Information on the effect of endogamy and combining ability of inbred families is essential in hybrid maize (Zea mays L.) breeding programs. The objective of this study was to evaluate the effect of inbreeding in a maize population and the performance of top-cross hybrids from this population, with a broad genetic base tester. First, 110 S1 families were generated and established in the field along with families from the original population. The experiment was arranged in a randomized block design with three replicates, in 3.0 m plots with 15 plants. Traits of agronomic importance, inbreeding depression, and the general effect of dominance deviations were estimated the first stage. In the second stage, 69 inbred families (S2) with low inbreeding depression were evaluated by top-cross tests using the F2 generation of the commercial hybrid AG 6040 as tester. The same traits from the first stage were evaluated. Inbreeding depression in the first stage was higher for traits related to production, which indicates that the heterozygous loci contribute more to these traits, with the additive effects being less important. In the second stage, the best estimates of the general combining ability (GCA) for grain weight were found in progenies 51, 33, 17, 9, 3, and 67, showing good performance and good potential for use in breeding programs.

Citrus fruit tree has great importance in Brazil. Despite having many commercial cultivars, the lemon crop in Brazil is basically from “Tahiti” cultivar and there is a lack of studies about the characterization and assay of genetic diversity of sweet lemon (Citrus limetta) fruits. Therefore, this work aimed to characterize and evaluate the genetic diversity from nine stock plants produced in Porto Nacional-TO. Fruits in fully physiologic ripening were harvested and evaluated for weight, length, diameter, juice yield, soluble solids content, and color of peel and pulp. The experimental design was completely randomized with 9 treatments (stock plants) and five replications. For the characterization, the data were subjected to Tukey’s test and similarity measure and clustering of the stock plants were performed by Tocher’s method and UPGMA dendrogram. Weight, length, and diameter of all stock plants have not differed from each other. The coordinate b* indicated that stock plant 1 had fruits with peel and pulp clear when compared to the yellow color of the other stock plants. There was genetic diversity between the assessed stock plants and three groups were created, which stock plant 1 and 2 were the most divergent and compose group 3, according to Tocher’s method. The features contributed similarly to total variation.

The propagation of ‘cajá-manga’ (Spondias dulcis) is usually performed by seeds. The presence of dormancy is an obstacle for seedling production and the commercial use of its main product, the fruit. This research aimed to evaluate the use of phytoregulators associated with the scarification of the distal region of the embryo in dormancy overcoming and in the standardization of germination of ‘cajá-manga’ seedlings. Endocarps extracted from fruits of six matrices were subjected to the following treatments: control (T1), mechanic scarification in the distal region of the embryonic axis (T2); all following treatments involved scarification and imbibition in a solution of: water for 6h (T3); GA3 (750 mgL-1) for 6h (T4); GA3 (350 mg L-1) for 12h (T5); Cytokinin (750 mg L-1) for 6h (T6); Cytokinin (350 mg L-1) for 12h (T7); GA3 and Cytokinin (750 mg L-1) for 6h (T8); and GA3 and Cytokinin sowing 25 endocarps in expanded polystyrene trays using a washed sand substrate. The following variables were evaluated: emergence, first emergence count, emergence speed index, mean emergence time, shoot and root length of seedlings, and relative emergence frequency. The experimental design was in randomized blocks, with 9 treatments and four replications consisting of 25 endocarps each. The data obtained were subjected to the F Test at a 1% level of probability, as well as to the Scott-Knott method. The use of mechanic scarification in the opposite region of the embryonic axis, followed by the imbibition in a solution of gibberellin + cytokinin at the concentration of 350 mgL-1 for 12 hours is promising for dormancy overcoming in seeds of Spondias dulcis.

Abstract The peach tree is a temperate fruit tree propagated by grafting with the scion cultivar and the rootstock from seeds, generating low uniformity, a viable alternative is propagation by herbaceous cuttings. The objective of this study was to evaluate the performance of different genotypes of peach rootstock propagated by herbaceous cuttings. The experiment was carried out with standardized cuttings of 15 cm in length treated with 3,000 mg L-1 of IBA solution, then were transplanted into 3 L polyethylene bags. A completely randomized design with five replications was adopted, each plot consisting of three plants. Sixteen peach genotypes from UFV breeding program were tested: 713-3, 713-6, 713-7, 713-10, 813-2, 813-3, 813-5, 813-15, 913-3, 913-6, 913-11, 913-17, C6, C7 and C8. After 80 days the following parameters were evaluated: stem length (cm), stem diameter (mm) and internode length (cm). Data were subjected to analysis of variance by the F test and averages compared by the Scott-Knott test at a 5% probability level with the GENES statistical software. It can be concluded that the lower initial development was observed in genotype 1113-11 and the highest initial development was from genotypes 713-13 and 813-5.

The Anacardium humile A. St.- Hil. fruit tree has productive potential, being their fruits appreciated in the Cerrado region for having characteristic flavor, however, this species is still exploited in an extractive way, being necessary studies for its domestication. The aim of this work was to estimate the leaf area of Anacardium humile. One hundred leaves were collected in the biological collection from a genetic resources field and evaluated for length, width and fresh weight, and scanned at resolution of 300 dpi to determine the leaf area with the aid of the ImageJ image analysis program. Subsequently, a leaf disc with a diameter of 22.27 mm was detached at the basal portion of each leaf, in which the fresh weight of the discs was obtained. Data were submitted to descriptive analysis and the relationship among the features explained by Pearson’s correlation with the software Rbio. The data were also subjected to regression analysis to explain the relationship between leaf area and measurements of width, length and leaf weight, and to fit the proper statistical model with the software Origin. It was concluded that leaf area can be determined by image analysis software and linear measurements are correlated to leaf area.

This research studied the morphology of seeds and seedlings, in addition to obtaining information about the type and time of germination of sweet lemon seeds in five substrates (on blotting paper, between blotting paper, on washed sterilized sand, between washed sterilized sand and in paper roll). C. limetta seeds were measured, and external description was performed. Afterwards, sown in the sand and kept at 25 ºC to monitoring germination and morphological description of the resulting seedlings. A second experiment was evaluated for substrate efficiency: paper roll, on and between paper, on and between sand in the germination of C. limetta seeds. Speed index, average time and relative frequency of germination were evaluated. In addition, date of the first and last germination count was established. Treatment averages were compared using the Tukey test at 5% probability. C. limetta seeds are ovoid, slightly wrinkled and polyembryonic. Germination is hypogeal, cryptocotylar or phanerocotylar. The seedlings have leathery eophylls with simple leaves, elliptical shape or close to the elliptical, tending to ovate. It has a pivoting root system that is colored yellow to cream with the presence of secondary roots. The average germination time is between 18 and 22 days. The substrate indicated for seed germination is on paper.

Maize is the second most produced grain in Brazil, which has the potential to produce green maize, which is maize harvested before physiological maturation. Aimed with this work evaluate three packages for postharvest conservation of green maize at room temperature in the conditions of the Brazilian cerrado. The double hybrid AG-1051 were planted. After the cobs were harvested, they were submitted to three treatments, each treatment with three repetitions and each repetition contained 4 cobs. The analyzes carried out were: fresh weight loss, instrumental coloring, titratable acidity content, ascorbic acid content and soluble solids. The results were submitted to the 5% Tukey test and regression. The treatment with polyethylene stood out for the loss of fresh mass, color of the maize cobs as for the levels of titratable acidity, presenting the best results and, for the same parameters, the maize cobs of the treatment with straw showed the lowest results, showing that the conservation straw cobs is the least suitable treatment. As for the content of ascorbic acid and soluble solids, the results showed no statistical difference for any of the treatments showing that they kept the contents unchanged during storage.

In plant breeding programs, the selection of potential progenies in early generations of inbreeding is an essential step. Considering that, the adoption of topcrosses helps the breeder in the selection, this study aimed to verify the potential of S 2 strains for synthesis of synthetic varieties and to obtain experimental information on yield and agronomic potential of topcross hybrids. As such, 75 topcross hybrids were generated from crossing 75 S 2 lines with F 2 generation of the commercial hybrid. The 75 hybrids were grown in a field, along with two commercial hybrids in a randomized complete block design with 4 replicates and in 4-meter plots. Flowering, plant height, height, diameter, length and weight in the ear, and grain yield traits were examined. Analysis of variance was performed, the combining ability was estimated, and, from the means, the Scott & Knott test was conducted. So, the topcross hybrids that distinguished themselves for grain yield were those composed by lines 67, 14, 44, and 69, presenting high CGA, therefore indicating good potential for producing synthetic or base population. For the other traits of agronomic interest that were assessed in maize, a potential for selection with different focuses was found: reduction of cycle and height and increase in length and diameter of the ear.