Sanitary improvement of the Citrus colletion in the Botanical Garden of Palermo (Italy)

Size effect in phase transition kinetics

The growth of a spontaneous lattice average magnetization in a magnetic system which is suddenly brought below the transition temperature is a stochastic process in which the very small fluctuations of the initial magnetization are amplified to a macroscopic size. The initial magnetization fluctuates in time around the zero average value because of the finite size of the system. As a consequence of the fluctuation-amplification phenomenon the nonlinear relaxation of the finite system is qualitatively different from that of the infinite one. The present paper studies this feature of phase-transition kinetics in the framework of a very simple model: the dynamical generalization of the spheric…

Recupero, conservazione e analisi genetica della collezion di agrumi dell'Orto Botanico di Palermo

Zygotic and nucellar embryo survival following dehydration and cryopreservation of citrus intact seeds.

A cryopreservation procedure by dehydration and direct immersion in liquid nitrogen was developed for seeds of four polyembryonic Citrus species, and the sexual or nucellar origin of the recovered seedlings was investigated. Seeds of three species could be desiccated in a sterile air flow to 16 percent (C. sinensis) or 10 percent (C. aurantium and C. limon) moisture content with a negligible reduction in germination levels. Differently, the germinability of C. deliciosa seeds dropped to 50 percent after drying to 15 percent moisture content. Following dehydration treatments, a reduction in the average number of seedlings per germinated seed was always observed. However, all four species ben…

Non linear relaxation in the presence of an absorbing barrier

Recupero, conservazione ed analisi genetica della collezione di agrumi dell’Orto Botanico di Palermo