Optimizing wheat seed treatment with entomopathogenic fungi for improving plant growth at early development stages

Aim of study: Entomopathogenic fungi (EPF) are biocontrol agents, plant growth promoters, and increase tolerance to biotic-abiotic stresses. In this study we investigated the factors associated to the application method, which are crucial for the interaction between the fungus and the host plant at initial crop growth stages. Area of study: The study was performed in Cordoba (Spain) Material and methods: Three experiments were performed to investigate: (i) the effect of different concentrations of the surfactant Tween® 80 (0, 0.5, 1, 5, and 10%) on wheat seed coating with conidia of Metarhizium brunneum and seed and conidia viability; (ii) the performance of wheat seedlings at first growth stages after their inoculation with Beauveria bassiana or M. brunneum via seed coating or soil drenching; and (iii) the role of soil sterilization and seed disinfection on leaf concentration of chlorophyll (SPAD) and B. bassiana or M. brunneum colonization. Main results: Tween® 80 concentration linearly improved seed coating (up to 127%) without altering wheat seeds and fungal conidia germination. Seedling length of inoculated plants was significantly increased with B. bassiana and M. brunneum (67% and 46%, respectively) via seed coating. Seed disinfection was key to achieve an enhancement in wheat SPAD (10-18%) with B. bassiana or M. brunneum concerning Control, that combined with sterilization of soil showed the highest endophyte colonization rates (up to 83.3% with both fungi) Research highlights: The surfactant concentration, application method, seed disinfection, and soil sterilization are key parameters to improve the potential benefits on the EPF-plant relationship.

Pircinque: new strawberry cultivar for Brazilian producers

ABSTRACT The strawberry cultivar ‘Pircinque’ was developed by the breeding program of Consiglio per la Ricerca in Agricoltura e l’Analisi dell’Economia Agraria - Centro di Olivicoltura, Frutticoltura e Agrumicoltura (CREA-OFA-FRF), an Italian research entity, and introduced in Brazil in 2013 by the Centro de Ciências Agroveterinárias da Universidade do Estado de Santa Catarina (CAV-UDESC). In the breeding program in which it originated, ‘Pircinque’ was selected for plant rusticity and resistance to soil pathogens. It can be cultivated where soil sterilization techniques are not used. In Brazil, the cultivation of ‘Pircinque’ has shown to be promising in the major strawberry producing regions. The main characteristics that allowed the development of this cultivar among the growers were plant vigor, productivity, rusticity, flavor, pulp firmness, crispness, sweetness and fruit color. When grown with excessive nitrogen fertilization fruit sensitivity to Botrytis cinerea fungal attack has been found, and a high vegetative plant growth. Due to fruits peculiarity, many growers make differentiated sales, adding value to quality product. Also, due to the high post-harvest period, many growers allocate part of the production to more distant locations. These characteristics are determinant for the cultivar Pircinque be distinguishable from other strawberry cultivars already marketed in Brazil. The cultivar was registered at the Ministério da Agricultura, Pecuária e Abastecimento (MAPA) in 2016, and the commercialization of plants started in 2017 with five nurseries accredited to produce and market ‘Pircinque’ plants throughout Brazil.

Direct Biotic Plant–soil Feedback Promotes Dodonaea Viscosa Growth in a Dry-hot Valley, China

Biotic plant-soil feedback has been widely studied, and may be particularly important in resource-poor areas. However, the roles of soil nutrient cycling in affecting plant growth in this process still remained unclear. The aim of this study was to explore the roles of soil biota in regulating nutrient cycling by conducting a two-phase feedback experiment in a dry-hot valley, with a conditioning phase during which there were Dodonaea viscosa or no D. viscosa growing in the soil, and a feedback phase in which the effect of the conditioned soil biota on D. viscosa performance was measured. The growth of D. viscosa significantly reduced soil N after the conditioning phase. However, D. viscosa showed a positive plant-soil feedback. In the feedback phase, the D. viscosa conditioned soil promoted the stem diameter, leaf area, and leaf dry mass content of D. viscosa. Total biomass was also significantly higher in D. viscosa conditioned soil than that in not conditioned soil. In contrast, soil sterilization had a negative effect on the growth of D. viscosa, with a significant reduction in plant biomass, especially in D. viscosa conditioned soil, and soil sterilization significantly increased the root: shoot biomass ratio and litter mass. Furthermore, we showed that although the biota-driven changes in enzyme activities correlated with the leaf N and P amount especially P amount, the enzyme activity was not the main reason to promote D. viscosa growth in the conditioned soil.

Arbuscular Mycorrhizal Fungi Can Compensate for the Loss of Indigenous Microbial Communities to Support the Growth of Liquorice (Glycyrrhiza uralensis Fisch.)

Soil microorganisms play important roles in nutrient mobilization and uptake of mineral nutrition in plants. Agricultural management, such as soil sterilization, can have adverse effects on plant growth because of the elimination of indigenous microorganisms. Arbuscular mycorrhizal (AM) fungi are one of the most important beneficial soil microorganisms for plant growth. However, whether AM fungi can compensate for the loss of indigenous microbial communities to support plant growth and metabolism is largely unknown. In this study, a pot experiment was conducted to investigate the effects of AM fungi on plant growth and secondary metabolism in sterilized and unsterilized soil. We used liquorice (Glycyrrhiza uralensis Fisch.), an important medicinal plant as the host, which was inoculated with the AM fungus Rhizophagus irregularis or not and grown in unsterilized or sterilized soil. Plant photosynthesis traits, plant growth and nutrition level, concentrations of the secondary metabolites, and expression levels of biosynthesis genes were determined. The results showed that soil sterilization decreased plant growth, photosynthesis, and glycyrrhizin and liquiritin accumulation, and moreover, downregulated the expression of related biosynthesis genes. Inoculation with R. irregularis in sterilized soil offset the loss of indigenous microbial communities, resulting in plant growth and glycyrrhizin and liquiritin concentrations similar to those of plants grown in unsterilized soil. Thus, AM fungi could compensate for the loss of indigenous microbial communities by soil sterilization to support plant growth and secondary metabolism.