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ABSTRACT The stunt complex, transmitted by Dalbulus maidis, has become one of the main maize diseases in recent years in Brazil and Latin America. Genetic resistance is one of the best ways to control and prevent plant diseases due to its efficiency, low environmental impact, and reduced need for phytosanitary products. We sought to identify maize genotypes tolerant to the stunt complex and quantify the levels of damage caused by the disease in commercial hybrids and native varieties. A two-year field experiment was conducted to evaluate the maize stunting. We used an augmented block design with 60 genotypes and 3 test hybrids, arranged in 4 blocks. We assessed the incidence and severity of stunting between stages R2 and R3. We evaluated the agronomic characteristics of the different genotypes to compare them with the effects caused by the stunt complex and each genotype’s tolerance. We found more than 1,000 kg ha-1 of losses for commercial and native hybrids due to the stunt complex. Regression and multivariate analyses showed results that prove the effect of the maize stunt complex in reducing productivity, which allowed the classification of the evaluated genotypes into tolerance and resistance levels. The genotypes GNZ 7788 VIP3, Sempre 10A40 VIP3, DKB 360 PRO3, FS 575 PWU, NK Defender VIP3, and MG 540 PWU proved to be the best genotypes to serve as resistance sources to the stunt complex. The results emphasized the importance of genetic improvement in adding resistance/tolerance traits to breeding programs and increasing maize productivity and global sustainability.

ABSTRACT One of the bottlenecks for maize (Zea mays L.) production is the need for a large supply of nitrogen fertilizers, which burdens farmers. A solution to this problem is the use of proteobacteria Azospirillum brasilense as an inoculant. However, experimental results regarding this inoculant vary depending, for instance, on the soil cultivation practices used. The objective of this study was to evaluate the influence of inoculation with Azospirillum brasilense on morphophysiological characters and yield characteristics of three maize genotypes in two off-season cultivated in no-tillage system (NT). Fallow soil (FS) was used as control. The results showed that soil cultivation had a significant effect on morphophysiological and productivity parameters compared to inoculation with Azospirillum brasilense. There were no distinct morphophysiological differences among the treatments. FS (inoculated or not) was more closely related to productivity parameters (grain yield-YI, weight of 100 seeds-100SW, plant height-PH and number of leaves-NL) than NT in both off-seasons. Among the hybrids, Dekalb 255 PRO3 (DKB 255) showed the highest YI and 100SW. Thus, this hybrid was considered well-adapted to off-seasons in western Paraná, Brazil. The inoculation effect was practically null and did not influence the estimated productivity of the different chosen hybrids.

Production costs in Brazilian agriculture have increased with the rising prices of imported soluble fertilizers. To circumvent this import dependence, low-cost indigenous nutrient sources have been tested, including basalt rock powder (BRP). In this study, we assessed BRP and limestone effects on soil fertility, and soybean and maize dry mass (DM) accumulation. Four greenhouse pots experiments were arranged in a 2 × 4 factorial design with two soils (Clay and Sandy Clay Loam) and four doses of each material (0, 33, 66, and 99 Mg ha−1 BRP and 0, 1, 2, and 4 Mg ha−1 limestone), evaluated in two species (soybean and maize). At the end of the experiments, DM, shoot P and K concentrations, and soil pH and P, K, Ca, and Mg concentrations were assessed as a function of BRP and limestone application. Applying BRP increased DM production and improved soil fertility parameters such as pH, and Ca and P concentrations, with leaf P content also increasing. Meanwhile, limestone only triggered significant changes in pH and soil Ca content.

The objective of this study was to determine the duration of the main phenological stages, plant growth development, yield, and cone quality of hop cultivars grown under artificial light (17 h per day) during vegetative development (early season) in a subtropical climate region. The study was conducted in Palotina, Paraná, Brazil (24° S), during the 2021 and 2022 growing seasons. The plants were cultivated in a 5.5 m high trellis system with artificial light supplementation during vegetative development. The hop cultivars Hallertau Mittelfrüher, Mapuche, Northern Brewer, Spalter, and Yakima Gold were used in the treatments. The duration of the phenological stages, vegetative growth (plant height, fresh mass of the plants, number of lateral branches per plant), components of productive yield (number of cones per side branch, number of cones per plant, fresh mass, length, and width of the cone, production of fresh cones per plant, and yield), and chemical components of the cones (alpha- and beta-acid contents, and essential oil concentrations) were recorded. The duration of the phenological stages was visually evaluated, and plant growth was analyzed using non-linear log-logistic regression. The remaining data were subjected to analysis of variance and the means were compared using Tukey’s test. The data were also subjected to multivariate analysis using the principal components test, correlation analysis, and hierarchical grouping. The cultivar Mapuche was considered an early hop in both seasons, and the cultivars Spalter and Yakima Gold were considered early cultivars in the second season. In both seasons, the productive yield components were positively correlated with the precocity of the cultivars, in which Mapuche in the 2021 season and Mapuche, Spalter, and Yakima Gold in the 2022 season had the highest mean of the number of cones per side branch and per plant, production per plant, and productivity. The cultivar Yakima Gold had a positive correlation with the chemical quality of cones, alpha and beta acid contents, and essential oil concentrations, for both seasons.

Thirty-three coffee SSR primers from enriched genomic library with (GT)15 and (AGG)10 repeats were analyzedin 24 coffee tree accessions. Twenty-two primers were polymorphic among accessions; the number of alleles ranged from 2 to13, with the mean number of 5.1 alleles per primer. PIC values ranged from 0.08 to 0.79. The highest mean PIC values werefound for C. canephora (0.46), and the lowest values for C. arabica (0.22) and triploids (0.22) accessions. The polymorphicSSR markers used in this study were useful for genetic fingerprinting in the coffee tree, especially in the C. canephora and theleaf rust resistant arabica cultivars.

The study was done with the objective of assessing the genetic diversity existing among Ethiopian and ICARDAbarley germplasm using multivariate data analyses. The experiment was conducted at Asasa and Ambo in Ethiopia, in 10 x 10simple lattices with two replications. To quantify the differentiation among genotypes canonical discriminant analysis, clusteringanalysis and Mahanalobis (D2) distance were used. The study indicated that the first two canonical variates explained 95%and 91% of the total variation at Asasa and Ambo, respectively. At both the locations, genotypes showed maximum differentiationon days to maturity, grain filling period, tiller per plant and spike per plant. Analysis of clustering grouped the 100 genotypesinto four cluster groups at Asasa and six clusters at Ambo. Ethiopian landraces and genotypes from ICARDA grouped in thesame cluster groups indicated the germplasm exchange between the Ethiopian and ICARDA barley breeding programs.

With the objective of developing new SSR markers for Coffea arabica, two enriched genomic libraries withprobes (GT)15 and (AGG)10 were constructed. A total of 835 clones were sequenced and 756 presented good quality sequences.Redundant sequences were observed for 113 clones (14.94%). SSRs were found in 287 clones (38%). An estimated size of417.5Kb of the C. arabica genome was sampled, with an average of one SSR per 1.46Kb. Dinucleotide repeats were morefrequent than trinucleotides. Four repeat sequences, (AG/CT)n, (AC/GT)n, (AAG/CTT)n, and (AGG/CCT)n represented 61.1%of the total observed. A total of 96 SSR primers were designed and tested by PCR for two C. arabica genotypes. Ninety new SSRmarkers were validated for further genetic studies of C. arabica.

O trabalho teve como objetivo avaliar o desenvolvimento de mudas de pupunheira (Bactris gasipaes H.B.K.) cultivadas em amostras de um Latossolo Vermelho eutroférrico de textura argilosa compactado artificialmente em subsuperfície. As amostras de solo que foram compactadas a quatro níveis de densidade (1,0; 1,13; 1,28 e 1,44kg dm-3) estavam nas camadas intermediárias de 3,5cm de vasos de PVC de 20cm de diâmetro, que constavam de outras camadas superiores de 15cm e inferiores de 10cm. As avaliações foram realizadas em quatro épocas (4, 6, 8 e 10 meses). O aumento dos níveis de densidade do solo não influenciou no desenvolvimento da parte aérea das mudas de pupunheira. Independentemente da época estudada, os níveis de densidade do Latossolo argiloso não impediram a penetração das raízes da pupunheira.This study was carried out to evaluate the development of peach palm (Bactris gasipaes H.B.K.) seedlings submitted to artificiality subsurface compacted layers of a clayly texture eutroferric Red Latossol. The compacted soil was at the middle ring of the PVC pots. They were 20cm of diameter, divided in tree rings with 15; 3,5 and 10cm from the up side. The soil was submitted to four density levels (1,0; 1,13; 1,28 and 1,44kg dm-3), which determined the treatments. The evaluations were accomplished in four times (4, 6, 8 and 10 months). The increase of the soil density levels didn't influence in the development of the aerial part of the peach palm seedlings. Independent of the studied time, the clayly Latossol density levels, didn't prevent the peach palm roots penetration.

The main goal of our research was to search for SSRs in the Eucalyptus EST FORESTs database (using a software for mining SSR-motifs). With this objective, we created a database for cataloging Eucalyptus EST-derived SSRs, and developed a bioinformatics tool, named Satellyptus, for finding and analyzing microsatellites in the Eucalyptus EST database. The search for microsatellites in the FORESTs database containing 71,115 Eucalyptus EST sequences (52.09 Mb) revealed 20,530 SSRs in 15,621 ESTs. The SSR abundance detected on the Eucalyptus ESTs database (29% or one microsatellite every four sequences) is considered very high for plants. Amongst the categories of SSR motifs, the dimeric (37%) and trimeric ones (33%) predominated. The AG/CT motif was the most frequent (35.15%) followed by the trimeric CCG/CGG (12.81%). From a random sample of 1,217 sequences, 343 microsatellites in 265 SSR-containing sequences were identified. Approximately 48% of these ESTs containing microsatellites were homologous to proteins with known biological function. Most of the microsatellites detected in Eucalyptus ESTs were positioned at either the 5’ or 3’ end. Our next priority involves the design of flanking primers for codominant SSR loci, which could lead to the development of a set of microsatellite-based markers suitable for marker-assisted Eucalyptus breeding programs.