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• Sensitivity to drought differed among the cultivars and depends on the severity of stress. • Cultivars-1 and 2 shows stronger tolerance mechanism to drought condition. • Foliar application of H 2 O 2 enhanced glycine betaine and total soluble sugar. • H 2 O 2 differentially induced accumulation of inorganic ion among the cultivars. Soybean (Glycine max) is a valuable and highly nutritional crop with many cultivars in the Temperate and Tropical environments but threatened by drought. Further to this, the application of signaling molecules as ameliorative strategy against adverse effects of drought on soybean cultivars still remains unclear. This study investigates the variation in drought tolerance and effects of foliar application of hydrogen peroxide (H 2 O 2) on drought stress in three soybeans cultivars (NGBO 03519 , 03515 and 03524) under normal irrigation, mild drought and severe drought. Mild and severe drought exerted negative effects on growth and metabolic processes of G. max cultivars. Severe drought decreased the photosynthetic pigments in all cultivars, but substantially increased the root biomass and triggered the accumulation of glycine betaine in NGBO 03519 and NGBO 03515. Drought significantly enhanced total soluble sugar in NGBO 03515 and NGBO 03524 cultivars while severe drought decreased Ca2+, Mg2+, Cl−, and SO 4 2− in NGBO 03524. Foliar-applied H 2 O 2 ameliorated impact of drought and positively enhanced biomass, photosynthetic pigment, ion accumulation, and consequently resulted into improved plant growth. The results indicated that H 2 O 2 sustained higher cell turgor in NGBO 03515 and NGBO 03524 cultivars by significantly enhancing K+ under severe drought. Conclusively, the study indicated that while NGBO 03519 may have sturdy fitness to resist severe drought, H 2 O 2 is essential for cell expansion and growth of NGBO 03515 and 03524. [ABSTRACT FROM AUTHOR]

Intercropping may improve community stability and yield under climate change. Here, we set up a field experiment to evaluate the advantages of cultivating Z anthoxylum bungeanum with Capsicum annum, and Z. bungeanum with Glycine max as intercrops, compared with cultivating Z. bungeanum in monoculture. Effects of extreme drought stress conditions on morphological, physiological, and biochemical traits of the three crop species cultivated in the three contrasting planting systems were compared. Results showed that extreme drought conditions induced negative impacts on Z. bungeanum grown in monoculture, due to reduced growth and metabolic impairment. However, limited stomatal conductance, reduced transpiration rate (Tr), and increased water use efficiency, carotenoid content, catalase activity, and accumulation of soluble sugars in Z. bungeanum indicated its adaptive strategies for tolerance of extreme drought stress conditions. Compared with cultivation in monoculture, intercropping with C. annum had positive effects on Z. bungeanum under extreme drought stress conditions, as a result of improved crown diameter, leaf relative water content (LRWC), net photosynthetic rate, and proline content, while intercropping with G. max under extreme drought stress conditions increased net CO2 assimilation rates, LRWC, Tr, and superoxide dismutase (SOD) activity. In conclusion, Z. bungeanum has an effective defense mechanism for extreme drought stress tolerance. Intercropping with G. max enhanced this tolerance potential primarily through its physio-biochemical adjustments, rather than as a result of nitrogen fixation by G. max. [ABSTRACT FROM AUTHOR]

Drought is one of the major environmental stresses altering forest productivity. However, nutrient availability can modulate drought resistance. Phoebe zhennan (gold Phoebe) is a high‐quality timber‐producing but threatened tree species in China, facing serious anthropogenic disturbances and abiotic constraints that restrict its growth and development. However, little attention has been given to designing adaptive strategies for its management by evaluating the possible role of major nutrients, particularly nitrogen (N), on its morphological and physio‐biochemical responses under water stress. To evaluate these responses, a complete randomized design was followed to investigate the effects of two irrigation levels (well‐watered and drought‐stressed conditions) and N fertilization treatments (with and without N). Drought stress significantly affected the growth of seedlings, as indicated by impaired photosynthesis, pigment degradation, disrupted N metabolism, over‐production of reactive oxygen species and enhanced lipid peroxidation. Nitrogen supplementation under drought stress had remarkable positive effects on the growth through physio‐biochemical adjustments as shown by higher level of nitrogenous compounds and up‐regulation of N‐associated metabolic enzymes activities which might be due to N‐mediated improved leaf relative water contents and photosynthetic efficiency. In addition, N application reduced oxidative stress and membrane damage, and maintained a high accumulation of osmolytes. However, in well‐watered seedlings N fertilization significantly improved root biomass and net CO2 assimilation rate suggesting high N‐use efficiency of the seedlings. These findings reveal that drought significantly affects the growth of P. zhennan, while N fertilization plays a crucial role in alleviating water stress damage by improving its drought tolerance potential at low metabolic costs. Therefore, N fertilization could be considered as an effective strategy for the conservation and management of P. zhennan in the face of future climate change. [ABSTRACT FROM AUTHOR]

Background and aims: The incidence of extreme weather events, particularly drought is predicted to increase in the future and alter the ecosystem process. Despite that the interplay between plant species play a critical role in reducing the vulnerability of soil ecosystem to drought, whether the presence of legumes in plant community could maintain nutrient uptake of focal species by stabilizing soil biota and ecosystem processes under drought conditions remains essentially unexplored. Methods: In a field experiment, the soil biota community and ecosystem processes were studied using four planting systems contain monoculture of focal species Zanthoxylum bungeanum, mixed cultures of Z. bungeanum and Capsicum annuum, Z. bungeanum and Medicago sativa, and Z. bungeanum and Glycine max subjected to drought. Results: Drought had no significant effects on soil microbial biomass in monoculture and mixed cultures, but significantly increased microbial stress indices. Drought significantly increased the densities of total nematodes, herbivores, bacterivores and fungivores in Z. bungeanum and M. sativa mixed culture, but significantly decreased the total nematodes, bacterivores and fungivores in Z. bungeanum and G. max mixed culture. Under drought stress, leaf nitrogen concentrations of Z. bungeanum were significantly higher in Z. bungeanum and M. sativa mixed culture than Z. bungeanum monoculture and the other mixed cultures, this is mainly due to higher microbial activity and net nitrogen mineralization rate. Conclusion: Differences in resistance traits of neighbors had additive effects and rapidly reflected in different soil ecosystem processes and nutrient uptake of focal species. Our results revealed that specific legume species intercropping management could stabilize focal species by maintaining soil ecosystem processes under drought condition. [ABSTRACT FROM AUTHOR]

Phoebe zhennan (Gold Phoebe) is a threatened tree species in China and a valuable and important source of wood and bioactive compounds used in medicine. Apart from anthropogenic disturbances, several biotic constraints currently restrict its growth and development. However, little attention has been given to building adaptive strategies for its conservation by examining its morphological and physio-biochemical responses to drought stress, and the role of fertilizers on these responses. A randomized experimental design was used to investigate the effects of two levels of irrigation (well-watered and drought-stressed) and phosphorous (P) fertilization treatment (with and without P) to assess the morphological and physio-biochemical responses of P. zhennan seedlings to drought stress. In addition, we evaluated whether P application could mitigate the negative impacts of drought on plant growth and metabolism. Drought stress had a significant negative effect on the growth and metabolic processes of P. zhennan. Despite this, reduced leaf area, limited stomatal conductance, reduced transpiration rate, increased water use efficiency, enhanced antioxidant enzymes activities, and osmolytes accumulation suggested that the species has good adaptive strategies for tolerating drought stress. Application of P had a significant positive effect on root biomass, signifying its improved water extracting capacity from the soil. Moreover, P fertilization significantly increased leaf relative water content, net photosynthetic rate, and maximal quantum efficiency of PSII under drought stress conditions. This may be attributable to several factors, such as enhanced root biomass, decreased malondialdehyde content, and the up-regulation of chloroplast pigments, osmolytes, and nitrogenous compounds. However, P application had only a slight or negligible effect on the growth and metabolism of well-watered plants. In conclusion, P. zhennan has a strong capability for drought resistance, while P application facilitates and improves drought tolerance mostly through physio-biochemical adjustments, regardless of water availability. It is imperative to explore the underlying metabolic mechanisms and effects of different levels of P fertilization on P. zhennan under drought conditions in order to design appropriate conservation and management strategies for this species, which is at risk of extinction. [ABSTRACT FROM AUTHOR]