Effect of compost application on the dynamics of carbon in a nectarine orchard ecosystem.

The aim of the present study was to compare the quantity and the type of carbon (C) stored during the 14-year lifetime of a commercial nectarine orchard ecosystem fertilized with mineral or organic fertilizers. The study was carried out in the Po valley, Italy, in a nectarine orchard of the variety Stark RedGold, grafted on GF677 hybrid peach × almond. Since orchard planting in August 2001, the following treatments were applied in a randomized complete block design with four replicates per block and compared: 1. unfertilized control; 2. mineral fertilization (including P and K at planting and N applied as NO3NH4 yearly at the rate of 70-130 kg ha-1); 3. compost application at a rate of 5 Mg DW ha-1 yr-1; 4. compost application at a rate of 10 Mg DW ha-1 yr-1. Compost was obtained from domestic organic wastes mixed with pruning material from urban ornamental trees and garden management after a 3-month stabilization period. Application of compost at the highest rate increased C in the soil; the amount of C sequestered was approximately 60% from amendment source and 40% from the net primary production of trees and grasses with a net increase of C compared to mineral fertilization. Compost application was found to be a win-win strategy to increase C storage in soil and, at the same time, to promote plant growth and yield to levels similar to those obtained with mineral fertilization. The rate of C application is crucial, indicated by the fact that compost supply at the rate of 10 Mg ha-1 yr-1 was the only fertilization strategy of the ones tested that resulted in higher C sequestration. This shows that compost amendment may stimulate an increase in the net primary production of plants.

[VISPA's group (evaluation of the implementation strategies of the measurements instruments adopted in the Italian nursing practice)]. / Come imparare a fare ricerca nell'infermieristica: sintesi di un'esperienza applicativa.

An innovative teaching strategy focused on problem based approach rather than theorical aiming to facilitate the learning of the research methodology in advanced nursing student has been introduced. Through out a qualitative evaluation of the diary kept by the student nurses involved, advantages and disadvantages of this innovative approach have been evaluated. This paper reports a synthesis of the teaching strategy and its impact on the competences in the research methodology as it has been perceived by the students participants.

Storage of foliar-absorbed nitrogen and remobilization for spring growth in young nectarine (Prunus persica var. nectarina) trees.

The effectiveness of spraying foliage with urea to provide nitrogen (N) to augment the seasonal internal cycling of N in young nectarine trees (Prunus persica (L.) Batsch var. nectarina (Ait. f. Maxim.), cv. Stark Red Gold) was studied. One-year-old trees were grown with contrasting N supplies during the summer and foliage was sprayed with a 2% urea solution labeled with (15)N just before leaf senescence started. After leaf abscission had finished, the trees were repotted in sand and given no further N. Remobilization of both labeled and unlabeled N for leaf growth the following spring was quantified. Leaves absorbed between 58 and 69% of the (15)N intercepted by the canopy irrespective of tree N status. During leaf senescence, the majority of (15)N was withdrawn from the leaves into the shoot and roots. Remobilization of (15)N the following spring was also unaffected by tree N status. About 38-46% of (15)N in the trees was recovered in the new growth. More unlabeled N (derived from root uptake) was remobilized for leaf growth in the spring than was withdrawn from leaves during canopy senescence the previous autumn. Therefore, soil-applied N augmented N storage pools directly, and contributed more to N remobilization the following spring than did foliar-absorbed (15)N.

Dopamine synthesis, uptake and metabolism in embryonic rat mesencephalic cultures.

We have developed an HPLC method using electrochemical detection (ED) to study the synthesis, uptake and metabolism of dopamine (DA) in primary cell cultures dissociated from rat embryonic mesencephalon. The method is rapid and simple and is also able to detect, after 7 days in vitro incubation (DIV), intracellular levels of L-3,4-dihydroxyphenylalanine (L-DOPA) and 3,4-dihydroxyphenylacetic acid (DOPAC). The amount of DA synthesized and taken up from the cells is directly proportional to in vitro development time; the contents of endogenous DA is related to the number of mesencephalic neurons originally plated. When the dopa decarboxylase inhibitor alpha-methyldopa is added to the incubation medium, it reduces DA levels and conversely increases the amount of L-DOPA in a dose-dependent manner. In mesencephalic-striatal cocultures a statistically significant increase in the amount of DA is observed. This is not observed when either cerebellar or cortical cells are used in the cocultures which confirms the importance of target striatal cells in the maturation of dopaminergic mesencephalic neurons.