Light is the only key factor essential for plant growth, and ultraviolet (UV) rays, the harmful part of solar radiation, have the ability to decrease the metabolic rate in photosynthesis, causing deterioration in their growth. Accurate handling of the ultraviolet light that reaches the crops allows the improvement of different aspects of production, such as the shape and color of the plants, the precocity of the crops, and an improvement in the control of pests and diseases. The present study was carried out with the purpose of studying the responses in terms of germination and growth of four plant species—Glycine max, Triticum aestivum, Helianthus annuus, and Pinus maximartinezii—exposed to different doses of UV-C and UV-B radiation, for evaluation through the standard germination and accelerated aging tests, registering the germination rate (GR) and vigor (V), the number of normal seedlings (NS), and the average lengths of radicle (ALR) and plumule (ALP). Seeds treated with UV-C radiation showed a significant difference (p <0.05) between treatments (doses) and species, both in the standard germination and accelerated aging tests for the ALR and ALP variables. Seeds of G. max showed low sensitivity in both tests, with the dose 43.20 kJ/m²/day. The seeds of H. annuus and P. maximartinezii showed high sensitivity in both tests under UV-C radiation, with the doses 8.64 kJ/m²/day and 0.864 kJ/m²/day, respectively. Both tests under UV-B radiation showed a significant difference (p < 0.01) between species and treatments in the variables NS and ALP, with the minimum dose (T2).

Pecan nut (Carya illinoensis) pericarp is usually considered as a waste, with no or low value applications. Its potential as a densified solid biofuel has been evaluated, searching for alternatives to generating quality renewable energy and reducing polluting emissions in the atmosphere, based on particle size, that is an important feedstock property. Therefore, agro-industrial residues from the pecan nut harvest were collected, milled and sieved to four different granulometry: 1.6 mm (N° 12), 0.84 mm (N° 20), 0.42 mm (N° 40), and 0.25 mm (N° 60), used as raw material for biofuel briquette production. The carbon and oxygen functional groups in the base material were investigated by Fourier transform infrared spectroscopy (FTIR) and proximate analyses were performed following international standards, for determining the moisture content, volatile materials, fixed carbon, ash content, and calorific value. For the biofuel briquettes made from base material of different particle sizes, the physical characteristics (density, hardness, swelling, and impact resistance index) and energy potential (calorific value) were determined to define their quality as a biofuel. The physical transformation of the pecan pericarp wastes into briquettes improved its quality as a solid biofuel, with calorific values from around 17.00 MJ/kg for the base material to around 18.00 MJ/kg for briquettes, regardless of particle size. Briquettes from sieve number 40 had the highest density (1.25 g/cm³). Briquettes from sieve number 60 (finest particles) presented the greater hardness (99.85). The greatest susceptibility to swelling (0.31) was registered for briquettes with the largest particle size (sieve number 20). The IRI was 200 for all treatments.

Biofortification aims to increase the concentration of bioavailable elements in crops, to increase their nutritional quality. Selenium is a trace element of great impact on the antioxidant metabolism of plants and its accumulation is poor in species such as Solanum lycopersicon, so adding it is part of biofortification programs. The present work analyzes the capacity of sodium selenite (Na₂SeO₃) to increase the concentration of Selenium in tomatoes plants and fruits. For this, three treatments were applied (0, 2, and 5 mg L⁻¹ of sodium selenite) using irrigation water as a vehicle. 40 days after transplanting, the accumulation of selenium and macronutrients in leaves, stems, and fruits was quantified, as well as their impact on tomato plant productivity. Agronomic variables such as height (cm), diameter (mm) of stems, number and weight (g) of fruits produced were determined. The results were analyzed by ANOVA and later, a Tukey mean comparison test was performed. An increase in the accumulation of Se was observed, being up to 53% in the fruits under the 5 mg L⁻¹ treatment compared to the control. However, this increase did not have a noticeable impact on macronutrient content and tomato yield, but rather, contributed to the improvement of the nutritional quality of the tomato.

Cactaceae are subject to strong anthropogenic pressure, which motivates the search of strategies for its conservation. This paper aimed to evaluate the survival and growth of eight native species from northeastern Mexico, in order to propose their in-situ conservation, applying three substrates (perlite/peat-moss, zeolite/peat-moss and natural soil), in two sun exposures (west and east). The variability of both survival and growth resulted dependent on substrate type and sun exposure. Astrophytum myriostigma presented higher diameter at eastern aspects (51.20 and 42.63 mm on zeolite/peat-moss and perlite/peat-moss, respectively), and the higher heights were also registered at eastern aspects, with Sclerocactus scheeri (7.38.cm on perlite/peat-moss and 6.98 cm on natural soil) and A. myriostigma (6.8 cm on zeolite/peat-moss and 6.08 cm on perlite/peat-moss). As for survival, the highest value (100%) was recorded with the treatments of West-Zeolite/peat-moss and East-Perlite/peat-moss, in six of the eight species evaluated (A. myriostigma, Acharagma roseana, Escobaria dasyacantha, S. scheeri and Mammillaria prolifera), while the lowest value (0%) was recorded with M. plumosa in the three western combinations. The best growth and survival responses were observed in A. myriostigma and S. scheeri under east exposure and zeolite, being the best combination, to be considered for their optimal establishment.

Biofuels are sustainable alternatives to fossil fuels. However, they must comply with energy efficiency requirements and contribute to environmental protection. This study was focused on elemental composition (carbon, hydrogen, nitrogen, sulphur and chlorine) of different plants’ components (stems, branches, twigs and leaves) from pyrolysed (charcoal) and non-pyrolysed samples of five semi-arid trees: Acacia berlandieri, A. wrightii, Ebenopsis ebano, Havardia pallens and Helietta parvifolia. Carbon fluctuated from 80.77% to 89.30% in charcoal and 44.99% to 49.70% in non-pyrolysed biomass, and hydrogen ranged from 2.38% to 2.69% in charcoal and 5.89% to 6.62% in non-pyrolysed biomass. Nitrogen accounted for 0.39%–0.65% (branches) and 0.32%–0.64% (stems) in charcoal, and the ranges for non-pyrolyzed material were 2.33–4.00% (leaves), 1.06%–1.76% (twigs), 0.21%–0.52% (branches) and 0.15%–0.28% (stems). Considerably higher concentrations of sulphur compared to chlorine were found, with increasing values for both elements from the base of trees to the leaves. Non-pyrolysed samples were characterized by 68.05 mg/kg–769.16 mg/kg (stems), 118.02 mg/kg–791.68 mg/kg (branches), 225.11 mg/kg–1742.25 mg/kg (twigs) and 374.73 mg/kg–6811.52 mg/kg (leaves) for sulphur, and 117.86 mg/kg–528.08 mg/kg (stems), 109.18 mg/kg–464.15 mg/kg (branches), 905.47 mg/kg–4205.19 mg/kg (twigs) and 2799.68 mg/kg–5072.76 mg/kg (leaves) for chlorine. In charcoal, the concentration ranges for sulphur were 47.54 mg/kg–376.95 mg/kg (branches) and 42.73–292.20 mg/kg (stems) and 139.34 mg/kg–419.68 mg/kg (branches) and 177.39 mg/kg–479.16 (stems) for chlorine. The study has shown that pyrolysis increased the amount of carbon and decreased the amount of hydrogen. Coincidentally, the amount of nitrogen, chlorine and sulphur could be decreased significantly by pyrolysis which means an improvement of the fuel considering the flue gas emissions. Besides the influence of the type of combustion plant and the influence of the source of biofuel, the treatment has a significant influence on the amount and composition of flue gases emitted in the combustion.