Interactions between the parasitic angiosperm Orobanche aegyptiaca and its tomato host: growth and biomass allocation

Abstract

The influence of the parasitic angiosperm Orobanche aegyptiaca on the growth and shoot/root allometry of tomato plants was studied in two experiments. In the first, the density of infection was manipulated, with host and parasite biomass being measured 56 d after planting (d.a.p.). In the second, multiple harvests were made from 14 to 91 d.a.p. at one level of infection (20 mg seed dm""). The first experiment demonstrated an approximately linear reduction in host biomass up to 10 mg seed dm"^ soil, beyond which there was no further reduction. The parasite also depressed shoot/root ratio, which changed prior to any decrease in total biomass. These trends were maintained in the second experiment, becoming more pronounced with time. Significant reductions were observed in host biomass compared with that of uninfected controls from 42 d.a.p., following the emergence of the parasite above ground, and corresponded with the onset of lower relative growth rates (RGRs) in the infected plants. Infection also influenced components of RGR: there was a stimulation of leaf area ratio (LAR) and a depression of unit leaf rate (ULR). The data are discussed with respect to the influence of other parasitic weeds on host growth.

Elevated atmospheric CO2 influences the interaction between the parasitic angiosperm Orobanche minor and its host Trifolium repens

“…the biomass of infected plants was lower than that of their uninfected counterparts, consistent with reports of other host : Orobanche associations (Zaitoun, Al-Menoufi & Weber, 1991 ;Barker et al, 1996 ;Hibbered et al, 1996Hibbered et al, , 1998. Initially (33 d.a.p.…”

“…), infected plants had greater calculated biomass than uninfected plants. Consistent with this observation, ter Borg (1986) and Barker et al (1996) reported a slight stimulation of relative growth rate of the host soon after infection with Orobanche, although such accounts are rare. The combined biomass of infected T. repens and O. minor (association biomass) was lower than that of control T. repens at ambient CO # .…”

The Role of Endogenous Strigolactones and Their Interaction with ABA during the Infection Process of the Parasitic Weed Phelipanche ramosa in Tomato Plants

“…However, unlike some other reports which showed a reduction of shoot biomass of the infected host (Barker et al, 1996; Mauromicale et al, 2008), total biomass of wild type plants in the present study was mainly reduced through a decrease in root biomass ( Figure 3 ). This may be due to the different tomato cultivars that were used, and/or the different growing conditions.…”

Differential Responses of Commercial Tomato Rootstocks to Branched Broomrape

“…These results join those of Press, [53] and of Barker et al, [54] which underlines the reduction in the photosynthetic capacity and in the ratio aerial-parts DW / roots DW of tomato plants parasitized by the specie P. aegyptiaca. Such an impact seems to be a common response to the plants parasitized by the broomrape [55,56].…”