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Potassium (K) influences the variables that determine quality of fruit and the concentration of phytonutrients to human health and therefore consumer preferences. The objective of this study was to evaluate the effect of different concentrations of K in the nutrient solution (5, 7, 9 and 11 mM of K) on yield and quality of Cantaloupe fruits under greenhouse conditions. The experiment was conducted in pots using a completely randomized design with 15 replications. Analysis of variance, correlation, regression and multiple comparisons among means (Tukey p<0.05) were performed. Results showed higher values of yield, average fruit weight, equatorial diameter, pulp thickness, fruit firmness, soluble solids content, phenolic content and antioxidant capacity of fruits at the concentrations of 9 and 11 mM of K. All variables, except equatorial diameter, increased their values as K concentrations increased, showing a lineal, positive and significant trend, which evidences that the optimal dose of K in muskmelon is higher than 11 mM, being suggested for future research, to evaluate concentrations above this value.

Salinity stress limited the production in over 30% of irrigated crops and 7% of dryland agriculture worldwide. The objective was to evaluate the effects of NaCl-stress on the enzymatic activity in tomato. Two experiments were carried out in germination and early vegetative growth stages. The activity of proline and peroxidase of eight varieties (Missouri, Yaqui, Vita, Feroz, Rio Grande, Tropic, Ace, and Floradade) submitted to NaCl concentrations (0, 50, 100, 150 and 200 mM de NaCl) and the semi-quantitative activity of 19 enzymes APY ZYM® were measured under a completely randomized design with four replications. Data were analyzed using univariate-multivariate analysis of variance, Tukey’s HSD (p = 0.05), canonical discriminant and cluster analysis. The results showed significant differences between varieties and NaCl in proline content. Proline increased as the NaCl concentration increased. Peroxidase did no show significant differences. Eight enzymes were included within the model to properly classify the varieties and NaCl. In shoots, varieties and NaCl showed that enzymatic activity was higher in the order of alkaline-phosphatase > leucine arylamidase > acid phosphatase > naphthol-AS-BI-phosphohydrolase > n-acetyl-β-glucosaminidase > β-galactosidase, while in roots was higher in the order of alkaline-phosphatase > naphthol-AS-BI-phosphohydrolase > acid phosphatase > n-acetyl-β-glucosaminidase. Acid and alkali phosphatase, lipase, esterase, β-galactosidase, and trypsin can be a potential biomarker for NaCl-stress tolerance in tomato.

<p><strong>Background:</strong> Zinc (Zn) is an important element in human health and is consumed through foods of animal origin. However, the biofortification of plants with Zn can be a strategy for the consumption of this micronutrient and to increase the morphology, physiology, and plant yield. <strong>Objective:</strong> Quantify the effect of Zn application on yield, nutraceutical quality and antioxidant activity of lettuce. <strong>Methodology:</strong> Foliar application of ZnSO₄(0, 25, 50, 75 and 100 µM L^-1) on lettuce plants was made. Yield, nutraceutical quality and the concentration of Zn in the plant tissue was determinate. <strong>Results:</strong> The optimum Zn dose that maximized yield and nutraceutical quality, as well as the recommended consumption concentration in lettuce in this study was 75 µM L^-1 (ZnSO₄). <strong>Implications: </strong>Higher doses of Zn decreased bioactive compound biosynthesis. <strong>Conclusion:</strong> Zn biofortification is an alternative to increase phytochemical compound biosynthesis and yield with the possibility of improving public health.</p>

Cacti are particularly sensitive to habitat disturbance since they have slow growth and a longlife cycle. Their development and establishment depend on several factors, includingenvironmental requirements for germination and establishment of seedlings. Two of the mostinfluential factors are soil and water salinity. The objective of this study was to quantify seedsgermination and seedling biomass production of the Aborigine’s comb cactus (Pachyceruspecten-aboriginum) in salt stress using sodium chloride (NaCl) as the main salt source. Theexperiment was arranged in a completely randomized design using six salt levels (0.11, 2.03,4.00, 6.03, 8.03 and 10.07 dS m-1) with five replicates of 20 seeds each one. The seeds werecollected in a wild population of P. pecten-aboriginum in Ejido Álvaro Obregón, BajaCalifornia Sur, Mexico in June 2011. The results showed that germination and seedlingbiomass were significantly affected by salt stress, which was higher at 2.03 and 0.11 dS m-1,followed by 6.03 and 4.00 dS m-1, lower at 8.03 dS m-1, and no growth at 10.07 dS m-1. It isconcluded that saline levels using sodium chloride as the main source of salt, affect seedgermination and seedling biomass production of P. pecten-aboriginum significantly.

Capsicum annuum var. aviculare is one of the most extremely hot chilies, measuring between 50,000 and 100,000 Scoville Units. In the present work we studied the growth and development of chiltepin (Mazocahui), under field conditions, inoculated with previously selected and cultivated native strains of Bacillus amyloliquefaciens and Azospirillum halopraeferens. The seed was inoculated by the vacuum technique, and later at 34, 120, 180 and 210 days after germination. A drip irrigation system with a salinity (TDS) = 0.8 ppt was used. The results show that germination is significantly favored by the promoter effect caused by the beneficial bacteria. These inoculants increased some parameters of growth and development. We found significant differences regarding the control for the total weight and length of root and stem of the plants, as well as the total content of proteins, and in some parts of the plant analyzed as stem and leaf. Both bacteria increased fruit yield in the Mazocahui genotype. Our findings suggest that the application of strains of Bacillus amyloliquefaciens and Azospirillum halopraeferens, influence the increase in yield of Capsicum annuum var. aviculare, under field conditions. In addition, the data show the usefulness of the inoculation of chiltepin seed for agricultural producers in semi-arid areas where salinity is a problem.