No abstract

Se ha realizado un gran número de estudios para identificar los efectos de los metales pesados en plantas cultivadas y en algunas especies consideradas como hiperacumuladoras. Sin embargo, po¬cos esfuerzos se han dedicado a la evaluación de especies vegetales nativas de zonas áridas para fitorremediación. Este estudio se llevó a cabo ex situ para evaluar la tasa de fitoextracción de plomo en Acacia farnesiana L. Will. Se utilizaron árboles jóvenes (n=48), colocados en macetas plásticas, en donde se agregó una combinación de tres concentraciones de plomo (0, 250 y 500 mg•kg-1) en forma de Pb(NO3)2 y cuatro dosis de nitrógeno (0, 100, 300 y 500 mg•kg-1) en forma de Fosfo-Nitrato (33-03-00). Se evaluó la tasa fotosintética y la concentración de plomo en raíz, tallo y hoja. Las dosis de nitrógeno y las concentraciones de plomo por separado no produjeron diferencias significativas en la tasa fotosintética de las plantas de huizache, pero la interacción entre esos dos factores fue es¬tadísticamente significativa (P=0.0074), encontrándose que la mayor acumulación de plomo ocurrió en la parte aérea de la planta con una media de 352.34 mg•kg-1.

Drylands are of high ecological vulnerability due to low vegetative cover and erratic and torrential rainfalls. The aim of this study was to evaluate the use of different sources and rates of soil moisture retainers in the establishment of buffel grass (Cenchrus ciliaris L) in a micro watershade system of rainwater. A randomized block design with three replications was used. Four hydrogel doses: 0, 5, 10 and 15 kg ha -1 and two vermicompost doses: 0 and 40 t ha -1 , were tested. The dose effect of the hydrogel was independent of vermicompost dose effect, on soil moisture retention and the growth and development of the plant. The soil moisture values when 5, 10 and 15 kg hydrogel ha -1 were applied (25, 23.2 and 23.4 %, respectively) were higher (P0.05), than the control (17.5 %) 241 d after sowing (das). However, there were not statistical differences among doses of hydrogel other than the control. A similar effect was found at 346 das; but not to 372 das, where the effect was lost. Plant emergency was significantly higher (47.7 %) when 15 kg ha -1 of hydrogel were applied, compared to the control (29 %) (P0.05). Plant height and weight of dry matter and a higher photosynthetic activity were significantly greater in treatments with hydrogel than in the control; there were not statistical differences among doses. Finally, the application of 40 t ha -1 vermicompost significantly increased the moisture content in the soil and a higher amount of buffel grass dry matter.

The aim of this study was to determine the soil microbiome throughout mass sequencing in coffee plantations managed with either an organic (OAM; i.e., bio-fertilizers Azospirillum brasilense and Glomus intraradices) or a conventional (CAM; i.e., traditional NPK-fertilization) agronomic systems. Soil microbiome samples were collected in tropical eastern Mexico (Veracruz, 19°28’ N & 96° 52’ W), with annual average temperature and rainfall of 24.8° C, and 882.6 mm, respectively. Upon DNA soil-microbiome extraction, the V3-V4 16S rRNA region was amplified, and sequenced (Illumina). Results were analyzed with QIIME based on the EzBioCloud reference. Diverse phyla (n=16), classes (n=40), orders (n=90), families (n=135) and genera (n=333) were identified. The diversity index values were similar in both treatments, with Shannon's being 9.7 and Simpson's 0.99. While the phylum Proteobacteria was more abundant in CAM-soils and classified as copiotrophic, the phylum Acidobacteria was more abundant in OAM-soils and classified as oligotrophic. This classification may be related to the application of microorganisms and their effect on the soil´s state of organic matter and carbon fractions. Our research outcomes indicate that the application of bio-fertilizers promoted an increased presence of Acidobacteria, a phylum positively correlated with organic matter while significantly involved in carbon sequestration. Undisputable, metagenomics emerges as an interesting up-to-date genomic technology for unveiling the hidden content of the soil microbiome black box.

Palabras clave: química del agua, cationes, metales pesados, contaminación química RESUMEN La Comarca Lagunera es un área agrícola que hace uso intensivo de los recursos suelo y agua, éste último de alto impacto por la escasez del mismo. El objetivo del presente estudio fue hacer una valoración de la calidad química del agua de riego de pozo profundo en campos productores de maíz forrajero en la Comarca Lagunera, México. Se realizaron cuatro muestreos de agua durante los meses de abril, mayo, junio y julio del 2014. Se midió conductividad eléctrica (CE) en mS/cm, dureza del agua en grados franceses (ºf), así como concentraciones de los cationes Ca +2 , Mg +2 , Na + y K + en meq/L y metales pesados Cd, Pb y As en mg/L. La salinidad del agua en la Comarca Lagunera medida en términos de CE es de alto a muy alto, con valores de 1732 y 3386 µS/cm, en tanto que la sodificación expresada en Índice de Absorción de Sodio (IAS) es medio con un valor de 3.66 meq/L, la dureza del agua varió de dura a muy dura con promedio de 50.47 y 114.00 ºf, respectivamente. Las mayores concentraciones de elementos químicos presentes en el agua de riego procedente de pozo profundo fueron Ca +2 , Mg +2 y Pb, principalmente el último. Sin embargo, el Cd y As también rebasaron los límites máximos permisibles por la norma oficial del agua para uso agrícola (SCFI-2001 y NOM-117-SSA1-1994), con el consecuente riesgo para la salud y el ambiente.Key words: chemical of water, cationic elements, heavy metals, chemical contamination ABSTRACTThe Comarca Lagunera region from Mexico is an agricultural area which makes intensive use of soil and water resources, this latter of high impact due the it´s scarcity. The aim of this study was to assess the chemical quality of irrigation water from deep wells in producing fields of fodder maize in the Laguna region, Mexico. Four samplings were conducted in April, May, June and July 2014. The variables measured were the electrical conductivity (EC) in mS/cm, water hardness in French degrees (ºf), cations Ca +2 , Mg +2 , Na + and K + in meq/L, as well as heavy metals Cd, Pb, and As, in mg/L. The salinity in