Abstract:The study aimed to investigate the effects of commercially available AMF inoculate (Glomus sp. mixture) on the growth and the nutrient acquisition in tomato (Solanumlycopersicum L.) plants directly after transplanting and under different levels of salinity. Inoculated (AMF+) and non-inoculated (AMF´) tomato plants were subjected to three levels of NaCl salinity (0, 50, and 100 mM¨NaCl). Seven days after transplanting, plants were analyzed for dry matter and RGR of whole plants and root systems. Leaf tissue was analyzed for mineral concentration before and after transplanting; leaf nutrient content and relative uptake rates (RUR) were calculated. AMF inoculation did not affect plant dry matter or RGR under fresh water-irrigation. The growth rate of AMF´plants did significantly decline under both moderate (77%) and severe (61%) salt stress compared to the fresh water-irrigated controls, while the decline was much less (88% and 75%,respectively)and statistically non-significant in salt-stressed AMF+ plants. Interestingly, root system dry matter of AMF+ plants (0.098 g plant -1 ) remained significantly greater under severe soil salinity compared to non-inoculated seedlings (0.082 g plant -1 ). The relative uptake rates of N, P, Mg, Ca, Mn, and Fe were enhanced in inoculated tomato seedlings and remained higher under (moderate) salt stress compared to AMF´plants This study suggests that inoculation with commercial AMF during nursery establishment contributes to alleviation of salt stress by maintaining a favorable nutrient profile. Therefore, nursery inoculation seems to be a viable solution to attenuate the effects of increasing soil salinity levels, especially in greenhouses with low natural abundance of AMF spores.

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Soilless culture systems are currently one of the fastest-growing sectors in horticulture. The plant roots are confined into a specific rootzone and are exposed to environmental changes and cultivation factors. The recent scientific evidence regarding the effects of several environmental and cultivation factors on the morphology, architecture, and performance of the root system of plants grown in SCS are the objectives of this study. The effect of root restriction, nutrient solution, irrigation frequency, rootzone temperature, oxygenation, vapour pressure deficit, lighting, rootzone pH, root exudates, CO2, and beneficiary microorganisms on the functionality and performance of the root system are discussed. Overall, the main results of this review demonstrate that researchers have carried out great efforts in innovation to optimize SCS water and nutrients supply, proper temperature, and oxygen levels at the rootzone and effective plant–beneficiary microorganisms, while contributing to plant yields. Finally, this review analyses the new trends based on emerging technologies and various tools that might be exploited in a smart agriculture approach to improve root management in soilless cropping while procuring a deeper understanding of plant root–shoot communication.

The study aimed to investigate the effects of commercially available AMF inoculate (Glomussp. mixture) on the growth and the nutrient acquisition of field pea (Pissum sativumL) plants. Inoculated (AMF+) and non-inoculated (AMF-) pea plants were subjected to two levels of salinity by the addition of sodium chlorate into the tap water (0 and 50mM NaCl). Several times during the growing cycle, in randomly selected plants the morphology of root system was analyzed and the dry matter of roots and the aboveground biomass were individually measured. Furthermore, plant tissue samples were analyzed regarding N, P and K concentration and the total uptake and specific absorption rate of these elements (SAR N , SAR P , SAR K ) per unit of root length, root surface area and root volume were calculated. Saline irrigation water strongly diminished the growth of pea plants and strongly reduced the absorption capacity of their root system. The inoculation of AM fungi in the growing substrate contributed to the increase of plant biomass and alleviation of the salinity stress by improving the specific absorption rate of main nutrient elements by the root system. Therefore, the artificial inoculation of AM fungi could be considered as an effective alternative to improve growth of pea plants under saline irrigation water conditions.

This study investigated the effects of specific strains of two arbuscular mycorrhizae fungi (AMF) (Rhizophagus irregularis and Claroideoglomus claroideum) and of two plant growth-promoting bacteria (PGPB) (Rhizobium leguminosarum and Burkholderia spp.), supplied either individually or as combination of a mixture of both arbuscular mycorrhizae fungi with each bacteria on root morphology, growth and fresh grain yield in pea (Pisum sativum L.) plants. Inoculated and non-inoculated pea plants were subjected to two levels of salinity (0 and 50 mM) by the addition of sodium chloride into tap water. Prior to fresh grain harvesting the morphology of root system was analyzed and the dry matter of roots and shoots were individually measured in randomly selected plants. Fresh pods were individually harvested per each plant; fresh (green) grains were separately counted and weighted per each pod at each individual plant, and the average grain weight was calculated by dividing total grain weight of plant with the respective number of green grains. The raise of salinity in the irrigation water strongly diminished the growth of pea plants by significantly reducing weight, length, surface area and root volume of pea plants. The relationships of pea plants with beneficiary fungi and bacteria were specific to each microorganism and highly depended on the environment. We found that under saline conditions, Rhizophagus irregularis provided a better vegetative growth and a higher yield than Claroideoglomus claroideum. Although, single application of Burkolderia spp. provides a better vegetative growth than single application of Rhizobium leguminosarum the best results, in terms of growth and harvested yield, were still obtained by combined application of AM fungi with Rhizobium leguminosarum. This combination was able to sustain the average grain weight at the level of non-saline plants and provided a significantly higher yield than the control plants.