1.09 ns | 7.81** | 5.70** | 1.45 ns | 0.86 ns | 1.36 ns | 1.29 ns | 0.55 ns | |
B0, 0 t ha–1 biochar; B15, 15 t ha–1 biochar; B30, 30 t ha–1 biochar; B60, 60 t ha–1 biochar; N0, 0 kg ha–1 nitrogen; N150, 150 kg ha–1 nitrogen; N300, 300 kg ha–1 nitrogen, and N450, 450 kg ha–1 nitrogen. Different letters within the columns show a significant difference between the treatments at p = 0.05 according to the LSD test, and asterisks represent a significant difference at *p < 0.05, **p < 0.01, and ***p < 0.001 level; ns, not-significant.