Biofertilizers are a large part of the global agricultural economy.
Recently, there has been an increase in the number of companies producing fungal inoculants.
Whether these inoculants are useful is not clear; they are difficult to monitor in the field.
The unintended consequences of inoculants in natural systems is not known, but if invasive, they may pose a threat to soil and plant biodiversity and ecosystem functioning.


A plain language summary is available for this article.

https://besjournals.onlinelibrary.wiley.com/doi/pdf/10.1111/1365-2435.12976

Fungal inoculants in the field: Is the reward greater than the risk?

Global population growth poses a threat to food security in an era of increased ecosystem degradation, climate change, soil erosion and biodiversity loss. In this context, harnessing naturally-occurring processes such as those provided by soil and plant-associated microorganisms presents a promising strategy to reduce dependency on agrochemicals. Biofertilizers are living microbes that enhance plant nutrition by either by mobilizing or increasing nutrient availability in soils. Various microbial taxa including beneficial bacteria and fungi are currently used as biofertilizers, as they successfully colonize the rhizosphere, rhizoplane or root interior. Despite their great potential to improve soil fertility, biofertilizers have yet to replace conventional chemical fertilizers in commercial agriculture. In the last ten years, multi-omics studies have made a significant step forward in understanding the drivers, roles, processes and mechanisms in the plant microbiome. However, translating this knowledge on microbiome functions in order to capitalize on plant nutrition in agroecosystems still remains a challenge. Here, we address the key factors limiting successful field applications of biofertilizers and suggest potential solutions based on emerging strategies for product development. Finally, we discuss the importance of biosafety guidelines and propose new avenues of research for biofertilizer development.

/pdf/rethinking-crop-nutrition-in-times-of-modern-microbiology-30w2os1sdb.pdf

Rethinking Crop Nutrition in Times of Modern Microbiology: Innovative Biofertilizer Technologies

Trichoderma spp. are highly interactive fungi that live in soil, root, and foliar environments. In addition to assisting plants to resist various diseases and drought stress, Trichoderma has been reported to have positive effects on the growth of many crops. While Trichoderma inoculants have been developed for use with numerous crops, explorations of the use of Trichoderma inoculants in rice farming systems are still in a nascent stage. In this study, a field experiment using a randomized complete block design was conducted to determine the ability of Trichoderma-based biofertilizer (TBF) to enhance the growth, physiological traits, and yield of rice under System of Rice Intensification (SRI) management. The results showed significant potential for TBF to increase a rice crop’s growth, physiological traits, and productivity. Trichoderma-inoculated rice plants exhibited significantly greater plant height, photosynthetic rate, chlorophyll a and b content, stomatal conductance, and tiller and panicle numbers. The grain yield of Trichoderma-inoculated rice plants was 30% more than that from the uninoculated SRI control plots, which simply due to changes in management practices produced paddy yields that were twice the current average in Malaysia. A simple, efficient, and farmer-friendly method for producing TBF, developed for SRI farmers’ use to get these results, is reported here.

A simple, efficient, and farmer-friendly Trichoderma -based biofertilizer evaluated with the SRI Rice Management System

Appraisal of Biofertilizers in Rice: To Supplement Inorganic Chemical Fertilizer

Arbuscular mycorrhizal fungi (AMF) can increase plant nutrient uptake and chemical defense production, both of which can improve plants’ ability to resist insect herbivory. Cover crops—non-commercial species planted in between cash crops in a crop rotation—can naturally alter both soil nutrients and AMF. We tested whether different cover crop species alter AMF colonization, plant nutrient status and plant–insect interactions in a subsequent maize crop. Cover crop species were either non-mycorrhizal, non-leguminous (canola, forage radish), mycorrhizal non-leguminous (cereal rye, oats), mycorrhizal leguminous (clover, pea) or absent (fallow). We measured the cascading consequences of cover crop treatment on maize root AMF colonization, maize growth and performance of an herbivorous insect (European corn borer) feeding on the maize. Maize AMF colonization was greater in plots previously planted with mycorrhizal (rye, oats) than non-mycorrhizal (canola, radish) cover crops or no cover crop (fallow). AMF colonization was linked to increased plant phosphorous and nitrogen, and maize growth increased with low plant N:P. Induced jasmonic acid pathway plant defenses increased with increasing maize growth and AMF colonization. European corn borer survivorship decreased with lower plant N:P, and insect development rate decreased with increased induced plant defenses. Our data describe a cascade in which cover crop species selection can increase or decrease mycorrhizal colonization of subsequent maize crop roots, which in turn impacts phosphorus uptake and may affect herbivory resistance in the maize. These results suggest that farmers could select cover crop species to manage nutrient uptake and pest resistance, in order to amend or limit fertilizer and pesticide use.

Cover crop species affect mycorrhizae-mediated nutrient uptake and pest resistance in maize

Inoculation of Medicago sativa cover crop with Rhizophagus irregularis and Trichoderma harzianum increases the yield of subsequently-grown potato under low nutrient conditions

François Ferrais

Papers

Inoculation of Medicago sativa cover crop with Rhizophagus irregularis and Trichoderma harzianum increases the yield of subsequently-grown potato under low nutrient conditions