Physiological Responses of a Grapefruit Orchard to Irrigation with Desalinated Seawater.

Desalinated seawater (DSW) has emerged as a promising solution for irrigation in regions facing water scarcity. However, adopting DSW may impact the existing cultivation model, given the presence of potentially harmful elements, among other factors. A three-year experiment was carried out to assess the short-term effects of four irrigation waters-freshwater (FW), DSW, a mix 1:1 of FW and DSW (MW), and DSW with low boron (B) concentration (DSW-B)-on a 'Rio Red' grapefruit orchard. These irrigation waters exhibited varying levels of phytotoxic elements, some potentially harmful to citrus trees. Sodium (Na+) and chloride (Cl-) concentrations exceeded citrus thresholds in all treatments, except in DSW-B, whilst B exceeded toxicity levels in DSW and MW treatments. Leaf concentrations of Cl- and Na+ remained low in all treatments, whereas B approached toxic levels only in DSW and MW-irrigated trees. The rapid growth of the trees, preventing excessive accumulation through a dilution effect, protected the plants from significant impacts on nutrition and physiology, such as gas exchange and chlorophyll levels, due to phytotoxic elements accumulation. Minor reductions in photosynthesis in DSW-irrigated trees were attributed to high B in leaves, since Cl- and Na+ remained below toxic levels. The accelerated tree growth effectively prevented the substantial accumulation of phytotoxic elements, thereby limiting adverse effects on tree development and yield. When the maturation of trees reaches maximal growth, the potential accumulation of phytotoxic elements is expected to increase, potentially influencing tree behavior differently. Further study until the trees reach maturity is imperative for comprehensive understanding of the long-term effects of desalinated seawater irrigation.

Deficit Irrigation Applied to Lemon Trees Grafted on Two Rootstocks and Irrigated with Desalinated Seawater.

The use of desalinated seawater (DSW) for irrigation in semi-arid regions is taking hold. Citrus tolerance to ions that predominate in DSW and water stress depends on the rootstock. Deficit irrigation was applied to DSW-irrigated lemon trees and grafted on rootstocks with different tolerance (Citrus macrophylla (CM) and sour orange (SO)). Plants were irrigated with DSW or Control treatment (distilled water), and, 140 days later, irrigation treatments were started: full irrigation (FI) or DI (50% of the volume applied to FI). After 75 days, differences between CM and SO plants irrigated with DSW and under DI were found. The higher concentrations of Cl- and Na+ in CM and B in SO were the main causes of shoot growth reduction. The osmotic adjustment of CM plants was made possible by the accumulation of Na+, Cl-, and proline, but SO failed to adjust osmotically. In CM and SO plants, photosynthesis reduction was due to lower chlorophyll levels, but also to stomatal factors (CM plants) or alterations of the photochemical machinery (SO plants). Finally, unlike CM, SO had a good antioxidant system. In the future, knowing the different responses of CM and SO under these stressful conditions could be useful in citrus-growing areas.

Tratamiento sintomático de la rinitis alérgica o vasomotora con la aplicación local de nitrato de plata / Topical nasal use of silver nitrate solution in allergic or vasomotor rhinitis

Se estudió la aplicación tópica sobre los cornetes inferiores de solución de nitrato de plata, para mejorar la sintomatología nasal en quince pacientes con rinitis alérgica o vasomotora. En todos había obstrucción nasas, en 14 rinorrea y en 11 estornudos. El diámetro horizontal promedio del cornete inferior derecho se estimó en un promedio de 6.8 mm ñ 1.3 y 6.0 ñ 1.9 mm del izquierdo. La distancia entre el cornete y el séptum fue de 2.7 mm ñ 1 del lado derecho y de 2.9 mm ñ 1.5 del izquierdo. Posteriormente a la aplicación de Ag NO3 no se encontró una disminución significativa del tamaño de los corentes (1.6 mm en promedio) y un aumento de espacio del séptum al cornete (1.6 mm en promedio). Hubo mejoría sintomática de la obstrucción nasal 100 por ciento de los pacientes, de la rinorrea en 84 por ciento y de los estornudos en el 78 por ciento. Los efectos adversos en 105 aplicaciones fueron cefalea leve a severa en 14 (aplicaciones), ardor nasal en 13, estornudos inmediatos en seis, epistaxis en dos y parosmia en uno. No se presentaron efectos secundarios persistentes ni complicaciones