Ricardo Trejo-Calzada

Effects of surface and subsurface water application on nitrogen and sodium relations of desert graminoids of different geographic origin

ABSTRACT This greenhouse study evaluated nitrogen and sodium relations of three desert graminoids (Distichlis spicata, Leymus triticoides, and Juncus arcticus) as affected by availability of surface water, subsurface water or both. These species are amply distributed in desert wetlands of western USA where surface and subsurface water are differentially available. Plants of the three species were collected from two areas of ecological distribution: Bishop, California and Burns, Oregon. Because nitrogen and sodium uptake by plants is highly linked to water availability we established three general hypotheses for this study: (1) nitrogen uptake would be greater when plants have surface water available, (2) sodium uptake would be greater when plants do not have surface water available, and (3) there are populations’ differences in the response of the species to water availability. We grew plants in two-layer pots in which soil water content in the upper and lower layers was controlled independently. The first hypothesis was partially supported as only Leymus triticoides seemed to preferentially depend on the top layer for nitrogen acquisition. With respect to the second hypothesis sodium concentration was indeed greatest when plants had no surface water, but only in D. spicata. The third hypothesis was also partially supported. The Oregon population of J. arcticus had 15% more nitrogen than the California population and the California population of D. spicata had 18% more sodium than the Oregon population. Our results underline the plant nutrient uptake implications of differential availability of water pools for common desert graminoid species.

Growth and leaf chemistry of Atriplex species from Northern Mexico as affected by salt stress

ABSTRACT Atriplex species are tolerant to salinity and water stress and thus they are suitable for restoration of many degraded ecosystems. In addition, many Atriplex species offer good value as forages. We compared growth and leaf chemistry of Atriplex canescens, a well-known halophyte, and A. acanthocarpa, a poorly-studied species, as affected by salinity in a greenhouse study. Seeds and soil were collected in northern Mexico, the native range of these species. Plants were grown in pots containing native soil and irrigated with NaCl solutions of 0, 50, and 100 mM. Shoot growth of A. canescens declined 37% as NaCl treatments increased from 0 to 100 mM while shoot growth of A acanthocarpa was not significantly affected by salinity. The high salt tolerance of A. acanthocarpa was linked to a high accumulation of leaf sodium (Na) (7- to 13-fold higher than A. canescens). A. acanthocarpa had also higher growth rate than A. canescenes, making the former species a good candidate for cultivation, especially under saline conditions. Tissue concentration of potassium (K) in both species was minimally affected by the salinity treatments. Leaf nitrogen (N) concentration increased as plants faced higher salinity treatments, especially in A. canescens. The high salt tolerance and higher Na accumulation of A. acanthocarpa make this species an attractive choice for reclamation of saline areas. We suggest A. acanthocarpa should be explored as viable forage for cultivation and for reclamation of degraded areas just as A. canescens has been throughout the world.

Effect of biofertilizers on growth of aloe (Aloe barbadensis Miller) and gel quality under different soil moisture contents

Universidad Autónoma Chapingo, Unidad Regional Universitaria de Zonas Áridas. Carretera Gómez PalacioChihuahua km 38, Bermejillo, Durango, C. P. 35230, MÉXICO. Centro Nacional de Investigación Disciplinaria en Relaciones Agua, Suelo, Planta, Atmósfera. Canal Sacramento km 6.5, Zona Industrial 4ta Etapa, Gómez Palacio, Durango, C. P. 35140, MÉXICO. Oregon State University. 120 Withycombe Hall, Corvallis, Oregon, P. C. 97331, USA. *Corresponding author: apedroza@chapingo.uruza.edu.mx, tel. 871 28 07 145.

Respuestas morfogénicas en la propagación in vitro de nogal pecanero (Carya illinoinensis [Wangenh] K. Koch)

RESUMEN L as respuestas embriogenicas y organogenicas en nogal ( Carya illinoinensis [Wangenh] K. Koch) se observaron bajo el cultivo in vitro de segmentos de hojas, yemas axilares y embriones cigoti-cos. El necrosamiento se controlo empleando carbon activado (CA: 1 %), polivinilpirrolidona (0.1 %), nitrato de plata (AgNO 3 : 1 %), acido citrico (150 mg·L -1 ) y acido ascorbico (100 mg·L -1 ), con presencia de luz y en oscuridad. Se utilizo el medio basico de Murashige y Skoog suplementado con 0.40 mg·L -1 de tiamina, 100 mg·L de myo-inositol, 3 % de sacarosa, incorporando 2,4-D para hojas, tidiazuron (TDZ) para embriones, y las combinaciones de benciladenina (BA), kinetina (KIN), acido naftalenacetico (ANA) y acido indolbutirico (AIB) para yemas axilares. El necrosamiento de tejidos se redujo en 75 % y 83 % adicionando CA y AgNO 3 , respectivamente. El 33 % y 66 % de los callos embrio-genicos se indujeron a partir de hojas, utilizando 1 y 3 mg·L -1 de 2,4-D. La mayor produccion de callos (58 %) a partir de embriones se obtuvo con la concentracion de 3 mg·L