Non-structural carbohydrates (NSC) affect tree growth and survival when photosynthesis is impacted by climate change, such as seasonal drought and extreme precipitation. Nevertheless, it is still unclear whether Eucalyptus suffers growth limitation under natural conditions and if trees recover under artificial cultivation. In present study, we conducted a field control experiment to compare the NSC storage in Eucalyptus urophylla × Eucalyptus grandis trees on fertilization and dry-season irrigation to determine the variations of NSC under drought stress. The results indicated total soluble sugar (TSS) was the primary existing form of NSC. In spatial patterns, NSC concentration showed gradient differences from source organ to sink organ, and finally accumulated in root. The TSS concentration showed a decreased trend with height except leaf, while the trend of starch concentration was contrast. Surprisingly, fertilization and dry-season irrigation had not changed the carbon distribution among all tissues but reduced the TSS concentration in most organs. The fast-growing E. urophylla × E. grandis will consume the assimilates and carbohydrates of storage organs, but maintains the NSC concentration at a certain threshold. Our results help to comprehend the NSC allocation and improve the productivity of E. urophylla × E. grandis plantations in seasonal arid areas.

Leaves are essential for photosynthesis and gas exchange, and their growth characteristics are the key factors that influence the carbon budget. Eucalyptus is widely afforested in south China due to its fast-growing and high-yield features. Water and fertilizer are the main factors affecting plant growth. Studying the effects of different water and fertilizer treatments on the growth of Eucalyptus leaves under seasonal drought could further elucidate the optimal additions for Eucalyptus productivity. In this study, we investigated the leaf area, length, width, perimeter, and expansion rates of the commercial species E. urophylla × E. grandis under different treatments of dry season irrigation and fertilizer application to elucidate the growth dynamics of the leaves. The results indicated that both dry season irrigation and fertilizer could affect whole leaf expansion. Leaf area was largest when water and fertilizer were added at the same time. In this experiment, we found that fertilization had a significant effect on the leaf shape index of the Eucalyptus leaves. The leaf shape index was larger with the fertilizer treatment, which made the leaves slender. Dry season irrigation shorten the peak period of leaf growth and increase the leaf area. Our results help to further understand the mechanism of Eucalyptus productivity under seasonal drought and provide theoretical support for Eucalyptus production.

Plantation forests productivity is severely limited by the seasonal drought and fertilization practices in South China. Soil nutrient and water availability influence soil fungal community, functional group diversity and the variation of plant productivity; however, the effects of irrigation and fertilization on fungal responses have rarely been studied. Here, we investigate the responses of fungal community structure and functional groups in Eucalyptus plantation soils to short-term fertilization (F), dry-season irrigation (W), short-term fertilization combined with dry-season irrigation (FW), and control (CK) treatments for ten months. A higher proportion of Basidiomycota was observed in the irrigation and/or fertilization treatments; conversely, lower proportions of Ascomycota and Mucoromycotina were observed in the only irrigation and fertilization treatments. Higher soil carbon contents and symbiotroph fungi (mainly Ectomycorrhizas) proportion were detected in the FW treatment, while low proportions of saprophytic and pathogenic fungi were observed in the FW treatment when compared with those in other treatments. These results may indicate that Eucalyptus tree growth under irrigation and fertilization condition was better than under fertilization only, irrigation only, or neither management. The results highlight that short-term fertilization and dry-season irrigation can shift fungal community structure and functional groups by regulating available soil moisture and nutrients. They also provide a theoretical basis for the development of more appropriate management approaches in the early stages of forest plantation.

Instytut Dendrologii PAN w Kórniku - Institute of Dendrology PAS (Kórnik, Poland)

Moringa is a perennial tree with high nutritional value, and it is drought tolerant and barren but has poor cold resistance during the seedling stage. This study selected Piriformospora indica (PI) and arbuscular mycorrhizal fungus (AM) as inoculants, Moringa seedlings were inoculated, and their growth and physiological responses were evaluated under different low-temperature stress times. The research results show that PI and AM can symbiotically associate with Moringa successfully and promote their nutritional growth. At low temperature, Moringa inoculated with PI and AM exhibited better physiological resistance. However, the effect of mixed inoculation of PI and AM is not as significant as that of single inoculation of any strain. Inoculating plant growth-promoting rhizobia (PGPR) reduced the richness of fungal communities and the number of unique operational taxonomic units (OTUs), with PI being the most prominent. Vaccination with PGPR also increased bacterial diversity, richness, and the number of unique OTUs, with AM inoculation showing the most prominent performance. This suggests that Moringa seedling growth and responsiveness to low-temperature stress are significantly influenced by PGPR, and there may be interactions between different bacterial strains. The results suggest that PGPR can improve the yield and quality of Moringa by promoting growth and regulating stress resistance.