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La agricultura es la base de la alimentación, se desarrolla en suelo e hidroponía. La hidroponía se explica cómo cultivos sin suelo, en soluciones nutritivas, para el caso del tomate y del pepino es en sustrato. Los sustratos han incrementado la productividad, con uso eficiente de agua y fertilizantes. Si la agricultura consume 70% de agua y en gasto 30% es fertilizantes, el objetivo de este trabajo fue utilizar hidrogel de acrilato de potasio por su capacidad de disminuir la pérdida de fertilizantes como ser reserva de agua, permitiendo mantener la producción de tomate y pepino. La investigación se realizó en Querétaro en 2017. Se evaluó diferentes capacidades de saturación del hidrogel para sus propiedades, la mezcla de sustrato y el rendimiento de tomate y pepino, encontrando diferencias significativas.

The need to produce food in a sustainable way to counteract the effects of excessive use of agrochemicals opens the door to the generation of new technologies that are not based on fossil fuels and are less toxic to ecosystems. Plant growth-promoting bacteria (PGPB) could represent an alternative to chemical biofertilizers and pesticides offering protection for biotic and abiotic stresses. In this work, a bacterial isolate from roots of castor bean (Ricinus communis) was identified and named as Bacillus cereus strain “Amazcala” (B.c-A). This isolate displayed the ability to solubilize inorganic phosphate and produce gibberellic acid (GA3). Moreover, this bacterium provided significant increases in height, stem width, dry weight, and total chlorophyll content in tomato plants. Interestingly, B.c-A also significantly decreased the severity of bacterial canker disease on tomato caused by Clavibacter michiganensis (Cmm) in preventive disease assays under greenhouse conditions. Based on our results, B.c-A can be considered as PGPB and a useful tool in Cmm disease control on tomato plant under greenhouse conditions.

This study was aimed at evaluating the different concentrations of nitrogen for tomato seedling production (Lycopersicon esculentum Mill.), hybrid Loreto. Five concentrations of nitrogen were analyzed: 0, 4, 8, 12 and 16 mEq / L, using as a basis the Steiner nutrient solution. A pilot randomized block design was used with six replications and five treatments. Thirty-five days after sowing, the following variables were analyzed: seedling height, stem diameter, fresh stem weight, fresh leaf weight, leaf area, dry steam weight, dry leaf weight, dry root weight and total nitrogen content. An ANOVA analysis (p

Stevia rebaudiana (Bertoni) is a perennial shrub native from Paraguay whose leaves accumulate steviol glycosides. Plants increase the production of phytochemicals as a response to stress factors to cope with possible damage. Elicitors are biological stress factors that can induce plant response to stress. Steviol glycosides are the phytochemicals responsible of the sweetener power of stevia (Stevia rebaudiana Bertoni cv. Morita II), which is up to 300-fold stronger than sucrose. Elicitors might affect Steviol glycosides content and gene expression-associated to their biosynthesis. The aim of this research was to evaluate the effect of controlled elicitation using salicylic acid, chitosan and hydrogen peroxide on plant performance, steviol glycosides contents and gene expression-associated to steviol glycosides biosynthesis (SrKA13H, SrUGT85C2, SrUGT74G1 and SrUGT76G1) in stevia cultivated under greenhouse conditions. Weekly applications of elicitors were foliarly sprayed during four weeks, morphological measurements were made and samples were lyophilized and processed to evaluate SGs content. Gene expression-associated was analyzed by Ultra-Performance Liquid Chromatography coupled to a Quadrupole-Time of Flight. Results showed that all the evaluated elicitors (especially salicylic acid 0.1 mM) enhanced steviol glycosides content, which correlated with inducement of gene expression-associated to the biosynthesis of these compounds and increase in leaf number in stevia. Thus, controlled elicitation of stevia cultivation might be used to improve the yield of steviol glycosides for industrial purposes.

The effects were examined of plant-response signaling compounds, salicylic acid (SA) and methyl jasmonate (MeJA), on resistance to pill-bugs (Armadillidium vulgare) attack in lettuce plants. Foliar SA and MeJA applications were made at weekly intervals from the emergence of the plant until one week before harvesting. SA and MeJA induced detectable levels of hydrogen peroxide (H2O2) at least during 5 days post-application in these plants throughout their cultivation. On the whole, SA and MeJA in the concentrations and application scheme evaluated in this research did not significantly influence the dry and fresh weight matter of plants, or the chlorophyll and nitrate contents. In addition, both signal elicitors significantly diminished lettuce mortality due to pill-bugs, which was positively correlated with phenolics and flavonoids contents. Our results suggest that SA and MeJA, especially in low concentrations, should be further evaluated in lettuce production and priming resistance.

Success in greenhouse production is due, in part, to the use of a well-characterized substrate and a suitable fertigation schedule, among others. The behavior of several mixtures of stone substrate (tezontle, pumice) with improvers (potassium acrylate copolymer and agave fiber) was evaluated in this research. The physical properties of the resultant mixtures, such as water- and air-retention, drainage and apparent density. Were measured and then, the energetic state of the mixture (Field Capacity (FC)) was calculated in laboratory. Afterwards, the mixtures were exposed to irrigation in greenhouse conditions; the FC and drainage were measured. T-3 (pumice with 8g of potassium acrylate copolymers) and T-6 (pumice agave fiber) were distinguished by having a favorable moisture retention, T-1 (pumice) was selected as control. These treatments were carried in a greenhouse cucumber crop cycle.

A germin-like gene (CchGLP) cloned from geminivirus-resistant pepper (Capsicum chinense Jacq. Line BG-3821) was characterized and the enzymatic activity of the expressed protein analyzed. The predicted protein consists of 203 amino acids, similar to other germin-like proteins. A highly conserved cupin domain and typical germin boxes, one of them containing three histidines and one glutamate, are also present in CchGLP. A signal peptide was predicted in the first 18 N-terminal amino acids, as well as one putative N-glycosylation site from residues 44–47. CchGLP was expressed in E. coli and the recombinant protein displayed manganese superoxide dismutase (Mn-SOD) activity. Molecular analysis showed that CchGLP is present in one copy in the C. chinense Jacq. genome and was induced in plants by ethylene (Et) and salicylic acid (SA) but not jasmonic acid (JA) applications in the absence of pathogens. Meanwhile, incompatible interactions with either Pepper golden mosaic virus (PepGMV) or Pepper huasteco yellow vein virus (PHYVV) caused local and systemic CchGLP induction in these geminivirus-resistant plants, but not in a susceptible accession. Compatible interactions with PHYVV, PepGMV and oomycete Phytophthora capsici did not induce CchGLP expression. Thus, these results indicate that CchGLP encodes a Mn-SOD, which is induced in the C. chinense geminivirus-resistant line BG-3821, likely using SA and Et signaling pathways during incompatible interactions with geminiviruses PepGMV and PHYVV.