Silvia Nietsche

Avaliação das cultivares de bananeira Prata-Anã, Thap Maeo e Caipira em diferentes sistemas de plantio no norte de Minas Gerais

Banana is one of the tropical fruits more consumed in the world, answering for approximately 10% of the world trade of fruits. The purpose of this work was to evaluate the growth and production of three banana cultivars under three planting systems, in two production cycles, in the period from March 2004 to October 2006, in Janauba, Minas Gerais. The experimental design was in randomized blocks and two statistical analyses: first: Prata Ana in six different planting systems; second: factorial 2 x 2 + 1, with four repetitions and six useful plants per parcel. The evaluated characteristics were: plant height, pseudostem circumference, total number of leaves, number of green leaves in the crop, number of days from planting to harvest, bunch weight, productivity, number of hands and fingers per bunch. The appraised characteristics were submitted to the variance analysis, being the treatments effects compared by the test of Tukey to 5% of probability. The cultivar mixture and the usage of borders did not influence most of the growth characteristics on the three studied cultivars. The cultivar Thap Maeo was superior to the Caipira in most of the appraised characteristics in the first and second cycles. The planting system with one border was superior. The analysis of the cultivar Prata Ana presented significant difference for the characteristics of green leaves number in the crop in the second cycle, number of hands/ bunch and number of fingers/bunch inside of the six planting systems.

Tamanho da semente e substratos na germinação e crescimento inicial de mudas de cagaiteira

A cultura da cagaiteira apresenta perspectivas de expansao no cerrado e no Nordeste brasileiro. Com o presente trabalho teve-se como objetivo avaliar as caracteristicas de germinacao de sementes de cagaiteira de diferentes tamanhos em tres tipos de substratos. O delineamento experimental utilizado foi de blocos inteiramente casualizados em um esquema de parcela subdividida, com fatorial (2 x3), consistindo de dois tamanhos de sementes, grandes (13,5 mm de largura, 15,91 mm de comprimento e 1,41 g de massa) e pequenas (9,94 mm de largura, 12,19 mm de comprimento e 0,68 g de massa) em tres tipos de substratos (plugmix; areia, argila e esterco de curral, na proporcao v/v 1:1:1; e areia e argila na proporcao v/v 1:1). Pelos resultados, observou-se que, independentemente do tamanho da semente e do tipo de substrato, nao houve diferencas significativas quanto a porcentagem de emergencia, que foi superior a 90%. Nas caracteristicas de indice de velocidade de emergencia, altura e numero de folhas, observou-se superioridade para as plantas provenientes de sementes grandes. Em relacao aos diferentes tipos de substratos, houve diferencas significativas para as caracteristicas de altura e numero de folhas, indicando a superioridade dos substratos a base de areia e argila.

Efeito de horários de polinização artificial no pegamento e qualidade de frutos de pinha (Annona squamosa L.)

O Brasil tem se destacado como grande produtor de frutas, especialmente a pinha. A cultura e encontrada desde o norte do pais ate o estado de Sao Paulo. Atualmente, o cultivo desta fruteira se espalhou, com a ocorrencia de grandes areas em varios estados brasileiros. A polinizacao inadequada e um dos fatores limitantes na producao comercial destes frutos. Com o objetivo de estudar os efeitos da polinizacao artificial foram utilizadas 20 plantas provenientes de um pomar comercial de pinha localizado no municipio de Nova Porteirinha, Minas Gerais. As flores foram polinizadas no estadio de femea por meio do uso de um pincel numero dois. O delineamento experimental foi inteiramente casualizado. Os tratamentos foram compostos de seis horarios de polinizacao (5, 6, 7, 8, 9 e 10 horas), com cinco repeticoes, utilizando-se 10 flores por parcela. Foram avaliados a porcentagem de pegamento dos frutos, o comprimento, o diâmetro e o peso dos frutos, a porcentagem de frutos desuniformes, o peso da casca, polpa e sementes, o numero de sementes e o teor de solidos soluveis totais. Os melhores tratamentos para as caracteristicas de peso de frutos e porcentagem de pegamento foram obtidos entre 6 e 10 horas. O teor de solidos soluveis totais nao foi afetado. Foram detectadas correlacoes positivas e significativas para os seguintes pares de caracteres: peso de fruto e diâmetro e peso de fruto e peso de casca.

Efeito do ensacamento na qualidade dos frutos e na incidência da broca-dos-frutos da atemoieira e da pinheira

BAGGING EFFECT UPON EITHER QUALITY OF THE FRUITS AND INCIDENCE OF THE FRUIT BORER IN ATEMOYA AND SWEETSOP This study was conducted to evaluate the effect from using different involucres for fruits of the atemoya and sweetsop upon either physiochemical quality of the fruits and incidence of the fruit borer Cerconota anonella. The experiments were set up in two commercial orchards: one with atemoya at Matias Cardoso county and the other one with sweetsop at Verdelândia on northern Minas Gerais state. The treatments for atemoya consisted of: 1) Control (without bagging); 2) Milky plastic bag; 3) White, bottomless, tissue–non-tissue (TNT) bag; and (4) With bottom TNT bag. For the sweetsop, only treatment 2 was modified to brown paper bag. The following evaluation were performed: the number of days from pollination to harvest, number of days from harvest to ripening, occurrence of injuries and borers, and the physiochemical characteristics of the fruits. The no-bagged sweetsop fruits showed higher number of days between the harvest and ripening and higher firmness. The use of the milky plastic controlled the borer in atemoya fruits. The following physiochemical characteristics were not affected by the use of those involucres: weight, length, fruit diameters, and the content of the total soluble solids in the pulp.

Variability in reproductive traits in Jatropha curcas L. accessions during early developmental stages under warm subtropical conditions

Variability in floral, fruit, and seed characteristics, and oil content of 15 accession of Jatropha curcas during early development were assessed during two flowering periods in south Florida subtropical climate. The two flowering periods had leaf flushing in March. Field evaluation using 18 quantitative traits showed significant variation among accessions. The number of female flowers and female : male flower ratio ranged from 1 to 15 and 1 : 8.8 to 1 : 67.8, respectively. Fruit set by natural pollination was 89 and 66% during the first (1st) and second (2nd) flowering periods, respectively. A higher number of female‐type inflorescences were observed during summer. There were significant differences in seed traits, except for number of seeds per fruit. Accession TREC 31 had the highest individual seed dry weight and 100‐seed weight (0.83 g and 79.7 g, respectively). The oil content varied from 19.30% to 35.62%. Seed dry weight had positive correlation with seed fresh weight, seed length, seed thickness, seed width, and 100‐seed weight, but negative correlation with oil content. Based on the cluster analysis using 15 morphological traits, jatropha accessions were grouped into five main clusters and accessions from different geographic regions grouped together in a cluster. Principal component analyses (PCA) revealed morphological variation. The first three components explained 73.5% of the total variation and seed dry weight, 100‐seed weight, total flowers per inflorescence, male flowers per inflorescence and fruit set can be used to distinguish accessions. The PCA also indicated that flowering traits were more influenced by seed origin while seed traits were affected by flowering spans. Although evaluations were performed in plants during the juvenile phase, accessions TREC 31 and TREC 55 had superior averages for almost all characters evaluated. These results provide a preliminary assessment of the high variability in jatropha accessions evaluated and their potential for use in breeding and genetic improvement programs.

Assessment of reproductive characteristics of Jatropha curcas L. in south Florida

Jatropha curcas L. (jatropha) is a species identified for biofuel production because of the high quality of the oil produced by its seeds. However, jatropha is undomesticated and little information is available about its reproductive characteristics. Breeding and genetic improvement programs are much needed for the jatropha development as a bioenergy crop. Information about floral display and mode of reproduction are considered essential for breeding programs. In this study, the total number of female flowers, male to female flower ratio, fruit set, in vitro pollen germination, and the formation of fruits by apomixis, self‐pollination, and natural pollination were evaluated in 17 jatropha accessions planted in South Florida. The total number of female flowers per inflorescence and male to female flower ration ranged from 2.8 to 9.1 and 9.9:1 to 55.4 : 1, respectively. During summer 2011, high fruit setting average was observed (75.5%). In vitro pollen germination varied from 64.6% during spring 2011 to 51.6% during fall 2011. The fruit set observed was from 10.1% to 64.0% through natural pollination and apomixes, respectively. Characteristics such as fruit fresh weight, number of seeds per fruit, seed dry weight, and oil content were influenced by mode of reproduction.

Tratamentos físicos e químicos na emergência e no crescimento de plântulas de pinheira

O objetivo do presente trabalho foi verificar o efeito do armazenamento e a influencia de tratamentos fisicos e quimicos sobre a emergencia e o crescimento de plântulas de pinheira. Frutos de pinheiras foram coletados em um pomar comercial no municipio de Nova Porteirinha, Minas Gerais. Os frutos colhidos maduros foram despolpados e suas sementes, lavadas em agua corrente. O delineamento utilizado foi o de blocos casualizados, em um esquema fatorial, com cinco tratamentos (testemunha, imersao em vinagre, escarificacao com lixa, escarificacao em liquidificador e desponte com alicate) e quatro epocas de armazenamento em geladeira (0, 2, 4 e 6 meses). Trinta dias apos o plantio de cada epoca, foi avaliada a porcentagem de plântulas emergidas, tempo medio para emergencia, numero de folhas, diâmetro, altura das plantas, materia fresca e materia seca da parte aerea e do sistema radicular. Dentre os principais resultados pode-se destacar que nao foram observados efeitos significativos dos tratamentos na quebra de dormencia das sementes de pinheira e o armazenamento em geladeira por seis meses nao prejudicou a emergencia e o desenvolvimento das plântulas de pinheira.

Branching, flowering and fruiting of Jatropha curcas treated with ethephon or benzyladenine and gibberellins

Jatropha curcas L. has been identified for biofuel production but it presents limited commercial yields due to limited branching and a lack of yield uniformity. The objective of this study was to evaluate the effects of single application of ethephon or a combination of 6-benzyladenine (BA) with gibberellic acid isomers A4 and A7 (GA4+7) on branch induction, flowering and fruit production in jatropha plants with and without leaves. Plants with and without leaves showed differences for growth and reproductive variables. For all variables except inflorescence set, there were no significant statistical interactions between the presence of leaves and plant growth regulators concentration. The total number of flowers per inflorescence was reduced as ethephon concentration was increased. As BA + GA4 +7 concentration increased, seed dry weight increased. Thus, ethephon and BA + GA4 +7 applications appeared to affect flowering and seed production to a greater extent than branching. The inability to discern significant treatment effects for most variables might have been due to the large variability within plant populations studied and thus resulting in an insufficient sample size. Therefore, data collected from this study were used for statistical estimations of sample sizes to provide a reference for future studies.

Variabilidade genética de isolados de Fusarium oxysporum f. sp. cubense obtidos de bananais do norte de Minas Gerais

Banana is one of the most consumed tropical fruits in the world, accounting for approximately 10% of world trade in fruits. Panama disease, caused by Fusariumoxysporum f. sp. cubense is a major disease of banana. RAPD marker have been used for taxonomic studies, analysis of variability of virulence in pathogenic fungi, characterization of races and variability inter and intra-specific populations from different regions. The objective of present study was to evaluate the genetic variability of 36 isolates of F. oxysporum f. sp. cubense using RAPD marker. Thirteen RAPD primers were selected and data analysis was performed using the similarity coefficient of Nei and Li. A total of 178 bands were obtained, of which 167 (93.82%) showed polymorphism at least two isolates and only 11 (6.18%) showed monomorphism, demonstrating the high variability among isolates. The genetic distances ranged from 5.7 to 54.6%, and the average distance of 30.2%. According to cluster analysis (UPGMA) no correlation among isolates were found. The results suggest a high genetic variability among isolates and no correlation between molecular groupings and their geographical origin were observed.