Passifloras silvestres: área foliar, relações alométricas e potencial como porta-enxerto do maracujazeiro-amarelo / Wild passifloras: leaf area, allometric relationships and potential as a rootstock of yellow passion

AUTOR(ES)
FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

21/12/2011

RESUMO

The objectives of this work were to develop linear models that allow to predict leaf area of P. alata, P. coccinea, P. gibertii, P. ligularis, P. misera, P. mucronata, P. nitida and P. setacea by using simple linear measurements; to quantify growth traits and allometric relationships of P. cincinnata, P. edulis f. flavicarpa, P. gibertii, P. morifolia and P. mucronata; to study the potential use of P. alata, P. cincinnata, P. edulis, P. gibertii, P. morifolia and P. mucronata as rootstocks of yellow passion fruit. Three hundred leaves per species were randomly sampled in experiment 1, in different exemplars of each species. The leaves were carefully collected and transported in cooled boxes to laboratory, where the leaf area was measured with leaf area bench meter. Length of the principal vein (l) and the greatest width of the leaf (w) were measured in non-lobed leaves. Length of the principal vein (L) and the greatest width between distal extremities of the outer lobes were measured in species with more than one lobe per leaf. The dependent variable (total leaf area) was estimated by linear regression by using the independent variables such as length, width and the product between them. It was used 50 leaves to correlate the measured values with the estimated ones to statistically evaluate performance of models developed to estimate leaf area in the different species. It was found that use of linear dimensions such as length and width provided a satisfactory estimative for the different species of Passiflora as well as it was possible to observe that coefficient of determination (R) were superior to 0.92, resulting in excellent estimates of leaf area, considered as very good for this culture and the models proposed to estimate leaf area by measure of linear dimensions of the leaf presented an excellent performance inasmuch as the index c was greater than 0.85 for all species. In experiment 2, seeds of Passiflora were germinated in washed sand in plastic boxes of 40 cm of width x 20 cm of height x 100 cm of length and after cotyledonal leaf was completely expanded, 48 seedlings of each species were transplanted into PVC tubes of 100 mm of diameter and 150 centimeters of height containing a mixture of sand, earth and manure at the proportion of 3:1:1. Characteristics of root growth and aerial section of the plant were determined in eight plants of each species, in which the first was determined after transplant and the others at 15, 30, 45, 60, 75, 90 and 105 after transplanting. The characteristics evaluated were plant height, number of leaves, leaf area, number of secondary roots, radicle root length, volume of the root system. Afterwards, the material was packed separately (stem, leaf and root) in paper bags and dried at 65oC in an air forced circulation oven until constant weight, for evaluation of dry mass. Based on leaf area and dry mass the following physiological parameters were evaluated: absolute growth rate, relative growth rate, net assimilatory rate, leaf weight ratio and root weight ratio. P. cincinnata, P. gibertii and P. morifolia presented growth rate equal to or greater than P. edulis for all the evaluated characteristics, during the whole evaluation period and the root system of P. gibertii and P. morifolia presented better distribution over substrate, suggesting a better exploration of the soil profile in volume and deepness. P. mucronata obtained less growth than the other species, for the aerial part as well as for root system. P. alata, P. cincinnata, P. edulis f. flavicarpa, P. gibertii, P. morifolia and P. mucronata were used as rootstock for Passiflora edulis f. flavicarpa in experiment 3. It was used as control treatment P. edulis f. flavicarpa. The seedlings were obtained by direct sowing of 20 seeds of each species in 10 L of substrate. Cleft grafting was done at 10 cm of the plant stem 60 days after sowing. Evaluations were done every month and they started 75 days after sowing. Percentage of established grafts, plant height, number of leaves, diameters of the rootstock and diameter of grafts were the characteristics evaluated in the experiment. Rootstock P. mucronata provided the highest height of the aerial part for P. edulis f. flavicarpa and it also promoted the longest length of internodes among all the species used as rootstock. Dwarfing effect was induced by P. gibertii when it was used as rootstock of yellow passion fruit. P. mucronata and P. cincinnata showed to be promising to be used as rootstock of yellow passion fruit.

ASSUNTO(S)

fitotecnia passiflora maracujazeiro silvestre enxertia Área foliar passiflora passion wild grafting leaf area

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