Iodine, silicon, and selenium are considered elements not essential for the metabolism of plants. However, these elements are vital for humans, and their presence as traces in food is beneficial. The use of I, Si, and Se in the fertilization programs of the plants allows, on the one hand, the mineral biofortification of the crops and, on the other hand, through mechanisms not yet fully understood, the production and accumulation of more antioxidants in the edible organs. This chapter provides an overview about the use of I, Si, and Se both for mineral biofortification and for the increase in the concentration of antioxidants in plants, with an emphasis on redox metabolism adjustments and antioxidant chemical species studied. The scope of the chapter is on horticultural species in the open field and under greenhouse or tunnels.

Cucumber is a vegetable crop of economic importance in Mexico. In 2023, fresh or frozen cucumber and pickle international sales reached USD 783M, placing Mexico in second rank among countries with the highest currency inflow in the world. This crop is mostly grown under protected environments with new production technologies, including rootstocks that are tolerant to biotic and abiotic factors that limit the yield and quality of the harvest. Therefore, the goal of this work was to assess three cucurbits as rootstocks (Cucurbita maxima, Cucurbita moschata and Citrullus lanatus), as well as studying the response of cucumber crop to the tested rootstocks. The following treatments were assessed: T1:PSP = cucumber Cv. Paraizo F1 without rootstock; T2:P/MA = cucumber grafted over Cucurbita maxima; T3:P/MO = cucumber grafted over Cucurbita moschata; T4:P/CL = cucumber grafted over Citrullus lanatus Citroides Var. The assessed variables included the number of fruits per plant (NFPP), fruit weight per plant (PFPP), average fruit weight (PPF), plant dry weight (PSP), xylem vessel area (AVX), number of xylem vessels (NVX), vascular bundle area (AHV) and number of vascular bundles (NHV) in roots (R), basal stalk (TB) and apical stalk (AT). Significant differences among treatments were found in the results for variables: NFPP, highlighting that T2:P/MA was superior by 46.15% versus T1:PSP and by 67.69% versus T3:P/MO. Regarding PFPP, T2:P/MA achieved the highest weight (5445 g), as it proved superior by 99.45% than the cucumber without rootstock (T1:PSP). Regarding PSP, T2:P/MA achieved the highest weight (196.65 g), significantly exceeding T1 by 137.5%. Regarding AVXR, T4:P/CL had the highest value (30,063 µm²). Regarding NHVR, watermelon had (T4:P/CL) 39.33% more vascular bundles than the root system of cucumber (T1:PSP). Treatments T2:P/MA and T4:P/CL had the highest values at AVXTB, while for variable NVXTB, treatments T3:P/MO and T2:P/MA were almost equal, surpassing non-grafted cucumber by 175.47%. However, T2:P/MA showed the greatest AHVTB, and T1:PSP was significantly superior to T3:P/MO, by 34.93%, for NHVTB. Furthermore, positive and significant correlations were found among PFPP, AHVR, and AVXTB, as well as among PSP, AVXTB, and AHVTB. Therefore, we may say that having a larger area of vascular vessels in the roots and a larger area of xylem vessels in the basal stalk leads to higher fruit yields per plant. In the same vein, the use of rootstocks is a sustainable alternative to increase fruit yield.

Pinus greggii Engelm. ex Parl. is an endemic pine of Mexico with notorious adaptability to eroded, shallow and poor soils. It is widely used in reforestation programmes worldwide. The purpose of the present study is to develop an ectomycorrhizal fungi (ECM) treatment with different native ectomycorrhizal fungal species (collected in P. greggii and Abies vejarii stands) to improve seedling survival of P. greggii. Four-month-old P. greggii var. greggii seedlings were inoculated with ground fruiting bodies of the ECM species Astraeus spp., Boletus barrowsii, Geastrum minimum, Lactarius deliciosus var. deterrimus, Russula cf. atroglauca, Russula spp., Suillus caerulescens, as well as a mixture of three species (Russula sp., R. lutea and L. deliciosus) and soil litter with mycelium from the base of a fruiting body of L. deliciosus. Agronomic variables, and total phosphorous and glucosamine contents were measured in P. greggii seedlings. Inoculated treatments with B. barrowsii, Geastrum minimum and S. caerulesc...

Habanero chili pepper has great economic importance in Mexico, but its production is limited due to different factors that affect quality. Given the high demand and prices of the fruit, the production of this crop is spreading to other regions in search of new production systems. The aim of this research work was to assess the yield and antioxidant components of the fruit by supplementing potassium from organic sources. The “Campeche”, “Palenque”, and “Jaguar” varieties were studied in five NPK treatments; replacing the % of potassium with humus and compost: (T1) 240-200-120+50% of K from liquid earthworm humus; (T2) 240-200-180+25% of K from liquid earthworm humus; (T3) 240-200-120+50% of K from vermicompost; (T4) 240-200-180+25% of K from vermicompost; and (T5) 240-200-240 (control, 100% chemical nutrition). For yield components, there were significant differences, highlighting the importance of the nutrition source for the yield and weight of fruits per plant. The control (T5) presented a value of 39 t·ha⁻¹ and was similar to treatments T2 and T3 with a supplement of 25 and 50% organic K. For the polar and equatorial diameter of fruit, as well as for plant height and leaf area, treatments supplemented with 50% organic K (T1 and T3) were more effective. For the varieties evaluated, no differences in yield and fruit weight were found; however, Campeche produced more fruits per plant with a greater equatorial diameter, while Palenque obtained fruits with a greater polar diameter and taller plants. The results of antioxidant compounds show that organic K supplementation improves the quality of total carotenoids, β-carotenes, and xanthophylls compared to 100% chemical fertilization, since total carotenoid content is improved by 54.2%, β-carotenes by 46.4%, and xanthophylls by 37.8%, respectively. The Campeche variety was the one that presented the best fruits with the highest antioxidant quality. These results indicate a positive effect of the combined application of chemical fertilizer with worm humus on yield and its components in pepper and other crops and show an economic, ecological, and sustainable alternative to the production of habanero chili pepper.

Arbuscular mycorrhizal fungi (AMF) are obligate symbionts that require a host plant (tramp) and support (substrates) to be applied as bio-fertilizers in agriculture. The objective of this study is to assess eight native AMF consortia of semi-arid zones (C1-ART, C2-GEC, C3-PAR, C4-VIE, C5-CUC, C6-SAC, C7-SAB, and C8-MUZ) and their reproduction response in three organic substrates: coffee pulp (CP), bovine manure (BM) and sugarcane bagasse (SB) on bean Phaseolus vulgaris. Plant height, stem diameter, number of leaves, root length, fresh and dry biomass, and mineral content in root were measured. The organic substrates (CP and BM) and C5-CUC and C8-MUZ consortia increased plant height, root length, and total fresh and dry biomass considerably. After day 75 of inoculation, root colonization oscillated from 5.7% in C8-MUZ to 46.1% in C2-GEC and C4-VIE; the greatest number of spores (201) was obtained in CP substrate in a 100-g sample. N, P, K, Ca, Mg, Fe, Zn, Cu, and Mn contents in root and leaves were signif icantly high (P ≤ 0.001). To conclude, native AMF inoculation and substrates had positive effects on biomass content and nutrient levels in leaf and root with the C2-GEC and C3-PAR consortia and CP and BM substrates, which produced better effects in beans, making them a biofertilization alternative in agricultural crops.

The strawberry fruit (Fragaria × ananassa Duch.) is appreciated for its aroma, color, texture and nutritional value. In conventional agriculture, the use of fertilizers damages the environment since it causes loss of soil fertility, salinity and its erosion, hence production alternatives, without harming the environment, are sought. The objective of this study was to evaluate the effect of a biostimulant based on humic substances and rhizobacteria, on the production and quality of the strawberry cultivar ‘San Andreas’. Strawberry plants cultivar ‘San Andreas’ were treated with fulvic acids + mixture of microorganisms, humic acids + Pseudomonas fluorescens, fulvic acids + Azospirillum brasilense, fulvic acids + Pseudomonas fluorescens and the mixture AH and AF + Azospirillum brasilense with two doses (d1, d2) in total 10 treatments were applied plus the control. Humic substances were applied every 15 days and rhizobacteria every 30 days. The results showed that the AFyAzoz d1 increased over control plants, the number of leaves in 38.3%, root volume in 42.6%, the fresh weight in 130% and dry weight in 63.8%, the number of fruits 50.0% and the yield in 59.5%. The AFyPF d1 favored Photosynthesis in 127.3%; AFyPF d1 increased TSS in 25%, AFyPF d2 vitamin C in 17.1% and MHyF + Azoz d1 increased in 20% the content of Phenols. Humic substances plus rhizobacteria are an ecological alternative to be used as biostimulant in the production and quality of strawberry plants.