Influence of Polyamines on the Long Distance Transport of K (86Rb) in Potato Cuttings (Solarium tuberosum cv. Sirtema)-- Comparative Study with some Phytohormones

Plantlets of Solanum tuberosum L. cv. Sirtema were used to studythe regulation of the long-distance transport of potassium.The effects of polyamines and two plant hormones, abscisic acid(ABA) and benzyladenine (BA), on this process were investigated.Foliar sprays of putrescine or BA increased the transport of(K) ⁸⁶Rb to the upper part of the plant. In contrast, spermidinetreatment enhanced the translocation into the growing tuber,as did ABA. These specific effects were partially correlatedto the distribution of endogenous polyamines within the plant.Spermidine was the predominant polyamine in the tuber whileputrescine was as abundant as spermidine in the leaves. Thetotal amount of putrescine, spermidine and spermine decreasedwith the physiological age of the leaves and tubers. Moreover,from heat-girdling experiments, it was shown that the polyamine,¹⁴C-putrescine, supplied to a leaf, was transported via thephloem. It is suggested that polyamines like phytohormones havea regulatory role in long-distance transport. Key words: Hormone-directed-transport, K, phloem, polyamines, potato, ¹⁴C-putrescine transport     

Daily activity rhythm and use of shelter in the slugs Deroceras reticulation and Arion distinctus under laboratory conditions

Daily activity of slugs, Deroceras reticulatum and Arion distinctus, was studied in the laboratory in relation to the presence of shelters so as to define optimal conditions for using traps to forecast crop damage. Under constant temperature and humidity, activity of slugs began with the lights off. Its arrest occurred after a period of activity with the lights on. Slugs rested most frequently under a shelter on bare earth and rarely used the same shelter for more than two consecutive days. When food was placed under the shelter, the number of slugs found under the shelter was more constant throughout the 24 h period, but lower during diurnal rest. The presence of 4% methiocarb pellets under the shelter led to an increased occupation by slugs, due to the poisoning of some of them. Acts of aggression were more numerous in A. distinctus than in D. reticulatum. In D. reticulatum the smallest slug was the least aggressive and suffered more attacks from the other slugs. In A. distinctus the numbers of attacks suffered or provoked varied little with the size of the slug, but the smallest slug showed less interactions with other slugs.     

Daily variation in the number of slugs under refuge traps

Daily variation in the number of slugs under and around 25 cm × 25 cm pad‐traps was recorded in plots of crop cultures. Grey field slugs Deroceras reticulatum and garden slugs (Arion distinctus and Arion hortensis) left traps at dusk and came back at the end of the night. The time of day at which the number of trapped slugs was maximal did not occur in the middle of the day, when slugs were inactive, but in the early morning and in the evening, a few hours before dusk. This was due to a rise in temperature under the traps in the middle of the day. However, the grey field slugs stayed under traps throughout the morning, when temperatures under the traps reached values more favourable for rest.     

Migration and range use of Asian Houbara Bustard Chlamydotis macqueenii breeding in the Gobi Desert, China, revealed by satellite tracking

Four adult male Asian Houbara Bustards Chlamydotis macqueenii were caught on their breeding grounds in the Gobi Desert of China and tracked by satellite from July 2000 for from 5 months to > 3.5 years. Wintering areas were identified for two individuals, one on the Turkmenistan/Uzbekistan border in the Amur-Darya valley, the second at the Iran/Turkmenistan border. One individual used the same wintering and breeding areas for three consecutive years. Overall departure dates from breeding grounds ranged from 29 September to 14 October, with arrival on wintering quarters from 23 October to 7 November. Birds left their wintering grounds between 2 and 21 March and reached their breeding areas between 11 and 21 April. The mean overall migration distance was 3935 km (sd = ± 229, n  = 9). Houbara Bustards mainly followed steppe areas to migrate avoiding the highest elevations of the Himalayan massif and travelling 267 km/day on average. Pre-breeding migration lasted longer than post-breeding and included more and longer stopovers. The Taukum Desert and Jungar Basin are critical areas for migration of eastern Houbara populations. Breeding range, used for 5.5 months, was 274 km² (sd = ± 53, n  = 4), whereas wintering range, used for around 4 months a year, was 76 km² (sd = ± 22, n  = 3). Range use pattern appeared similar for Asian Houbara released in central Saudi Arabia, but differed from the African Houbara Bustard. More investigations are required to determine the effects of food availability and meteorological conditions on the migration pattern and on the use of stopovers by Asian Houbara Bustards.     

Potential effects of climate change on DOC release from three different soil types on the Northern Pennines UK: examination using field manipulation experiments

Three field manipulation experiments were carried out during 1993–1995 on the Northern Pennines to investigate the influences of temperature, solar radiation and rainfall on the release of dissolved organic carbon (DOC) from vegetated soil cores using zero‐tension lysimeters. The cores were manipulated by being translocated to four sites down a climatic gradient, by artificial soil heating or being exposed to double normal rainfall. In each experiment three soil types, a brown earth, a micropodzol and a peaty gley, with differing organic matter content and distribution within the profile, were studied. DOC data, expressed as mg C m^?2 day^?1, were analysed following log₁₀ transformation, by a repeated measures analysis of variance procedure, using climatic variables measured concurrently with sampling, and 1 and 2 months before sampling. DOC release was dominated by rainfall but was also associated with solar radiation and temperature. With each of the three climatic variables, rainfall, solar radiation and temperature, both positive and negative effects on DOC release have been found significant, indicating that the concurrent and delayed effects of the same variable may be different. DOC release was positively related with all three soils to concurrent rainfall, indicating rainfall's primary leaching action. DOC release was also negatively related to rainfall of the previous month indicating that its action depletes the leachable pool of DOC in the soil. DOC release was positively associated with solar radiation 2 months earlier, indicating that DOC's main source is that of primary production; DOC peaks closely followed peaks of annual primary production. DOC release was linked with temperature, the strongest association being with temperature 2 months earlier, indicating that temperature effects both primary production and DOC regeneration via organic matter decomposition. A conceptual model, relating our findings to those processes known to govern DOC release from soils, has been presented.     

FEEDING ACTIVITY OF LIMAX VALENTIANUS FERUSSAC: NOCTURNAL RHYTHM AND ALIMENTARY COMPETITION

Feeding activity of the slug Limax valentianus Férus-sacthroughout a 24-hour period began with the decrease in light.Feeding began 41 minutes after the start of locomotor activityand showed a maximum level in the beginning of the night L.valentianus had two to five meals each night, each meal lasting8.5 to 14 minutes. The overcrowding of the slugs induced a shorterduration of individual feeding periods and acts of aggressionduring meals. ^*Present address: Centre de Neurochimie, Laboratoire de neurobiologiemolécuiaire des interactions cellulaires. 5 rue BlaisePascal, 67084 Strasbourg, France (Received 7 July 1996; accepted 21 April 1997)     

Mouvements nycthéméraux foliaires chez le Cassia fasciculata inversé dans le champ de la pesanteur

Nyctinastic movements of leaves of Cassia fasciculata inversed in the field of gravity. Plants of Cassia fasciculata Michx, were grown under controlled conditions with a diurnal rhythm of 14 h light and 10 h dark. The nyctinastic movements performed by the leaves were observed by time lapse photography, on plants inverted in the field of gravity and compared to those recorded on plants remaining in natural position. The movements were observed on leaves from which the petiolar gland has been removed as well as on leaves in which it has been preserved. In plants inverted in the field of gravity, the leaflet movements were not disturbed but the petiolar ones were opposite to those observed on plants in natural position and smaller in amplitude (52 and 15 degrees difference between maximum and minimum positions respectively). This was not influenced by the removal of the petiolar gland. Inverting plants greatly shortened duration of closing and time spent maximally closed while increasing both duration of opening and time spent maximally opened. Removal of the petiolar gland did not influence the opening-closing schedule of the plants in normal position but in inverted plants it caused marked changes in this schedule. These results are discussed in connection with what is known about IAA. K⁺ and amyloplasts and their role in causing changes in pulvinus turgor.     

Migrations Orientées et Phytohormones — Valeur de la Feuille Détachée comme Matériel Expérimental

Directed Transport and Hormones — Value of Isolated Leaf as Experimental Material. Local application of aqueous phytohormonal solution (0.1 ml of various concentrations, from 50 to 0.025 mg-l^?1, of IAA, 2,4-D, NAA, BAP, GA₃) on isolated leaves influences the direction of ion transport. All tested hormones are efficient but the action depends upon the ionic species [positive action with ³²P, ³⁵S, ³⁶Rb (K), but null with ⁴⁵Ca or ⁴⁶Cl]. The movement of ions occurs through the phloem tissue and is not a cell-to-cell transfer. Competition between different parts of the leaf is demonstrated (a) between petiole which appears to be an important attractive centre and other parts of the leaf; (b) in a depetioloted leaf, between different centres induced by different phytohormones. In this respect, GA₃ appears to be the most efficient hormone in the tested material — leaves of Pelargonium zonale (L.) Aiton. The effects on directional transport are discussed in relation to other processes controlled by hormones, for instance growth, senescence, protein synthesis. A direct relation of directional transport with growth or delay of senescence may be discarded. The value of isolated leaves as simplified experimental systems is underlined by the fact that weak hormonal doses are efficient (0.025 mg.l for GA₃ and 0.5 mg.¹ for 2,4-D) as compared to the higher doses used in other plant systems.