Interaction of Claroideoglomus claroideum co-inoculation with saprophytic phosphofungi: effect on the development of micropropagated native potato plantlets Interacción de la co-inoculación de Claroideoglomus claroideum con fosfohongos saprófitos: efecto en el desarrollo de plántulas micropropagadas de papa nativa In many agricultural crops, arbuscular mycorrhizal fungi co-exist and interact with saprophytic fungi. This study aimed to analyze the effects of two free-living phosphofungi on the growth of potatoes co-inoculated with Claroideoglomus claroideum. Micropropagated native potato plantlets were transferred to a sterile Andisol previously inoculated with C. claroideum and subsequently two saprophytic fungi. The treatments were: C. claroideum (T0), C. claroideum + Talaromyces pinophilus (T1), C. claroideum + Penicillium albidum (T2), and C. claroideum + T. pinophilus + P. albidum (T3). At harvest, the most relevant results show that in T3 the height, shoot dry weight, root length and P acquisition of the potato plants were increased. Therefore, dry weight and P absorbed by minitubers were enhanced two and three-fold, respectively, compared with T0, along with an increase in the length of the thinnest roots. It is concluded that co-inoculation of this fungal consortium could be an advantageous alternative to be used as a bioinoculant by potato tuber seed producers in sustainable agriculture.

Soursop (Annona muricata L.) is a tropical fruit tree highly valued for its organoleptic characteristics, and is the most important Annonaceae species in Mexico. This study aimed to generate maps of the natural geographic and eco-climatic distribution where soursop grows in Mexico, and to model potential zones according to climate change scenarios estimated for 2050. The natural distribution model showed that this species is found in most tropical and some subtropical areas of Mexico. This fruit tree grows in three different eco-climatic regions (two tropical and one temperate): A_w1 (found on the edges of the Balsas basin, and in the south, southeast and central north of the Veracruz region, as well as in the center of the Mexican Pacific coast), Am (north and central south of the Veracruz region, and the Yucatán peninsula) and C_(w0) (east of the Trans-Mexican Volcanic Belt). Modelling of suitable climate adaptation zones showed that the Pacific coast of Mexico and Veracruz, as well as some areas of the Balsas basin and the Yucatán peninsula, have potential for soursop cultivation. Likewise, in the scenario of global climate change, beneficial effects on the adaptation of this species are predicted.

The objective of this study was to compare the effect of different types of inoculants (control, vesicular arbuscular mycorrhizae fungi [VAMF], phosphate-solubilizing bacteria [PSB], and co-inoculant [VAMF-PSB]) on root colonization, plant growth, macronutrient (P and N) uptake, and metal element uptake under heavy metal-contaminated soil conditions. Three species of vegetable plants, namely tomato (Solanum lycopersicum L. cv. Ratna), red chili (Capsicum annuum L. cv. Gada), and hot chili (Capsicum frutescens L. cv. Pusaka Brengolo), were grown in heavy metal (Zn, Ca, Ni and Cd) –contaminated soil for eight weeks. Plants co-inoculated with VAMF-PSB showed significantly higher root colonization by VAMF as well as P and N concentrations in shoot and root than plants inoculated with only VAMF or PSB; consequently, the plant biomass also increased. In heavy metal-contaminated soil, VAMF colonization and PSB application could significantly improve the essential metal concentration (Cu and Zn) in the shoot, although there were no significant effects on the roots. On the contrary, co-inoculation with VAMF-PSB could significantly decrease Cd and Ni concentrations in the shoot, although Cd and Ni concentrations did not show a significant difference in the root. The concentrations of Cu, Zn, Cd, and Ni were higher in the roots than in the shoots of the three plant species tested. The type of inoculant used in this study selectively discriminated between plant essential (Cu, Zn) and non-essential elements (Cd, Ni).

The methodology for mixture design can be used to optimize the proportions of ions in nutrient solution, thereby maximizing crop yield; however, it is rarely used. The aim of this work was to apply a mixture design to evaluate nutrient solutions with different proportions of K⁺, Ca²⁺ and Mg²⁺ on the average weight, number and yield of fruits, and to determine the optimal combination that maximizes the fruit yield of tomato (Solanum lycopersicum cv. Legionario) grown in a closed hydroponic system. The simplex-lattice experimental design {3,2} was used, with 10 nutrient solutions and a total concentration of 40 meq∙L^-1 of ions in each solution. The maximum values of fruit number and yield (27 and 135.8 t∙ha^-1, respectively) were obtained with proportions of 0.375 K⁺, 0.400 Ca²⁺ and 0.225 Mg²⁺ in the nutrient solution, equivalent to 7.5, 8 and 4.5 meq∙L^-1, respectively. The polynomial regression model estimated to predict yield as a function of K⁺, Ca²⁺ and Mg²⁺ mixtures is of the fourth degree (special quartic), with a coefficient of determination (R2) equal to 0.81, which explains 81 % of the variability of the yield data. The maximum estimated yield was 142 t∙ha^-1, with partial desirability of 0.964, which would be obtained with 0.358 K⁺, 0.421 Ca²⁺ and 0.220 Mg²⁺, equivalent to 7.28, 8.26 and 4.46 meq∙L^-1, respectively, in the nutrient solution.

Polyembryony is a common trait in most citrus varieties. The level of polyembryony has the potential to be used as a descriptor in the characterization of varieties or to select parents in conventional hybridization work. The aim of this research was to find an efficient methodology to detect, count and estimate the potential number of embryos per seed, the percentage of polyembryonic seeds and the level of polyembryony in the varieties ‘Colimex’ and ‘Lise’ of Mexican lime, and the variety ‘Rosenberger’ of true lemon. Four methodologies were evaluated: 1) direct counting of embryos in mature seeds (DCEMS), 2) direct counting of embryos in immature seeds (DCEIS), 3) counting of seedlings derived from mature seeds germinated in vitro (CSMSGV) and 4) counting of seedlings derived from mature seeds germinated in substrate (CSMSGS). The highest averages of embryos per seed and percentage of polyembryonic seeds were recorded with the DCEMS and CSMSGV methods (P ≤ 0.01), so it was concluded that they are adequate to estimate these variables in the genotypes studied. The varieties ‘Colimex’ and ‘Lise’ had 80.65 and 78.27 %, respectively, of seeds with two or more embryos, resulting in a high level of polyembryony, while ‘Rosenberger’, with 18.37 %, was slightly polyembryonic (P ≤ 0.01).