Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

Yerba mate, Ilex paraguariensis A. St. Hil. (Aquifoliaceae), waste is one of the most common byproducts generated in households in southern Brazil due to the traditional consumption of mate. However, the decomposition of this waste by fungi has not been thoroughly evaluated. In order to study the fungal succession in mate residue, 450 samples were evaluated during the autumn, winter, and spring, and kept for two months in a humid chamber (aerobic medium) for the growth of associated filamentous fungi. We morphologically identified the fungi by means of a microscopy device and taking into consideration only the surface-developed mycelia. Twenty-two genera of filamentous fungi were found, of which the Zygomycota (Rhizopus spp. and Mucor spp.) microflora deserve special attention since they were the only fungi growing  in the first 19 days. After this period, the fungi Deuteromycota (mainly Aspergillus spp.) and Oomycota (Pythium spp.) develop more vigorously, supplanting the previous ones. The species of Curvularia, Fusarium, Verticillium, and Pythium are phytopathogens and end up having their inoculum source increased with the irregular disposal of this residue in nature. The presence of numerous fungal genera, which are known to be pathogenic according to the literature, highlights the importance of implementing proper waste disposal practices in the environment. Improper disposal of the yerba mate waste can result in contamination not only of yerba mate itself but also of other commercial crops. Therefore, it is imperative that greater attention be paid to the disposal of this waste.

The goldenberry (Physalis peruviana) is an exotic fruit that in recent years has acquired great importance in both the local and international markets; one of the limiting phytosanitary problems for this crop is vascular wilt caused by Fusarium oxysporum f. sp. physali, which causes losses of 80-90%. The management of this pathogen is difficult and so far, it is based on preventive measures; however, there are alternatives such as genetic resistance, which is one of the most effective and profitable measures for its management. Taking that into account, the objective of this study was to evaluate the reaction of 40 genotypes of goldenberry against F. oxysporum under greenhouse conditions, by means of pathogenicity tests. The experiment was conducted in a selected place in the city of Pasto (Nariño department, south of Colombia). It was carried out with 40 genetic materials corresponding to different genotypes, one commercial control and four replicates per experimental unit; the statistical design was completely randomized. The traits evaluated were plant height (cm), disease severity (%), AUDPC area under the disease progress curve (units), disease incidence (%) and degree of vascular discoloration. The genotypes 09U138 and 12U399 have greater plant height (50.19 and 47.36 cm), lower AUDPC (zero units), lower incidence (0%) and lower degree of vascular discoloration (zero), with statistical differences from the rest of the genotypes, including the control. Field evaluations should be conducted with the same isolation and other commercial controls, as this research is only a step forward in the search for the resistance of uchuva to F. oxysporum.

The impact of altitude on the different sugars and acids of the feijoa fruit is unknown. For that reason, the objective of this study was to evaluate the altitudinal effect on the content of organic acids (citric and malic) and sugars (glucose, fructose, and sucrose) during the development of feijoa fruits. The study took place in the towns of Tenjo (2,580 m asl with 12.3°C, 76.4% RH, 190mm precipitation) and San Francisco de Sales (1,800 m asl, with 18.5°C; 86.1% RH, 573 mm precipitation), located in Cundinamarca (Colombia). In the first locality (Tenjo), the fruits developed with 1,979 growth degree days (GDD) (180 days after anthesis (daa), while in the second locality (San Francisco), 2,728 GDD were required (155 daa). For organic acids, the predominant acid was citric. During the fruit development, the contents of these acids presented low values with a later irregular behavior, finally showing 14.21mg g-1 FW (fresh weight) at harvest for citric acid at San Francisco and 7.95mg g-1 FW at Tenjo. For malic acid, 9.14mg g-1 FW was recorded in San Francisco, and 6.88mg g-1 FW in Tenjo, with significant differences for citric acid between altitudes. The monosaccharides fructose and glucose increased during fruit development. However, the disaccharide sucrose showed a significant much higher content at 2,580 m asl (4.27mg g-1 FW) than at 1,800 m asl (1.03mg g-1 FW), for which it is concluded that the higher temperature in the low locality originated greater respiration and loss of sucrose in the fruit.

Caesalpinia ebano is a tropical tree from Colombia; its conservation status is in the endangered category since the remaining populations are suffering genetic erosion. The objective of this study was to estimate the phenotypic (rF) and genetic (rG) correlations among biometric fruit and seeds traits, and the path analysis for the fruit weight. Ten trees (treatments) were evaluated under the random effects model, with 10 fruits/tree as replications. There was significant variability between trees for seven quantitative traits. The fruit weight showed genetic correlations with six traits (0.56* > rG < 1.00**). The number and weight of the seeds per fruit showed high genetic correlations with five traits (rG ≥ 0.85**). The weight of the seeds per fruit exerted direct and indirect effects of greater importance in determining the fruit weight. It is possible to improve the production and physiological quality of the seed by directly selecting trees with fruits of greater seed weight.

Pigeonpea (Cajanus cajan (L.) Millsp.) is a grain legume crop from the tropics and subtropics cultivated for its highly nutritious seeds. Relatively low yields have been observed among African accession with little information on germplasm performance. Therefore, it is needed to identify resilient germplasm, varieties or accessions to improve agronomic performance. This study assessed the morphological variability among selected accessions of Nigerian pigeonpea to identify potential lines for agronomic improvement. A total of 52 Nigerian pigeonpea accessions were evaluated using 10 qualitative and 13 quantitative morphological traits. They were planted using a completely randomised design. Yield performance, trait correlation, principal component (PC), and cluster analysis were used to identify potential breeding lines. The study revealed a wide variability among pigeonpea accessions with both qualitative and quantitative traits. The 52 pigeonpeas were clustered into three major groups. Four principal components with eigenvalue > 1 accounted for 68.95% of the total variation observed.  The first PC accounted for 30.13% with yield components, which include days to 50% flowering, plant height, days to 50% maturity, and vigour at 50% flowering as major contributors. These traits also showed strong significant correlations between themselves. Hence, they can be improved simultaneously.  The study identified several potential accessions based on performance that can be selected for multilocational evaluations and crop improvement.

The identification of resistance of plants to pathogens is crucial for the development of hybrids by breeding programs. To achieve that, it is of great relevance to establish effective inoculation methods for characterizing genotypes with adequate plant resistance levels. Several inoculation methods have been investigated in the search for resistance to corn ear rot disease. However, studies evaluating different corn genotypes cultivated under Neotropical field conditions remain unexplored. Here, we compared three inoculation methods (i.e., aspersion, injectable, and natural) of Fusarium verticillioides in corn ears, and evaluated disease severity and grain yield of 10 corn genotypes. The experiments were conducted in two consecutive experimental corn crop (i.e., 2015 and 2016) seasons located in cities with different environmental temperatures and belonging to different Brazilian states (i.e., Gurupi – Tocantins State, Itumbiara – Goiás State, Planaltina – Brazilian Federal District, and Toledo – Paraná State). We evaluated the mass of 1000 grains and the severity of the disease. Regarding the disease severity, our results showed that the artificial inoculation was more efficient in the regions of Planaltina and Toledo, not affecting grains’ mass in these localities. The severity of disease on the conditions of Toledo was similar for the ten genotypes. However, it was possible to identify two contrasting genotypes since P4285H (low severity) and 32R48YH (medium severity) exhibited significantly more disease symptoms in all other regions. Although the differences regarding the efficiency of inoculation methods are more evident in regions with milder temperatures, the results showed that the characterization of genotypes susceptible to the pathogen is more efficient in regions with higher temperatures.

Pepper (Capsicum annuum L.) is one of the most consumed horticultural products worldwide. However, pepper seeds have slow and asynchronous germination. Organic agriculture encourages using natural substances for the pre-germinative treatment of seeds. The objective of the present work was to evaluate the effect of priming sweet pepper seeds with bromelain crude extract (obtained from pineapple stem residues) on subsequent seedling emergence and growth. The effects of the proteolytic activity of the extract (0, 3.16, 6.25, 12.25, and 25.0 totalU), imbibition time (0, 3, 6, 9, 12, and 15 h), and imbibition temperature (15, 25, 35 and 45 ℃) on seedling emergence and growth were assessed. The significantly best emergence, based on a range of indicators (emergence percentage: E, time to 50% emergence: TE50, emergence index: EI, mean emergence rate: MER, mean emergence time: MET, and synchronization index: SI), was obtained when the seeds were treated for three h at 35°C with a 6.25 totalU bromelain crude extract. Seeds subjected to this treatment combination also yielded the most vigorous seedlings (number of true leaves, length and thickness of the stems, fresh mass, dry mass, leaf area) . In conclusion, pre-germinative treatment with bromelain crude extract of 6.25 totalU proteolytic activity for three h at 35°C improved seedling emergence and growth in sweet pepper seedlings relative to untreated seed. This result offers an organic priming alternative for seeds of sweet pepper.

In Colombia, vascular rotting of passion fruit (P. ligularis) caused by the fungus Fusarium is considered the most important pathological problem in the cultivation of this fruit. Plants affected by the pathogen wilt and die, causing considerable yield losses and increased production costs. The objective of this work was to determine the genetic variability of the Fusarium species associated with this disease. For this, 50 samples were collected from producing farms in three municipalities of the department of Nariño. A total of 35 isolates were characterized morphologically and molecularly. The morphological identification was carried out using taxonomic keys. Molecular characterization was performed by PCR with primers ITS1 – ITS4 and TEF1α. The PCR products were sent to Macrogen (Korea) for sequencing. Sequencing results indicated that Fusarium oxysporum f.sp. passiflorae is associated as a causal agent of the disease. In addition, the presence of Ilyonectria robusta was determined, which, has not been reported before in passion fruit plants. The phylogenetic analysis allowed determine that there was little variability among the isolates evaluated; no grouping was observed associated to the geographical origin of the samples. The morphological characters corroborated the species information obtained from the molecular analysis.

Hard ticks are a problem of great importance in the national livestock industry due to their capacity to be vectors of diseases that affect the productivity of animals and humans, becoming an arthropod of veterinary-medical importance. The methods used for their control have not been efficient; therefore, different integrated control alternatives have become crucial to mitigate their population growth. Products such as calcium polysulfide have shown to be an effective alternative in controlling mite populations. The present study was carried out at the Center for Research and Breeding of Natural Enemies of the University of Caldas using nymphs of Amblyomma cajennense, arranged in Petri dishes and sprayed with an average volume of calcium polysulfide of 1.3ml. From there, the lethal concentration of calcium polysulfide at 31.5°B, on the individuals of this species was determined. The evaluations were carried out at 24, 48 and 96h after application, finding, by Probit analysis, Cl50 of 1.05% and Cl95 of 1.35% concentration of the product, which indicates that this compound has the potential to be used in the integrated management plan of A. cajennense.

World production of coffee (Coffea spp.) has increased in recent decades due to its growing demand. Nitrogen (N) is one of the most required nutrients by coffee crops and in many cases, the most yield-limiting; nevertheless, a high percentage of supplied N is lost, generating pollution, greenhouse gases, and economic losses. Given this scenario, it is a priority to adopt practices that increase nitrogen use efficiency related to the capacity of plants to absorb and use N to produce biomass. This article provides context about NUE and determining factors in coffee: plant, soil, climate, and management. On the plant side, despite advances in genetics and the results of genotype evaluation, it may be a decade or more before improved coffee varieties with high EUN become available or used in world coffee farming. Both the physical, chemical, and biological properties of the soil and the elements of the climate, mainly temperature, precipitation, and solar radiation, have an influence on coffee growth and many of the processes that intervene in the N cycle and NUE; however, some components of these two factors are not fully controllable. Management of the factors that determine NUE should focus on reducing N losses in the system, increasing its uptake and utilization by plants, and maintaining or increasing productivity.