Francisco Pinheiro de Araújo

Divergência genética entre acessos de Passiflora cincinnata mast com base em descritores morfoagronômicos

This study had the objective of evaluating the genetic divergence among passion fruit (Passiflora cincinnata Mast.) accessions maintained in the collection of Embrapa Tropical Semi-Arid, Petrolina-PE, Brazil. The experiment was carried out in a randomized complete block design with four replications. Thirty-two accessions were evaluated considering thirty-three characters: two related to the plant, three to the leaves, six to the flowers, four to the fruits, four to the seeds, two to the chemical characteristics of fruits and two to the yield. The behaviour of accessions was evaluated by univariate and multivariate analyses, with dissimilarities obtained by the generalized distance of Mahalanobis (D2) and the grouping technique by the Tocher method. The accessions showed genetic variability for all the evaluated descriptors. The genetic distances between pairs of accessions ranged from 17 to 598, with an average of 152. The accessions indicated as the most divergent should be included in intercross programs and recommended to experimental growing at farm level. The characteristics which most contributed to genetic divergence were total fruit yield (42.29%), pollen viability (8.62%) and leaf area (7.16%). The accessions grouping was not correlated to the original Geo-Environmental Units.

Stomatal changes induced by intermittent drought in four umbu tree genotypes.

Transpiration (E), diffusive resistance (rs) and anatomical parameters were measured in plants of four grafted umbu tree genotypes (GBUs 44, 48, 50 and 68) in order to evaluate alterations induced by intermittent drought and possible genotypic variations. Transpiration measurements were taken daily until stomatal closure by withholding water. Measurements were also taken, when the plants were re-watered and the watering was interrupted again. This cycle was repeated for a period of 31 days (stress period). The control plants were also irrigated daily. A regular pattern in the stomatal opening/closing mechanism was observed throughout the watering period, exhibiting intra-specific differences. Stomatal behavior of GBU 44 and GBU 68 were influenced by air temperature (Tar), relative humidity (RH) and vapor pressure deficit (VPD), whereas GBU 50 was influenced by photosynthetically active radiation (PAR). GBU 48 was not influenced by these environmental factors. Anatomical alterations in response to drought were observed in stomatal density (SD), reductions in the stomatal index (SI) and stomatal aperture size (SA). The anatomical features of the GBU 48 genotype remained unaltered. There was an inversion in tissue proportion in GBU 44 under stress conditions, reducing the spongy parenchyma and increasing palisade parenchyma thickness. The inverse occurred with GBU 68, while the remaining genotypes were unaltered. The results found in this study suggest that GBU 68 is the most drought-sensitive genotype and anatomical changes induced by intermittent drought are not enough to explain the physiological differences between genotypes.

Fotoperíodo, temperatura e reguladores vegetais na germinação de sementes de Passiflora cincinnata Mast.

The species Passiflora cincinnata Mast., which belongs to the Passifloraceae family, is wild and commonly known as Crato Passion Fruit and it is also considered potentially important for rootstock production due to its tolerance to drought, bacterial diseases and nematodes. It can also be used in genetic breeding programs. This objective of this research was to study the effect of light and temperature and the interaction between temperature and plant growth regulators, on Passiflora cincinnata Mast. seed germination. Three experiments were developed: the first verified the effect of light and temperature on seed germination; the second, the effect of different concentrations of GA4+7 + N-(phenylmethyl)-1H-purine-6-amine plant growth regulators on seed germination; and the third, the interaction between temperature and plant growth regulators on seed germination. A randomized complete design was used in all the experiments and data were subjected to analysis of variance followed by mean comparison by the Tukey test, at 0.05 significance. Light had an inhibitory effect on seed germination, and GA4+7 + N-(phenylmethyl)-1H-purine-6-amine were efficient in breaking dormancy and increasing temperature limits. Alternating temperatures, 20-30oC, were the most appropriate for seed germination in this species.

Response of Passiflora setacea to Mycorrhization and Phosphate Fertilization in a Semiarid Region of Brazil

The Caatinga is a unique biome that encompasses nearly 11% of Brazils territory and contains diverse vegetation composed of trees and bushes that have been scarcely studied from the economic perspective. In this context, Passiflora setacea may constitute a strategic alternative for agriculture because it produces fruit that has commercial potential and is tolerant to some diseases. Some species of Passiflora show more robust growth when associated with arbuscular mycorrhizal fungi (AMF) and are dependent on mycorrhization. In this study, the response of P. setacea to phosphate (P) fertilization and mycorrhization with Claroideoglomus etunicatum was evaluated. The experimental design included eight replicates of four randomized treatments: non-inoculated plants (NI), plants fertilized with phosphorus (P), mycorrhized plants (AMF), and plants that were both fertilized and mycorrhized (P+AMF). The plant height, leaf number, leaf area, fresh biomass (FB), and dry biomass (DB) of the shoots and roots, nutrient content, mycorrhizal colonization (MC), and the number of glomerospores (NG) in the rhizosphere were evaluated. The MC and the NG were reduced by phosphate fertilization. The development of the mycorrhized plants was significantly better than the NI and P treated plants for all of the variables tested. Inoculation with C. etunicatum promoted the growth of P. setacea seedlings even in the absence of phosphate fertilization, reducing production costs and strengthening the potential of P. setacea as a viable agricultural alternative for the semiarid region.