The use of avocado rootstocks is very common, but these have been little studied from the anatomical and physiological point of view of the leaf, variables that can be useful to understand their role when grafted, such as those related to stomata and gas exchange. The aim of this research was to study the stomatal and gas exchange characteristics of the leaf blade in seedlings derived from ‘Colín V-33’ avocado seed to determine possible relationships between them. Ninety-three six-month-old ‘Colín V-33’ seed-derived plants were used. Four stomatal and five gas exchange variables were evaluated in the eleventh leaf of each plant. Stomata were classified as anomocytic, and their length ranged from 13.11 to 19.65 µm, their density varied from 317.65 to 105.88 stomata·mm^-2 and their stomatal index was from 11.78 to 26.16 %. A significant positive correlation was found between the physiological variables stomatal conductance and transpiration rate (r = 0.96**), while the CO₂ assimilation rate and internal CO2 concentration were negatively correlated (r = -0.64**). No association was found between gas exchange characteristics and stomarelated variables. Due to the variation found in stomatal density and stomatal index, it is possible to select contrasting genotypes that could have an impact on grafting when used as rootstocks, given the evidence from other studies where there are modifications in these variables.

Zinc (Zn) fertilization of pecan trees is carried out by foliar spraying, since the nutrient in the soil is bound to carbonates, which hinders its absorption by the tree. This practice has environmental repercussions because it is an aerosol. Therefore, the objective of this study was to generate an alternative to foliar Zn application with soil-applied chelated Zn combined with beneficial microorganisms to maintain or improve pecan production. Fifteen homogeneous trees were selected based on trunk cross-sectional area and crown volume in a pecan orchard in Chihuahua, Mexico. During four years (2015-2018), three treatments with five replications were evaluated under a completely randomized design. The treatments were: 1) foliar Zn (36 % ZnSO4), 2) soil Zn (14 % Zn chelated with carboxylic acids) and 3) soil Zn + mycorrhizal fungi (Pisolithus tinctorius + Azospirillum brasilense). The orchard studied had native communities of P. tinctorius, which was found in 83.7 % of the roots analyzed. Pecan production, in the four years, with the different treatments was 27 kg with foliar Zn, 25.4 kg with chelated Zn and 26.9 kg with chelated Zn plus microorganisms. The results indicate that soil-applied Zn is a viable and environmentally friendly option.

The consumption of edible flowers has increased the search for new species to improve their nutritional impact. Therefore, the aim of this study was to determine the phenolic profile and nutritional value of the flowers of some Dahlia x hortorum clones (C1Var – variegated, C2Gui – cherry, C3Roj – red, C4Nar – orange, C5Ama – yellow, C6Fuc – fuchsia) and C7Ros – pink). The experiment was conducted at the Department of Plant Science, Universidad Autónoma Chapingo, Mexico, under a completely randomized experimental design with three replications. Phenolic acids (gallic, caffeic and chlorogenic) and flavonoids (quercetin and hesperidin) were detected. Similar contents of gallic acid (between 1.91 and 3.19 µg·g^-1) were found in C7Ros, C1Var, C5Ama and C4Nar, where C1Var also stood out for the presence of quercetin (81.46 µg·g^-1). The highest incidence of caffeic acid and hesperidin was found in C2Gui and C6Fuc. In general, C1Var showed a high percentage of crude fiber, crude fat and protein, although the last one was similar to C7Ros and C5Ama (13.68 and 13.72 µg·g^-1, respectively). Likewise, C2Gui, C4Nar and C3Roj showed variation with respect to total carbohydrates (64.09, 61.64 and 62.37 %, respectively). According to the results, dahlia ligulate flowers have a significant content of phenolic acids, flavonoids, fiber and protein, as well as a variable caloric level, so they can be considered as a functional food and be integrated into daily intake.

Broccoli is one of the most economically important vegetables in Mexico, and one of the diseases that reduces its yield and quality is head rot, which has been associated with different phytopathogens. The objective of this study was to morphologically and molecularly identify the causal agents of head rot in broccoli cultivation in Mexico. Florets with rot symptoms were collected in different municipalities of the state of Guanajuato (León, San Francisco del Rincón, Valle de Santiago, Abasolo, Juventino Rosas and Dolores Hidalgo). The isolates obtained were identified based on their cultural, morphological and molecular characteristics (by PCR-ITS) as Alternaria alternata (AA), Fusarium oxysporum (FO) and Fusarium verticillioides (FV). The pathogenicity of these fungal species was corroborated by Koch’s postulates. The fungal isolation frequency was 55, 26 and 19 % for AA, FV and FO, respectively, of the total samples analyzed. The sequence obtained from a representative isolate of each fungus was compared with those reported in the NCBI gene bank, where the highest similarity percentages were 99.6, 98.9 and 98.2 % for FO, FV and AA, respectively, thus confirming the morphological identification results. This is the second report of the presence of AA and FO associated with broccoli head rot in Mexico, and the first report of FV as part of the complex of causal agents of this disease.

Determinations of nitrogen (N) and chlorophyll (Chl) by destructive methods are precise but time-consuming and frequently expensive. The objective of this study was to determine the relationship between SPAD, atLEAF, and MC-100 readings with the concentrations of Chl, N, and fresh matter (FM) in basil ‘Nufar’. In addition, we determined the relationship of the N concentration with fresh matter (FM). The plants were irrigated with five levels of N (0, 4, 8, 12, and 16 mEq·L^-1 of NO₃) based on a modified Steiner solution for 42 days after transplant. Plants were evaluated weekly with SPAD, atLEAF and MC-100 portable chlorophyll meters in the greenhouse, while FM and the concentration of Chl and N were determined in the laboratory using conventional techniques. The relationship between SPAD readings, Chl, N, and FM was strong, positive, linear, and significant, with correlation coefficients (R² ) between 0.94 and 0.98. For atLEAF and MC-100 readings, R² values were 0.96 to 0.99 and 0.96 to 0.99, respectively. The relationships between SPAD, atLEAF and MC-100 readings were strong, positive, and significant, with R² values of 0.98. Similar behavior was shown by the relationship of N concentration and FM with R² of 0.88. With these results, we conclude that SPAD, atLEAF, and MC-100 can be used to estimate the nutrient status of N in a non-destructive, rapid and reliable manner during basil production.