Farmer Perceptions of Adopting Novel Legumes in Traditional Maize-Based Farming Systems in the Yucatan Peninsula

Intercropping constitutes the traditional farming system practice used in various forms for maize production in the Yucatan peninsula. Although practiced for centuries, problems persist with competition for water, nutrients and light between crop species in traditional farming systems. Furthermore, little is known about farmers’ perceptions regarding changes to traditional maize-legume intercropping systems and their interest in novel crop adoption to increase yields in the system while maintaining the practice. The objective of this study was to investigate the maize-based traditional cropping system by assessing the underlying motives and concepts of farmers to practice intercropping in the Yucatan Peninsula and to examine the association between farmers’ level of knowledge about legumes and decisions to adopt intercropping and related practices therein. Farmer surveys were conducted in nine different regions of the Yucatan Peninsula. We selected Xoy, Euan, Muna, Mama, Tahdziú (Yucatan), Becal, Hecelchacam, Dzitbalché and San Antonio Sahcabchén (Campeche) which are representative of agroecological small-scale farming systems. We used a mixed methods case study analysis involving key informant interviews in eight associations of farmers. A sample frame with 73 farmers was selected in total during February 2021 and April 2021. Basic information such as land use, labor inputs, agricultural production and farmer’s perceptions regarding their intercropping systems were collected. Our research shows that the primary motives for intercropping were due to the ability of intercropping to offer a more diversified range of food for human and animal consumption, as well as to take advantage of different harvest periods that this practice offers. The majority of respondents were likely to favor the idea of introducing new legume species in their maize-based cropping systems. Factors such as the type of cropping system (i.e., intercropping or monocropping), access to water and level of knowledge about legumes influenced their decision to adopt intercropping in their farming systems considerably. This paper contributes to the knowledge on the current state and farmers’ perceptions of intercropping systems in the Yucatan Peninsula

Understanding the physiological responses of a tropical crop (Capsicum chinense Jacq.) at high temperature.

Temperature is one of the main environmental factors involved in global warming and has been found to have a direct effect on plants. However, few studies have investigated the effect of higher temperature on tropical crops. We therefore performed an experiment with a tropical crop of Habanero pepper (Capsicum Chinense Jacq.). Three growth chambers were used, each with 30 Habanero pepper plants. Chambers were maintained at a diurnal maximum air temperature (DMT) of 30 (chamber 1), 35 (chamber 2) and 40°C (chamber 3). Each contained plants from seedling to fruiting stage. Physiological response to variation in DMT was evaluated for each stage over the course of five months. The results showed that both leaf area and dry mass of Habanero pepper plants did not exhibit significant differences in juvenile and flowering phenophases. However, in the fruiting stage, the leaf area and dry mass of plants grown at 40°C DMT were 51 and 58% lower than plants at 30°C DMT respectively. Meanwhile, an increase in diurnal air temperature raised both stomatal conductance and transpiration rate, causing an increase in temperature deficit (air temperature - leaf temperature). Thus, leaf temperature decreased by 5°C, allowing a higher CO2 assimilation rate in plants at diurnal maximum air temperature (40°C). However, in CO2 measurements when leaf temperature was set at 40°C, physiological parameters decreased due to an increase in stomatal limitation. We conclude that the thermal optimum range in a tropical crop such as Habanero pepper is between 30 and 35°C (leaf temperature, not air temperature). In this range, gas exchange through stomata is probably optimal. Also, the air temperature-leaf temperature relationship helps to explain how temperature keeps the major physiological processes of Habanero pepper healthy under experimental conditions

Efecto del ácido salicílico en la germinación y crecimiento radicular del tomate

Tomato (Solanum lycopersicum L.), is a vegetable belonging to the Solanaceae family. This crop is important in several countries, mainly due to its high economic value reflected in its great demand, with markets for fresh or industrialized consumption. Due to its commercial importance, research is carried out on its crops to obtain good quality seedlings. Salicylic acid has been proposed as a plant growth regulator, due to its induced effects on some physiological processes in plants. The objective of this study was to evaluate the effect of different concentrations of salicylic acid on the germination and quality of tomato seedlings. The seed imbibition tests and the preparation of salicylic acid were carried out in the plant physiology and biotechnology laboratory of the Technological Institute of Conkal, Yucatán, during 2016-2017. Tomato seeds of the Rio Grande variety with a determined growth habit were used. The seeds were subjected to an imbibition process for 24 h under controlled laboratory conditions. The evaluated treatments were 0, 1, 0.01 and 0.0001 μM of salicylic acid (AS) and as a control one without imbibition. An analysis of variance was performed with the results, as well as the test of comparison of means by the Tukey method (p≤ 0.05), using the SAS statistical package see 9.3. The results showed that the time of seed imbibition in concentrations of salicylic acid does not inhibit germination and stimulates the differentiation of secondary roots in concentrations of 1 and 0.01 μM AS.El tomate (Solanum lycopersicum L.), es una hortaliza perteneciente a la familia de las solanáceas. Este cultivo es importante en varios países, principalmente por su alto valor económico reflejado en su gran demanda, con mercados para consumo fresco o industrializado. Debido a su importancia comercial, se realizan investigaciones de sus cultivos, para obtener plántulas de buena calidad. El ácido salicílico ha sido propuesto como un regulador de crecimiento vegetal, debido a los efectos inducidos en algunos procesos fisiológicos de las plantas. El objetivo de este estudio fue evaluar el efecto de diferentes concentraciones de ácido salicílico sobre la germinación y calidad de plántulas de tomate. Las pruebas de imbibición de las semillas y la preparación del ácido salicílico se realizaron en el laboratorio de fisiología y biotecnología vegetal del Intituto Tecnológico de Conkal, Yucatán, durante 2016-2017. Se utilizaron semillas de tomate variedad Río Grande con hábito de crecimiento determinado. Las semillas se sometieron a un proceso de imbibición durante 24 h en condiciones de laboratorio controladas. Los tratamientos evaluados fueron 0, 1, 0.01 y 0.0001 μM de ácido salicílico (AS) y como control uno sin imbibición. Con los resultados se realizó un análisis de varianza, así como la prueba de comparación de medias por el método de Tukey (p≤ 0.05), mediante el paquete estadístico SAS ver 9.3. Los resultados demostraron que el tiempo de imbibición de semillas en concentraciones de ácido salicílico no inhibe la germinación y estimula la diferenciación de raíces secundarias en concentraciones de 1 y 0.01 μM AS

Physiological responses to increased air temperature.

<p>Figure 5. A) CO₂ Assimilation rate (<i>A</i>_N); B) Stomatal conductance (<i>g</i>_e); C) Intercellular CO₂ concentration (<i>C_i</i>); D) Ratio of intercellular CO₂/atmospheric CO₂ (<i>C_I/C_a</i>); E) Transpiration (<i>E</i>); and F) Temperature deficit (<i>T_air</i> – <i>T_leaf</i>) of Habanero pepper plants at three maximum diurnal temperatures (T_air = 30°C, 35°C and 40°C). Data are means ± SE. <i>n</i> = 15. NS: no significance, *: significant (ANOVA, P<0.05).</p

Leaf area and dry mass of Habanero pepper plants.

<p>Figure 1. A) Leaf area and B) dry mass of Habanero pepper plants in different phenological stages at three maximum diurnal temperatures (T_air = 30, 35 and 40°C). Data are means ± SE. Different letters in the same phenology stage represent statistically significant differences (Tukey, α = 0.05). <i>n</i> = 5.</p

Stomata number of Habanero pepper plants.

<p>Figure 4. Stomata number (adaxial and abaxial) at three height levels of plants (top, middle, and bottom) and different phenological stages, A) Adaxial juvenile; B) Adaxial flowering; C) Adaxial fruiting; D) Abaxial juvenile; E) Abaxial flowering and F) Abaxial fruiting) of Habanero pepper plants at three maximum diurnal temperatures (T_air = 30, 35 and 40°C). Data are means ± SE. Different letters represent statistically significant differences (Tukey, α = 0.05). <i>n</i> = 5. The scale of graphs on the left is different to the graphs on the right.</p

Growth parameters of Habanero pepper plants.

<p>Figure 3. A) Relative growth rate (dry mass); B) Relative growth rate (leaf area); C) Net assimilation rate; D) Leaf area ratio; E) Specific leaf area; and F) Leaf weight ratio of Habanero pepper plants at three maximum diurnal temperatures (T_air = 30°C, 35°C and 40°C) by phenological stage. Data are means ± SE. Different letters in the same phenology stage represent statistically significant differences (Tukey, α = 0.05). <i>n</i> = 5.</p

Physiological responses to increased leaf temperature.

<p>Figure 6. Intercellular CO₂ concentration (<i>C_i</i>), maximum photosynthetic rate (<i>A</i>_max), stomatal conductance (<i>g</i>_e) and stomatal limitation (<i>l</i>) of Habanero pepper plants at three leaf temperatures (T_leaf = 30°C, 35°C and 40°C). Data are means ± SE. Different letters in the same parameter represent statistically significant differences (Tukey, α = 0.05). <i>n</i> = 5.</p

Productividad de Stevia rebaudiana Bertoni con diferentes láminas de riego e inoculantes microbianos

Abstract Introduction Leaves are the most important organ in the plant of Stevia rebaudiana Bertoni, because in them is the greater amount of sweetener. Leaf emission is determined by adequate root growth and the amount of water available in the soil. The objective of the present study was to evaluate the respond of S. rebaudiana Bert plants to four irrigation sheets calculated from reference evapotranspiration (ETo) in interaction with microbial inoculants. Method Treatments were irrigation with 60, 80, 100 and 120% of the estimated ETo with an "A" type evaporimeter tank in previously inoculated plants. A mixture of Bacillus spp. and Azospirillum brasilense, Rhizophagus intraradices and a control (uninoculated). A randomized complete block design with bi-factorial arrangement and four replicates was applied. Growth, production and distribution parameters of dry biomass, gas exchange and water efficiency were evaluated. Results Statistical difference (P≤0.05) was found by separate factors. The best height was obtained with 120% ETo, although it was statistically equal (P≤0.05) to 100% ETo registering 42.86 and 40.58 cm respectively, 120% ETo was recorded greater leaf area. Treatment with Rhizophagus intraradices showed significant differences (P≤0.05) in the root length against the control, but not against the mixture of rhizobacteria. In the same way R. intraradices improved the root volume by registering 2.49 cm3 with respect to the control, and allowed to reduce the application of ETo by 20% to obtain the highest production of dry leaf and root biomass. The interaction R. intraradices + 80% ETo favored the assimilation of CO2 with 5.41 μmol m-2 s-1, thus providing better conditions for transpiration and efficient water use (1.87 μmol CO2 mmol-1 H20). Conclusion The irrigation factor showed effect on leaf height, leaf area, stem diameter and dry leaf yield, while inoculating factor only affected root length, root volume, MSV / MSR ratio and yield. Finally, the interaction of both factors was only significant in the parameters of dry biomass production and gas exchange.Resumen Introducción Las hojas son el órgano más importante en la planta de Stevia rebaudiana Bertoni, debido a que en ellas se encuentra la mayor cantidad de edulcorante. La formación de hojas está determinada por el adecuado crecimiento de raíces y la cantidad de agua disponible en el suelo. El objetivo del presente estudio fue evaluar la respuesta de plantas de S.rebaudiana Bert. a cuatro láminas de riego calculadas a partir de la evapotranspiración de referencia (ETo) en interacción con inoculantes microbianos. Método Se aplicaron tratamientos de riego con 60, 80, 100 y 120% de la ETo estimada con un tanque evaporímetro tipo “A” en plantas previamente inoculadas. Se evaluaron como inoculantes una mezcla de Bacillus spp. y Azospirillum brasilense, Rhizophagus intraradices y un testigo (sin inocular). Se utilizó un diseño de bloques completos al azar con arreglo bi-factorial y cuatro repeticiones. Se evaluaron parámetros de crecimiento, producción y distribución de biomasa seca, intercambio de gases y uso eficiente del agua. Resultados Se encontró diferencia estadística (p ≤ 0.05) causada por los factores separados. La mayor altura se obtuvo con 120% ETo, aunque fue estadísticamente igual a 100% ETo (p ≤ 0.05), alcanzando 42.86 y 40.58 cm, respectivamente; la mayor área foliar se obtuvo con 120% ETo. El tratamiento con Rhizophagus intraradices mostró diferencias significativas (p ≤ 0.05) en la longitud de raíz contra el testigo, pero fue estadísticamente similar a la mezcla de rizobacterias. De igual forma, R. intraradices mejoró el volumen de raíz registrando 2.49 cm3 con respecto al testigo y redujo en 20% la aplicación de la ETo para obtener la mayor producción de biomasa seca de hoja y raíz. La interacción R. intraradices + 80% ETo favoreció la asimilación del CO2 con 5.41 µmol m-2 s-1, de esta manera se proporcionó mejores condiciones para la transpiración y el uso eficiente del agua (1.87 µmol CO2 mmol-1 H20). Conclusión Los tratamientos de riego mostraron efectos en la altura, área foliar, diámetro del tallo y rendimiento de hoja seca, mientras que el factor inoculante sólo afectó la longitud de raíz, volumen de raíz, relación MSV/MSR y rendimiento. Por último, la interacción de ambos factores solo fue significativa para la producción de biomasa seca e intercambio de gases

Dry mass proportion in different phenophases.

<p>Figure 2. Average dry mass proportion of Habanero pepper plants in different phenological stages at three maximum diurnal temperatures (T_air = , 35 and 40°C). Different letters in the same organ represent statistically significant differences (Tukey, α = 0.05). <i>n</i> = 5.</p