Resumo Cycnoches haagii é uma orquídea epífita alvo de muitos coletores, mas nenhuma referência foi encontrada na literatura sobre sua biologia reprodutiva. Assim, o objetivo deste estudo foi obter informações preliminares sobre os tipos de polinização e sua influência na viabilidade das sementes desta orquídea nativa do Cerrado brasileiro, a fim de viabilizar futuros programas de multiplicação e preservação. Foram realizadas polinizações entre flores da mesma planta (geitonogamia) ou plantas diferentes (xenogamia). As sementes obtidas das cápsulas foram semeadas em meio B&G, com concentração total e parcial de sais. Sementes de geitonogamia resultaram em 25% dos protocormos albinos e consequentemente em plântulas albinas. Este fenômeno não ocorreu em sementes oriundas de polinização xenogâmica. A análise de pigmentos mostrou que mesmo as plântulas albinas apresentaram clorofilas e carotenoides, porém em concentrações significativamente menores, 16% e 37% respectivamente, em relação às plântulas pigmentadas. A polinização geitonogâmica deve ser evitada em programas de propagação da orquídea C. haagii devido à origem de plântulas albinas. Além disso, a polinização xenogâmica mostrou-se um método muito interessante para a obtenção de mudas com fenótipo albino, material vegetal muito intrigante para futuras investigações.

Abstract Cycnoches haagii Barb. Rodr. is an epiphytic orchid very targeted by collectors, but no reference was found in the literature about its reproductive biology. Thus, the purpose of this study was to obtain initial information regarding pollination types and its influence on seed viability of this native orchid of the Brazilian Cerrado, in order to enable future propagation and preservation programs. Pollination among flowers of the same plant (geitonogamy) or different plants (xenogamy) were carried out. Seeds extracted from the capsules were sown in B&G medium, with full and half strength. Seeds from geitonogamic resulted in 25% of albino protocorms and consequently in albino seedlings. This phenomenon did not occur in seedlings derived from xenogamic pollination. Pigment analysis showed that even the albino seedlings presented chlorophylls and carotenoids, however, in significantly minor concentrations, 16% and 37% respectively, in relation to green seedlings. Geitonogamic and xenogamic pollinations resulted in C. haagii viable seeds with high germination percentage (90%) under in vitro conditions. The germination of seeds from xenogamic pollination resulted in chlorophyll or normal seedlings only, and can be recommended at conservation programs. On the other hand, although geitonogamic pollination should be avoided at conservation programs of this orchid species as it leads to albino seedlings, it showed a very interesting system to obtain seedlings with this phenotype, an interesting plant material to future investigation.

Abstract Fifty-five watermelon accessions were inoculated in pots using Fusarium oxysporum f. sp. niveum chlamydospores in a completely randomized design with five replications. Among the 42 accessions that were resistant, twelve accessions with a mean score ≤1 were selected for morpho-agronomic characterization. ‘Sugar Baby’ and ‘Charleston Gray’ were used as controls. Field research was conducted over two production cycles in a randomized block design with three replications and five plants per plot. For the characterization 13 quantitative agronomic traits were used. The dissimilarity measures were obtained by the sum of the matrices of standardized mean Euclidean distance. Coefficients of variation ranged from 5.33% (number of days until 50% of plants with at least one female flower) and 17.20% (mass of characterized fruit). In the second cycle, a reduction in days was observed for the flowering. For soluble solids content, the accession BGH-UNIVASF 40 was statistically equal to the commercial cultivars in the second cycle. Accessions were grouped similarly using two grouping methods, Tocher and the farthest neighbor method. The most promising accessions were BGH-UNIVASF 40, 169, 177 and 210 for use in future hybridizations. BGH-UNIVASF 76, 128 and 185 (Citrullus lanatus var. citroides) can be used as resistant Fusarium wilt rootstocks.

O objetivo deste trabalho foi estudar o efeito de doses de silicato de potássio em condições de casa de vegetação e campo, na proteção do cafeeiro contra Cercospora coffeicola, além de avaliar o efeito do silicato de potássio nas atividades de peroxidase, polifenoloxidase, e no conteúdo de pigmentos e lignina solúvel em ácido. Utilizou-se em casa de vegetação o silicato de potássio nas doses de 0,75; 1,5; 3,0; 6,0 mL/L de água. Em casa de vegetação, a dose de 1,5 mL/L proporcionou maior proteção da cercosporiose em mudas de cafeeiro, sendo esta dose utilizada no campo e nas determinações bioquímicas. No campo, o silicato de potássio proporcionou proteção de 31% em relação à testemunha, ao passo que o fungicida epoxiconazole + piraclostrobin proporcionou proteção de 61%. Parte desta proteção conferida por silicato de potássio pode ser explicada pelo aumento nas atividades de peroxidases, polifenoloxidases e o maior acúmulo de lignina.

The objective of this work was to study the effect of potassium silicate doses in greenhouse and field conditions, for the protection of coffee seedlings against Cercospora coffeicola, and to evaluate the effect of potassium silicate on the activities of peroxidase, polyphenoloxidase and on the content of lignin, carotenoids and chlorophyll a and b. Potassium silicate was tested in greenhouse at doses 0.75, 1.5, 3.0 and 6.0 mL/L of water. In these conditions, the dose of 1.5 mL/L provided greater protection against brown eye spot on coffee seedlings, this dose having been chosen for the field trial and biochemical determinations. In the field, potassium silicate provided protection of 31% in relation to the control, while the fungicide mixture of the epoxiconazole + pyraclostrobin provided 61% of protection. Part of this protection conferred by potassium silicate can be explained by the increase in the activities of peroxidases, polifenoloxidases and the higher accumulation of lignin.