Table 3.
Effect of the number of applications of two growth regulators (cytokinins (CK) or brassinosteroids (BR)) on biochemical variables in rice plants of genotype F2000 subjected to combined heat stress (40°C day/30°C night) at 88 days after emergence (DAE).
| Treatments | Chl amg g-1 (FW) | Chl bmg g-1 (FW) | Total Chl mg g-1 (FW) | Cx+cmg g-1 (FW) | MDA µmol g-1 (FW) | Proline µmol g-1 (FW) |
|---|---|---|---|---|---|---|
| Absolute control | 2.54 ab | 0.80 ab | 3.34 ab | 0.40 bc | 4.45 b | 2.11 c |
| Heat stress control | 2.22 bc | 0.82 bc | 3.04 bc | 0.47 ab | 16.19 a | 1.49 c |
| One spray of CK | 1.58 e | 0.74 cd | 2.32 d | 0.25 e | 6.43 b | 12.48 ab |
| Two sprays of CK | 1.68 de | 0.70 d | 2.37 d | 0.31 de | 6.84 b | 4.65 bc |
| Three sprays of CK | 2.67 a | 0.96 a | 3.63 a | 0.55 a | 3.09 b | 6.33 bc |
| One spray of BR | 1.81 d | 0.75 cd | 2.55 d | 0.34 cd | 7.72 b | 13.78 ab |
| Two sprays of BR | 2.40 ab | 0.94 a | 3.35 ab | 0.47 ab | 4.21 b | 17.81 a |
| Three sprays of BR | 2.23 bc | 0.87 ab | 3.10 bc | 0.44 b | 3.87 b | 19.43 a |
| Significance | *** | *** | *** | *** | *** | *** |
The treatments evaluated were as follows: absolute control (AC), heat stress control (SC), one foliar spray of CK (CK1), two foliar sprays of CK (CK2), three foliar sprays of CK (CK3), one foliar spray of BR (BR1), two foliar sprays of BR (BR2) and three foliar sprays of BR (BR3). Data represent the mean of five data points ± standard error (n = 5). Data followed by different letters indicate statistically significant differences according to Tukey’s test (P ≤ 0.05). Equal letters indicate that the means are not statistically significant (≤0.05). NS, *, ** or *** not significant or significant at P ≤ 0.05, 0.01 or 0.001, respectively.