This paper reports the results of an investigation carried out on the seed germination beha- viour of Artemisia caerulescens L. var. palmata (L.) Fiori. The species is a perennial wild low shrub belonging to the family of Compositae, aromatic, tomentose and characterized by lea- ves that are alternate and divided pinnately. It is considered rare in the center and Western part of the Mediterranean region. Moreover, at least in Italy, it is a characteristic plant of saline or subsalse environments and shoreline as for example, the moderately salt zone at the “Lame” of the Presidential Estate of San Rossore (PI) (1, 2, 3), where the plant material was collected. The interest for this species originates from the poor knowledge about its ecology and physiology, and particularly about its response, during seed germination and the early stage of growth, to environmental factors. The germination tests were carried out in relation to seed dormancy, temperature (5, 10, 20, 10-30 and 10-20 °C, in the dark and with photoperiod conditions day/night 12/12h), salinity (NaCl 0, 12.5, 25, 50, 75, 100 mM), and the seed after-ripening time. Alternate temperatures of 10/20 °C with photoperiod 12/12h are optimal conditions for the germination of this spe- cies. Introduction of salinity determines a significant decrease of germination percentage, which is reduced with respect to control with only 50 mM of NaCl. The germination tests show in addition to the presence of absolute dormancy until 60 days, the presence of a biorhythm that corresponds to vegetative cycle of plant, with a maximum peak of germination in the spring time for the control. With salt concentrations of 25 and 50 mM nevertheless, a maximum peak was shown in the warmer months: considering that the substrate colonized by A. caerulescens in the study area is characterized by moderately high values of electrical conductivity, is obvious that the spread of this species through seed could be, at least in salt grounds, seriously compromised. Moreover, in all the treatments during the first year, the seeds have always shown germination ability proportionally inverse to salinity. The above consideration on germination behavior is also confirmed by repeated observations in field, which have never recorded a high percentage of seedlings arises from seed. It can be assumed, therefore, that A. caerulescens, in environments of this type, reproduces nearly ex- clusively for vegetative way. This behavior of A. caerulescens explains its wide spread in the study area, only in the points with low-medium salinity.
The effects of after-ripening, alternating temperatures, light and salinity on the ger- mination of Artemisia coerulescens L. var. palmata (L.) Fiori seeds
LOMBARDI, TIZIANA
2009-01-01
Abstract
This paper reports the results of an investigation carried out on the seed germination beha- viour of Artemisia caerulescens L. var. palmata (L.) Fiori. The species is a perennial wild low shrub belonging to the family of Compositae, aromatic, tomentose and characterized by lea- ves that are alternate and divided pinnately. It is considered rare in the center and Western part of the Mediterranean region. Moreover, at least in Italy, it is a characteristic plant of saline or subsalse environments and shoreline as for example, the moderately salt zone at the “Lame” of the Presidential Estate of San Rossore (PI) (1, 2, 3), where the plant material was collected. The interest for this species originates from the poor knowledge about its ecology and physiology, and particularly about its response, during seed germination and the early stage of growth, to environmental factors. The germination tests were carried out in relation to seed dormancy, temperature (5, 10, 20, 10-30 and 10-20 °C, in the dark and with photoperiod conditions day/night 12/12h), salinity (NaCl 0, 12.5, 25, 50, 75, 100 mM), and the seed after-ripening time. Alternate temperatures of 10/20 °C with photoperiod 12/12h are optimal conditions for the germination of this spe- cies. Introduction of salinity determines a significant decrease of germination percentage, which is reduced with respect to control with only 50 mM of NaCl. The germination tests show in addition to the presence of absolute dormancy until 60 days, the presence of a biorhythm that corresponds to vegetative cycle of plant, with a maximum peak of germination in the spring time for the control. With salt concentrations of 25 and 50 mM nevertheless, a maximum peak was shown in the warmer months: considering that the substrate colonized by A. caerulescens in the study area is characterized by moderately high values of electrical conductivity, is obvious that the spread of this species through seed could be, at least in salt grounds, seriously compromised. Moreover, in all the treatments during the first year, the seeds have always shown germination ability proportionally inverse to salinity. The above consideration on germination behavior is also confirmed by repeated observations in field, which have never recorded a high percentage of seedlings arises from seed. It can be assumed, therefore, that A. caerulescens, in environments of this type, reproduces nearly ex- clusively for vegetative way. This behavior of A. caerulescens explains its wide spread in the study area, only in the points with low-medium salinity.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
