Will the endophytic fungus Phomopsis liquidambari increase N-mineralization in maize soil?

Endophytes can be developed into biocontrol agents and can be fungi, bacteria, or archaea that live inside plant tissues without causing symptoms of disease. Phomopsis liquidambari is an endophytic fungus that plays an important ecosystem role as a biofertilizer by helping its host obtain soil nitrogen. How this fungus impacts N mineralization and microbial communities is little known. Our understanding of soil nutrient transformations and soil-plant-microbe interactions in Phomopsis liquidambari-crop versus conventional crop systems is incomplete. This study provided a better understanding of the effect of Phomopsis liquidambari on nitrogen mineralization and investigated the interaction between P. liquidambari and nitrogen, which in turn will be helpful to the farmer in reducing the required amount of soil N fertilizer. This change in N availability in maize soil will have significant implications for soil productivity and plant N utilization, especially in N-limited soils, and significantly reduce the required amount of soil N fertilizer. The effect of P. liquidambari on N mineralization in maize soil was investigated by treating it with four levels of N (urea) at rates of 0, 1.25, 2.5, and 3.75 g of nitrogen. N-mineralization was determined by the anaerobic incubation method. Were stored for 7 days in an incubator at a constant 37 C. A colorimetric microplate procedure was used for NH4+-N analysis. A significant increase in the available NH4+-N contents was reported in soil maize (Zea mays L.) inoculated with P. liquidambari, which increased by 80%. A significant increase in N-mineralization was observed under all N conditions. This work highlighted the importance of the fungal endophyte for soil N-mineralization with lower N input. Using this fungal agent will almost certainly help reduce fertilizer input.

Reduction of Pythium Damping-Off in Soybean by Biocontrol Seed Treatment.

Pythium spp. is one of the major groups of pathogens that cause seedling diseases on soybean, leading to both preemergence and postemergence damping-off and root rot. More than 100 species have been identified within this genus, with Pythium irregulare, P. sylvaticum, P. ultimum var ultimum, and P. torulosum being particularly important for soybean production given their aggressiveness, prevalence, and abundance in production fields. This study investigated the antagonistic activity of potential biological control agents (BCAs) native to the U.S. Midwest against Pythium spp. First, in vitro screening identified BCAs that inhibit P. ultimum var. ultimum growth. Scanning electron microscopy demonstrated evidence of mycoparasitism of all potential biocontrol isolates against P. ultimum var. ultimum and P. torulosum, with the formation of appressorium-like structures, short hyphal branches around host hyphae, hook-shaped structures, coiling, and parallel growth of the mycoparasite along the host hyphae. Based on these promising results, selected BCAs were tested under field conditions against six different Pythium spp. Trichoderma afroharzianum 26 used alone and a mix of T. hamatum 16 + T. afroharzianum 19 used as seed treatments protected soybean seedlings from Pythium spp. infection, as BCA-treated plots had on average 15 to 20% greater plant stand and vigor than control plots. Our results also indicate that some of these potential BCAs could be added with a fungicide seed treatment with minimum inhibition occurring, depending on the fungicide active ingredient. This research highlights the need to develop tools incorporating biological control as a facet of soybean seedling disease management programs. The harnessing of native BCAs could be integrated with other management strategies to provide efficient control of seedling diseases.