# Biochar Improved Sugarcane Growth and Physiology under Salinity Stress
## 4 Discussion  
Soil salinity is one of the most widespread forms of environmental stress that results in the reduction in crop productivity [37]. Here, we revealed that salt stress diminished growth characteristics like plant height, stem diameter, and plant dry biomasses of sug  
Figure 4: Relative ion leakage of sugarcane in response to biochar treatments of 0, 5, and 10 tons ha\({}^{-1}\) under non-saliné and saline conditions on the final treatment day (**A**) and 4 weeks after the final treatment day (**B**). Vertical bars represent \(\pm\) SD, \(n\) = 9. Different letters showed significance among biochar rates under non-salinity (capital letters) and salinity (lowercase letters), respectively, by [PERSON]’s multiple range tests at \(p\leq\) 0.05. For salinity treatment, significance levels (\(t\)-test) are demonstrated as follows: ns: non-significant; *: \(p\) < 0.05. Figure 5: Water saturation deficit of sugarcane leaves in response to biochar treatments of 0, 5, and 10 tons ha\({}^{-1}\) under non-saliné and saline conditions on the final treatment day (**A**) and 4 weeks after the final treatment day (**B**). Vertical bars represent \(\pm\) SD, \(n\) = 9. Different letters showed significance among biochar rates under non-salinity (capital letters) and salinity (lowercase letters), respectively, by [PERSON]’s multiple range tests at \(p\leq\) 0.05. For salinity treatment, significance levels (\(t\)-test) are demonstrated as follows: ns: non-significant; *: \(p\) < 0.05; **: \(p\) < 0.01; ***: \(p\) < 0.001. -arcane plants. These results are in line with previous studies which reported that saline conditions reduced the growth of plants [38], and compromised root and shoot growth. This was probably due to a reduction in the ability of plants to take up water under salinity stress, causing an imbalance in osmotic potential, ionic equilibrium, and nutrient uptake [39]. Furthermore, the saline condition declined the Fv/Fm value and chlorophyll content, but it heightened the water deficit. This was not in keeping with previous studies which concluded that the maximum photochemical efficiency of PSII (Fv/Fm) remained unaffected by salinity [21; 40]. This inconsistency might be due to the differences in the severity and duration of the salinity exposed to plants in different experiments. Of note, the significant decrease in Fv/Fm values was only recorded after 8 days with high salinity levels [41]. The decrease in the photosynthetic capacity of plants under salt stress could be linked to a lower stomatal conductance, an impairment in carbon uptake and metabolism, the inhibition of photochemical ability, or the combined effects of all of the above [42; 43]. Furthermore, [PERSON] et al. [8] described that photosynthetic activity decreases when plants are grown up under saline conditions, leading to reduced growth and productivity. The reduction in photosynthesis under salinity was attributed to a decrease in chlorophyll content [44] and the activity of photosystem II [45]. Salinity can affect chlorophyll content by inhibiting chlorophyll synthesis or accelerating its degradation [46]. In this study, we found that biochar significantly improved plant growth performances including stem diameter, plant height, and plant dry biomasses. Additionally, the positive influences on the physiological characteristics of sugarcane derived from biochar application were also observed. Application of biochar, specifically with the rate of 10 tons ha\({}^{-1}\), had the most significant influence for mitigating the impacts of salinity. Our results agree with the mainstream of the previous reports. The effects of biochar on crop growth and physiology have been well documented [21; 47; 41] in wheat, watermelon, and lettuce. In sugarcane, [PERSON] et al. [48] confirmed that biochar promoted the root system at the seedling stage.