Exogenous silicon (Si) can enhance plant resistance to various abiotic factors causing osmotic stress. The objective of this research was to evaluate the application of 1 and 2 mM Si to plants under normal conditions and under osmotic stress. Morelos A-98 rice seedlings, were treated with 1 and 2 mM SiO2 for 28 d. Subsequently, half of the plants were subjected to osmotic stress with the addition of 10% polyethylene glycol (PEG) 8000; and continued with the addition of Si (0, 1 and 2 mM SiO2) for both conditions. The application of Si under both conditions increased chlorophyll b in leaves, root volume, as well as fresh and dry biomass of roots. Interestingly, the number of tillers, shoot fresh and dry biomass, shoot water content, concentration of total chlorophyll, chlorophyll a/b ratio, and the concentration of total sugars and proline in shoot increased with the addition of Si under osmotic stress conditions. The addition of Si under normal conditions decreased the concentration of sugars in the roots, K and Mn in roots, and increased the concentration of Fe and Zn in shoots. Therefore, Si can be used as a potent inorganic biostimulant in rice Morelos A-98 since it stimulates plant growth and modulates the concentration of vital biomolecules and essential nutrients.

Global climate change affects agriculture and tends to aggravate the effect of various environmental stress factors including soil salinity. Beneficial elements such as titanium (Ti) may improve the performance of plants facing restrictive environments such as saline soils. This research work evaluated the individual effect of sodium chloride (0, 50, and 100 mM NaCl) in solution, that of leaf-applied Ti (0, 500, and 1000 mg L−1 Ti), and their interactions on physiological, biochemical, and nutritional variables of tomato (Solanum lycopersicum L.) seedlings cv. Rio Grande in a factorial design in greenhouse hydroponics. NaCl reduced seedling height, stem diameter, leaf area, SPAD units, and sugar and K concentrations, and increased antioxidant activity in stems and roots, photosynthetic pigments, sugars. Titanium increased the N, P, K, Ca, Mg, and Ti concentrations in leaves, but the concentration of total sugars in leaves was reduced when applying 500 mg Ti L−1. Under moderate salinity conditions (50 mM NaCl) the application of Ti increased the antioxidant activity in roots, while, at all salinity levels tested, Ti increased the concentrations of macro-nutrients and Ti in leaves. Titanium is concluded to have a positive effect on the antioxidant activity and nutrition of seedlings under saline stress conditions.

Introducción.  Jaltomata procumbens (Cav.) J. L. Gentry, de uso alimenticio, se considera una especie semi-domesticada (poblaciones que han tenido un proceso de selección artificial pero aún tienen la capacidad de sobrevivir y reproducirse sin la intervención del ser humano) y que cumple con los criterios para su futuro uso. Objetivo. Evaluar caracteres agronómicos de dos poblaciones de J. procumbens, en invernadero e hidroponía. Materiales y métodos. La investigación se realizó en el Colegio de postgraduados, Campus Montecillo, Texcoco, Estado de México, de julio a diciembre de 2019. Se aplicaron los siguientes tratamientos en un sistema hidropónico abierto: dos poblaciones (erguida y decumbente), tres niveles de conductividad eléctrica (CE): 1, 2 y 3 dS m-1 y dos niveles de poda (con y sin poda). Las variables evaluadas fueron: altura de planta (AP), diámetro de tallo (DT), número de hojas (NH) y de racimos (NR), flores por racimo (FLR), frutos por racimo (FR), peso de fruto (PF), rendimiento (REND) y lecturas SPAD. Resultados. Para ambas poblaciones, su cultivo en condiciones de invernadero e hidroponía promovieron el desarrollo en altura de planta, diámetro de tallo y peso de fruto. Se observó una variabilidad dentro y entre poblaciones para poda y conductividad eléctrica; el cultivo a 3 dS m-1 registró la menor altura de planta y el mayor diámetro de tallo, mientras que con 1 dS m-1 se obtuvo el mayor rendimiento; para el tratamiento con poda, los valores más altos se presentaron en flores por racimo, frutos por racimo y peso de fruto. Conclusiones. Ambas poblaciones presentaron el potencial para ser consideradas en estudios en ambientes controlados.