Establishment of Mimosa biuncifera (Fabaceae) inoculated with arbuscular mycorrhizal fungi in greenhouse and field drought conditions / Establecimiento de Mimosa biuncifera (Fabaceae) inoculada con hongos micorrízicos arbusculares en invernadero y campo, en condiciones de sequía

AbstractMexico is dominated by arid or semi-arid ecosystems, predominantly characterized as xeric shrublands. These areas are frequently deteriorated due to agriculture or over-grazing by livestock (sheep and goats). The vegetation type mainly consists of thorny plant species, and among these, the dominant one in overgrazed areas is catclaw (Mimosa biuncifera). This is a nurse plant that facilitates establishment of other vegetation and promotes plant succession. Catclaw plants form a mutualistic association with arbuscular mycorrhizal fungi (AMF), which improves uptake of nutrients and water. The objective of this study was to determine the effect of inoculating catclaw plants with native AMF and starting their growth under a low water availability treatment in a greenhouse, and later transplanting them to field conditions of drought and deterioration. Field plants were evaluated according to their survivorship and growth. The seeds of catclaw plants and soil with AMF spores were collected in the Mezquital Valley of Hidalgo State, in Central Mexico. Seedlings were grown in individual pots in a greenhouse. The experimental design consisted of two levels of pot irrigation, wet (W) and dry (D), as well as the presence (M+) or absence (M-) of AMF inoculum, with 20 replicates for each treatment. The following plant parameters were recorded every week: height, number of leaves and pinnae, and mean diameter of coverage. After 20 weeks in the greenhouse, determination was made of fresh and dry biomass, relative growth rate (RGR), root/shoot ratio, real evapotranspiration (RET), water-use efficiency (WUE), and percentage of mycorrhizal colonization. The remaining plants growing under the dry treatment (M+ and M-) were then transplanted to a semi-arid locality in the Mezquital Valley. During one year, monthly records were kept of their height, number of leaves, mean diameter of coverage and survival. Results showed that compared to greenhouse plants under other treatments, those under the wet mycorrhizal (WM+) treatment were taller, had more pinnae, and were characterized by greater coverage, faster RGR, and greater fresh and dry biomass. Moreover, inoculated plants (WM+ and DM+) showed higher WUE than those uninoculated (WM- and DM-, respectively). After one year in field conditions, there was a higher survival rate for previously inoculated versus uninoculated plants. Hence, mycorrhization of M. biuncifera with native AMF inoculum increased plant efficiency in biomass production, thus favoring establishment and survival in field conditions. We concluded that inoculation of catclaw plants is recommendable for revegetation programs in deteriorated semi-arid zones. Rev. Biol. Trop. 64 (2): 791-803. Epub 2016 June 01.

ResumenMás de la mitad del territorio mexicano está dominado por ecosistemas áridos y semiáridos. El principal tipo de vegetación de estos ambientes son matorrales xerófilos y normalmente están deteriorados por agricultura y sobrepastoreo de ovejas y cabras inducido por la actividad humana. Las plantas espinosas dominan en estas zonas, como el gatuño (Mimosa biuncifera Benth., Fabaceae), que es una planta nodriza que promueve la sucesión vegetal. Las plantas de gatuño forman junto con hongos micorrizógenos arbusculares (HMA), una asociación mutualista llamada micorriza arbuscular que mejora la captación vegetal de nutrimentos y agua. El objetivo de este trabajo fue determinar el efecto de la inoculación con HMA nativos en plantas de gatuño, para evaluar su crecimiento y establecimiento bajo un tratamiento de baja disponibilidad hídrica, tanto en condiciones de invernadero como de campo. Para esto, se recolectaron semillas de Mimosa biuncifera y suelo con esporas de HMA en el Valle del Mezquital, estado de Hidalgo, en el Centro de México. Las plántulas fueron cultivadas en macetas individuales en condiciones de invernadero bajo un diseño experimental que consistió en dos tratamientos de riego de las macetas, húmedo (W) y seco (D), y dos tratamientos de inoculación: con y sin inóculo de HMA (M+, M-). Cada tratamiento tuvo 20 repeticiones. Semanalmente se registró altura, diámetro medio de la cobertura y número de hojas y pinnas de las plantas. Después de 20 semanas, se determinaron biomasa húmeda y seca, tasa relativa de crecimiento (TRC), proporción raíz vástago, evapotranspiración real, eficiencia en el uso del agua (WUE) y porcentaje de colonización micorrícica. Posteriormente, los individuos del tratamiento seco (M+ y M-) fueron trasplantados a una localidad semiárida en el Valle del Mezquital, donde la altura, número de hojas y supervivencia fueron registrados mensualmente durante un año. Los resultados muestran que las plantas en el tratamiento húmedo y micorrizado (WM+) tuvieron una mayor altura, cobertura vegetal, biomasa húmeda y seca, TRC y más pinnas que las plantas de los otros tratamientos; también los tratamientos micorrizados (WM+ y DM+) tuvieron mayor WUE que la plantas sin inóculo (M-). En condiciones de campo, después de un año, la supervivencia de las plantas M+ fue mayor que en los testigos. Se concluyó que la micorrización de M. biuncifera con inóculo nativo incrementa su eficiencia en la producción de biomasa y favorece el establecimiento y supervivencia en condiciones de campo. Finalmente, se recomienda la inoculación de plantas de gatuño con HMA en programas de revegetación de zonas semiáridas deterioradas.

Establishment of Mimosa biuncifera (Fabaceae) inoculated with arbuscular mycorrhizal fungi in greenhouse and field drought conditions.

Mexico is dominated by arid or semi-arid ecosystems, predominantly characterized as xeric shrublands. These areas are frequently deteriorated due to agriculture or over-grazing by livestock (sheep and goats). The vegetation type mainly consists of thorny plant species, and among these, the dominant one in overgrazed areas is catclaw (Mimosa biuncifera). This is a nurse plant that facilitates establishment of other vegetation and promotes plant succession. Catclaw plants form a mutualistic association with arbuscular mycorrhizal fungi (AMF), which improves uptake of nutrients and water. The objective of this study was to determine the effect of inoculating catclaw plants with native AMF and starting their growth under a low water availability treatment in a greenhouse, and later transplanting them to field conditions of drought and deterioration. Field plants were evaluated according to their survivorship and growth. The seeds of catclaw plants and soil with AMF spores were collected in the Mezquital Valley of Hidalgo State, in Central Mexico. Seedlings were grown in individual pots in a greenhouse. The experimental design consisted of two levels of pot irrigation, wet (W) and dry (D), as well as the presence (M+) or absence (M-) of AMF inoculum, with 20 replicates for each treatment. The following plant parameters were recorded every week: height, number of leaves and pinnae, and mean diameter of coverage. After 20 weeks in the greenhouse, determination was made of fresh and dry biomass, relative growth rate (RGR), root/shoot ratio, real evapotranspiration (RET), water-use efficiency (WUE), and percentage of mycorrhizal colonization. The remaining plants growing under the dry treatment (M+ and M-) were then transplanted to a semi-arid locality in the Mezquital Valley. During one year, monthly records were kept of their height, number of leaves, mean diameter of coverage and survival. Results showed that compared to greenhouse plants under other treatments, those under the wet mycorrhizal (WM+) treatment were taller, had more pinnae, and were characterized by greater coverage, faster RGR, and greater fresh and dry biomass. Moreover, inoculated plants (WM+ and DM+) showed higher WUE than those uninoculated (WM- and DM-, respectively). After one year in field conditions, there was a higher survival rate for previously inoculated versus uninoculated plants. Hence, mycorrhization of M. biuncifera with native AMF inoculum increased plant efficiency in biomass production, thus favoring establishment and survival in field conditions. We concluded that inoculation of catclaw plants is recommendable for revegetation programs in deteriorated semi-arid zones.