Seedlings of maize (Zea mays L. cv Pioneer 3906), hydroponically grown in the dark, were exposed to NaCl either gradually (salt acclimation) or in one step (salt shock). In the salt-acclimation treatment, root extension was indistinguishable from that of unsalinized controls for at least 6 d at concentrations up to 100 mM NaCI. By contrast, salt shock rapidly inhibited extension, followed by a gradual recovery, so that by 24 h extension rates were the same as for controls, even at 150 mM NaCI. Salt shock caused a rapid decrease in root water and solute potentials for the apical zones, and the estimated turgor potential showed only a small decline; similar but more gradual changes occurred with salt acclimation. The 5-bar decrease in root solute potential with salt shock (150 mM NaCI) during the initial 1 O min of exposure could not be accounted for by dehydration, indicating that substantial osmotic adjustment occurred rapidly. Changes in concentration of inorganic solutes (Na+, K+, and CI-) and organic solutes (proline, sucrose, fructose, and glucose) were measured during salt shock. The contribution of these solutes to changes in root solute potential with salinization was estimated.

Interception loss, gross precipitation, throughfall and stemflow solution chemistry beneath pine (Pinus pseudostrobus Lindl.), oak (Quercus sp.) and pine-oak natural forest canopies in northeastern Mexico were measured. Coefficients of variation for throughfall were 12% in pine and oak canopies and 17% in the mixed pine-oak canopy. The variability of stemflow averaged 66, 126 and 73% for pine, oak and the mixed pine-oak canopies, respectively. Linear regression analysis of net versus gross precipitation for the three canopies showed highly significant correlations (r = 0.974-0.984). Total precipitation during the experimental period was 974 mm and estimated interception loss was 19.2, 13.6 and 23% for the pine, oak and pine-oak canopies, respectively. Stemflow did not occur following rainfall events of less than 4 mm and, in all canopies, stemflow represented a minimal proportion of gross precipitation (0.60, 0.50 and 0.03% for pine, oak and pine-oak, respectively). Throughfall pH in pine (6.2), oak (6.3) and pine-oak (6.3) canopies was significantly more acidic than gross precipitation (6.6). Stemflow pH ranged from 3.7 (pine) to 6.0 (oak). The pine-oak canopy registered the highest throughfall and stemflow electrical conductivities, 104 and 188 microS cm(-1), respectively. Net nutrient leaching of K, Mg, Na, Fe, Mn and Zn was significantly higher from the pine-oak canopy than from the pure pine and oak canopies. Mean depositions of Ca and Cu in throughfall behaved similarly among the three types of canopies. A greater proportion of Zn in gross precipitation was absorbed by the oak canopy than by the pine and pine-oak canopies. Enrichment factors beneath the pine-oak canopy relative to gross precipitation varied from 1.2 to 3.2 for macro-nutrients (Ca, K, Mg and Na) and from 1.4 to 3.1 for micro-nutrients (Cu, Fe, Mn and Zn). Stemflow depositions of Ca, K, Mg and Cu were higher in the pine-oak canopy, whereas stemflow depositions of Na, Fe, Mn and Zn were higher in the pine canopy.

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Type 2 diabetes management hinges on various determinants, including the role of interpersonal relationships in self-management behaviours. The aim of this study was to explore the types and sources of social support received by adults in the diabetes diagnosis and self-management processes. We conducted qualitative interviews with 28 men and women at two rural clinics in the Dominican Republic and used a combination of narrative and thematic analytic techniques to identify key sources and types of social support in their diabetes experiences. Participants described three stages in their diabetes experience: diagnosis, programme-enrolment, and long-term management. During diabetes diagnosis, most participants described receiving no support. At the programme-enrolment stage, friends and neighbours frequently provided informational or instrumental support to get to the clinic. In long-term management, cohabiting partners provided the most support, which was often assistance with their diet. Our findings highlight he need to assess and leverage distinct types and sources of social support at different stages of the diabetes experience.

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