This review compiles and discusses current scientific information relating to the role of urease in plants; moreover, it addresses its catalytic function, distribution, influence of pH on hydrolysis of urea and Ni as a cofactor in its activation. This enzyme is of vital importance in nitrogen metabolism. To be activated, urease requires binding with two nickel (Ni) atoms, and in plant cells it participates in the metabolism of compounds containing nitrogen (N). To date, urease activation appears to be the only enzymatic function of Ni in higher plants. The importance of Ni in the physiological and biochemical processes of plants, and the typical responses to the presence of Ni in soil and plants are discussed. Evidence of a close relationship between urease and Ni in the physiology of some plants is provided, thereby indicating that urease activity could be considered as a biochemical indicator of Ni deficiency before symptoms are visibly present. 

Residual mushroom waste has the potential to be composted. Sustainable agriculture considers compost and vermicompost as alternatives to be incorporated into organic vegetable production. The aim of this study was to determine the effect of compost (T2), vermicompost tea (T3), compost extract (T4), and their combination plus the addition of an inorganic element (urea) (T5), against a conventional control (T1), on soil properties and yield parameters of tomato plants grown under shade house conditions. Organic matter, moisture, pH, electrical conductivity (EC), cation exchange capacity (CEC), bulk density, leaf nutrient content during flowering (N, P, K, Ca, Mg, Cu, Fe and Zn), chlorophyll content (SPAD units), fruit number and weight, and yield were the variables assessed during this research. A completely randomized experimental design was used. The organic applications showed significant increases in soil moisture (25.4 % T3), EC (0.38 dS·m-1 T5), and CEC (38.6 meq·100 g-1 T4). Crop nutrient requirements were achieved 102 days after transplanting. The chlorophyll content ranged between 46.9 and 51.4 SPAD units. The cv “Grandella” fruits attained optimal weight (152 to 155 g). The number of fruits and yield did not statistically differ between treatments; therefore, it was concluded that the organic substances by themselves or in combination with inorganic fertilizers were able to produce the same effect on yield, and also improve the physicochemical characteristics of the soil.

El objetivo de esta revisión fue analizar información científica de Moringa oleifera Lam. sobre su distribución, composición química y caracterización, que permite sustentar sus usos medicinales, agrícolas, pecuarios e industriales. La moringa es un árbol nativo de la India e introducido a América. Su hábitat de crecimiento es el trópico (< 2000 msnm). En la planta se han cuantificado proteínas, fibra, carbohidratos, aminoácidos, vitaminas, minerales y metabolitos secundarios (carotenos y tocoferoles); lo que explica parcialmente sus usos como alimento, tratamiento de enfermedades (respiratorias, gastrointestinales, inflamatorias, cardiacas, nutricionales y cutáneas), mejorador de suelo, materia prima para la industria alimentaria y de cosméticos y para el tratamiento de agua contaminada. Los resultados permitieron identificar los atributos y aplicaciones de moringa; así como la necesidad de realizar estudios específicos para potenciar su producción y aplicación tecnológica en beneficio del consumidor.

Recognizing native populations as genetic reservoirs necessitates their conservation, especially when referring to characters that are of interest for breeding new cultivars and in light of the limited genetic variation present in current commercial varieties. This research sought to evaluate the genetic variation in 55 collections of native tomato (Solanum lycopersicum L.) from nine states of Mexico, through their morphological and molecular characterization, and to create a strategy for their sustainable and efficient conservation. The collections were characterized morphologically under greenhouse conditions based on 62 descriptors used by the International Plant Genetic Resources Institute (IPGRI). Molecular characterization was performed using ISSR markers with 16 primers, which generated 118 amplified products, of which 81 allowed differentiating collections (68.7 % polymorphism). Multivariate analysis detected three groups based on morphological descriptors of leaves, flowers, stem and fruit, while the molecular characterization generated seven groups, coinciding by only 26.5 %. The origins of the collections had no association with the clusters. The presence of significant genetic variability in the native tomatoes was detected, so it is concluded that within the groups generated it is possible to identify materials with traits of interest for breeding. On the other hand, sustainable conservation of this genetic variability in seedbanks may be more efficient by requiring the safeguarding of 67 % of the collections studied.

Iodine is a beneficial micronutrient, but its metabolic function is still unknown. The aim of this study was to evaluate the effect of iodine application on biomass and antioxidant concentration in tomato seedlings. Iodine was applied in the form of iodide (I-) and potassium iodate (IO3-), at concentrations of 1 μM daily and 100 μM biweekly, directly to the substrate or by foliar application to tomato var. Río Grande seedlings under greenhouse conditions. The effect of iodine on enzymatic antioxidants (superoxide dismutase, catalase, ascorbate peroxidase, and glutathione peroxidase), as well as the concentration of non-enzymatic antioxidants (ascorbate, glutathione, and total phenols) was analyzed. No treatment with I- or IO3- had a negative effect on seedling biomass. In addition, the biweekly I- treatments both by foliar and substrate application, as well as the daily IO3- and I- treatments via foliar application showed a 54 to 86 % decrease in superoxide dismutase enzymatic activity, without showing changes in the other enzymes. On the other hand, in both cases with daily I- foliar application, the non-enzymatic antioxidant concentrations for ascorbate and glutathione increased by 22 and 85 %, respectively. Phenolic compounds showed no changes in the different treatments.