Interactive actions of drought and salinity on physiological and biochemical traits of barley and alfalfa in different cropping practices
摘要
To comprehend the independent and combined influences of drought and salinity on the physiological and biochemical properties of barley and alfalfa crops grown under diverse cropping systems, a pot experiment was conducted. Three stress treatments (for both monocropped and intercropped plants) and control were employed: (1) no-stressed plants (T0: plants were not subjected to any stress), (2) drought-stressed plants [T1: plants were watered at a level of 35% field capacity (FC) and they were not subjected to any salt stress], (3) salt-stressed plants (T2: plants were watered at a level of 75% FC and they were subjected to a salt treatment with 120 mM NaCl), and (4) drought-salt-stressed plants (T3: plants were watered at a level of 35% FC and they were subjected to a salt treatment with 120 mM NaCl simultaneous). The results of drought, salinity, and their co-existing effects on the physiological and biochemical aspects of both species were statistically representative. The adoption of an intercropping system had a positive impact on mitigating the individual and associated consequences of drought and salinity for both species. Intercropping significantly enhanced shoot and root dry weights by 23% and 100% in barley and by 83% and 100% in alfalfa, respectively, compared to their corresponding monocultures under T3. Moreover, under drought-salinity stresses, intercropping decreased malondialdehyde (MDA) and H2O2 concentrations by 15% and 8% in barley and 13% and 9% in alfalfa, respectively, over their corresponding monocultures. Our results showed that the individual effects of drought and salinity are less damaging to plant development than the cumulative impacts of both stresses. Moreover, plants deployed the same mechanisms against drought and salinity stress, namely the accumulation of osmolytes and the activation of enzymatic antioxidant system. Adopting a compatible intercropping system can mitigate the negative effects of drought and salinity stress, thereby promoting plant resilience, improving growth and production, and ensuring food security.