ABSTRACT - Lima bean (Phaseolus lunatus L.) develops at an optimal temperature in the range of 20-30°C, temperatures above 30-35°C compromise the photosynthetic efficiency of the crop. Considering the importance of lima bean cultivation, the objective of this study was to carry out a morphoagronomic and phenological characterization of 46 lima bean accessions tolerant to high temperatures from the core collection of lima bean at the Universidade Federal do Piauí. The experiment was conducted from February to July 2021 in a completely randomized block design with four replications, where the plot consisted of a pot with two plants. Genotype characterization was performed based on 20 morphoagronomic and phenological descriptors of lima bean. Based on Pearson's correlation, the number of emitted and aborted flowers had a greater genetic correlation with the total number of seeds and pods produced. Pod length and width were positively correlated with seed thickness, length, and width. Five groups were formed based on UPGMA grouping. It was observed that the UFPI-922 and UFPI-945 accessions had a higher performance under high-temperature conditions in relation to the number of flowers and pods emitted, as well as lower values for the number of aborted pods. The accessions UFPI-1037, UFPI-876, UFPI-1036, UFPI-1028, UFPI-1052, UFPI-1064, UFPI-1038, and UFPI-1062 are promising for precocity, productivity, emission of flowers and pods formed, and can be used in breeding programs.

ABSTRACT The objective of this work was to verify the contribution of seed inoculation with the bacterium Azospirillum brasilense to promote growth on yield components in wheat crop. For this, experiments were carried out in different locations (Santa Maria and Cruz Alta, RS, Brazil), sowing times (June and July) and years of cultivation (2013 and 2014). A randomized block design with three replications was used. The treatments were composed by the combination of ten cultivars, three nitrogen managements and two types of inoculation (10 x 3 x 2). Inoculation was carried out with liquid inoculant in the seeds. The components of grain yield were evaluated. The average number of tillers per plant was influenced by seed inoculation (1.63 and 1.72) when uninoculated and inoculated, respectively. On the other hand, the hectoliter mass responded inversely, reducing to 75.7 kg hL-1. Inoculation with A. brasilense increased the grain mass (1%) and had no positive influence on the variables number of ears and spikelets per ear, grain yield and hectoliter weight.

ABSTRACT The characterization of genetic divergence in common bean cultivars for various traits related to plant architecture and grain yield is unprecedented. This study proposes to determine whether common bean cultivars of different grain types differ for 12 traits of plant architecture and grain yield; examine the correlations between these traits; analyze the genetic divergence of these cultivars; and select superior cultivars for these traits. A total of 22 common bean cultivars with the grains types most produced in Brazil were evaluated in two growing seasons. Plant architecture was analyzed based on 12 traits, and grain yield was determined at maturity. Significant genotype and genotype × environment interaction effects were obtained, indicating the existence of genetic variability for all evaluated traits. Several plant architecture traits were correlated, but none was highly correlated with grain yield. Firstand second-internode lengths are more important in differentiating common bean cultivars. Principal component and Tocher’s analyses resulted in the formation of four and seven groups of cultivars, respectively. Both methods are efficient in analyzing genetic divergence; however, Tocher's method is more informative. Cultivars BRS Campeiro, SCS 205 - Riqueza, BRS Esteio, IAC Imperador and Guapo Brilhante have a high grain yield potential, but only BRS Campeiro, BRS Esteio and Guapo Brilhante have upright plant architecture.

ABSTRACT The objective of this work was to evaluate the effect of soil application of different boron (B) rates to the soil, with and without application of zinc (Zn), on growth, production components, and grain yield of maize crops grown in a Lithic Quartzipsamment with low B and Zn contents. A randomized block experimental design was used, in a 6×2 factorial arrangement corresponding to six B rates (0, 1, 2, 3, 4, and 5 kg ha-1), with and without application of Zn (2.0 kg ha-1), applied to the soil at sowing, with four replications. Growth variables (stem diameter and plant height), and chlorophyll SPAD index were evaluated at the R1 phenological stage. Maize ear length, one-thousand grain weight, and grain yield, and the B maximum efficiency rate were evaluated at the R6 phenological stage. Application of B and Zn to the soil increases maize grain yield in soils with sandy clay loam texture and low B and Zn contents; the plant absorption and metabolism indicated synergism between these elements when using soil applications of 1.0 kg ha-1 of B combined with 2.0 kg ha-1 of Zn to the planting furrows. The rates with maximum technical efficiency for grain yield were 3.29 and 4.31 kg of B ha-1 in treatments without and with application of Zn, respectively.

ABSTRACT The use of resistant cultivars is one of the strategies for downy mildew management. The objective of this study was to evaluate the vertical and horizontal resistance of F5:6 progenies of carotenoidbiofortified lettuce to virulence phenotypes of Bremia lactucae 63/63/51/00, 63/31/19/00 and 63/63/19/00. The experimental design was completely randomized and subdivided into plots that were evaluated over time. In the plots, 12 genotypes of lettuce were used, and the subplots were monitored over time (7th to the 18th day after inoculation). For each virulence phenotypes of Bremia lactucae, a separate experiment was performed with three replicates. To select resistant genotypes, plants were inoculated with distilled water, sporangia removed from infected tissues and Tween 20. The genotypes were evaluated when sporulation appeared on cotyledonary leaves of the susceptible cultivar Solaris, verifying the proportion of necrotic and sporulated plants. There was a correlation between genotypes and times for all virulence phenotypes evaluated. Genotypes UFU-189#2, UFU-206#1, UFU-215#3 and UFU-215#14 showed vertical resistance to virulence phenotypes 63/63/51/00, 63/31/19/00, and 63/63/19/00 of B. lactucae. Horizontal resistance levels were observed in genotype UFU 206#1 for virulence phenotypes 63/63/51/00 and 63/31/19/00; in genotype UFU-66#7 for virulent phenotype 63/31/19/00; and in genotype UFU-215#10 for virulence phenotype 63/63/19/00.

ABSTRACT Loss of genetic variability in natural populations affects negatively the adaptive and evolutive process of plant species. In this context, the objective of this work was to evaluate the existing genetic variability between and within natural populations of P. platycephala, using biometric characters of fruits and seeds and physiological characters of seeds and seedlings, and, thus, assess the potential for selection of mother trees, indicate areas for seed collection and use, and generate support for conservation and pre-breeding of plant species. A completely randomized experimental design was used, with 45 treatments (progenies) and four replications of 25 seeds. The progenies were evaluated in laboratory, using seeds collected from 45 mother trees sampled in three natural populations. The following characters were evaluated: seed germination percentage, germination speed index, and mean germination time; shoot and main root lengths; and seedling shoot and root dry weights. The data were subjected to RELM/BLUP analysis for estimating genetic parameters and correlations and to analyses of genetic divergence (UPGMA). The populations present genetic differences to each other and a significant variation between progenies for all characters evaluated, and the variation was greater within the populations. The characters evaluated present high genetic control; therefore, they can be used in analysis of genetic variability of populations and progenies of P. platycephala, thus assisting in the identification of areas for seed collection, conservation programs, and pre-breeding of the species.

ABSTRACT In precision agriculture, determining management zones for soil and plant attributes is a complex process that requires knowledge of several variables, which complicates management and decisionmaking processes. This study evaluated the spatial variability of soybean yield and soil chemical properties using geostatistical and multivariate analyses to define management zones in an Oxisol. The soybean yield and soil chemical properties between 0 to 0.2 and 0.2 to 0.4 m soil depths were sampled at 70 points. Geostatistical and multivariate analyses were then performed on these data. The soil chemical properties showed higher variability at 0.2 to 0.4 m soil depth. The semivariogram parameters of the principal component analysis (PCA) data (PCA 1, PCA 2, and PCA 3) for both depths were more homogeneous than the original data. The maps of soil chemical properties showed high similarity to the soybean yield map. The PCA explained 65.34% (0 to 0.2 m) and 70.50% (0.2 to 0.4 m) of data variability, grouping the soybean yield, organic matter, pH, phosphorous, potassium, calcium, magnesium, and sodium. PCA spatialization allowed for the definition of management zones indicated by PCA 1, PCA 2, and PCA 3 for both depths. The result indicates that the area must be managed using different strategies of soil fertility management to increase soybean yield.

ABSTRACT Forage cactus (Opuntia ficus-indica Mill) is an important forage resource in the Northeast region of Brazil due to its adaptation to the edaphoclimatic conditions of the region, mainly to the drought periods. The objective of this work was to assess the effects of diets with forage cactus combined with different sources of fibers on dry matter and water intakes, digestibility, microbial protein production, balance of nitrogen compounds, and performance of Red Sindhi cows in the Semiarid region of Brazil. The silages used were prepared from plants of Atriplex nummularia Lindi., Sorghum bicolor (L.) Moench, Gliricidia sepium (Jacq.) Walp., and Manihot pseudoglaziovii Pax & K. Hoffm. They were included in forage cactus-based diets at a roughage to concentrate ratio of 58:42. The cows were distributed in a 4×4 double Latin square design with 12 days for each period. Water intake presented differences (p<0.05) when using the diet with A. nummularia silage (19.42 L d-1). The diet with S. bicolor silage resulted in lower (p<0.05) coefficient of digestibility of dry matter (48.71%) than the diet with A. nummularia silage (68.46%). The diet with A. nummularia silage resulted in higher (p<0.05) microbial synthesis than that with G. sepium silage, 115.01 and 80.07 g CPmic kg-1 TDN, respectively. The silages evaluated, combined with forage cactus, can be used as diets for lactating Red Sindhi cows without affecting the daily dry matter intake, milk production, fat content, microbial protein synthesis, and balance of nitrogen compounds.

ABSTRACT Considering the losses of phosphorus (P) in the soil by the adsorption process and that the use of biochar seems promising from the agricultural point of view, the aim of this research was to evaluate P adsorption by the Ultisol incubated with different biochar doses through kinetic and isothermal study. The experiment was carried out with poultry litter biochar pyrolyzed at 350 °C. Ultisol was incubated with increasing biochar doses, from 0.0 to 61.95 t ha-1. After 60 days, the phosphorus adsorption rate, kinetics and adsorption isotherms were evaluated. The results showed that the soil had the highest capacity to adsorb phosphorus (1.105 mg g-1). Biochar was not a good P adsorbent; regardless of the applied doses, it released P to the equilibration solution. Langmuir model was better at describing the adsorption of P. The pseudo-second order model fitted well to the adsorption kinetics of P, showing that the adsorption is chemically controlled. These results suggest that biochar can increase the availability of P, limiting adsorption; therefore, it could be used as a fertilizer and/or soil conditioner.

ABSTRACT This study aimed to validate the artificial hybridization without emasculation in lima beans, identifying F1 generation using microsatellite markers (SSR). We used four accessions from the Active Germplasm Bank of Phaseolus, Universidade Federal do Piauí (BGP-UFPI), with contrasting growth habits and days-to-maturity traits. The 241 crosses performed had a percentage of hybrid pods of 5.8%, obtaining 42 seeds in F1. Artificial cross-fertilization was confirmed by microsatellite markers (BM 211, BM 141, BM 154, and GAT 591), and four plants were identified as hybrids. Thus, the proposed method is effective in performing artificial crosses for lima beans.