Marinês Pereira Bomfim

Patogenicidade causada pelo fungo Colletotrichum gloeosporioides (Penz) em diferentes espécies frutíferas

The present work had as objective to evaluate the pathogenicity of C. gloeosporioides isolated from mango, papaya, guava and passion fruit. The inoculation with C. gloeosporioides was through a direct way, opening a hole on the fruit and inoculating PDA disks with a mycelium of the fungus. The control was inoculated with PDA disks without the fungus. A completely randomized blocks design was used, with 25 treatments and 3 repetitions. A factorial scheme (5 x 5) was used for evaluations. The results obtained demonstrate that all the isolated show pathogenicity in all fruit species studied. Guava is the host, which showed smaller susceptibility to the several isolated of C. gloeosporioides. Tommy Atkins and Rosa Mangoes and also papaya present larger lesions growth, therefore a larger susceptibility.

Antagonic effect in vitro and in vivo of Trichoderma spp. to Rhizopus stolonifer in yellow passion fruit

Floral rot of passion fruit is caused by the fungus Rhizopus stolonifer, which attacks newly open flowers and young little fruits. The infection starts in the inner parts of the flower buds where it causes water-soaked lesions, whose floral tissues acquire a dark-brown coloration. The presence of dark mycelium and fungus fructification is often noticed on the lesions. The present work aimed at studying the in vitro and in vivo antagonistic potentiality of species of Trichoderma spp. to Rhizopus stolonifer. In order to assess the antagonistic efficiency of biological control agents in the floral rot of yellow passion fruit, in vitro and in vivo tests were carried out with these species: Trichoderma viride, T. virens, T. harzianum and T. stromaticum, at the Biofactory of the State University of Southwestern Bahia (Universidade Estadual do Sudoeste da Bahia), campus of Vitoria da Conquista - BA, and at a farm in the municipality of Eunapolis - BA. In the in vitro tests the mycelial growths of the phytopathogen and antagonists at the temperatures of 10oC, 15oC, 20oC, 25oC and 30oC were evaluated as well as the mycelial growth within 24h and 48h, in order to verify the growth rate of the isolates. To inhibit the mycelial growth of the phytopathogen, the pairing of cultures was carried out to assess the potentiality of antagonists and the production of volatile and non-volatile metabolites. Field, the antagonists were assessed according to their capacity. In the of preventing the infection by Rhizopus stolonifer, the average number of effective fruits being evaluated on the 15th and 30th day after the application of antagonists. Through the obtained results, it was noticed that the best temperatures for the growth of antagonists and phytopathogen were at 25oC and 30oC for all isolates. During the incubation periods of 24 and 48h, significant differences in the mycelial growth were evidenced among isolates of Trichoderma spp. In relation to R. stolonifer, the antagonists demonstrated growth speed significantly higher than the phytopathogen. In paired culture, all the isolates of Trichoderma spp. showed fast mycelial growth, thus preventing the development of the phytopathogen, demonstrating antagonism in the production of volatile and non volatile metabolites with fungal action against R. stolonifer. In the field test, there was significant effect in the treatments, a higher fruit set of 74% was noted for the treatments T3 - Trichoderma harzianum and T5 - T. virens, and 75% for. The treatments T2 - T. viride and T4 - T. stromaticum the control obtained a lower percentage 42%.

Desempenho vegetativo e reprodutivo da pinheira (Annona squamosa L.) em função de diferentes comprimentos de ramos podados

O objetivo do presente estudo foi avaliar a influencia exercida por diferentes comprimentos de ramos podados no crescimento vegetativo e reprodutivo da pinheira. O experimento foi conduzido no periodo de 21-02 a 1o-07-2003, no municipio de Anage, regiao de clima semi-arido do Estado da Bahia. O delineamento experimental foi em blocos casualisados, com seis tratamentos, quatro repeticoes e tres plantas uteis por parcela. Os tratamentos utilizados foram: T1- ramos podados com 5 cm de comprimento; T2- ramos podados com 10 cm de comprimento; T3- ramos podados com 15 cm de comprimento; T4- ramos podados com 20 cm de comprimento; T5- ramos podados com 25 cm de comprimento; T6- ramos podados com 30 cm de comprimento. Constatou-se, nas condicoes estudadas, que ramos podados com menores comprimentos tendem a reduzir a emissao de flores e a aumentar o vigor de brotacoes e tamanho de frutos.

Marcha de absorção de nutrientes em anonáceas

Mineral nutrition is related to the growth and reproduction physiology of Annonaceae. Each species of Annona genus has a genetic load that presents specific nutritional requirements for their metabolic functions. The absorption march of nutrients is fundamental for determining the appropriate development stage and doses of applying fertilizers and getting the maximum productive yield. There are few scientific studies about nutrition and fertilization in this family, in spite of requiring large amount of nutrients. This study has the purpose of presenting major mineral requirements in Annona genus, with emphasis on custard apple (A. squamosa) and soursop (A. muricata), related to vegetative and reproductive growth and fruit quality (sugar content, acidity, firmness and crack fruit, etc.). The mineral absorption march in soursop during growth of seedlings is in decreasing order: K>N>Ca>Mg>P and Fe>Zn>Mn>Cu. Significant amount of N, K, Ca, Mg and P are extracted by Annonaceae as compared to other fruits. The export of nutrients by sugar apple is superior to those exported by oranges, pineapple, avocado and many other fruits. In respect of the micronutrient is known that B and Zn are very important in tropical soil with pH below 6.5. Nevertheless, in soil with pH superior to 7.0 Fe and other micronutrients may be restrictive to Annona growth and reproduction. The increasing importance of fresh and processing markets requires scientific investigations in absorption march and nutrition for the various species of Annonaceae.

Incidência e severidade da malformação floral em seis cultivares de mangueira

The present work was developed with the objective to evaluate the incidence and the severity of mango flower malformation in different cultivars, in conditions of semi-arid region, in Santa Maria da Vitoria, Bahia State, Brazil. The experiment was carried out in july, 2001, in a mango orchard composed of different cultivars. The used treatments cultivars were: T1- Rosa; T2- Haden; T3 Bourbon; T4- Palmer; T5- Tommy Atkins; T6- Van Dyke. In the conditions that this work was carried out, the highest percentage of incidence and severity of flower malformation was gotten by Haden variety. Rosa and Bourbon cultivars presented minimum occurrence of the disease.

Uso de extratos vegetais no controle in vitro do Colletotrichum gloeosporioides penz. Coletado em frutos de mamoeiro (Carica papaya L.)

Several alternatives have been studied and used in the control of plant diseases, in order to achieve the needs of producers and consumers desiring to reduce the use of pesticides. Thus, the objective of this study was evaluating the activity of plant extracts Azadirachta indica A Juss., Annona muricata L. and Lippia alba (Mill) N. E. Brown. in controlling of Colletotrichum gloeosporioides Penz. in vitro. The experiment was conducted in State University of Southwest Bahia, campus of Vitoria da Conquista city, State of Bahia, Brazil. Aqueous extracts of leaves of soursop leaves and lemongrass, and aqueous extracts of neem seeds and soursop were used to inhibit mycelial growth of pathogen of anthracnose from papaya fruits. The antifungal activity of the extracts was determined by measuring the mycelial growth of cutures. The experimental design was CRD in factorial (3x3x3) with four repetitions in both experiments. The results suggested inhibitory action of the leaf extract of lemongrass and the seed extract of soursop.

THE DEVELOPMENT OF CUSTARD APPLE FLOWER BUD UNDER NITROGEN AND POTASSIUM NUTRITION

The custard apple tree (Annona squamosa L.), has increased in cultivation due to good prices in the national market. However, there are few studies regarding the fruit’s nutrition. The aim of this study was to verify the influence of N and K levels in developing the flower buds in two growing cycles, corresponding to the time of high temperatures (spring-summer) and another milder season (autumn-winter). The experiment was conducted in a rural property located in the municipality of Anage, Bahia, installed in a randomised complete block design with 3 blocks, arranged in a factorial 4 x 4, obtained by the combination of the following levels of N (0, 16.875, 33.750 and 67.500 g plant-1) in the form of urea and K (0, 22.5, 45.0 and 90.0 g plant-1) in the form of potassium chloride, applied every fifteen days (every fortnight / every two weeks). It was evaluated the vigor of floral buds, measured by determining its weight and the length of them. At the end of the study it was concluded that the vigor of the floral buds tended to increase with elevated levels of nitrogen in the coldest period of the year (dry season with low in temperature). In the spring-summer period (rainy season and high temperature) the vigor of the flower buds was reduced as they increased the doses of N. Potassium did not affect the vigor of the flower buds in these considered periods. There was no interaction between N and K levels for the vigor of the flower buds.The custard apple tree (Annona squamosa L.), has increased in cultivation due to good prices in the national market. However, there are few studies regarding the fruit’s nutrition. The aim of this study was to verify the influence of N and K levels in developing the flower buds in two growing cycles, corresponding to the time of high temperatures (spring-summer) and another milder season (autumn-winter). The experiment was conducted in a rural property located in the municipality of Anagé, Bahia, installed in a randomised complete block design with 3 blocks, arranged in a factorial 4 x 4, obtained by the combination of the following levels of N (0, 16.875, 33.750 and 67.500 g plant-1) in the form of urea and K (0, 22.5, 45.0 and 90.0 g plant-1) in the form of potassium chloride, applied every fifteen days (every fortnight / every two weeks). It was evaluated the vigor of floral buds, measured by determining its weight and the length of them. At the end of the study it was concluded that the vigor of the floral buds tended to increase with elevated levels of nitrogen in the coldest period of the year (dry season with low in temperature). In the spring-summer period (rainy season and high temperature) the vigor of the flower buds was reduced as they increased the doses of N. Potassium did not affect the vigor of the flower buds in these considered periods. There was no interaction between N and K levels for the vigor of the flower buds.