RCAAP Repository

ABSTRACT Acrocomia aculeata (Jacq.) Lodd. ex. Mart. (Arecaceae) is a neotropical oil palm of widespread occurrence in the American continent and with great economic potential for the energy and food sectors. Genetic breeding studies for the species are very recent, with a need for basic knowledge from the genetic diversity in agronomic traits. Thus, the aim of this work was to estimate genetic variance, heritability, and genetic gain as well as to propose strategies of selection. Two-year evaluations of eight agromorphological characteristics were carried out in two experimental fields composed of 50 open-pollinated progenies. The results revealed moderate heritability for progeny average to thorn density in the abaxial side ( = 0.402 in Pindorama) and relative chlorophyll index ( = 0.458 in Presidente Prudente). The selective accuracy was 0.634 and 0.677 for the same traits, respectively. In the combined analysis, the higher values of heritability were obtained to thorn density on the abaxial region of leaves and relative chlorophyll index (0.616 and 0.666, respectively). Moderate to high magnitude values of genetic gain was reached for traits with greatest agronomic interest, as plant height Gs (%) = 19.64, number of leaves Gs (%) = 26.43, stipe diameter at breast height Gs (%) = 12.51, and relative chlorophyll index Gs (%) = 38.12. In conclusion, the results indicate considerable genetic variability for the evaluated traits and suggest that their most effective use for the purpose of genetic gains would be based on the combined selection between and within progenies.

ABSTRACT Cell suspension culture has been used as a model to study metabolic changes to several stresses. To have detailed information of nitrogen (N) limitation on sugarcane metabolism, a controlled study of the primary metabolites and representative compounds of secondary metabolism was developed using suspension cells growing under three different N regimes: normal condition (40 mmol·L–1 NO-3), slightly deficient (12 mmol·L–1 NO-3) and completely deficient (0 mmol·L–1 NO-3). Sugarcane cells were harvested after 3 and 7 days of treatment. A range of changes in the levels of amino acids, organic acids, sugars and phenolic compounds were observed upon the growth conditions applied. Nitrogen limitation remarkably affected the amino acids and carbohydrates biosynthesis, which, associated with the changes observed on phenolic compounds contents, indicates the upregulation of carbon sink compensation mechanisms in these sugarcane cells exposed to N starvation. As expected, the results showed that N limitation might cause an extensive metabolic reprogramming of both carbon and N metabolism in sugarcane cells, and these changes are related to the intensity of the starvation. Nitrogen is essential for plant growth and development, and its limitation sharply reduces crop yield. Thus, these results open new perspectives for in planta studies concerning carbon and N metabolisms balance in this crop.

ABSTRACT This study aimed to estimate the production of seeds per umbel and to assess both the effect of gibberellic acid (GA3) and umbel order on seed germination in Amazon chicory species. The experiment was conducted in two steps. Firstly, traits related to seed production were evaluated. Afterward, a germination test was carried out, and the following parameters were assessed: germination speed index (GSI), average germination time (AGT), germination percentage (%G), percentage of abnormal seedlings (%AS), and percentage of non-germinated seeds (%NGS). Remarkably, there was strong interaction between the analysed factors. The highest production of seeds per plant was observed in the treatment containing the blend of seeds from different umbels (1.41 g·plant-1), in which the number of umbels by order and the total number of seeds per plant were the major traits related to the improved yield. The application of GA3 at 200 mg·dm-3 increased %G in second-order seeds. Regardless of GA3 application, seeds from secondary umbels showed shorter AGT by up to two days, while no difference in GSI was observed. Collectively, these results offer novel and timely information on the seed germination behavior in Amazon chicory, revealing practical advice of utmost importance for local producers.

ABSTRACT The iron concentration (FeC) and zinc concentration (ZnC) in common bean grain are quantitative traits, and appropriate breeding techniques are required to achieve genetic gain. The aim of this study was to obtain a recurrent selection population of black bean to increase the FeC and ZnC in the grain and to select the superior progenies for formation of the next cycle and obtain lines. The base population was formed by crosses among ten parents. A total of 351 progenies were obtained, and, after two generations of selection, the 27 best progenies were evaluated in two field trials for FeC, ZnC, 100 seed weight and yield. Analyses of variance were carried out and genetic parameters were estimated. The heritability estimates ranged from 59 to 94% for the four traits. The estimates of expected gain from direct selection for each trait (3 to 21%) and simultaneous selection (1 to 4%) indicate success from selection. The eight progenies, selected based on simultaneous selection, have superior mean values, including to those of ‘BRS Supremo’ (10% for FeC, 8% for ZnC, 5% for 100 seed weight and 3.8% for yield), the Brazilian black bean cultivar with the highest FeC and ZnC. The recurrent selection population shows high genetic variability and potential for obtaining lines superior to the cultivars currently on the market, allying high agronomic performance and high FeC and ZnC in the grain. Furthermore, this population shows potential for generating a new recurrent selection cycle, from recombination of the eight superior progenies.

ABSTRACT Most Brazilian soils have restrictions on agricultural use related to acidity and nutrient availability. This study aims to evaluate a zinc (Zn) and lead (Pb) mining by-product (Zincal™), regarding its capacity to correct soil acidity, and to serve as a source of Zn. For evaluation of its efficacy, a comparison with dolomite + Zn sulfate was conducted. The experiment was set up in two soils, a Quartzarenic Neosol and a Red Latosol, and conducted under controlled conditions in the laboratory. Treatments consisted in the application of two doses, aiming at 75 and 95% base saturation of both liming materials, as well as in a control treatment without acidity correction. The effect of said treatments on pH, base saturation, Al3+, H+Al, Ca2+, Mg2+, Zn, Mn and Pb contents were evaluated over 120 days. Similar responses were obtained from both liming materials, regarding their capacity to increase the pH of the soil, reduce Al3+ and potential acidity (H+Al), and increase base saturation. Differences observed in these attributes were dose-related. In regard to Ca and Mg, the content released in soil correlates with the content present in the liming materials. Zincal™ released more Mg and less Ca than dolomite, hence proving to be efficient in releasing Zinc.

ABSTRACT Super sweet corn breeding must develop hybrids that fully meet the expectations of the market. In this sense, the determination of keytraits for the selection of sweetcorn genotypes is a fundamental condition for breeding success. The objective of this work was to identify key traits for the selection of promising and contrasting genotypes of super sweet corn. The experiments were carried out in Guarapuava (PR), in two sowing dates. Seventeen traits related to the yield and quality of the ear were evaluated. To perform the multivariate analysis, data were subjected to diagnosis of multicolinearity, analysis of canonical variables, genetic divergence, hierarchical clusters, factor analysis, and canonical correspondence analysis. Grain yield, yield of dehusked ears, and number of commercial ears were considered related key traits in the identification of promising super sweet corn genotypes. Hybrid D3-20 × D5-41 presented higher averages than the others, considering the yield related keytraits.

ABSTRACT Deficiencies of boron and zinc occur in coffee plantations despite the many fertilizer sources offered by the industry for the agriculture. Sparingly soluble fertilizers (SSF) have been used in several countries for many years. However, their effectiveness when applied to leaves is highly contested, and information about their use efficiency is still lacking. Experiments were set up to characterize the SSF of B and Zn according to particle size of fertilizers, and the spreading and retention of the particles in the leaf, comparing SSF (calcium borate, Zn oxide, and Zn borate) with soluble sources (boric acid and Zn sulfate) in four doses (mg.L-1): Experiment I (B 0, 130, 260, and 520), Experiment II (Zn 0, 200, 600, and 1,800), and experiment III (B 0, 43, 129, and 387, and Zn 0, 200, 600, and 1,800), to supply B and Zn for coffee plants. Microparticles of the SSF were found adhered to coffee leaves, and the Zn oxide was the one with the smallest particle size. SSFs were effective at increasing the Zn and B leaf concentrations in coffee. Dry matter of coffee increased 15% with applications of 270 mg.L-1 of B as calcium borate and 384 mg.L-1 of B as boric acid. Foliar application of Zn oxide at the dose of 1,800 mg.L-1 of Zn increased the leaf areas of the plants. High doses of Zn sulfate caused toxicity to coffee plants due to high saline concentrations. The microparticles found retained on the surface of the coffee leaves increased leaf concentration of B and Zn, which explained variations in the dry matter measurements and show the potential of the SSF for the development of fertilizers to improve the availability of micronutrients to coffee.

ABSTRACT Nutrient loss from the weathering process is a major challenge for tropical agriculture. Biochar with nutrient retention capacity has been proposed as an amendment to retain plant-available nutrients. Meanwhile, information on diazotrophic population responses to biochar application in the humid tropics is still poorly explored. A field study was carried out over three cropping cycles of maize in a typic paleudults of Peninsular Malaysia. During the first cropping cycle, the soil was amended with palm kernel shell biochar (PK), rice husk biochar (RH), palm kernel biochar with fertilizer (FPK), rice husk biochar with fertilizer (FRH), fertilizer (F), and control soil (C). Soil samples were taken at each harvesting stage and analyzed for pH, cation exchange capacity (CEC), total N, ammonium (NH4+–N), nitrate (NO3––N), microbial biomass N, and urease activity. Total and active diazotrophs were quantified from soil DNA and RNA, respectively, employing quantitative polymerase chain reaction (qPCR) amplification of the nifH gene. Palm kernel shell and rice husk biochars maintained a significant NH4+–N and NO3––N, respectively, during the second cropping cycle. Both biochars promote the total and active diazotrophic population. A detrimental impact on the nifH transcript was detected from fertilization even when biochar was co-amended. Two possible land management options for tropical soil were proposed from the overall data. First, the application of fertilizer with biochar can reduce N loss against weathering. Second, the application of biochar alone may improve biological N2 fixation in tropical soils.

ABSTRACT Most studies on genomic selection in plant breeding compare different statistical methods of univariate approach. However, multi-trait methodologies should be considered since they allow the simultaneous selection of superior genotypes in several economic traits. Here, the aims were to compare the selection accuracy and efficiency of the multivariate partial least square (MPLS) method compared with random regression best linear unbiased predictor (rrBLUP), Bayesian Lasso (Blasso) and univariate partial least square (UPLS) and to develop genomic selection indexes efficient for superior genotypes identification in plant breeding. Ten F2 populations with 800 individuals were simulated, considering four traits with different heritabilities. Genomic selection analyses using rrBLUP, Blasso, UPLS, and MPLS were conducted. Four genomic selection indexes were elaborated by the sum of the marker effects obtained for each trait, weighted by the respective residual variance. Multi-trait indexes were developed based on the assumptions of each methodology mentioned (rrBLUP, Blasso, UPLS, and MPLS), and were denominated I-rrBLUP, I-Blasso, I-UPLS, and I-MPLS. Processing time, selective accuracy, selection gains, and selection coincidence were used to compare the methods and the selection indexes proposed. The MPLS method had similar results compared to UPLS method for the low heritability traits and was less efficient than the rrBLUP and Blasso. The genome selection indexes provided the highest total genetic gains. The I-rrBLUP and I-MPLS indexes stood out for high efficiency in selecting superior genotypes in the shortest processing time. Results suggest that the genomic selection indexes proposed in this study may be promising for plant breeding programs.

ABSTRACT Guava is of great economic importance in Brazil. The development of new cultivars by obtaining inbreeding lines has been a promising option. The objective of this work was to evaluate the S2 families of Psidium guajava using seed attributes. Different characters of physiological quality of guava seeds were studied, in addition to performing digital phenotyping of characteristics of geometry, texture and colors of the seeds. The variables were analyzed simultaneously using the Ward-Modified Location Model (MLM) method and carried out individual analyses of variance for estimating genetic parameters of the population. The formation of more than one group of divergent genotypes was observed, the geometry characteristics were more impacting for the discrimination of the genotypes, a high phenotypic correlation was observed with the germination variables and dry matter weight. High heritabilities were verified for the variables related to seed quality, indicating success in selecting vigorous genotypes. The Ward-MLM method is a useful tool to detect genetic diversity among genotypes of inbred guava. Thus, the most divergent genotypes with high germination potential can be recommended for future crosses or self-fertilized to obtain new lines in the guava breeding program.

ABSTRACT The excess of nitrogen (N) causes the overgrowth of sweet potato foliage, increasing the self-shading and reducing the root yield. Therefore, a combined N and paclobutrazol (PBZ) application can reduce the vegetative overgrowth and benefit the sweet potato yield. The purpose of this study was to evaluate the plant growth, yield, uptake and removal of N by sweet potato plants fertilized with N and treated with PBZ during two planting seasons. The treatments consisted of four N rates (0, 50, 100 and 200 kg·ha–1), three forms of PBZ application (PBZ-10: PBZ applied at 10 days after side-dressing N fertilization [DASNF]; PBZ-25: PBZ applied at 25 DASNF, and PBZ-10 + 25: PBZ applied at 10 plus 25 DASNF), and a control (without PBZ application). Paclobutrazol application temporarily reduced the length of the main branches of sweet potato planted in the rainy season, but it did not reduce the shoot biomass of plants in both planting seasons. A single application of PBZ at 10 DASNF increased the yield of fresh storage roots in the two planting seasons, but, during the rainy season, the increases were greater when two applications were carried out. The application of 50 kg·ha–1 N in the rainy season was sufficient to reach the maximum yield of fresh storage roots, but, in the dry season, the N fertilization increased the N uptake without benefiting the root yield.

ABSTRACT Producing high-quality seeds for agroecological agriculture is needed because the plants will be exposed to a diversity of environments and management practices. Sowing times and population densities can influence the quality of seeds produced by landraces. Further, seeds for agroecological cultivation must not be contaminated by transgenes. In this context, it is necessary to know the agronomic performance of landraces outside of the recommended growing period to avoid gene flow with transgenic cultivars. Thus, the objective of this work was to determine the germination rate, vigor and sanitary quality of seeds of maize genotypes cultivated in an agroecological system at different sowing times and densities. A split-split-plot design was used in the 2016/2017 and 2017/2018 growing seasons. The physiological quality evaluation was based on germination and vigor tests, and the sanitary quality was obtained by visually examining the seeds. The results showed a significant simple effect of genotype, sowing time and density, as well as double and triple interactions among factors for all evaluated traits. The most suitable time for sowing the corn landraces evaluated in an agroecological system in western Santa Catarina is September, when the seeds exhibited the highest percentage of germination and vigor and there was a lower incidence of pathogens. At this time, a density of 55,000 plants·ha–1 had the best result for germination. Late sowing was tested to avoid gene flow from transgenic varieties that usually are sown in September, but the results indicated penalties, such as a decrease in seed yield and quality.

ABSTRACT In spite of the chemical, physical, and biological benefits that Crotalaria spectabilis can provide to the soil, it is little used as a green manure crop by farmers. Inoculation with strains of legume-nodulating nitrogen-fixing bacteria that are efficient and competitive may be a strategy to enhance accumulation of N in C. spectabilis and stimulate adoption of this green manure crop. The aims of this study were i) to evaluate the symbiotic and agronomic efficiency of new strains of Bradyrhizobium on C. spectabilis in an oxisol (red latosol) compared to that of noninoculated controls (without and with mineral N) and with the approved strain BR2811, seeking to corroborate possible recommendation as inoculants for this species; and ii) to determine, the contribution of these treatments to N accumulation in the plant of C. spectabilis in four periods of cutting for determining possible and ideal periods for its incorporation in the soil. Experiments were carried out in pots and field. Inoculation with the new strains UFLA05-03, UFLA05-09, and UFLA05-14 and with BR2811 on C. spectabilis is effective since it increases the production of N-enriched plant biomass when compared to the control without N mineral. However, UFLA05-03 stands out among these strains because it behaves similarly to the control with mineral N both in relation to shoot N accumulation and dry matter just after 150 days in the field.

ABSTRACT The objective of this work was to evaluate soil attributes and root distribution in areas under forest conversion to cultivated environments. The study was carried out in four areas: forest, cupuaçu, guarana and annatto, located in the municipality of Canutama, state of Amazonas. Soils and volumetric rings were collected in the layers 0.00 – 0.10; 0.10 – 0.20; 0.20 – 0.30; 0.30 – 0.40; and 0.40 – 0.50 m for analyses of physical and chemical attributes and root distribution. Univariate statistical analyses were carried out, the means were compared with the Tukey’s test (p < 0.05) and Pearson’s correlation (p < 0.05 and < 0.01). The forest area and the cultivated environments present soil chemical limitations for agricultural production, whereas the physical attributes presented satisfactory values. The chemical attributes underwent major changes and degradations upon conversion to agriculture. Major changes were observed in the layers of 0.00 – 0.10 and 0.10 – 0.20 m for the studied areas. Cupuaçu cultivation showed higher values of roots dry weight (RDW) and roots distribution (RD), with the highest values found in the 0.00 – 0.10 and 0.10 – 0.20 m layers.

ABSTRACT The root system is essential for sugarcane regrowth and the vigor of ratoon cycles as it represents the unique source of carbon skeletons and energy for the initial plant development. However, root system dynamics after shoot harvesting and its role in sugarcane regrowth remains poorly known. Here, it was hypothesized that sugarcane plants with small volume of root system will accumulate less biomass after shoot harvesting than plants with larger volume and that such regrowth is dependent on root reserves. In sugarcane plants grown in nutrient solution, shoots were cut, and two root treatments were established: reference plants with the entire root system (100%); and plants with half of the root system (50%), randomly removing half of root system. After 37 days of shoot harvesting, plants with the entire root system showed higher shoot, root and total dry mass, root length, root diameter, root area and root volume, when compared with those with 50% of the root system. Sugarcane plants with the entire root system had higher root content of starch, soluble sugar and nonstructural carbohydrates as compared to plants with 50% of the root system. A significant positive correlation was found between the variation of shoot dry mass and the variation of root nonstructural carbohydrates. Interestingly, this data revealed a disproportionate effect of root system size on sugarcane regrowth, with plants with the entire root system accumulating almost three times more biomass than plants with half of the root system during regrowth.

ABSTRACT Based on climate change scenarios predicted for northwestern Mexico, an experiment was carried out during the 2016–2017 and 2017–2018 crop cycles, under field conditions in wheat, in the Yaqui Valley, Sonora, Mexico. The assay consisted on canopy temperature increase by + 2 °C with respect to ambient temperature, using a temperature free-air controlled enhancement (T-FACE) system for temperature manipulation and control. This experiment aimed to determine the existing correlation among vegetative and reproductive variables that can result precise indicators of warming tolerance. A total of 30 variables divided into: morphological (6), physiological (7), biochemical (8) and agronomic (9) indicators were evaluated, using CIRNO C2008 cultivar as experimental model. For each variable, the response index, in a total of five repetition each year, was computed. Results indicated that, during the vegetative stages, the most precise variables for heat tolerance evaluation were: dry matter, vegetal vigor, water potential, nitrate reductase and transpiration indexes; while during the reproductive stage were: grain and biomass yield, spike mass and vain grain per spike indexes. There was a positive correlation among the most majority of vegetative and reproductive variables, being water and osmotic potential indexes those with the greatest contribution to biomass and grain yield. From the 30 evaluated variables, water and osmotic potential, transpiration, grain yield and field water use efficiency indexes were the most precise indicator of heat tolerance in CIRNO C2008 under canopy temperature increase in + 2 °C.

ABSTRACT Whiteflies (Bemisia tabaci) are a serious threat to tomato (Solanum lycopersicum) yield and production since all varieties are highly susceptible to this insect. The wild tomato Solanum pennellii shows resistance towards whiteflies infestation due the high contents of acylsugars presents in its leaflets, which is not observed in S. lycopersicum. Thus, plants from the F2BC2 population derived from the cross between the cultivar S. lycopersicum ‘Redenção’ and S. pennellii (accession LA-716) were selected for acylsugars levels and evaluated for resistance to whitefly and fumagine, a saprophyte fungus from genus Capnodium (sooty mold) that grows on leaves using whiteflies excretion. Biological behavior of B. tabaci was significantly influenced by the levels of acylsugars on the leaflets of the different genotypes. Solanum pennellii and the genotypes with higher acylsugars contents exhibited the lowest whitefly oviposition preference, number of nymphs, exuviae and adult survival. Also, the percentage of leaf coverage with fumagine was significantly reduced on leaves of the S. pennellii and the genotypes with higher acylsugars. Thus, it confirms that the use of S. pennellii LA-716 enabled the introgression of genes to increase the degrees of resistance in the F2BC2 genotypes. Finally, the results presented suggest that the genotypes RVTA-2010-31-177pl#39, RVTA-2010-31-319pl#214 and RVTA-2010-83-347pl#257 can be used as potential sources of genes for resistance to B. tabaci in tomato breeding programs.

ABSTRACT The crop succession and nitrogen splitting fertilization are managements that can affect the common bean technological quality and, consequently, the profitability of producer and the food biological value. The aim of this study was to evaluate whether crop succession and N splitting fertilization promote differences in the technological quality of common bean grains. The experiment was carried out during winter over two agricultural years in southeastern Brazil. A randomized block design was used in a split-plot scheme, with four replications. The plots were composed of three crop successional systems (maize sole, maize + Urochloa ruziziensis, U. ruziziensis sole) and the subplots contained nine combinations of N splitting fertilization at a rate of 90 kg·ha-1 N top-dressing in the phenological stages V3, V4, and R5 of the common bean and a control without fertilization. The evaluated variables were: sieve yield greater than or equal to 12 (SY ? 12), crude protein content, cooking time, and hydration ratio. Crop succession promotes differences in the technological quality of common bean; however, the N splitting fertilization did not change the technological attributes of grains. The highest technological quality of common bean was obtained after succession with U. ruziziensis sole, generating large size and crude protein content of grain, followed by the succession with maize + U. ruziziensis intercropping, and finally, the succession with maize sole. Therefore, the crop succession is a fundamental factor for obtaining common bean with higher technological quality, affecting the food biological value and the profitability of producers.

ABSTRACT The objective of this study was to evaluate cotton cultivars based on the compensatory increase of cotton squares in response to the simulation of the boll weevil damage. The first experiment aimed to evaluate cotton cultivars with greater compensatory increase in squares removed artificially from the plant. The experimental design was in randomized blocks, in a 4 × 2 factorial scheme with 100% removal of cotton squares at 50, 70 and 90 days after the emergence of the FM975WS, TMG81WS, IMA6501B2RF and BRS432B2RF cotton cultivars and passive production (without removal) and active (with removal) of cotton squares, with four replications. In the second experiment, boll weevil damage in the TMG80WS and BRS432B2RF, with greater and lesser compensatory increase of cotton squares, after their removal at 50 days of age, was evaluated. The experimental design was in randomized blocks, in a 2 × 2 factorial scheme, with the former cultivars sprayed with carbamate or not (control). The compensatory increase of cotton squares, mainly after their artificial removal at 50 and 70 days of age, of the TMG81WS, was greater. The cotton square compensatory increase after being artificially removed in the cotton cultivars was higher during the period of exponential production of these reproductive structures and can be used to select cultivars tolerant to boll weevil damage.

ABSTRACT High incidence of sprouts and loss of quality of sweet potato is one of the negative aspects that compromises the commercialization most, and the methods of sprout control are still very limited. The appearance of sprouts promotes the wilting of sweet potato roots, reducing their commercialization period. The main objectives of this study were to evaluate sprout control and physiological and biochemical changes, in addition to the impact on the quality of postharvest chips in sweet potato roots cultivar BRS Cuia treated with methyl jasmonate (MeJa) and nonanoic acid (NA). Roots were fogged with 10 μmol·L–1 MeJa or 5 μmol·L–1 NA applied at first sprout initiation and control. Physiological and biochemical alterations such as fresh weight loss assessment, sprouting incidence and sprout length, total soluble sugars, reducing sugars, nonreducing sugars, enzymatic peroxidase and polyphenol oxidase, chips quality after frying were then assessed. Besides that, to determine the influence of treatments and storage periods, multivariate analysis was also performed using the main components. The MeJa reduced the incidence of sprouting and maintained the root quality during storage at room temperature. Notably, such events led to an increased both shelf life and potential of commercialization. Moreover, MeJa-treated chips displayed lighter color appearance after frying than control and NA-treated roots. Roots fogged with NA did not suppress the growth of sprouts, which consequently triggered a higher browning intensity in fried sweet potato chips.