Resumo em Inglês:

ABSTRACT Tomato is considered a fruit with a high food demand across the world due to its high antioxidant capacity. Lycopene content in tomato has been widely studied, particularly in cherry-type tomatoes which are considered a high source of lycopene for humans. The aim of this study was to analyze the differences in terms of concentration and variation of diverse physicochemical parameters of quality (acidity, vitamin C, pH, °Brix, color coordinates L*, a* and b*) and, antioxidants like ?-carotene and lycopene in 11 accessions of cherry-type tomatoes, considering the advantages of antioxidants for human health. Multicriteria analysis and other tests showed substantial differences among the accessions. IAC401 was associated with the best physicochemical characteristics of a promissory cherry-type tomato for cultivation due to its association with functional food, followed by IAC426R and IAC1624. This study allowed an innovative association of physicochemical characteristics and antioxidant contents of cherry-type tomatoes through multicriteria analyses which enable the analysis, elimination, and proposal of promising accessions for their use in future crops which will promote the best intrinsic features of tomato to be used in the studied region. In this case accessions with the highest scores offer not only optimum amounts of antioxidants and highest levels of organic acids and sugars.

Resumo em Inglês:

ABSTRACT Although source–sink relationships in wheat are well studied, the performance of tillers as transient sinks is still unclear, especially under stress conditions. Thus, this work aimed to study the yield relationships of wheat stems in contrasting genotypes as affected by tiller treatment under stress conditions. Two experiments were conducted under greenhouse conditions using BRS Guamirim (high tillering) and BRS Parrudo (low tillering) wheat cultivars. Four tillering treatments were applied on late tillers in the first growing season (2016) and three in the second (2017): (i) free-tillering, (ii) detillering, (iii) physical suppression (only in the first season) and (iv) “spikes removal”. The main stem and the first four emitted tillers were considered as primary tillers. Plants were submitted to drought (2016) and defoliation stress (2017) at preanthesis. Intraspecific competition among tillers increased under drought stress conditions and decreased the plant performance. Nonproductive late tillers do not improve the performance of primary tillers of wheat plants under drought stress, mainly in high-tillering cultivars. The reduction on the thousand grain weight of only ‘Parrudo’ detillered plants indicates that assimilate remobilization from late tillers to primary tillers and main stem seems to be more effective in low-tillering cultivars.

Resumo em Inglês:

ABSTRACT Sugarcane (Saccharum L. spp. hybrids) is a globally important crop. While roots contribute to its net primary production, knowledge of sugarcane root growth is incomplete and limited in scope. The objective of this study was to determine cumulative root density (LA), root distribution, effective rooting depth (ERD), and root growth rate for four sugarcane genotypes across three crop cycles (plant cane [PC], first ratoon [FR], and second ratoon [SR]). The experiment was conducted in a rain shelter on four sugarcane genotypes (ROC22, YZ04-241, YZ05-194, and YZ05-51) using minirhizotron tubes to a soil profile depth of 1.08 m. Most roots in were found at 0–0.36 m-depth, and about 85.0% were within a 0–0.72 m depth in PC. In FR and SR, however, > 81.8% of roots were found at 0–0.54 m-depth regardless of genotype. The LA of ROC22 was often significantly higher than that of the other genotypes at depths < 0.54 m regardless of crop cycle. The genotype ROC22 had greater root length and faster root growth rate than YZ05-194 at 0.18–0.36 m in PC and FR, while SR YZ05-194 had slower root growth than the other genotypes at 0–0.18m. Ratooning ability of sugarcane genotypes may be related to these root growth attributes.

Resumo em Inglês:

ABSTRACT Brassica oilseed species are becoming increasingly popular for industrial uses, with emphasis on biodiesel. It is of importance to evaluate the yield and oil production potential of nontraditional oilseeds for use as feedstock in Brazil. In this study, growth, yield, and oil content and their correlations were determined for eight accessions of B. juncea and B. rapa in two years under tropical conditions of southeastern Brazil. Significant variation was observed between B. juncea and B. rapa accessions for yield components and oil content. B. rapa was the earliest maturing and had the highest oil content, whereas B. juncea had the highest number of pods and the highest yield and oil yield. Brassica rapa accessions flowered early, with an average cycle of 97 days, whereas B. juncea reached maturation after 110 days on average. Accessions were grouped according to the oil content of each species, with the most promising accessions having an oil content of 45–47%. Accessions of Brassica species had high oil yields, reaching 910 kg ha-1 of oil yield for B. juncea PI 180266. There was a linear correlation between oil content and thousand seed weight, pod length, and seeds per pod of the Brassica species accessions. Considering oil content and oil yield across years, Brassica species show promise as alternative oilseed crops for biodiesel production in tropical conditions.

Resumo em Inglês:

ABSTRACT Rhodiola rosea L. is an endangered medicinal plant distributed in mountains and in high latitude regions. For its conservation, sustainable methods for the obtaining of its bioactive compounds must be developed. This work hypothesized that leaf, stem and rhizome explants of R. rosea from different geographical origins respond differently to inoculation with Rhizobium rhizogenes agropine strain ATCC43057. The objective was to generate R. rosea hairy roots (HRs) containing rol-genes. These HRs could be cultivated under axenic conditions for the extraction of the medical compounds rosavinoids and salidroside. Hereby, production of bioactive compounds could be improved per plant biomass. Thirteen R. rosea accessions of Alpine, Scandinavian, Nordic Gene Bank (NGB) and Russian origins were compared for their explant survival and HR formation. Significant differences were observed among plants from different geographical origins, where the NGB leaf explants exhibited up to 70% of HR formation and the Russian accessions did not exhibit HRs at all. Moreover, maintaining explants in light conditions after R. rhizogenes inoculation resulted in higher explant survival and HR formation rate (35%) when compared with explants kept in darkness (9%). Taken together, an efficient HR formation in roseroot by inoculation of R. rhizogenes following culturing in light was reported as a required step. This work represents a stepping-stone to R. rosea HR cultivation in bioreactors as well as regenerating whole plants. Hence, it is initiating a novel route towards high-throughput production of bioactive compounds as well preventing depletion of natural roseroot populations.

Resumo em Inglês:

ABSTRACT Developing biofortified foods such as lettuce is a frequent goal of breeding programs. One obstacle to the success of these efforts is the high temporal and financial cost of determining leaf constituents. Image phenotyping has been increasingly used in crop breeding, but not in lettuce breeding. Until now, the use of image phenotyping to indirectly select carotenoid-rich lettuce inbred lines has not been reported. Therefore, the goal of this study was to use image phenotyping to select lettuce inbred lines with different carotenoid levels. Twenty-two inbred lettuce lines, resulting from the hybridization of the cultivars Pira 72 and Uberlândia 10000 and six successive selfings were evaluated. ‘Grand Rapids’, ‘UFU-Biofort’ and ‘Uberlândia 10000’ were used as controls. The following variables were evaluated: agronomic potential, apparent genetic diversity and image phenotyping. The data were submitted to the ANOVA F test (p ≤ 0.05) and means compared by the Scott–Knott test (p ≤ 0.05). Genetic divergence was represented by dendrograms constructed by UPGMA and the Tocher optimization method. The relative contribution of characters was assessed to identify the most relevant response variable. The genetic diversity of the evaluated germplasm bank was the greatest regarding soil plant analysis development (SPAD)/carotenoid values. Image phenotyping was successfully used to detect different levels of SPAD/carotenoid levels and could be a useful tool for plant breeding. The results of this study can be used to predict the nutritional values of the carotenoid content in lettuce leaves before commercialization.

Resumo em Inglês:

ABSTRACT The use of remote sensing in agriculture presents some practical applications in crop production forecast. In this context, studies with remote sensing are scarce for crops such as white oats, which may indicate the capacity of using this technique in the crop. The aim of this study was to evaluate the accuracy in validation of white oat biomass and grain yield estimates by spectral models previously calibrated using two vegetation indices (NDVI and IRVI) at three phenological stages. The mean values of NDVI and IRVI were correlated with the grain and biomass yield of white oats to obtain regression equations. The accuracy was verified by the determination coefficient (R2), root mean square error (RMSE) and mean bias error (MBE). The models were calibrated using data from a field experiment carried out in 2017 and validated with data from the same experiment, but conducted in 2018. The models had good generalization capacity for estimating yield of white oats, especially for biomass yield. Parametrized models in more advanced phenological stages, showed lower error of estimation. Models calibrated with the vegetation index IRVI had lower error of estimation than when calibrated with NDVI.

Resumo em Inglês:

ABSTRACT The evaluation of segregating populations in plant breeding programs is an onerous and time-consuming process. Early identification of populations with genetic potential can be done by m + a methodology. However, the possibility of a modification in the traditional methodology in order to make it more efficient, that is, faster and cheaper, was envisaged. Thus, the objective of this study was to compare the genetic gains obtained by both methodologies, the traditional one and the proposed modification. For this, ten segregating bean-cowpea populations were evaluated at two distinct levels of homozygous F3:4 and F3:5. Genetic values were predicted by two different statistical genetic models. This was possible due to the methodology proposed here to present a much shorter execution time than the traditional methodology. Thus, with a shorter evaluation time, the breeding program manager can plan the evaluation of a larger number of populations in a short time.

Resumo em Inglês:

ABSTRACT Stink bugs that affect soybeans are responsible for significant losses in seed production, quality and germination potential, in addition to hindering the mechanized harvest. To develop insect resistant materials, the breeder can compile a selection index by factor analysis. Therefore, the objective of this work was to validate the use of factor analysis, by means of its estimated gains, for the selection of highly productive and stink bugs resistant genotypes in two soybean segregating populations. For this, the phenotypic evaluation was performed in the generation F2:3, in two distinct experiments, being the populations from the crosses between IAC-100 × PI 295952 and IAC-100 × PI 306712. The experiments were installed in an 18 × 9 alpha-lattice design, with three replicates for each population. Agronomic and resistance characters were evaluated. The factorial scores for each character were obtained for the creation of “supercharacters”. These were designed to check if the selection in the new characters could provide satisfactory simultaneous gains in the original characters. Subsequently, the analysis of variance was performed for all factors, in both populations. The F test showed the presence of variability among genotypes, allowing the selection of superior genotypes. None of the factors selected progenies with all the characters favorably, and their use was not interesting for both populations. With this, complementary studies should be performed with other selection indices in these populations.

Resumo em Inglês:

ABSTRACT Kiwifruit vines are an alternative approach to diversify Brazilian fruit farming because of the low supply and increase in the demand for their fruits. Hydrogenated cyanamide, which is the most common rest-breaking agent, is highly toxic and its use is not allowed in organic production systems. This study aimed at evaluating the efficiency of alternative rest-breaking agents in kiwifruit vines by using the biological method of single node cutting. Twigs of the cultivar Bruno were collected in an organic orchard in Pelotas, a city located in Rio Grande do Sul state, Brazil. Seven-centimeter-long cuts with a single shoot at the ends were segmented. Cuttings were placed on plastic trays with phenolic foam and soaked in water, at 85% relative humidity on average, and kept in bio-oxygen demand (BOD) incubators at 25± 1 °C and a 16-h photoperiod. Budbreak was evaluated in 2-day and 3-day intervals. The experiment was conducted in a completely randomized design with ten treatments and three replications of ten sampling units each. The following variables were analyzed: average budbreak time (ABT), final budbreak rate (FBR), vigorous budbreak rate (VBR), velocity of budbreak (VB), percentage of open buds (POB) and dormancy index (DI). The rest-breaking agent garlic extract (GE) 10% + mineral oil (MO) 2% was the most efficient one in budbreak induction in both production cycles. Thus, this dose is recommended for budbreak induction in kiwifruit vines grown in an organic system.

Resumo em Inglês:

ABSTRACT Chardonnay cultivar has shown great potential of planting and development in sites above 900m of Brazilian southeast for sparkling wines production. The quality of this product is related to vineyard climate and management, since both affect the vine development and grape composition. In this study, three defoliation orientations (east, west and east/west face), at veraison, and a group without defoliation, were compared in order to observe the impacts of this management on the productivity, grape and base wine quality. Yield, grape components, must and base wine composition were analyzed for two years. East/west defoliation increased alcohol content and decreased acidity in base wines, while the group without defoliation increased acidity, according to the higher and lower sun exposure, respectively. Defoliation at veraison increased the incidence of bunch rots. Differences in the aromatic composition of the base wines between the harvests were identified. The east/west defoliation treatment presented more intense fruity, citrus and tropical aromas. For regions characterized by subtropical highland climate (Cwb) in the Brazilian Southeast, late defoliation is not recommended since defoliated plants were more susceptible to fungus infection at flowering and berry formation.

Resumo em Inglês:

ABSTRACT The widespread use of transgenic plants imposes selection pressure on insect pest populations to develop insecticide resistance. Evaluation of effectiveness of resistance management strategies is very important in resistance management programs. Resistance management to insecticides is widely believed to depend in part on associated fitness costs. Fitness costs can delay the development of resistance. In the present study, the effects of two entomopathogenic nematode species, Steinernema carpocapsae and Heterorhabditis bacteriophora were studied on the fitness of first insect population of Heliothis virescens selected with Vip3A in the laboratory. It was found that both nematodes species increased the fitness cost of Vip3A selected insects. The mortality of the Unsel subpopulation after exposure to either nematode species was significantly lower than that of the Vip3A-Sel subpopulation. Likewise, the reproduction of both nematode species was significantly greater in cadavers of the Unsel compared with the Vip3A-Sel subpopulation of H. virescens. There was positive correlation between nematode reproduction and the larval instar infected with nematodes. The penetration of infective nematode juveniles (IJ) was greater in the Vip3A-Sel subpopulation than in the Unsel subpopulation of H. virescens. It is concluded that entomopathogenic nematodes could increase the fitness costs and subsequently delay the resistance.

Resumo em Inglês:

ABSTRACT The pre-sprouted sugarcane plantlets (PSP) system aims the production of healthy and vigorous plants in reduced time, reducing the number of stalks needed for planting. Irrigation is used in all PSP system stages and water management plays an important role. Stage 1 acclimation follows the budding stage and lasts for approximately 21 days. At this stage the plantlets are grown within an agricultural greenhouse to improve initial development. The objectives of this trial were: to identify the irrigation management which results in highest plantlet growth; to evaluate if responses to irrigation management depends on the cultivar; to evaluate water consumption and water use efficiency at early stage under PSP system; and to assess the water management effect on substrate water matrix potential and stomatal conductance in the cultivar IACSP95-5000. The experimental design was a split-plot randomized block design with four replications. Treatments applied in the plots were different irrigation depths based on daily reference evapotranspiration (ETo): 96, 80, 64 and 48%, estimated by Penman–Monteith method. In the subplots, there were sugarcane cultivars IAC91-1099, IACSP95-5000 and IACSP97-4039. Irrigation management based on 80% ETo resulted in higher growth, dry mass accumulation and greater leaf area. Water use efficiency was not influenced by irrigation management. IAC91-1099 presented higher overall growth, leaf area and dry mass accumulation. Water consumption was cultivar-dependent in irrigation managements using 80 and 96% of ETo. Water use efficiency was higher in IAC91-1099 and lower in IACSP95-5000. Lower substrate water matrix potential reduced leaves stomatal conductance, impairing IACSP95-5000 plantlet growth.