-The objective of this work was to estimate genetic gains in physic nut (Jatropha curcas) using selection indexes and to establish the best selection strategy for the species. Direct and indirect selection was carried out using different selection indexes, totalizing 14 strategies. One hundred and seventy five families from the active germplasm bank of Embrapa Agroenergy, Brasília, Brazil, were analyzed in a randomized complete block design with two replicates. The evaluated traits were: grain yield; seeds per fruit; endosperm/ seed ratio; seed weight, length, width, and thickness; branches per plant at 0.5, 1.0, and 1.5 m; plant height; stem diameter; canopy projection on rows and between lines; canopy volume; juvenility (days to the first flowering); and height of the first inflorescence. Evaluations were done during the second year of cultivation. The use of selection indexes is relevant to maximize the genetic gains in physic nut, favoring a better distribution of desirable traits. The multiplicative and restrictive indexes are considered the most promising for selection.Index terms: Jatropha curcas, biodiesel, canopy volume, Cerrado, juvenility, seed size. Ganho genético em pinhão-manso com uso de índices de seleçãoResumo -O objetivo deste trabalho foi estimar o ganho genético em pinhão-manso (Jatropha curcas) com uso de diferentes índices de seleção e estabelecer a melhor estratégia de seleção para a espécie. A seleção direta e indireta foi realizada com diferentes índices de seleção, o que totalizou 14 estratégias. Foram analisadas 175 famílias pertencentes ao banco ativo de germoplasma da Embrapa Agroenergia, em blocos ao acaso, com duas repetições. Foram avaliadas as variáveis: produtividade de grãos; sementes por fruto; razão endosperma/ semente; peso, comprimento, largura e espessura de sementes; número de ramos a 0,5, 1,0 e 1,5 m; altura de plantas; diâmetro do caule; projeção da copa nas linhas e nas entrelinhas; volume da copa; juvenilidade (dias até o florescimento); e altura de inserção da primeira inflorescência. As avaliações foram realizadas durante o segundo ano de cultivo. A utilização de índices de seleção é relevante para maximizar os ganhos genéticos em pinhão-manso e favorece uma melhor distribuição de características desejáveis. Os índices multiplicativos e restritivos são considerados os mais promissores para uso na seleção.Termos para indexação: Jatropha curcas, biodiesel, volume de copa, Cerrado, juvenilidade, tamanho de sementes.

The cultivation of avocado cv. Hass (Persea americana Miller) in Colombia has grown in recent years. Among the country's challenges is to increase the orchards' productivity by guaranteeing grafts plants the best agronomic, genetic, and phytosanitary parameters. This work aims to evaluate for 90 days (nursery phase) the growth and development of avocado rootstocks originated from seeds with different weight ranges. A completely randomized experimental design was carried out, with treatments consisting in four Creole avocado seed weights (40-60 g, 60-80 g, 80-100 g, and over 100 g). In general, seeds greater than 80 g had the best germination percentage (over 70 %), a greater plant height, and a greater stem diameter in each of the evaluated periods. The seeds greater than 100 g presented the emergence of multiple stems at 30 days after transplanting; this fact was related to the size and reserves of the seed. The highest accumulated dry matter in stems, leaves, and total plant (without seeds) (cotyledons) were present in treatments with seeds above 80 g. These plants showed higher germination, significant more accumulation of biomass and greater vigor, which could shorten the nursery time while guaranteeing the quality of the material influenced by improved growth and seedling survival.

Rubus glaucus is widely distributed throughout the three mountain ranges of Colombia, where the blackberry growers have highlighted the need to standardize the supply of planting material, starting with plant breeding schemes that lead to more productive varieties with morphological characteristics that ease agricultural activities. Plant breeding activities have improved by considering the pollination mechanisms of plants. The implementation of controlled sexual hybridization depends on these pollination mechanisms, and several plant breeding methods have been adapted to crop pollination patterns. Morphological characteristics and studies on the floral biology of R. glaucus Benth were conducted to improve plant breeding processes. In addition, a study on pollen viability and stigma receptivity were performed. The reported morphological characteristics of R. glaucus enabled characterization of its flowers as complete and perfect with a regular, actinomorphic, perianth heterochlamydeous, dialipetalous, and dialisepalous structure. Meanwhile, the evaluation of different collection times for pollen viability revealed significant differences. The highest pollen viability occurred at 10:00 am, followed by 9:00 am. Qualitative evaluation of stigma receptivity led to the conclusion that the highest stigma receptivity is at anthesis at 12:00 m.

ABSTRACT:This study aimed to estimate the genetic diversity among soursop genotypes in terms of fruit yield evaluated in different crop years. Sixteen measurements for fruit yield in 71 soursop genotypes were carried out from 2000 to 2016. Based on ANOVA it was verified the existence of genetic variability among genotypes in the different measurements (harvests). The genotypes were clustered according to their respective fruit yield averages in the 16 years as well as from their means obtained in each measurement year by the Scott-Knott test (p<0.05). To study genetic diversity among genotypes, three methodologies were compared: Tocher hierarchical optimization, UPGMA method and principal components. Five groups were formed for all clustering methods used. It was identified that crossings between genotypes 124 and 145 with genotypes 59 and 170 are potential to generate population with large genetic variability and high fruit yield average. New researches should be developed aiming to exploit the genetic variability among soursop genotypes based on the results found in this study.

Characterizing potato cultivars provides information for diagnosing the needs of specific production and management. Techniques that enable rapid, objective, and low-cost identification of various aspects of plant physiology are important to producing this information. This study aimed to identify potato cultivars during three phenological phases using reflectance spectroscopy in the visible and near-infrared ranges. Reflectance spectra were measured using a portable spectrometer from leaves of five potato cultivars. Classification models were made to obtain the percentages of correct classification for each cultivar and phenological stage. General patterns in the reflectance spectra were obtained that were similar for all five cultivars in the measured range, with reflectance around 5% in the green region during the vegetative phase, decreasing slightly during the flowering phase and increasing up to 12% during the senescence phase. A decrease from 50–30% in reflectance was recorded in the measured NIR range during flowering with a variable increase that depended on the cultivar towards senescence. The identified wavelengths allowed the plants of each cultivar to be classified during the vegetative, flowering, and senescence phases, with correct classification rates of 87% for Var Paola, 96% for Var Paysandú, 93% for Var Violeta, and 100% for varieties 448 and 440. Var Paola obtained higher percentages of correct classification with values between 85% for Paysandú and Violeta, 90% for cv 440, and 100% for cv 448. The characterization of potato cultivars with spectroscopy techniques provides information that can be used as a basic input in precision agriculture systems.