Improved salt tolerance of mycorrhizal plants is commonly attributed to their better mineral nutrition, particularly phosphorus. However, the effect of arbuscular‐mycorrhizal (AM) fungi on salt tolerance may not be limited to this mechanism. We investigated the possibility that non‐nutritional effects of AM fungi, based on proline accumulation or increased photosynthesis and related parameters, can influence the tolerance of lettuce (Lactuca sativa L.) to salinity. Three levels of salt (3, 4 and 5 g NaCl kg‐1 dry soil) were applied and plants were maintained under these conditions for 7 weeks. The salt‐treated AM plants produced greater root and shoot dry weights than unfertilized or P‐fertilized non‐AM controls. With increasing salinity, both shoot and root dry weights were reduced, but this decrease was greater in uninoculated plants. In particular, shoot dry weight was not reduced in G. fasciculatum‐colonized plants as a consequence of salt, whereas in uninoculated plants it was reduced by about 35% at the highest salt level. Proline accumulation was considerably lower for P‐amended non‐AM and for AM plants except for G. mosseae‐colonized plants than was the case for unamended plants. Transpiration, carbon dioxide exchange rate (CER), stomatal conductance and water use efficiency (WUE) were higher in mycorrhizal plants. At 5 g NaCl kg‐1, both photosynthesis and WUE increased by more than 100% in mycorrhizal treatment relative to uninoculated plants. The contents of phosphorus of P‐fertilized non‐AM plants was similar to or higher than those of G. mosseae‐ and G. fasciculatum‐colonized plants. Plants colonized by G. deserticola had the highest P‐content regardless of salt level. Hence, the effect of G. mosseae and G. fasciculatum on salt tolerance in this experiment could not be attributed to a difference in the P content. The mechanisms by which these two fungi alleviated salt stress appeared to be based on physiological processes (increased CER, transpiration, stomatal conductance and WUE) rather than on nutrient uptake (N or P).

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Artículo de acceso abierto publicado por Revista U.D.C.A Actualidad & Divulgación Científica bajo una licencia Creative Commons CC BY-NC 4.0 RESUMEN La caña de azúcar (Saccharum officinarum L.) es una fuente importante de carbohidratos para la panela. En Colombia, la principal región panelera está ubicada en la Hoya del Río Suarez; sin embargo, falta aún consolidar una producción suficientemente rentable, competitiva y amigable con el ambiente. Uno de los aspectos más determinante en la producción de panela es la nutrición mineral, debido a que, actualmente, se hace de forma convencional, desconociendo los niveles de extracción de los materiales genéticos utilizados. El objetivo fue determinar el requerimiento nutricional, producción de biomasa y productividad en segundo corte, en el municipio de Suaita (Santander). El diseño empleado fue bloques al azar (BCA), con 3 tratamientos (las variedades CC 93-7711, CC 93-7510 y RD 75-11) y 5 repeticiones. Se realizaron 4 muestreos, a los 118, 252, 335 y 392 días después de corte (ddc). Se observó que la mayor absorción de N, Ca y Mg ocurrió a los 335 ddc, mientras que para P y K, aconteció a los 392. Los nutrientes se acumularon, especialmente, en los tallos; la CC 93-7711 superó a las otras variedades, con una absorción total en kilogramos por hectárea, de 448 N, 296 K, 85 Ca, 43 P y 40 Mg, seguida por RD 75-11, que presentó, aproximadamente, 16% menos en N-K-CaP -Mg. El patrón de absorción de los nutrientes fue N>K>Ca>P>Mg y, referente a la productividad, se destacó RD 75-11, luego CC 93-7711 y CC 93-7510, con 172,6, 171,1 y 159,9 toneladas de caña por hectárea, respetivamente.

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Colombia is among the countries of Latin America that produce about 80% of f ine or “prime” cocoa of the world; however, cocoa in Colombia has limitations related to the presence of cadmium (Cd) in some soils where it is grown and this reduces the safety of the product. The objective of this study was to evaluate the absorption of cadmium in a cocoa pattern (IMC 67) in association with arbuscular mycorrhizal fungi (AMF) to determine their potential use as Cd immobilizers in medium and long-term. A randomized complete block design with three replications and 20 treatments was established, in 4 × 5 factorial arrangement, one control, three types of mycorrhizae (Glomus macrocarpum, Rhizoglomus intraradices and AMF-native) and f ive Cd doses (0, 6, 12, 18 and 24 mg kg-1). Plant height, dry weight of stem, leaves and roots as well as Cd concentration in stems, leaves and roots were measured. The results showed that cacao plants translocate the Cd easily, that is, they can live under these conditions since it was found in all organs (stems, leaves and roots); however, the treatment inoculated with AMF‑native decreased signif icantly the accumulation of Cd in all the organs evaluated. These results conf irm the benef icial effects that AMF have to alleviate the stress that plants shows when translocating heavy metals such as cadmium.

Sugarcane crop for panela production in Colombia presents nutritional limitations especially with the low eff iciency of chemical fertilization. The use of arbuscular mycorrhizal fungi (AMF) optimizes fertilization, making it more eff icient and can reduce the application of synthetic fertilizers. The objective of this study was to evaluate the association of AMF with sugarcane plants for panela production in seedling stage. A characterization of soils was carried out in the regions of Cundinamarca and La Hoya del Río Suárez (Boyacá and Santander), characterized as the main sugarcane for panela production in Colombia and it was found that sugarcane plants establish a natural association with the AMF. The predominant AMF were Glomus microcarpum, Glomus fasciculatum, Glomus sinuosum, four morphotypes of Glomus sp., two of Acaulospora sp. and one of Funneliformis sp. The effect of the inoculation with AMF in the seedling stage was evaluated using three varieties of sugarcane widely cultivated in the Hoya del Río Suárez, CC93-7711 (Pierna Bella), CC93-714 and CC93-7510 (Vende Finca). Eleven (T1 to T8 inoculation with different communities of AMF, T9, T10 and T11 correspond to controls with fertilizations of 10, 50 and 100% of chemical fertilization) were evaluated in a randomized complete block design with three replications. Plant height and stem diameter, spore quantif ication and percentage of colonization were evaluated. The results showed that the three varieties responded to the benef icial effect of the plant-HMA association, f inding plants with higher yield with respect to the non-inoculated plants. The varieties CC93-7711 (Pierna Bella) and CC93-7510 (Vende Finca) showed a higher percentage of AMF colonization in response to the inoculation of Glomus sp.