Editorial Temas Agrarios Volume 26(2) of 2021 | Editorial Temas Agrarios Volumen 26(2) de 2021

1st International and 2nd National Symposium of Agronomic Sciences: The rebirth of the scientific discussion space for the Colombian Agro. | 1 Simposio Intenacional y 2 Nacional de Ciencias Agronómicas: El renacer del espacio de discusión científica para el Agro colombiano.

1 Simposio Intenacional y 2 Nacional de Ciencias Agronómicas: El renacer del espacio de discusión científica para el Agro colombiano.

The objective of this work was to analyze the behavior of the price of the smoke in the five main markets: Barranquilla, Cartagena, Montería, Sincelejo and Valledupar of the Caribbean Region of Colombia. The data used were from the DANE Price Information System in weekly periods during the years 2012 to 2019. With the use of cointegration techniques, the relationships between the series were identified, and causality was also determined by the Granger method. The work proved that there is integration of the markets in the price formation process. The results show the comprehensiveness of the markets and the absence of causality between the prices of the five cities without the size of the market affecting this situation. It is concluded that, even in the absence of causality between the markets, they are integrated in the long term, which shows compliance with the single price law.

To determine the viability of micrografting of Valencia orange and Tahiti Lime plants on Cleopatra mandarin rootstocks for possible use in massive plant propagation, different steps o the micrografting procedure were evaluated. Seeds of Cleopatra mandarin were established in semisolid MS (Murashige and Skoog) with, or without, GA3 to evaluate the effect on percentage and time time of germination. Plants of Valencia and Tahiti were, either, treated with 1 mg l -1 BAP or manually pruned to evaluate the effect on vegetative shoot production, and the effect of three positions of the shoot tip meristem (Topping, sided and slant) onto the decapitated surface of the rootstock on the percentage of success were evaluated. Treatments for all experiments were distributed with a complete randomized design and data for vegetative shoot production were analyzed with ANOVA and means separated with Tukey test. Results evidenced that GA3 had no effect on increasing percentage and reducing time of germination, pruning statistically increased the number of vegetative shoots in plants. Micrografting success of 28% for Valencia orange and 14% for Tahiti lime are consistent with reported studies for recovery of disease-free plants; however, to increase success level for massive plant propagation, it is recommended for further studies to consider evaluation of in vitro conditions such as increased sucrose concentration, in vitro adaptation of shoot tip meristems and auxin supply, among others.

Cañafistol (Cassia moschata Kunth) and yopo (Mimosa trianae Benth.) are important native species in the Colombian Orinoco Region, however, their behavior in a monoculture system and genetic variability are unknown. In a 7-year-old plantation located at La Libertad Research Center (Villavicencio, Meta), the phenotypic variability of 108 M. trianae trees and 52 C. moschata trees was evaluated using 37 quantitative and qualitative plant descriptors (crown, stem, leaf). Principal component analysis and multiple correspondence were used for quantitative and qualitative variables respectively, in order to reduce the dimensionality of the data, followed by cluster analysis using the WARD algorithm. C. moschata had a smaller size and a less vigorous crown, in comparison to M. trianae which stands out for its greater number of branches, crown diameter, wood volume and annual average increase of the total height and DBH. The cluster analysis allowed classifying the individuals of C. moschata and M. trianae into six and five groups retaining 99.92% and 99.58% of the original variability respectively. The variables trunk volume, crown diameter, number of branches and total height are the most important for the selection of timber trees and use in agroforestry systems. In M. trianae the number of leaflets per leaf and the size of the leaves are equally relevant variables for the selection of shade trees.

The modification of the landscape, the intense exploitation of natural resources through intensive agriculture and the advance of the agricultural frontier result in the homogenization of the landscape and alteration of soil physicochemical conditions. These soil alterations cause changes in the composition and diversity of edaphic arthropod communities that can be used as biomonitoring and diagnostic tools in local areas. The objective of the study was to evaluate the diversity of edaphic arthropods and their association to different physicochemical parameters (i.e., pH, real density, bulk density, %OC, %OM and gravimetric and volumetric humidity) in three soil uses (permanent crop, rotational crop and pasture) in the experimental farm Tunguavita Paipa - Boyacá. The plot sampling technique was used to obtain data on biological and physicochemical variables. Samples were taken in three soil uses, permanent crop, rotational crop and cattle ranch. The edaphic arthropods and physicochemical variables were determined in the soil laboratory of the Universidad Pedagógica y Tecnológica de Colombia. The highest diversity of edaphic arthropods (309 individuals) was recorded in the permanent crop plot, followed by the rotational crop plot, both with high average values of %OM (1.82 - 1.90) and %OC (1.05 - 1.10). The Oligochaeta, Diplopoda and Araneae group were the major contributors to the biological differentiation between land uses. The changes in the abundance of edaphic arthropods were related to % gravimetric humidity, %volumetric humidity, pH, %OM and %OC, while the values of real density and bulk density did not correlate to a great extent with the changes in abundance. These variations allow the differentiation of land uses in an intervention gradient.

Arrow cane (Gynerium sagittatum Aubl.) is a Poaceae associated to human development of the ancient Zenú culture present nowadays in the flat lands of Córdoba and Sucre department in the Colombian north Coast. Despite its importance, arrow cane is not cultivated in large scale and extraction from natural populations is the most common way for plant exploitation with negative environmental and economic consequences for the aboriginal communities. A research program based on biotechnology was implemented to generate information related to plant genetic diversity, plant propagation and genetic resource conservation in order to provide knowledge to contribute to implement technical crop development to minimize the impact of artisans´  activity on the environment and increase sustainability on fiber source for craftsmanship. Accessions from different zones of the Colombian territory were characterized using morphological and molecular markers founding low genetic diversity. Cultivars UC121, “Criolla”, “Criolla 1”, Costera and “Martinera” were in vitro established and micropropagation results indicated that large quantities of high quality, fully adapted, homogeneous plants can be produced from any cultivar. In vitro cultured arrow cane plants can be stored by means of slow growth or modified structures such as micro rhizomes developed in vitro.

The objective of this work was to analyze the behavior of the price of the smoke in the five main markets: Barranquilla, Cartagena, Montería, Sincelejo and Valledupar of the Caribbean Region of Colombia. The data used were from the DANE Price Information System in weekly periods during the years 2012 to 2019. With the use of cointegration techniques, the relationships between the series were identified, and causality was also determined by the Granger method. The work proved that there is integration of the markets in the price formation process. The results show the comprehensiveness of the markets and the absence of causality between the prices of the five cities without the size of the market affecting this situation. It is concluded that, even in the absence of causality between the markets, they are integrated in the long term, which shows compliance with the single price law.

Correlations and path analysis are important strategies to improve the selection of agronomic traits of commercial interest in various crops. The objective of this work was to estimate the correlations between 14 biometric characteristics of the fruit and the seed, and the path analysis for the weight of the fruit in B. hispida. 10 families of half siblings were evaluated, in a completely randomized design with five repetitions. Fruit weight showed direct significant phenotypic correlations with pulp thickness, fruit length, fruit width, number of seeds, seed cavity and seed weight, whose coefficients ranged between 0.64 * and 0.91 **, respectively. Seed length showed a significant direct association with the volume of a seed and the weight of a seed, with records of 0.66 * and 0.83 **, respectively. The width of the seed and the volume of a seed showed a correlation of 0.88 **, while the density of a seed presented a significant inverse correlation with the width of the seed and the volume of a seed, with records of -0.73 * and -0.89 **. Indirect effects mainly explained the significant correlation of fruit weight with the variables fruit width, seed cavity, seed weight and number of seeds. The length of the fruit presented the greatest direct and indirect effects on the weight of the fruit. The weight of the fruit and the length of the fruit can be used in the selection of B. hispida to obtain genotypes with greater weight and number of seeds per fruit.