Tomato crops are treated with high concentrations of synthetic fertilizers and insecticides to increase yields, but the careless use of these chemicals harms the environment and human health and affects plant pathogen resistance. The effect of foliar spray of three concentrations of chitosan (500, 1000, and 2000 mg L⁻¹) on plant growth, yield, fruit quality, and physiological performance in two tomato varieties (Floradade and Candela F1) was studied. Physiological traits such as photosynthesis, chlorophyll content, and leaf area index of the plants were positively affected by chitosan, an effective compound that biostimulates growth, with increases in biomass of organs with respect to the control treatment. Chitosan also improved tomato quality, such as increases in polyphenols, antioxidant capacity, flavonoids, carotenoids, vitamin C, and total soluble solids in both tomato varieties. Finally, yield increased by 76.4% and 65.4% in Floradade and Candela F1, respectively. The responses of tomato plants to chitosan application were different depending on the variety evaluated, indicating a differential response to the biostimulant. The use of chitosan in agriculture is a tool that has no negative effects on plants and the environment and can increase the productive capacity of tomato plants.

Soil Cd is absorbed by roots and accumulated in cocoa plants, which represents a problem in the commercialization of beans. In order to evaluate whether the exogenous application of macronutrients (N, N-P, N-P-K, N-P-K-S, N-P-K-S-Mg, and N-P-K-S-Mg-Ca) mitigates the absorption, translocation, and accumulation of Cd in plants, soil pH and electric conductivity, dry root and shoot biomass, leaf gas exchange, chlorophyll content, and macronutrient bioaccumulation were evaluated in two cocoa clones (CCN-51 and EET-103) grown in a greenhouse. An increase in macronutrients gradually increased the extraction capacity of Cd in both clones, with the highest Cd values being obtained with the application of N-P-K-S-Mg-Ca. Macronutrient fertilization did not affect leaf gas exchange; however, it caused significant reductions of 30, 40, and 60% in chlorophyll content, shoot, and root dry biomass, respectively. The greatest translocation of Cd from the root to the shoot was obtained with treatments that included N in clone EET-103 and Ca in clone CCN-51. Fertilization with macronutrients did not decrease the absorption and accumulation of Cd in the cocoa seedlings, because a greater removal force of Cd from the adsorption complex towards the soil solution was caused by the exogenous application of Ca and Mg and an increase in soil acidity.

Background: Coffee breeding programs in Ecuador have information on production and disease tolerance in many genotypes; however, they lack physiological information, especially on photosynthetic characteristics and their response to drought. Questions: Whether high genetic variability among coffee genotypes will explains the photosynthetic and production differences expected? Will the physiological response to the dry season (DS) be different between genotypes? Studied species: Coffea arabica L. Study site and dates: Pichincha canton, Manabí province, Ecuador during March-April 2017 (rainy season, RS) and June-July 2017 (DS). Methods: Leaf relative water content (RWC) and gas exchange of 21 coffee genotypes were measured during DS and RS. Coffee production during a period of three years was evaluated. Results: Significant differences were found in RWC, photosynthetic rate (A), stomatal conductance (gs) and water use efficiency (WUE) among genotypes, between seasons, an interaction effect of genotype × season. Drought caused a significant reduction in A and gs of 30 and 44 % respectively, while WUE was not affected. A positive linear relationship was found between A and gs, and a negative relationship between A and the leaf-air vapor pressure gradient (D W ) and between gs and D W . Differences in coffee production were found among genotypes. Conclusions: The high genetic variability of C. arabica genotypes may explain the significant differences in RWC and gas exchange and interaction genotypes x season, suggesting a differential response of each genotype to drought. Eleven of the 21 coffee genotypes were sensitive to drought, but showed different responses, suggesting possible genotypic differences in tolerance. Translate stop Translate stop

Tomato crops are treated with high concentrations of synthetic fertilizers and insecticides to increase yields, but the careless use of these chemicals harms the environment, human health, and plant pathogen resistance. The effect of the foliar application of three concentrations of chitosan (500, 1000, and 2000 mg L-1) on plant growth, yield, and physiological performance in two tomato varieties (Candela F1 and Floradade) was determined. Morphometric variables (height, stem diameter, and root, stem, and leaf dry biomass); production (number of bunches, number of fruits, and fruit weight), and physiological traits (water potential, gas exchange, leaf area index (LAI), and chlorophyll content (SPAD)) were evaluated throughout the experiment. Applying chitosan induced positive responses in biomass increase, yield, photosynthesis, SPAD, and LAI of the two tomato varieties. The responses of tomato plants to chitosan application were different depending on the variety evaluated, indicating a differential response to the biostimulant. Chitosan is an efficient compound to biostimulate the growth, positively modified the plants’ physiology, increasing the yield in both varieties of tomato. The use of chitosan in agriculture is a tool that has no negative effects on plants and the environment and can stimulate the productive capacity of tomato plants.

Background: Esmeraldas province has distinct agroecological zones with a natural rainfall gradient, with higher rainfall in the north-than-south. Hypotheses: Due to the high genetic variability in cocoa, clones from the south will be less affected by drought than those from the north. Plant material: Nine cocoa clones belonging to the National × Criollo complex: five from the north and four from the south, all grown in the field. Site and years of study: Esmeraldas province, Ecuador, during 2022. Methods: Seasonal variation was evaluated for: water potential (Y), hydraulic conductance (KL), photosynthetic rate (A), transpiration rate (E), stomatal conductance (gs), intercellular CO2 concentration (Ci), water use efficiency (WUE), leaf area index (LAI) and chlorophyll content (SPAD). Results: There were significant differences in Y, KL, A, E, gs, WUE, LAI and SPAD among clones, between seasons and the interaction clone × season. Drought caused a reduction in Y, which was associated with a differential reduction of 40 % in A and WUE, depending on the clone. No correlation was found between A and gs, suggesting that the reduction in A in drought was not due to the reduction in gs but to metabolic factors. Southern clones, showed drought had a smaller effect on Y, did not affect gs, E, LAI and SPAD and plants were more efficient in water transport due to higher rainfall KL. Conclusions: A differential physiological response to drought was found depending on the clone, supporting that genetic variability in the clones differently influenced physiological performance in drought.

Cocoa is an economical cash crop that is formerly planted worldwide. Cuttings are a method of vegetative propagation suitable for maintaining desirable characteristics in cocoa trees. A greenhouse experiment was performed to evaluate the optimal concentrations of Pectimorf® (0, 10, 50, and 100 mg L-1) for rooting ability and seedling establishment as well as some physiological trials of 4 months EETP-800 national cocoa cuttings grown under two different substrates (S1: 80% soil + 20% sand and S2: 70% soil + 20% sand + 10% rice husk). The data showed that in most cases there are no significant differences in vegetative growth and root characteristics as well as gas exchange parameters between the two substrates. On the other hand, the application of Pectimorf® concentration enhanced all tested traits compared to untreated plants. The most effective in this regard was 100 mg L-1, that giving the highest value of all trials. As for the interaction effect, the result also shows that the application of Pectimorf® concentration in special at 100 mg L-1 among two substrates had an additive effect on plant growth, gas exchange, and survival percentage compared to non-treated cuttings. The application of 100 mg L-1 Pectimorf® with S2 substrate produced stronger seedlings with a higher survival percentage. This protocol can be used commercially for cocoa propagation commercially.