Composition and abundance of weed-species in relation to physicochemical variables in soil for peach Prunus persica L. var. Rubidoux

Weeds are the main biological constraint for production and sustainability in agricultural systems. This is due to the ability of weeds to modify soil physicochemical conditions (i.e., nutrients, pH, organic matter). It is for this reason that having information on the physicochemical characteristics of the soil within the crop allows observing ecological aspects and the distribution of weed species. The objective of this study was to determine the composition and frequency of weed species and their relationship with soil physicochemical variables in peach Prunus persica L. var. Rubidoux. This study determined the composition and frequency of weed species in relation to physicochemical variables in soil for apeach crop with a total of twenty 10×10 m quadrats within a 2 ha peach crop. Weed species were identified taxonomically. A physicochemical characterization of the soil was performed in each quadrat. A total of 13 weed species were recorded, distributed in 10 families and 8 orders, with the Asteraceae family being the most representative. Additionally, physicochemical variations were found in the soil samples in the peach crop. The soil data were contrasted with the distribution patterns and frequency of weed species. Some weed species were not individually related to the soil physicochemical variables. Our results support efforts to explore how variations in soil physicochemical conditions in a crop can modulate weed species distribution patterns.

Postharvest application of growth regulators on Dioscorea alata (L.) and Dioscorea rotundata (Poir.)

Yam is a tuber that sees high demand and consumption in Colombia, whose post-harvest quality losses during storage have been a challenge for farmers. At the Universidad de Cordoba-Colombia, Agronomy Engineering program, between March and August of 2019, a trial was established to estimate the effect of two growth regulators on the variables: tuber weight loss (TWL), tuber sprouting (TS), starch on a dry basis (SD), and reducing sugars (RS) during storage for 120 days, with evaluations every 30 days. A completely randomized design with a 4×2 factorial arrangement plus two additional treatments with three replications was used. Four concentrations of abscisic acid (ABA) were tested: 0, 10, 15, and 20 mg L-1 in the species D. alata and D. rotundata, plus paclobutrazol (PBZ): 15 mL kg-1, for a total of 10 treatments. Each experiment unit consisted of 12 tubers that were preserved in darkness at 23°C and 53% relative humidity on average. ABA and PBZ exerted effective control over the sprouting and weight loss of the tubers during the first 90 days of storage in both species, which averaged 24.4%, i.e. approximately 488 g, favoring high starch contents, and did not influence the reducing sugar content.

Presence of Potyvirus in the Norte de Santander department and molecular characterization of NIb protein in Colombian SCMV isolates

Potyviruses are the largest genus of plant viruses that cause significant losses over a wide range of crops. In this paper, the presence of potyvirus in different plant crops in the provinces of Ocaña and Pamplona located in the north and south of the Department of Norte de Santander (Colombia) was evaluated with RT-PCR analysis using universal oligonucleotides specific to the region that encodes the NIB protein. The results indicate the presence of several potyvirus in Pamplona in economically important crops such as corn (Zea mays), tomato (Solanum lycopersicum), potato (Solanum tuberosum) and zucchini (Cucurbita pepo). In Ocaña, potyvirus was found in bean (Phaseolus vulgaris), corn and pumpkin (Cucurbita maxima). In corn, one of the most important crops, the presence of the Sugarcane mosaic virus (SCMV) was confirmed with nucleotide sequencing. This is the first report of this virus in the department. The presence of several potyviruses in different crops in Norte de Santander indicate an alarming phytosanitary condition that must be addressed with priority to establish detection and control systems that maximize production, ensure agricultural sustainability, and propose certification schemes and improvement programs to reduce economic losses.

Morphological characterization and hierarchical classification of 40 bush pea genotypes (Pisum sativum L.)

The Universidad de Nariño is home to a collection of bush pea plantlets that are a source of biodiversity for the genetic improvement of pea species in Colombia. The characterization of these accessions is required to identify genotypes with attributes that could be used in the search for new varieties. For the morphological characterization, 40 pea accessions were planted in Pasto, Colombia. 23 quantitative variables and 12 qualitative variables were documented, descriptors proposed for this species by the European Union in 2003. The data were subjected to Principal Component Analysis and Multiple Correspondence Analysis. Finally, a hierarchical classification method was applied using Ward’s method. The first four components, which explained 78.80% of the total variability of the population, were selected for the quantitative variables. Four groups were identified. Genotypes with the afila gene, which are of interest for pea breeding programs, were found in groups 1 and 2. The highest seed weight was in group 1, and the genotypes with the best reaction to powdery mildew were in group four. For the qualitative variables, the first six factors, which described 60.51% of the variability, were selected, and the hierarchical classification analysis resulted in five groups. The qualitative characteristics that contributed more to the differentiation of the groups included leaflet type, hilum color, degree of curvature of the pod, color and shape of the grain.

Use of multispectral images to evaluate the efficacy of pre-emergent herbicides in peas under greenhouse conditions

In Colombia, peas are the second most important legume after the bean, and weeds are the main biotic factor that limits production, causing losses of up to 100%. Manual control can represent up to 40% of the labor force. The critical period in the crop-weed competition is the first third of the crop cycle; therefore, pre-emergent herbicide applications are a cost-effective way to control weeds. Common variables for assessing weed-control efficacy include, weed density (individuals/area), which is precise but time consuming, and weed coverage (%), which is faster but very subjective. Therefore, pre-emergence herbicides and a weed-control evaluation method that standardizes, facilitates, and provides greater precision are needed for peas cultivation and experimentation. Five pre-emergent herbicides (linuron, S-metolachlor, metribuzine, oxifluorfen and pendimetalin) were evaluated at two doses in a greenhouse pea crop. Also, two methods (quantification process of multispectral images and conventional human visual) for assessing weed coverage and control efficacy were compared. The best herbicide treatment for the dry grain yield was metribuzine (2.36 t ha-1). Furthermore, the effectiveness of the weed control was 88% at 36 days after sowing, which is optimal. Finally, there was agreement between the weed assessment methods (human vs. machine). The intraclass correlation coefficient was over 0.95, which validates the use of machine quantification for weed coverage.

Genotype-environment interaction for production characteristics in cherry tomato (Solanum spp.)

Much of the tomato diversity is found in cherry-type populations. There are promising wild cherry tomato species with good behavior in terms of yield and quality that can be produced with a minimum of agro-inputs. The genetic expression of genotypes is influenced by the optimal environment they can develop in. The genotype-environment interaction must be known to estimate the phenotypic adaptability in different environments. The objective of this research was to evaluate the genotype-environment interaction for 10 cherry tomato introductions in nine environments, four of which were artificial environments (0, 60, 120 and 180 kg ha-1 of potassium) established in natural environments on the Farms Montelindo, Tesorito and CEUNP. The experiment design used randomized complete blocks with four replicates; the experiment unit consisted of five effective plants per introduction. The evaluated variables were production per plant (PFT) (kg/pl), number of fruits per plant (NFT), and average fruit weight (AWF) (g/fruit). The genotype×environment interaction and the stability of the 10 genotypes were estimated with the AMMI multivariate model. The environments for T120K and T180K were optimal for the variables associated with production (PFT, NFT and AWF), with IAC1621, IAC426 and IAC1624 being the most promising genotypes per environment on the Farms Tesorito, Montelindo and CEUNP, respectively. The results are useful for the identification of genotypes in key locations for selection and evaluation in breeding programs.

Analysis of the technical efficiency of yam cultivation (Dioscorea spp.) in the Caribbean Region of Colombia

The objective was to analyze the technical efficiency of yam cultivation in producing areas of the Caribbean Region. The data were obtained through 98 structured surveys applied to experienced farmers, which included socioeconomic information such as: age, schooling, size of the cultivated area, physical crop yields, and production destination. The sampling technique was simple and applied at random. The data were analyzed in the SPSS program, and techniques such as descriptive statistics and measures of central tendency were used. Likewise, a Cobb-Douglas type econometric model was designed that allowed formulation of a production function and estimation of the parameter values. The results showed that the production efficiency was low because of underutilization of some factors, such as labor, which is 78 wages on average, excessive for the cultivation of one hectare of yams; in addition, fertilizers are used without a soil analysis and without considering the nutritional requirements of the crop. The seed is an important factor that contributes to increases in production with a coefficient of 0.033881, so, if its quality is improved, efficiency can be increased. Experience and schooling contributed the most to the efficiency of the yam cultivation. Farmers can increase productivity with a better use of resources.

Current status of plant pathogens of agricultural importance for Colombia. A review

Plant disease still plays a major role in limiting agricultural production worldwide. Pathogens and pests reduce crop yield and can cause large reductions in crop quality. Colombia is no exception as it contends with many devastating pathogens that present a major threat to the country’s agricultural sector. This review is important because it highlights four of the more damaging pathogens that affect the economics of important crops in Colombia - Xanthomonas phaseoli pv. manihotis (Xpm), Fusarium oxysporum f. sp. cubense (Foc), Phytophthora palmivora, and Hemileia vastatrix. This paper was based on an extensive literature search for plant diseases in Colombia in databases such as PubMed and Google Scholar. Moreover, this search was complemented with research on crop production in the country in databases made available by the Food and Agriculture Organization of the United Nations (FAO). The four pathogens reviewed in this paper were chosen not only because of their current devastating effects on Colombia’s agricultural production but also because of their potential to cause further damage in the near future. Understanding the current situation of these crop pathogens in Colombia is imperative for state directives aimed at developing informed and efficient control strategies.

Fruit characterization of 36 cape gooseberry hybrids for identification of potential industrial or fresh consumption uses

The cape gooseberry is the second most exported fruit in Colombia. There are, however, little information available on genetic improvement processes and limited research on the fruit components. The objective of this study was to characterize the fruits of 36 hybrids, obtained from double haploid cape gooseberry lines from the Tibaitatá Research Center of the Colombian Corporation for Agricultural Research. Hybrids with potential uses in transformation processes or for fresh consumption were identified using Hierarchical Cluster (HC) and Principal Component Analysis (PCA) with 20 physical, physicochemical, compositional, and physiological fruit descriptors, obtained from four trials in the Andean region of southern Colombia. According to the PCA, three components represented 73.6% of the total variability: postharvest (37.5%), sensory and nutritional quality (21.3%) and cracking percentage (14.8%). Six conglomerates were identified. Groups two, four, and six had aptitude for fresh consumption because of the size of the berry, high vitamin C content, maturity index and low cracking levels. Group one showed aptitude for processing and fresh consumption. Groups three and five registered a high seed content, low maturity rates, and a high cracking percentage.

Regulating the postharvest life of Campomanesia lineatifolia R. & P. fruits through the interaction of ethylene, 1-methylcyclopropene and low temperatures

The champa (Campomanesia lineatifolia) is a very perishability berry with a pleasant taste. The objective of this research was to study the regulation and prolongation of the postharvest conservation of champa fruits using 1-methylcyclopropene (1-MCP) and refrigeration. Two experiments were carried out: In experiment 1, four treatments were evaluated to understand the regulation of maturation. The treatments were: control, 1-MCP, ethylene and 1-MCP + ethylene. The fruits were stored at room temperature. In experiment 2, the combination of the application of 1-MCP and two storage temperatures (room temperature [16±2°C] as well as 2±0.4°C) were used. In the two experiments, four repetitions were used, each one with approximately 500 g of fruits harvested at stage 2 of maturity (25% yellow and 75% green). The results of experiment 1 indicated that the fruits with 1-MCP presented the longest postharvest duration (17 days), firmness, and titratable acidity. They also had the lowest respiratory rate and weight loss during the 10 days. However, the fruits treated with ethylene had the opposite behavior, indicating that the changes evaluated during ripening were associated with this hormone. In experiment 2, the fruits refrigerated at 2°C, with or without the application of 1-MCP, had the longest postharvest duration, lasting 26 days, as compared to 12 days in the control fruits (without refrigeration and with 1-MCP). The fruits that lasted longer had a low respiratory rate during storage, as well as lower values for weight loss and, color index but, greater firmness and acidity. The 1-MCP was efficient when the fruits were at room temperature.