Laércio Junio da Silva

Priming and drying on the physiological quality of eggplant seeds

We evaluated the effect of the priming with polyethyleneglicol (PEG) 6000 followed or not of drying on two lots of eggplant seeds with medium and low vigor respectively. The seeds were submitted to the treatments of priming with PEG 6000 in the osmotic potentials of -0.6, -0.9 and -1.2 MPa during 48 or 96 hours of priming with and without subsequent drying. For the soaking of seeds in osmotic solutions, these were placed over three sheets of paper boxes such germitest gerbox conditioning moistened with each solution in a 3:1 ratio. The control group was represented by unprimed seeds. The priming for both lots provided higher values in relation to the vigor through the first counting of germination, seedlings and primary root length, germination and emergence rates, emergence and dry weight of seedlings when compared to the non-primed seeds. These results were not verified for germination; significant differences practically were not observed in relation to the controls. Improvements in relation to the vigour were not higher on lot 2 than those obtained on lot 1. The priming with PEG 6000 with subsequent drying increased the vigor of eggplant seeds of the cultivar Morro Grande in relation to those non-primed, however, without differences in the germination.

Relationship between fruit maturation stage and physiological quality of physic nut (Jatropha curcas L.) seeds

The physic nut (Jatropha curcas L.) has great potential for use in biodiesel production due to the high oil content of its seeds. Production of high quality seeds depends upon the appropriate time of harvest. A field experiment was carried out to monitor the maturation process of physic nut seeds and to establish the ideal harvest time of the seeds based on external fruit color. Fruits were collected at different maturation stages based on the external color: green, yellow-green, yellow, yellow-brown and brown. Seeds were extracted manually and, after natural drying, were submitted to the following tests and determinations: moisture content and dry matter, germination, first count seedling emergence, seedling growth, accelerated aging, electrical conductivity, the weight of thousand seeds and oil content. A randomized design was used with four replications. Data were subjected to analysis of variance and, for each test, treatment means were compared by Tukey test at 5% probability. Physic nut seeds with high physiological quality are obtained from yellow and yellow-brown fruits. Seeds from green fruits have lower physiological quality, dry matter and oil content than the other maturation stages. The seeds obtained from brown fruits have a high germination potential, but have low vigor in relation to yellow and yellow-brown stages.

FISIOLOGIA DA GERMINAÇÃO DE SEMENTES DE Dalbergia nigra(Vell.) Allemão ex Benth. SOB DIFERENTES TEMPERATURAS E TEMPOS DE EXPOSIÇÃO

The seeds germination depends on abiotic factors, the temperature being one of the most important, whose influence, in extreme conditions, causes damage to the seeds. The present study aimed to investigate the effect of different temperatures during germination of Dalbergia nigra and its implications in the physiology of the seeds. We evaluated the percentage of germination, germination speed index (GSI) and integrity of cell membranes by electrical conductivity test of seeds at different times of exposure to temperatures of 5, 15, 25 (control), 35 and 45 °C. The temperature of 25 °C was the ideal temperature for germination. At temperatures of 5 and 45 oC germination was null. There was a reduction of germination of D. nigra seeds with the increase of the exposure time of the seeds at temperatures of 5, 15, 35 and 45 °C. Unlike other temperatures, the semipermeability of the membrane is not recovered at temperatures from 5 to 45 °C. Electrical conductivity is an efficient technique to evaluate the physiological quality of the seeds at different temperatures.

Basal defoliation and their influence in agronomic and phytopathological traits in tomato plants

The incidence of leaf diseases is one of the main factors limiting the tomato crop production, increasing the production cost due to excessive pesticide application. The basal leaf removal could reduce inoculum sources, disease severity and contribute to reducing the use of pesticide. Aiming to evaluate the efficiency of this practice on the reduction of tomato leaf diseases and the effect in the quality and in the productivity of the tomato plants for in natura consumption, two experiments were carried out to test four levels of basal leaf removal. Basal leaves removal, at fruit harvesting, is efficient in reducing the infected plant area by disease, what can mean smaller disease severity and least inoculum source in the field. Also, the all basal leaf removal does not affect yield and quality of the tomato fruits. Other studies are necessary to evaluate the effect of adopting this practice in different planting dates, spacing, varieties, successive plantings and the financial viability of adopting this practice.

Teste de envelhecimento acelerado para avaliação do vigor de sementes de Jatropha curcas L.

Atualmente, ha grande interesse pelo cultivo do pinhao manso para a producao de biodiesel, o que tem levado a um aumento na procura por sementes, exigindo informacoes precisas sobre a sua qualidade fisiologica, especialmente o vigor. Objetivou-se avaliar a eficiencia do teste de envelhecimento acelerado, com variacoes, para a verificacao do vigor de sementes de pinhao manso. Sementes de quatro lotes foram incialmente caracterizadas quanto a qualidade fisiologica pelos testes de germinacao e de vigor. Para a realizacao do teste de envelhecimento acelerado, foram testadas as temperaturas de 42 e 45 oC, por 48; 72 e 96 horas. O experimento foi conduzido em delineamento inteiramente casualizado e as medias dos tratamentos comparadas pelo teste de Tukey (p<0,05). Foram calculados os coeficientes de correlacao de Pearson entre os resultados de envelhecimento acelerado e os dos demais testes. O teste de envelhecimento acelerado a 42 ou 45 oC por 48 horas, e eficiente para classificar lotes de sementes de pinhao manso em niveis de vigor.

Natural mortality factors of tomato leafminer Tuta absoluta in open-field tomato crops in South America: Natural mortality of tomato leafminer

BACKGROUND Little importance has been given to the role of natural mortality factors (biotic and abiotic) in the regulation of tomato leafminer Tuta absoluta (Lepidoptera: Gelechiidae) populations. The present study determined the action of mortality factors on T. absoluta populations infesting cultivated tomato crops. Eighty ecological life tables for T. absoluta in field cultivated tomato plants were constructed and analyzed. RESULTS Total T. absoluta mortality was 99.08%, with 38.76% mortality during the egg phase, 57.20% in the larva phase and 3.12% in the pupal phase. The main mortality factors during the egg stage were predation, parasitism and egg inviability. In the larval stage, the main mortality factors were predation, parasitism, entomopathogenic agents and physiological disorders. In the pupal stage, the main mortality factor was predation. The larvae of the third and fourth instar were more susceptible to the action of mortality factors and the predatory wasp, Protonectarina sylveirae, was the main insect predator of these larvae. CONCLUSIONS The T. absoluta population is regulated under field conditions by the action of natural enemies of the larvae. The predatory wasp P. sylveirae is very important in the regulation of T. absoluta populations in open-field tomato crops in Brazil.

The effect of fruit maturity on the physiological quality and conservation of Jatropha curcas seeds

The aim of this study was to evaluate the effect of fruit maturation stage on the physiological quality of J. curcas seeds during storage. Thus, seeds were extracted from fruits harvested at different maturity stages based on external color, i.e., yellow, yellow-brown and brown (dry fruits). After natural drying, the seeds were packed in Kraft paper bag and stored for 18 months at laboratory environment. Initially and every three months, the seeds were evaluated for moisture content, germination, first count of germination, accelerated aging, cold test, electrical conductivity and emergence. There was reduction in seed physiological quality, with decrease in germination and vigor, especially after nine months of storage. The seeds extracted from yellow and yellow-brown fruits are the most vigorous and can be stored for up to nine months without loss of physiological quality.

Seed Multiplication and Maintenance

The seeds are the instruments that lead to the farmer all the technology invested during the breeding of a certain cultivar. Thus, seed multiplication and maintenance stages are critical to the success of any breeding program. The breeding companies must maintain a minimum stock of genetic seeds, which corresponds to the first generation of a cultivar, and these should be maintained with high purity. These seeds are multiplied to meet the demand for seeds by grain producers. Therefore, special cares are essentials during multiplication of these seeds, aiming the maintenance of their identity and genetic purity. In this sense, some procedures are necessaries during all stages of seed production to reduce to the minimum the risks of contamination, as isolation of the fields destined for seed production, cleaning of machinery, identification and removal of plants that do not correspond to the cultivar planted, and certification of the genetic purity of seed lots. A general discussion of these topics is addressed in this chapter.

'Sensory analysis of specialty coffee from different environmental conditions in the region of Matas de Minas, Minas Gerais, Brazil

Specialty coffees can be differentiated in various ways, including the environmental conditions in which they are produced and the sensory composition of the drink. This study aimed to evaluate the effect of altitude, slope exposure and fruit color on the sensory attributes of cafes of the region of ​​Matas de Minas. Sampling points were georeferenced in four altitude ranges (< 700 m; 700 ≤ x ≤ 825 m, 825 < x < 950 m and ≥ 950 m) of the coffee crop; two fruit colors of var. Catuai (yellow and red); and two slope exposures (North-facing and South-facing). Coffee fruit at the cherry stage were processed and submitted to sensory analysis. The sensory attributes evaluated were overall perception, clean cup, balance, aftertaste, sweetness, acidity, body and flavor, which made up the final score. The scores were examined by ANOVA and means were compared by the Tukey test (p ≤ 0.05). From the sensory standpoint, coffee fruits of both colors are similar, as well as the coffees from both slope exposures when these factors were analyzed separately. However, at higher altitudes, Yellow Catuai produces coffees with better sensory quality. Similarly, coffees from North-facing slopes, at higher altitudes produce better quality cup. The altitude is the main factor that interferes with coffee quality in the area. All factors together contribute to the final quality of the beverage produced in the region of Matas de Minas.

Condicionamento osmótico e desempenho de sementes de repolho com diferentes níveis de vigor

O condicionamento osmotico de sementes vem sendo indicado como alternativa para uniformizar e acelerar a germinacao e a emergencia de plântulas, especialmente em hortalicas. Assim, objetivou-se avaliar o efeito do condicionamento osmotico sobre o desempenho de lotes de sementes de repolho com diferentes niveis de vigor. Foram utilizadas sementes de quatro lotes de repolho, cultivar 60 dias. No primeiro ensaio, as sementes foram condicionadas em solucao aerada de PEG 6000 a -1,0 MPa por 0, 2, 4 e 6 dias, a 20oC. As sementes de cada tratamento, submetidas ou nao a secagem ate atingir novamente o teor de agua inicial, foram avaliadas mediante testes de germinacao e de emergencia de plântulas em casa de vegetacao. Num segundo ensaio, sementes da mesma cultivar foram submetidas ao envelhecimento artificial a 42°C e 100% U.R. por 0, 24, 33 e 42 h e, em seguida, submetidas ao condicionamento em solucao de PEG 6000 a -1,0 MPa, a 20oC, por seis dias, sendo secadas em seguida. O condicionamento osmotico em PEG 6000, a -1,0 MPa por seis dias, beneficia a germinacao e o vigor de sementes de repolho, de maneira mais evidente em lotes de menor qualidade fisiologica.