Phenological phase influences allelopathic potential

0 downloads 0 Views 854KB Size Report
Results indicate that the potential phytotoxicity is related only to blooming phase, independently of other factors that could ... mechanisms and in a very fluctuating way and even ..... Botanica, 72(2): 231-239. ... Effect of Leaf Leachate of Four.
Journal of Allelochemical Interactions July 2016 (1)

I.S.S.N: 2312-8666

International Allelopathy Society

July 2016. JAI 2 (2): 9-15

Phenological phase influences allelopathic potential of water leachates of Acacia dealbata obtained using simulated rain Reigosa, M. J.* and Carballeira, A.**

* Fisiología Vegetal. Departamento de Bioloxía Vexetal e Ciencia do Solo. Facultade de Bioloxía de Vigo. Universidade de Vigo. Aptdo. 874, Vigo 36200. Spain Phone: 34-86-812616; Fax: 34-86-812556; e-mail: [email protected] ** Ecoloxía. Departamento de Bioloxía Fundamental. Facultade de Bioloxía. Santiago de Compostela. Spain

ABSTRACT

Water leachates of aerial parts of Acacia dealbata Link were artificially obtained during one complete year, beginning during flowering, and bioassayed to explore their allelopathic potential on germination and growth of Lactuca sativa L. Var. Great Lakes. Results indicate that the potential phytotoxicity is related only to blooming phase, independently of other factors that could also influence this allelopathic effect. A short methodological discussion about the validity of obtained results is done.

Keywords: Acacia dealbata, Allelopathy, Germination Bioassays, Lactuca sativa var. Great Lakes, water leachates.

Introduction Acacia dealbata Link is a leguminous plant coming from Australia and Tasmania introduced in the European continent in 1820 and it is very common in Mediterranean countries where it is found both in a wild manner and farmed for ornamental use; it can become a blight (García, 1979; Giuliani et al., 2016). It is considered an important invader in different parts of the world (Aguilera et al., 2015a), like other species of this genus (Hussain et al., 2011; Lazzaro et al., 2015; Lorenzo et al., 2012a) due to its phytotoxic capacity, that could produce allelopathic phenomena. It is of some usefulness in Galicia (NW Spain), but it presents several disadvantages: its invading ability makes it invade vineyards, growing in meadows, by destroying retaining walls, by pulling archaeological excavations down and by making the access to natural areas difficult. In addition to its great colonizing capacity it leads to a very low covering and scarcity of species as far as its undergrowth is concerned (Hernández et al., 2014; Lorenzo et al., 2012b; Reigosa et al., 1999). These phenomena cannot be obviously explained only by other competitive phenomena, so it was established as a starting

hypothesis the great allelopathic capacity of this species. Such hypothesis comes supported by the fact that, as T. A. Rabotnov (1974) affirmed, “allelopathic phenomena are chiefly possible between species originated in different regions (for example between native and exotic species) or under conditions where soil microorganisms are not capable to destroy toxic metabolites...”. Additionally, A. dealbata blooms for an uncommon period (January-February) and its steady phenological rhythm might be responsible for, at least partly, this phenomenon (Carballeira & Reigosa, 1999; Giuliani, 2016), and additionally the relationships with pollinators could influence the ecology of the invasion. Different allelochemicals have been identified, and its influence in the soil microorganisms and understory plants has been assessed (Aguilera et al., 2015b), and some possible effects related to symbionts have also been considered (Rodriguez-Echevarria & Traveset, 2015). The changes in the soil during the invasion process are very important, including not only the microorganisms, but also chemical properties (Lazzaro et al., 2014). So, a series of experiments previously conducted (Casal et al., 1985; Reigosa et al., 1984) showed a great potential allelopathic capacity through several 9

Reigosa, M. J. and Carballeira, A.

Normal  ombrotermic  diagram  local    station   180  

90  

140  

70  

temperature  ºC  

160   120   100   80   60   40   20   0  

80   60   50   40   30  

Rain  

temperature  

20   10   0  

Figure 1. Gaussen normal ombrotermic diagram corresponding to the study area: Rocha Vella station, Santiago de Compostela.

mechanisms and in a very fluctuating way and even in very short periods of time. Carballeira & Reigosa (1999) showed that naturally released leachates could produce allelopathic phenomena, influenced by several meteorological factors. It was intended establishing, by this work, some fixed water washing conditions in the laboratory in order to delimitate, concerning the phytotoxins release ways through the rain, that part of the effects were due to the phenological state of the A. dealbata to tell the effects due to the phenological capacity of the producer species and the effects of climatological factors. Materials and methods Area of study and soil and climate characteristics The area of study is located at 4°53’15’’ W and 42°52’14’’N (Santiago de Compostela) at an altitude of 170 m with a slope of 15% and an orientation of 215º N and it was already described widely by Casal et al. (1985). Carballeira et al. (1983) include the area of study within the climatic types whose denomination is “Perhumid-Mesothermal I - without lack of 10

water” as per the classification of Thornwaite, “Cool maritime” as per the one of Papadakis and belonging to the phyto-climatic subregion named “Atlantic European” of Allué. During the period of study the conditions have been similar to the normal ones in the zone, that is: yearly rainfall: 1865 mm, summer rainfall: 202 mm, average yearly temperature: 12.5º C, average temperature of maximum ones belonging to the warmest month and of minimum ones belonging to the coldest month: 23.5 and 3.1º C respectively. Its pluviometry regime is the one of Atlantic type with well spread rains during all of the seasons. Gaussen’s typical diagram corresponding to the area of study can be seen in figure 1. Sampling and preparation of samples It was collected 1.75 Kg of alive material fresh weight by cutting it from the crowns, in five points chosen at random during the whole sampling period. As a whole, the assay was carried out fifteen times along one year, after a period without rains at least of five days in order to be certain that we were measuring the phenological capacity of allelopathic compound release. In order to refer the results to Reigosa, M. J. et al. # JOURNAL OF ALLELOCHEMICAL INTERACTIONS 2 (2): 9-15

 

Phenological phase influences allelopathic potential of water leachates of “Acacia dealbata” obtained using simulated rain

Germina(on  of  Lactuca  sa(va  in  control  and  Ar(ficial  Leachates  from  Acacia  dealbata   120  

100  

80   Control  

60  

AL-­‐1   40  

AL-­‐2  

20  

0  

Rela-ve  effects  of  Ar-ficial  Leachates  of  Acacia  dealbata  on  Lactuca  sa.va  germina-on  

 

130,00%   120,00%  

%  of  control  

110,00%   100,00%   90,00%   80,00%  

AL-­‐1  

70,00%  

Al-­‐2  

60,00%   50,00%   40,00%  

Figure 2. Effects on Lactuca sativa germination produced by the water leachates obtained spraying 1.75 k fresh weight aerial plant parts. AL-1 corresponds to the first leached 600 ml, while AL-2 corresponds to the next leached 600 ml. Upper figure represents the values and standard deviations in the 15 assays. The second figure explains the differences with respect to control in those experiments. Squares mean LSD p