The effect of temperature on the photosynthesis, growth and reproduction of a Mediterranean submerged macrophyte, Ruppia drepanensis

The effect of different temperatures (14, 20 and 30 degrees C) and photoperiods (10 and 16 h) on the photosynthesis, growth and reproduction of Ruppia drepanensis Tineo plants from the Donana National Park (SW Spain) were studied. After 84-91 days of growth under a 16 h photoperiod, the plants showed maximal biomass yield at 20 degrees C (395 mg ash-free dry weight per plant), with lower yields at 14 and 30 degrees C (216 and 284 mg ash-free dry weight per plant respectively). A short photoperiod resulted in a lower biomass yield when combined with low temperatures (59 mg afdw per plant, at 10 h and 14 degrees C). Reproduction was also optimal at 20 degrees C, while low temperatures (14 degrees C) inhibited flower induction, No seed was produced at 30 degrees C. Photoperiod had little effect on flowering, as compared with temperature. According to the photosynthetic performance of R. drepanensis, we can define this species as cold-adapted but also capable of acclimating to higher temperatures (30 degrees C). Net photosynthesis at 250 mu mol photons m(-2) s(-1) (P-250) was maximal at 20 degrees C (72 to 82 mu g O-2 g(-1) afdw min(-1)). Photosynthetic plasticity allowed for high net production rates at 10 degrees C (P-250=65 to 68 mu g O-2 g(-1) afdw min(-1)), independently of the temperature experienced during growth. At 30 degrees C, however, net photosynthetic rates were lower in plants grown at 20 degrees C than at 30 degrees C (P-250 = 6.5 and 55.9 mu g O-2 g(-1) afdw min(-1) respectively). The cold- adapted character of this Mediterranean endemism is finely tuned to the requirements of its winter-annual life cycle, while its acclimation capacity is suited to cope with the rapidly increasing temperatures along late spring in the temporary wetlands it inhabits. [KEYWORDS: photoperiod; thermal response; acclimation; flower induction; seed production Fresh-water macrophytes; maritima l; light; ecology]

Influence of environmental parameters on the biomass development of Ruppia drepanensis populations in Doñana National Park: the importance of conditions affecting the underwater light climate

The development of submerged plant communities dominated byRuppia drepanensis Tineo in the brackish marsh of the Doñana National Park (SW Spain) was coupled to seasonal variation in environmental factors for two consecutive years. Plant biomass increased rapidly in early spring (March), with steady biomass yields (up to 100 g afdw m–2) together with abundant flowering and fruiting in late spring (April–May). Wind-induced sediment resuspension and periphyton growth strongly influenced the light climate experienced by the submerged vegetation, while a phytoplankton effect was generally negligible. Development of the submerged vegetation coincided with a decrease in water extinction coefficient and in bicarbonate concentration. Thus, where dense macrophyte meadows develop, light climate probably is the limiting factor in the early spring, while temperature and bicarbonate levels are so by the end of the season. Interannual variation was found to be very high, both in abundance and distribution of the submerged vegetation, mainly because of differences in rainfall which influenced the inundation cycle. Grazing by waterfowl accounted also for this effect, as in dry years birds concentrate in the few wetlands still containing water.

The motion control manipulators on mobile vehicles

Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1992.Includes bibliographical references (leaves 148-156).by Norbert A.M. Hootsmans.Sc.D

Flowering time as influenced by nitrate fertilisation in Ruppia drepanensis Tineo

In a laboratory experiment, Ruppia drepanensis Tineo seedlings from a brackish marsh in southern Spain were grown with and without potassium nitrate (1.4 g N m(-2) week(-1) added to the water column), both under nutrient-rich (clay:sand mixture) and nutrient-poor (sand) sediment conditions. Potassium nitrate fertilisation delayed flower initiation within both types of sediment, but it also resulted in increased flower abundance under nutrient-poor sediment conditions. Differences between plants in flower production were positively correlated with the above- to belowground biomass ratio, We thus propose that nutrient supply and biomass allocation should be incorporated in the age- and size-dependent models for plant reproductive effort. These models should also consider separately the induction of flowering and the production of flowers (flower abundance). [KEYWORDS: RUPPIA DREPANENSIS, NITRATE FERTILIZATION, FLOWERING TIME]

It's Food Fight! Introducing the Chef's Hat Card Game for Affective-Aware HRI

Emotional expressions and their changes during an interaction affect heavily how we perceive and behave towards other persons. To design an HRI scenario that makes possible to observe, understand, and model affective interactions and generate the appropriate responses or initiations of a robot is a very challenging task. In this paper, we report our efforts in designing such a scenario, and to propose a modeling strategy of affective interaction by artificial intelligence deployed in autonomous robots. Overall, we present a novel HRI game scenario that was designed to comply with the specific requirements that will allow us to develop the next wave of affective-aware social robots that provide adequate emotional responses.Comment: Accepted by the Workshop on Exploring Creative Content in Social Robotics at HRI202