Effect of Casuarina Plantations Inoculated with Arbuscular Mycorrhizal Fungi and Frankia on the Diversity of Herbaceous Vegetation in Saline Environments in Senegal

Land salinization is a major constraint for the practice of agriculture in the world. Considering the extent of this phenomenon, the rehabilitation of ecosystems degraded by salinization has become a priority to guarantee food security in semi-arid environments. The mechanical and chemical approaches for rehabilitating salt-affected soils being expensive, an alternative approach is to develop and utilize biological systems utilizing salt-tolerant plant species. Casuarina species are naturally halotolerant, but this tolerance has been shown to be improved when they are inoculated with arbuscular mycorrhizal fungi (AMF) and/or nitrogen-fixing bacteria (Frankia). Furthermore, Casuarina plantations have been proposed to promote the development of plant diversity. Thus, the aim of the current study was to evaluate the impact of a plantation comprising the species Casuarina inoculated with AMF and Frankia on the diversity of the sub-canopy and adjacent vegetation. Work was conducted on a plantation comprising Casurina equisetifolia and C. glauca variously inoculated with Frankia and Rhizophagus fasciculatus prior to field planting. The experimental area of 2500 m2 was divided into randomized blocks and vegetation sampling was conducted below and outside of the Casuarina canopy in 32 m2 plots. A total of 48 samples were taken annually over 3 years, with 24 taken from below the Casuarina canopy and 24 from outside the canopy. The results obtained show that co-inoculation with Frankia and Rhizophagus fasciculatus improves the height and survival rate of both species. After 4–5 years, there was greater species diversity and plant biomass in the sub-canopy environment compared with that of the adjacent environments. Our results suggest that inoculation of beneficial microbes can improve growth of Casuarina species and that planting of such species can improve the diversity of herbaceous vegetation in saline environments.

Exotic rats consume sporocarps of arbuscular mycorrhizal fungi in American Samoa

We sampled three exotic species of rats (Rattus exulans,Rattus norvegicusandRattus rattus) by live-trapping along two transects on Tutuila, American Samoa and searched for evidence of mycophagy by examining fecal pellets. We found spores of three species of arbuscular mycorrhizal fungi (Septoglomus constrictum,Rhizophagus clarusandRhizophagus fasciculatus) in 19 of the 26 samples examined. All the three species of rats consumed sporocarps, withR. clarusbeing the most widely consumed. We suggest that mycophagy by exotic rats is common in American Samoa and may facilitate invasion of exotic plants such as the treeFalcataria moluccana.

Inoculación micorrízico arbuscular en portainjertos de plantas de aguacate cv ‘Hass’ en viveros de Michoacán, México

El objetivo de este estudio fue evaluar el desempeño de 12 inoculantes de hongos micorrízicos arbusculares (HMA) en el desarrollo de portainjertos de plantas de aguacate cv. ‘Hass’ en etapa de vivero. El experimento fue llevado a cabo en Uruapan, Michoacán, México, utilizanso plantas de 60 días de edad, recientemente injertados. Los 12 tratamientos se distribuyeron en un diseño completamente al aleatorio, con 6 repeticiones: A) Gigaspora gigantea; B) Acaulospora delicata; C) Rhizophagus fasciculatus (foráneo); D) Consorcio de Veracruz MTZ1-UV; E) Rhizophagus fasciculatus; F) Rhizophagus irregularis 28-A; G) comunidad nativa de AMF; H) Rhizophagus irregularis (MUCL); I) Rhizophagus fasciculatus + Azospirillum; J) Sclerocystis aff. rubiformis; K) Acaulospora laevis; L) Scutellospora pellucida; y M) testigo. La altura de las plantas, diámetro de los tallos y número de hojas fueron medidos cada 2 semanas durante 5 meses, después de lo cual las plantas fueron cosechadas y se dtermino el peso seco del tallo y de la raíz. Las mediciones periódicas a lo largo del experimento, demostraron que Acaulospora delicata y el testigo tuvieron un mejor desempeño en la altura de las plantas, Scutellospora pellucida en lo referente al diámetro del tallo y el testigo en el número de hojas. En la cosecha, las plantas inoculadas con Rhizophagus intraradices 28-A y Scutellospora pellucida tuvieron 2 veces más peso del tallo y de la raíz con relación a los otros tratamientos. Además, se concluye que la inoculación del cuello de la raíz de las plantas recientemente injertadas, mostró respuestas claras a la inoculación con cepas eficientes de hongos micorrízicos, aunque pasaron 6 meses para que las diferencias fueran evidentes.

STUDIES ON THE ARBUSCULAR MYCORRHIZAL FUNGAL DIVERSITY OF SELECTED MEDICINAL PLANT SPECIES FROM KODIKUTHIMALA, MALAPPURAM, KERALA

The present investigation has brought out the AM fungal association in some plant species of Kodikuthimala, Malappuram district Kerala. Totally, 25 plant species belongs to 15 families were analyzed for arbuscular mycorrhizal association. The root samples of all collected plant species showed mycorrhizal infection. The percentage of colonization was varied with plant species and it ranges from 12 (Commelina benghalensis) to 79% (Sida rhombifolia). Maximum spore population was observed in Gloriosa superba (574/100g of soil) and minimum in Euphorbia hirta (143/10g of soil). Totally 26 AM fungal species belongs to 13 genera were found. Among this Glomus was most dominated. In most of the plants, spores of Rhizophagus fasciculatus are seen. Present study confirms the Arbuscular Mycorrhizal association in the collected plant species.

Improved rooting capacity and hardening efficiency of carob (Ceratonia siliqua L.) cuttings using arbuscular mycorrhizal fungi

The present investigation was undertaken to improve the performance of carob cuttings in terms of adventitious roots formation and hardening using arbuscular mycorrhizal fungi (AMF). Softwood cuttings were treated with 5000 mg L-1 of indole-3-butyric acid (IBA) and kept noninoculated (Non-AM) or inoculated with Funneliformis mosseae (Fmo) alone or combined with Rhizophagus fasciculatus (Fmo+Rfa) or R. intraradices (Fmo+Rin) or both (Fmo+Rfa+Rin) and then maintained under mist conditions. After two months, rooted cuttings were transplanted on sterilized substrate and transferred to a hardening greenhouse for five months. Obtained results showed that inoculation of the rooting substrate with AMF substantially improved the percentage of rooted cuttings and the number of roots per cutting. The highest rooting (63.33%) and number of roots per cutting (11.67) were recorded in the presence of the complex of the three AMF strains (Fmo+Rfa+Rin). Moreover, all mycorrhizal-rooted cuttings survived transplantation and hardening shocks and showed the highest growth and physiological performances. Indeed, in the Fmo-Rfa-Rin-plantlets the gains in plant height and shoot and root dry weights were 95.6%, 55.1% and 76.9% respectively. Furthermore, stomatal conductance, total chlorophyll content, photochemical efficiency of PSII (Fv/Fm) and nutrient concentrations were higher in mycorrhizal plantlets than in non-AM ones. Thus, AMF substantially improved carob cuttings? performance in terms of rooting capacity and hardening efficiency, thereby increasing the potential of carob propagation by cuttings.