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Healthy soil is a fundamental resource against hunger; it contributes to mitigating climate change and ensures sustainable production. The economic and social importance of coffee requires taking measures to promote its sustainable production. Shaded coffee production systems offer valuable ecosystem services indispensable for product diversification. In this context, we compared the quality of the soil, foliage, and seed of three coffee production systems: under mango shade (CM), under banana shade (CB), and under the full sun (CS). Using principal component analysis, we selected the minimum data set to designate quality indicators. For soil, the quality indicators were pH, cation exchange capacity, N content, the concentration of Ca, Mg, K, Fe, soil moisture, percentage specific conductance, soil penetration resistance and the number of worms. Foliar indicators corresponded to N content, the concentration of K, Ca, Fe, Cu, and Chlorophyll b; and seed indicators were concentration of P, K, Ca, Mg, Zn, and Cu. The soil quality index was moderate in the shaded coffee production systems, but deficient in the CS system. Foliar quality was very high in the CM system, moderate in CB and low in CS. Seed yield was low in the three systems. This research shows the main indicators influencing not only soil quality but also plant and seed nutrition in the three systems. Knowledge of the indices will allow establishing of better agronomic management practices in the shaded systems, improving soil fertility, plant nutrition, and coffee seed quality.

Glomalin is a glycoprotein produced by the hyphae of arbuscular mycorrhizal fungi (AMF). The chemical methods usually employed to extract glomalin from the soil obtain something more than this pure glycoprotein, and therefore it would be better to call this fraction soil protein related to glomalin (SPRG) or glomalin associated with humic substances (GAHS). On this account, its isolation is controversial. The SPGR or GAHS has a significant influence on the physical, chemical, and biological properties of soils and could then be considered as an indicator of soil use change. In the present study, the storage of SPRG was evaluated, as well as carbon (C) associated with the latter (CG) and the content of soil organic C (SOC) in cultivated tepetates in the State of Mexico. Tepetates are hardened volcanic tuffs of the fragipan type, ameliorated for agricultural production. The specific objectives of the present study were (1) to evaluate the SPRG levels in tepetates, (2) measure the contribution of carbon (C) ...

Metal contaminated soils are increasing worldwide. Metal-tolerant plants growing on metalliferous soils are fascinating genetic and microbial resources. Seeds can vertically transmit endophytic microorganisms that can assist next generations to cope with environmental stresses, through yet poorly understood mechanisms. The aims of this study were to identify the core seed endophyte microbiome of the pioneer metallophyte Crotalaria pumila throughout three generations, and to better understand the plant colonisation of the seed endophyte Methylobacterium sp. Cp3. Strain Cp3 was detected in C. pumila seeds across three successive generations and showed the most dominant community member. When inoculated in the soil at the time of flowering, strain Cp3 migrated from soil to seeds. Using confocal microscopy, Cp3-mCherry was demonstrated to colonise the root cortex cells and xylem vessels of the stem under metal stress. Moreover, strain Cp3 showed genetic and in planta potential to promote seed germination and seedling development. We revealed, for the first time, that the seed microbiome of a pioneer plant growing in its natural environment, and the colonisation behaviour of an important plant growth promoting systemic seed endophyte. Future characterization of seed microbiota will lead to a better understanding of their functional contribution and the potential use for seed-fortification applications. This research was supported by a BOF-BILA grant from Hasselt University, the UHasselt Methusalem project 08M03VGRJ

A field experiment was carried out to determine the effects of the inoculation of onion (Allium cepa L.) with Glomus sp. Zac-19 on the development of onion white rot (Sclerotium cepivorum Berk.) and on onion production. Mycorrhization delayed onion white rot epidemics by 2 weeks and provided a significant protection against the disease for 11 weeks after onion transplanting, as compared with nonmycorrhizal controls. Mycorrhizal plants showed an increase of 22% in yield, regardless of the presence of the white rot pathogen.