Study of the populations of Linaria orbensis Carretero & Boira: basis for a strategy of conservation

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1 Study of the populations of Linaria orbensis Carretero & Boira: basis for a strategy of conservation R. HERREROS, E. CARRIÓ & J. GÜEMES. Jardí Botànic, ICBiBE, Universidad de Valencia, c/ Quart 8, E-468, Valencia, Spain. Raquel.Herreros@uv.es,, Elena.Carrio@uv.es,, Guemes@uv.es Summary Linaria orbensis is an annual endemics of the province of Alicante (Spain), that inhabits mainly in dry farmings.it is a small bearing plant threatened by the anthropic pressure and the transformations of its habitat in irrigated lands. Furthermore, problems in the viability and germination of the seeds have been detected, and because of its annual character, the number of individuals can vary according to agrarian works realised in the crops and/or the enviromental conditions. All that reasons make this species suitable for go more deeply into studies that allow the development of conservation strategies, and with this aim we carried out the next work: - Studies about the breeding system: provided the low viability noted in the seeds of L. orbensis, this kind of analysis could provide information about the origin of the problem. - Germination tests: permit to search for the optimum germination protocol and to quantify the unviability degree of the seeds - Census: allow us to know the variations from year to year, and to evaluate the condition of the populations Key words: breeding system, germination, viability, census, Scrophulariaceae Introduction Linaria orbensis Carretero & Boira is an endemic species of the province of Alicante (Spain). It is a small annual plant, with a restricted distribution area, which habits in sunny dry lands, frecuently stony. Several problems like the transformations of its habitat in irrigated lands, the agrarian works realized in the crops during the flowering period, or the city planning, threat its populations. All that reasons made this species suitable for go more deeply into studies directed to the development of conservation strategies. The aims of our study were: (1) to achieve a better knowledge of the breeding system and to check the quality of the pollen grains of the species, (2) to test the germination of the seeds, (3) to take a census of the individuals and to evaluate the threat of each populations. Breeding system and quality of the pollen grains The study of the breeding system was performed by two types of pollination treatments: spontaneous self-pollination (the flowers were isolated prior anthesis with nylon mesh bags, so floral visitors were excluded) and control (the flowers were tagged and left to open pollination). The treatments were applied in spring 2 in Parcent. The fruits collected after maduration and the number of seeds per capsule was counted. We also calculated the fruit set (as the ratio of fruits to the number of flowers treated) and the seed set (as the ratio of seeds to the mean number of ovules per flower). The results of pollination treatments are shown in Table 1.

2 Pollination type flowers fruits Fruit set % Seeds per capsule Table 1. Fruit and seed production following different pollination types. Means values± S.D. Seed set % Spontaneous selfing ,3 3,66±2,88 9, Control , 39,6±12,2 98,3 Quality of pollen grains The quality of pollen grains was determinated in two anthers of five flowers using the stain of Alexander (198), which allow us to differentiate aborted and nonaborted pollen. The stain revelated high percentages of nonaborted pollen (87,86±7,41). Germination test We test two temperature regimens: (1) ºC (Figure 1) - with a 12 h photoperiod - without light (2) 2/1ºC (Figure 2) - with a 12 h photoperiod - without light The low viability of the seeds had been pointed out (LAGUNA et al., 1998), so several additional assays were performed, taking into account this statement: (3) ºC (Figure 3) - scarification of the seeds and 12 h photoperiod - treatment with giberelines ( mg/l) and 12 h photoperiod - cold stratification at ºC for 6 d without light (4) 2/1ºC (Figure 4) - scarification of the seeds and 12 h photoperiod For each assay, a hundred mature seeds were set to germinate in four sterile Petri dishes, on,6% water agar. Seeds were monitored daily for 3 d h photoperiod without light Figure 1. Percentage of germination at ºC.

3 h photoperiod without light Figure 2. Percentage of germination at 2/1ºC scarification giberelines stratification Figure 3. Percentage of germination at ºC

4 scarification Figure 4. Percentage of germination at 2/1ºC. Census We took a census of all territories where we found the species through directly counting the whole individuals of the population or by estimating when the number of effectives was higher than five thousands, and we evaluated the threats of the populations. The results are shown in Table 2. Population individuals Area (Km 2 ) Threats Orba e 1 City planning, agrarian works, transformation of its habitat in irrigated lands Coll de Rates 48 43e 2 Plant competition Bernia 36 e 2 Plant competition Parcent 78d 1 City planning, agrarian works, transformation of its habitat in irrigated lands Table 2. Results of the census with the area occupied and the threats of the populations (e: estimating, d: directly counting). Conclusions - All the sexual reproductive structures of L. orbensis are functional: most pollen grains were nonaborted and there is a high percentage of ovules which becomes into seeds. - L. orbensis is, mainly, an alogamous plant that produces high number of fruits and seeds by natural pollination, but in absence of insects the maintenance of the populations is put at risk, because of its low self-pollination ability. - The results of all germination test were negative. It should be necessary to realize profound studies in this sense, and/or to analyze the viability of the embryos. - The number of individuals is This result is not so low as we expected, but it could change among years, because of its annual character and the threats that have been detected.

5 - Some data available in this study allowed to propose several conservation strategies and to classified the species in the recent atlas and red book of the threatened vascular flora of Spain (BAÑARES et al., 3), according to the latest UICN (1) categories and criteria, as Endangered (A4c; B1ac(iv)+2ac(iv)). References ALEXANDER, M.P A versatile stain for pollen, fungi, yeast and bacteria. Stain Technology : BAÑARES, A. ; G. BLANCA, J. GÜEMES, J.C. MORENO & S. ORTIZ (eds) Atlas y Libro Rojo de la Flora Vascular Amenazada de España - Dirección General de Conservación de la Naturaleza. Madrid. LAGUNA, E. ; M.B. CRESPO, G. MATEO, S. LÓPEZ-UDIAS, C. FABREGAT, LL. SERRA, J.J. HERRERO- BORGOÑÓN, J.L. CARRETERO, A. AGUILELLA & R. FIGUEROLA Flora endémica, rara o amenazada de la Comunidad Valenciana - Generalitat Valenciana, Conselleria de Medi Ambient. Valencia. UICN Categorías y Criterios de la Lista Roja de la UICN: Versión 3.1. Comisión de Supervivencia de Especies de la UICN - UICN, Gland & Cambridge. Linaria orbensis Carretero & Boira Habitat