Benefits of nanotechnology in agriculture include reduced fertilizer loss, improved seed germination rate and increased crops quality and yield. The objective of this research was to evaluate the effects of zinc oxide nanoparticles (ZnO-NPs), at 1500 ppm, on tomato (Solanum lycopersicum L.) growth. ZnO-NPs were synthetized to produce either spherical or hexagonal morphologies. In this research, we also studied two application methods (foliar and drench) and nanoparticles’ (NPs) surface modification with maltodextrin. The results obtained indicate that ZnO-NP-treated tomato plants significantly increased plant height, stem diameter and plant organs (leaves, stem and root) dry weight compared to plants without NP treatment.

Marigolds are one of the most popular annual ornamental plants; both, the short-stature cultivars ( Tagetes patula L.) and the taller cultivars ( T. erecta L.) are used as container plants in landscape and garden settings. Tagetes erecta varieties can also make excellent cut and dried flowers for the florists' market. The present study was conducted to evaluate the response of T. patula ‘French Vanilla’ and T. erecta ‘ Flagstaff’ and ‘Yellow Climax’ to irrigation with saline water with and without pH control. Marigold plugs were transplanted into greenhouse sand tanks and established for 1 week under nonsaline conditions. Ten treatments were then applied with electrical conductivities of irrigation water (EC _w ) of 2, 4, 6, 8, and 10 dS·m ⁻¹ and pH levels of 6.4 and 7.8. Growth of all three cultivars decreased in response to irrigation with saline waters at pH 6.4. Compared with the nonsaline controls, ‘French Vanilla’ exhibited a 20% to 25% decrease in plant height, leaf dry weight (DW), and shoot DW when irrigated with 4 dS·m ⁻¹ water. However, the number of flowering shoots and the diameter and number of flowers were not significantly affected until the EC _w exceeded 8 dS·m ⁻¹ . Growth of ‘Flagstaff’ and ‘Yellow Climax’ also decreased as EC _w increased. Shoot DW of the tall cultivars decreased by 30% and 24%, respectively, in response to the 4 dS·m ⁻¹ treatment, but additional salt stress had no further effect on DW production. Marigolds were highly sensitive to high pH. Plants irrigated with nonsaline water with pH at 7.8 exhibited a 50%, 89%, and 84% reduction in shoot DW in ‘French Vanilla’, ‘Flagstaff’, and ‘Yellow Climax’, respectively, compared with plants irrigated with water with pH 6.4. Marigold cultivars were rated as moderately tolerant to salinity because growth was affected when water EC _w exceeded 8 dS·m ⁻¹ . Salinity tended to reduce internode elongation, resulting in attractive plants. Compactness was not increased as a result of a decrease in DW, resulting in attractive plants, which show great promise as bedding or landscape plants in salt-affected sites provided that the pH of the soil solutions remains acidic. Under our experimental conditions in the sand tank system, the EC _w was essentially equivalent to those of the sand soil solution; however, considering that the EC of the sand soil solution is ≈2.2 times the EC of the saturated soil extract (EC _e ), our salinity treatments may be estimated as 0.91, 1.82. 2.73, 3.64, and 4.55 dS·m ⁻¹ . Thus, the threshold EC _w at which marigold cultivars exhibited acceptable growth, 8 dS·m ⁻¹ , would be equivalent to EC _e of 3.64 dS·m ⁻¹ .

K and N are the nutrients with the highest influence on yield and fruit quality. From this perspective, the aim of this study was to determine the effect of N as NO₃⁻, K⁺ and their interactions on the yield and quality of strawberries grown under soilless conditions. A solution comprised of micronutrients based on an amended Steiner’s Universal Nutrient Solution was mixed with 4 levels of K⁺ (5, 7, 9 and 11 mol m⁻³) and 3 levels of NO₃⁻ (9, 12, and 15 mol m⁻³) to obtain 12 treatments. The results suggest that 15 mol m⁻³ of NO₃⁻ in the nutrient solution produced the highest yield, but fruit with low nutraceutical quality. On the other hand, 11 mol m⁻³ of K⁺ in the nutrient solution produced the highest yield and fruit with the best nutraceutical quality. The ionic concentration of the Universal Steiner’s Nutrient Solution proved to be the best nutritional option to maximize the yield and nutraceutical quality of strawberry fruit. The increase in NO₃⁻ concentration in the nutrient solution produced a higher yield of strawberries, while a higher concentration of K⁺ improved fruit quality, thus reaffirming the significance of nutrients within the plant functioning of this crop.

Landscape irrigation is the second largest user of reclaimed water in industrialized countries; however, its high concentration of soluble salts, especially Na ⁺ and Cl ^– , may induce growth reduction and leaf necrosis or bronzing in ornamental species. The present study was conducted to determine the growth and quality responses and nutritional ion imbalances of selected landscape species during the container production phase when subjected to irrigation with water of increasing NaCl + CaCl ₂ concentrations. Plants of boxwood [ Buxus microphylla var. japonica (Mull. Arg. ex Miq) Rehder & E.H. Wilson], escallonia ( Escallonia × exoniensis hort. Veich ex Bean), hawthorn [ Raphiolepis indica (L.) Lind. Ex Ker Gawl. × ‘Montic’], hibiscus ( Hibiscus rosa-sinensis L.), and juniper ( Juniperus chinensis L.) were grown in a greenhouse in the Spring–Summer and in the Fall–Winter in separate experiments. Saline irrigation consisted of solutions with electrical conductivities (EC _iw ) of 0.6, 2, 4, 6, and 8 dS·m ⁻¹ in the Spring–Summer experiment and 0.6, 4, 6, 8, and 12 dS·m ⁻¹ in the Fall–Winter. Growth of the five species decreased when irrigated with saline waters. Leaf growth was highly sensitive to salinity and the average decrease in leaf dry weight was the criterion used to rank the tolerance of the species. In the Spring–Summer experiment, the ranking was (higher tolerance to lower tolerance): juniper ∼ boxwood > escallonia > hawthorn > hibiscus, whereas in Fall–Winter, the ranking was: juniper ∼ boxwood > hibiscus > escallonia > hawthorn. The species were ranked according to their visual attractiveness in the Spring–Summer experiment. The threshold EC _iw at which visual attractiveness was affected gave the following ranking (higher to lower tolerance): hibiscus > juniper > escallonia > hawthorn > boxwood. Estimating the EC of drainage water from threshold EC _iw , boxwood was classified as sensitive, hawthorn as moderately sensitive, escallonia as moderately tolerant, and hibiscus and juniper as highly tolerant. Tolerance of juniper was ascribed to Na ⁺ and Cl ^– retention in the roots observed in both growing seasons and to the higher root biomass that allowed a higher accumulation of salts in this organ, preventing translocation to the leaves. Although boxwood exhibited acceptable tolerance in terms of growth, visual quality severely decreased; in contrast, growth of hibiscus was the most severely reduced but was rated as the most tolerant species in terms of visual quality. This opposite response may be the result of an excellent capacity to compartmentalize salts in hibiscus, whereas in boxwood, this mechanism may be absent.