Abstract:The regeneration capacity of six types of explants (segments from hypocotyl, cotyledons, epicotyl, leaf, internodes and petiole) was compared in 13 cultivars of tomato (Lycopersicon esculentum Mill). Explants were cultured on a regeneration medium containing 1 mg/l zeatin and 0.1 mg/l indole-3-acetic acid. The number of shoot primordia and shoots with 1 or more fully developed leaves was evaluated after 6 weeks. The regeneration capacity was significantly influenced by cultivars and explant types. The total number of shoot primordia produced in all types of explants was highest in the cultivars Hana and Premium and lowest in UC 82 and Money Marker. Cv. Hana also produced the highest number of shoots. The most responsive explants in most cultivars were hypocotyls and epicotyls with up to 100% regeneration and mean production of 6.3 and 6.5 shoot primordia per explant, respectively.

No abstract

ABSTRACT:We studied the effect of different plant growth regulators on in vitro regeneration and plant growth of three cultivars of tomato (Lycopersicon esculentum Mill.) from explants derived from hypocotyls and cotyledons of aseptically grown seedlings. The regeneration capacity was significantly influenced by cultivar and explant type. The highest number of shoots regenerated in both types of explants was recorded on MS medium supplemented with 1.0 mg/dm 3 zeatin and 0.1 mg/dm 3 IAA. The cultivar UC 82 showed the best regeneration capacity on all types of used media. The most responsive explants were hypocotyls with 90-92% regeneration in dependence on the used cultivars and mean production from 0.18 to 0.38 shoots per explant. 119of MURASHIGE and SKOOG (1962) (hereinafter abbreviated as MS), 100 mg/dm 3 myo-inositol, 2 mg/dm 3 thiamine.HCl, 0.5 mg/dm 3 pyridoxine. HCl, 0.5 mg/dm 3 nicotinic acid, 1% (w/v) sucrose and 0.7% (w/v) agar. The cultures were initially kept in the dark at 27 ± 1°C for two days and then maintained under a 16 h photoperiod at 50 µmol m 2 s, with day/night temperature of 25°C/20°C. Hypocotyl and cotyledon segments were cut from the seedlings grown in vitro. The hypocotyls were cut into three segments. Each cotyledon was transversally cut into two segments. Hypocotyls were transversally cut into 4-7 mm segments and leaf-blades into pieces of 30-40 mm 2 . The hypocotyl explants were placed horizontally on the medium surface and cotyledon explants with the adaxial surface in contact with the medium. Regeneration was induced on MS medium supplemented with different concentrations of cytokinins (ZEA, BAP, TDZ) and auxin (IAA) (Table 1). After 3 weeks cultured explants were transferred on: 1) MS without plant growth regulators (PGRs), 2) MS medium contains half concentration of PGRs and 3) MS medium with full concentration of PGRs (Fig. 1). The media were adjusted to pH 5.8 prior to autoclaving. Glass containers with 25 cm 3 of medium were used.Six weeks later the regeneration capacity of explants was assessed. The following parameters were evaluated: the frequency of regeneration (percent of regenerating explants) and the number of shoots per explant. Data on regeneration frequency (%) were transformed by arcsin√x prior to statistical analysis. The experiment was repeated twice using 30 explants per variant. Significance of difference between the results was estimated by analysis of variance (ANOVA). Variation among means was analysed using LSD (P ≤ 0.05) procedure. RESULTSThe effect of different tomato cultivars and different PGRs concentrations on shoot regeneration from aseptically grown hypocotyls and cotyledons showed significant variation in both the genotype and PGRs. A large variability in the number of shoots was observed between cultivars and between the different PGRs concentrations (Table 2). Cultivar mean comparisons (least significant difference, LSD, P ≤ 0.05) showed only two classes differing in the induction potential. The cultivar which produced the most shoots on hypocot...

No abstract

No abstract

In this study, seedlings of Pyrus pyraster and Sorbus torminalis were grown for 60 days in the regulated environment of a growth chamber under different water regimes. The measured indicators were the growth and distribution of mass to organs, total biomass, root to shoot mass ratio (R:S), and gas exchange parameters (gs, E, An, and water use efficiency (WUE)). The amount of total biomass was negatively affected by drought. Differences between species were confirmed only for the dry matter of the leaves. P. pyraster maintained the ratio of the mass distribution between belowground and aboveground organs in both variants of the water regime. S. torminalis created more root length for a given dry-mass under drought treatment, but its R:S was lower compared to P. pyraster. The water potential of the leaves (Ψwl) was affected by substrate saturation and interspecific differences. P. pyraster had a demonstrably higher water potential and maintained this difference even after prolonged exposure to drought. After 30 days of different water regimes, Pyrus maintained higher values of gs, An, and E in control and drought treatments, but over a longer period of drought (after 50 days), the differences between species were equalized. The changes of the leaf gas exchange for Pyrus were accompanied by a significant increase in WUE, which was most pronounced on the 40th day of the experiment. A significant and strong relationship between WUE and gs was demonstrated. The results confirmed the different physiological performances of seedlings of tree species and the different mechanisms of their response to water scarcity during drought treatment. P. pyraster presented more acclimation traits, which allowed this taxon to exhibit better performance over a longer period of water scarcity.

in accordance with priorities of sustainable development in Serbia, production and use of biomass is crucial for provision of annually renewable national sources of energy and for environmental quality conservation. Rural development has typically focused on improving agricultural production and promoting market orientation, however, as the examples of other countries in the EU accession process have shown (e.g. Slovakia), such an approach could threaten the survival of rural population. Biomass production is one of the key sectors with significant potential for diversification of rural economy. The results of multiannual research work supported by the Ministry of Education, Science and Technological Development of the Republic of Serbia through national scientific projects and several international initiatives are summarized in this paper. The research activities focus on Miscanthus × giganteus Greef et Deu. The production potentials of miscanthus on fertile and degraded soils were investigated since 2009 in experimental plots established on moderate and extremely degraded lands in Serbia, applying various agrotechnical measures in different ecological conditions. The results show that fertile agricultural land as well as moderate degraded areas provide suitable conditions for miscanthus biomass and viable rhizomes production for energy and ecoremediation purposes.

No abstract