Seleção e divergência genética de pessegueiros e nectarineiras e susceptibilidade a danos causados pelo frio na Estación Experimental de Aula Dei (CSIC)

The peaches and nectarines are highly appreciated by consumer, but it is climacteric fruits, with availability in the market in small time. It is necessary to invest to obtain genotypes with fruit quality and small perishability or that it presente less physiological disorders after storage. The aims of this work were i) to evaluate the genetic divergence among 40 peach and nectarine trees genotypes based on postharvest quality and select posible parents; ii) to evaluate the susceptibility to chilling injury in peaches and nectarines after cold storage; iii) to evaluate divergence of peaches and nectarines on the basis in the susceptibility for chiling injury and select superior genotypes; iv) evaluate the correlations between quality and susceptibility to chilling injury of peaches and nectarines v) select parents with the combination of lower susceptibility to chilling injury and higher quality fruit. The study was carried out in EEAD-CSIC, Zaragoza - Spain, during the production cycle 2013/2014. A total of 40 peaches and nectarines genotypes from germplasm collection were evaluated. The quality characteristics as flesh firmness, total soluble solids, titratable acidity, pH, rippining index and flesh color parameters were evaluated. The fruits were submitted to cold storage at 0 °C and 5 °C, with 95% average relative humidity. The evaluations were after 14 and 28 days, it being observed the presence of symptoms, such as wooliness through mealiness, flesh grainy, leatheriness and flesh color changes, through browning, bleeding and off flavor. As a selection parameter was adopted 20% of genotypes that had a higher frequency of superiority for quality characteristics, susceptibility to chilling injury and the combining of both. For quality characteristic presented greater divergence the ‘Queen Giant’, ‘Sudanel Blanco’ and ‘Borracho de Jarque’. Based on the quality the eight genotypes were selected, ‘Andross’, ‘San Jaime’, ‘San Lorenzo’, ‘Borracho de Jarque’, ‘Sudanell 1’, ‘Carson’, ‘Baby Gold 6’ and ‘Stanford’. All genotypes studied exhibited susceptibility to one or more symptoms caused by cold storage during 28 days, independent of temperature. For 14 days, the ‘Baby Gold 6’, ‘Flavortop’ and ‘Queen Giant’ genotypes did not show any physiological disorder caused by cold. In general, the temperature of 0 °C favored fruit postharvest conservation, it have a lower incidence and severity of symptoms caused by cold storage. The storage for 14 days contributed for the lower incidence of damage in the genotypes fruits studied. For 14 days, with both temperatures, it was observed divergence for ‘Queen Giant’, ‘Sudanell Blanco’, ‘Baby Gold 6’ ‘GF3’, ‘Baby Gold 8’, ‘Campiel’ and ‘Campiel Rojo’ genotypes. For 28 days, in the 5 °C condition, ‘Queen Giant’, ‘Big Top’, ‘Flavortop’ and ‘Redhaven’ genotypes were divergents. Based on susceptibility to chilling injury at 0 °C, the eight genotypes were selected, it being these, ‘Queen Giant’, ‘Keimoes’, ‘Flavortop’, ‘Big Top’, 'Redhaven', 'Sudanell 3', 'Bonet I' and ‘Carson’. The quality parameters as rippining index, soluble solids, firmness and titratable acidity presented correlation among them. These, also it had correlation with woolines and bowning, what it indicate that fruits with more ripening can have this symptoms more easily. The browning, mealiness, flesh grainy and off flavor variables were correlationed with the time period and temperartures, what it confirm that these symptoms are the main disorders caused by cold storage. The quality characteristics together susceptibility to chilling injury allowed selected ‘Baby Gold 6’, ‘Sarell’, ‘Keimoes’, ‘GF3’ ‘San Jaime’, ‘Big Top’, ‘Sudanell 1’, ‘Carson’, ‘Baby Gold 8’, and ‘San Lorenzo’ genotypes.

Efeito de fatores ambientais e tolerância a herbicidas em três espécies de plantas daninhas da família Rubiaceae

The strong selection pressure exerted by intensive use of glyphosate in cultivated areas has selected populations of the Rubiaceae weed species Borreria latifolia (Aubl.) K.Shum. (broadleaf buttonweed), Galianthe chodatiana (Standl.) E.L. Cabral (galiante) and Richardia brasiliensis Gomes (Brazilian pusley) with differential sensitivity to this herbicide in the South region of Brazil. The control of these weeds with herbicides is troublesome and signals the need to incorporate management practices of ruderal flora and crops, more sustainable and that results in more efficient control for long-term. Therefore, it is very important to expand the information about their biology and management. This study aimed: (a) select efficient methods to overcome dormancy of B. latifolia and G. chodatiana and determine how they influence the kinetics of seeds germination; (b) analyze the effects of temperature, irradiance, pH, aluminum and salinity on seed germination and initial growth of the B. latifolia, G. chodatiana e R. brasiliensis seedlings; (c) evaluate tolerance to glyphosate levels in biotypes of B. latifolia, G. chodatiana e R. brasiliensis through dose-response curves and compare two methods to evaluate herbicidal control; (d) and evaluated the effectiveness of alternative herbicides in pre-emergence and in early and late post-emergence of the three species. The treatment with KNO3 2%/3h + gibberellic acid 400 ppm resulted in higher percentage of G. chodatiana seed germination. This treatment and also the dry heat (60°C/30 min) + KNO3 2%/3h were more effective in overcoming dormancy of B. latifolia. G. chodatiana and R. brasiliensis tolerate lower temperatures during the germination process, while B. latifolia tolerate higher temperatures. B. latifolia and R. brasiliensis are positive photoblastic while G. chodatiana is indifferent to the photoperiod. B. latifolia shows higher germination and early development in pH 3, while G. chodatiana and R. brasiliensis prefer pH range between 5 and 7. B. latifolia and G. chodatiana were more tolerant to the aluminum during the germination process than R. brasiliensis. Low salt levels were sufficient to reduce the seed germination of the three species. Some biotypes of B. latifolia and R. brasiliensis showed medium-high glyphosate tolerance, not being controlled by higher doses than recommended. The G. chodatiana specie was not controlled with the highest dose used, showing a high glyphosate tolerance. The sulfentrazone, s-metolachlor and saflufenacil herbicides sprayed in pre-emergence showed high efficacy both on B. latifolia and R. brasiliensis, while chlorimuron-ethyl and diclosulan were effective only on R. brasiliensis. In early post-emergence the fomesafen, lactofem and flumioxazin herbicides efficiently controlled plants of all species, while bentazon showed high efficacy only on B. latifolia. Noteworthy the susceptibility of the G. chodatiana specie for applications in early post-emergence, because the control effectiveness and the number of effective herbicides are reduced with increasing the plant age. Many treatments with tank mix or sequencial applications with glyphosate, were effective in controlling B. latifolia and R. brasiliensis plants in advanced stage of development.