SEED GERMINATION AND PLANT DEVELOPMENT IN Escobedia grandiflora (OROBANCHACEAE): EVIDENCE OF OBLIGATE HEMIPARASITISM?

Abstract

Root parasitic plants can be facultative or obligate. Facultative parasites are able to complete their life cycle and their seeds can germinate without a host. Escobedia grandiflora is a poorly studied species in spite of its ancestral importance as dye of foods and medicinal use. The present study evaluates the states of seed, seedlings and mature plants, under presence and absence of possible hosts, for inferring the type of parasitism exhibited by E. grandiflora. Seeds were evaluated using two conditions each of light (12 and 0 hours) and temperature (20 ºC and 25 ºC); percentage germination, and germination speed were determined. The seeds did not require a host to germinate, as is typical of facultative parasitic plants. Percentage of germination varied between 66 % and 85.3 % and was not affected by light or temperature although germination speed was greater at 25 ºC. Larger seeds had a higher percentage of germination and produced larger seedlings. The seedlings planted without a host did not survive, while those planted with Paspalum notatum had a 45 % survival rate, demonstrating that this is a critical stage of development, even with a host. Escobedia grandiflora plants sowed with grasses began the reproductive stage at the 28 th week, and those planted with Pennisetum purpureum showed better performance, expressed in more haustoria, higher dry matter of total plant, rhizome and aerial stems. Plants sowed alone lived for more than six months, but they did not produce flowers or fruits. According to the behavior of seedlings and plants, E. grandiflora is an obligate parasite.Keywords: Escobedia, obligate hemiparasite, parasitic plant, root parasitism, seed germination. RESUMENLas plantas parásitas de raíces pueden ser facultativas u obligadas, las primeras pueden completar su ciclo de vida y sus semillas pueden germinar sin un hospedero. Escobedia grandiflora es una especie poco estudiada, a pesar de su importancia ancestral como colorante de alimentos y uso medicinal. Este estudio evaluó los estados de semilla, plántula y planta adulta, en presencia y ausencia de posibles hospederos para inferir sobre su tipo de parasitismo. En las semillas se evaluaron dos condiciones de luz (12 y 0 horas) y temperatura (20 ºC y 25 ºC), el porcentaje y velocidad de germinación. Las semillas no requirieron la presencia del hospedero para germinar. El porcentaje de germinación osciló entre 66 y 85,3 % y no fue afectado por la luz o la temperatura, aunque la velocidad de germinación fue mayor a 25 ºC. Las semillas con mayor tamaño presentaron mayor porcentaje de germinación y produjeron plántulas más grandes. Las plántulas sembradas sin hospedero no sobrevivieron, mientras que las sembradas con Paspalum notatum, tuvieron una sobrevivencia del 45 %, evidenciando que este estado es crítico, aún con hospedero. Las plantas de Escobedia grandiflora sembradas con pastos, iniciaron la etapa reproductiva en la semana 28, y aquellas sembradas con Pennisetum purpureum presentaron más haustorios, y mayor materia seca en la ...

Correlations and path analysis between fruit characteristics and seeds of Pachira aquatica Aubl.

“…These results partially agree with those reported by Marcal et al (2015), Cardona-Medina and Muriel (2015) and corroborated by Cruz (2006) in the sense that the phenotypic correlations have little practical value and can lead to errors, considering genetic as environmental effects, which according to these authors can lead to an inefficient selection due to the masking effect of the environment.…”

“…The FFW showed significant and direct genetic correlations with FL, FPW, WSF, SW and SV, with coefficients ranging from 0.65* (SV) to 1.00** (SW), while the correlation with PSF was significant and inverse (rG=-0.79**). The variable with the lowest degree of association with others was SD, but had a high, significant and direct genetic correlation with SV (rG=0.81**); these results are consistent with those reported by Marcal et al (2015) and Cardona-Medina and Muriel (2015).…”

“…) shows that the genetic control of such variables is given by genes. These genes act independently and by other variables that mask the true level of correlation between these characters, as was reported by Marcal et al (2015) and Cardona-Medina and Muriel (2015). The genetic correlation of the SW with the other characteristics of the fruit, allows to improve the seed physiological quality and the selection of trees with heavier seeds.…”

Post-seminal structure and development of the hemiparasitic plant <i>Escobedia grandiflora</i> (Orobanchaceae)

“…Naturally grown rootstocks of Pennisetum purpureum Schumach. (Poaceae) were collected in the Centro de Ciências Agrárias, Florianópolis, and used as a host based on its rapid growth and strong attachment of E. grandiflora haustoria (Cardona-Medina & Muriel, 2015).…”

“…Assays: We sowed E. grandiflora seeds on to moistened absorbent paper at a temperature of 25°C and 12 hours light-1 photoperiod within a growth chamber (Cardona-Medina & Muriel, 2015). To characterize general aspects of seed and penetration of the radicle through the surrounding seed tissues (Assay 1), E. grandiflora seeds were collected at six, ten, eleven and fifteen days after imbibition, according to germination sensu stricto, as detailed by Bewley, Bradford, Hilhorst, and Nonogaki (2013).…”