EFFICACY OF METAMITRON IN APPLE THINNING IN SERBIA.

The thinning of fruits is a required pomotechnical measure in intensive fruit production which ensures the production of good quality fruits and high yields. Metamitron, known as inhibitor of photosynthesis, has been successfully used in the thinning of apple fruits. This study had the aim to determine the efficacy of metamitron on the thinning of apple fruits in the agroecological conditions of Serbia and to evaluate the possibility of its practical application. Two varieties of apples that are widely grown in Serbia, dared and Golden Delicious, have been chosen for this research. The experiments were carried out during 2011 and 2012 according to the EPPO PP 1/158 (3) method. Metamitron has shown a good efficacy in the thinning of apple fruits. The effect of metamitron on the thinning of apple fruits depends on multiple factors, pri- marily the application dose, time of application, apple variety, but also on the number of fruits developed. The best efficacy on the Idared variety was in plots where metamitron was applied at a dose of 1.1 kg ha⁻¹, once (in the growth stage when the fruits were 8 mm in diameter) or twice (in the growth stages when the fruits were 8 mm and 12 mm in diameter), when the number of developed fruits per tree is smaller, or 1.65 kg ha⁻¹ applied once when the fruits are 12 mm in size when a larger number of fruits per tree is developed. On the Golden Delicious variety, the best efficacy was in treatments when metamitron was applied twice (in the growth stages when the fruits were 8 mm and 12 mm in diameter) in quantities of 1.1 kg ha⁻¹, when less fruits per tree were formed or 1.65 kg ha⁻¹, applied once or twice when a larger number of fruits per tree were formed.

The First Report of Stolbur Phytoplasma Associated with Phyllody of Calendula officinalis in Serbia.

Pot marigold (Calendula officinalis L.) is native to southern Europe. Compounds of marigold flowers exhibit anti-inflammatory, anti-tumor-promoting, and cytotoxic activities (4). In Serbia, pot marigold is cultivated as an important medicinal and ornamental plant. Typical phyllody, virescence, proliferation of axillary buds, and witches' broom symptoms were sporadically observed in 2011 in Pancevo plantation, Serbia (44°51'49″ N, 20°39'33″ E, 80 m above sea level). Until 2013, the number of uniformly distributed affected pot marigold plants reached 20% in the field. Due to the lack of seed production, profitability of the cultivation was seriously affected. Leaf samples from 10 symptomatic and 4 symptomless marigold plants were collected and total nucleic acid was extracted from midrib tissue (3). Direct PCR and nested PCR were carried out with primer pairs P1/16S-SR and R16F2n/R16R2n, respectively (3). Amplicons 1.5 and 1.2 kb in length, specific for the 16S rRNA gene, were amplified in all symptomatic plants. No PCR products were obtained when DNA isolated from symptomless plants was used. Restriction fragment length polymorphism (RFLP) patterns of the 1.2-kb fragments of 16S rDNA were determined by digestion with four endonucleases separately (TruI1, AluI, HpaII, and HhaI) and compared with those of Stolbur (Stol), Aster Yellows (AY), Flavescence dorée-C (FD-C), Poinsettia Branch-Inducing (PoiBI), and Clover Yellow Edge (CYE) phytoplasmas (2). RFLP patterns from all symptomatic pot marigold plants were identical to the Stol pattern, indicating Stolbur phytoplasma presence in affected plants. The 1.2-kb amplicon of representative Nv8 strain was sequenced and the data were submitted to GenBank (accession no. KJ174507). BLASTn analysis of the sequence was compared with sequences available in GenBank, showing 100% identity with 16S rRNA gene of strains from Paeonia tenuifolia (KF614623) and corn (JQ730750) from Serbia, and peach (KF263684) from Iran. All of these are members of the 16SrXII 'Candidatus Phytoplasma solani' group, subgroup A (Stolbur). Phytoplasmas belonging to aster yellows (16SrI) (Italy and Canada) and peanut witches' broom related phytoplasma (16SrII) group (Iran) have been identified in diseased pot marigold plants (1). To our knowledge, this is the first report of natural infection of pot marigold by Stolbur phytoplasma in Serbia. References: (1) S. A. Esmailzadeh-Hosseini et al. Bull. Insectol. 64:S109, 2011. (2) I. M. Lee et al. Int. J. Syst. Bacteriol. 48:1153, 1998. (3) J. P. Prince. Phytopathology 83:1130, 1993. (4) M. Ukiya et al. J. Nat. Prod. 69:1692, 2006.

Governing factors for motor oil removal from water with different sorption materials.

This paper has been focused on the sorbent efficiency for motor oil removal from water. Two types of sorbents were investigated: organic and inorganic. Natural wool fibers (NWFs) and recycled-wool-based nonwoven material (RWNM)) were tested as organic type of sorbents. Sepiolite, bentonite and zeolite have been chosen as representative inorganic sorbents. Sorption was carried out in batch sorption system. Efficiency of oil removal was determined by measuring the oil concentration before and after the sorption process. Extractive-gravimetric method and refractive index determination have been applied as analytical methods for determination of oil concentration in water. Governing factors for sorbent efficiency were proposed, analysed and compared. It was concluded that sorption process is mostly affected by mass of sorbent, sorption time, temperature and pH value of water. NWFs, which were the most efficient sorbent showed maximal efficiency and maximal sorption capacity: 0.1 g of NWFs after 10 min at 20 degrees C and pH 8.00 sorbed 3.3 g of motor oil from 300 mL of water polluted with 4.5 g of motor oil. Maximal efficiency for all sorbents investigated was reached after 30 min of sorption processes, it was 95.0% for NWF, 43.0% for NRWM, 20.7% for sepiolite, 19.6% for bentonite and 21.2% for zeolite. Physical adsorption onto all sorbents is a favorable process (sorption efficiency decrease with increasing temperature) while sorption onto bentonite and zeolite is a result of both physical adsorption and chemisorption (sorption efficiency increase with increasing temperature, up to 80 degrees C).

Efficiency of oil removal from real wastewater with different sorbent materials.

The aim of this paper was to investigate the efficiency of different sorbent materials for oil removal from wastewater. Two types of sorbents were investigated: organic (loose natural wool fibers (NWF) and recycled wool based nonwoven material (RWNM)) and inorganic (sepiolite). Sorption was carried out in continuous tubular contractor (initial oil concentration of 1511 mg/dm(3)) and batch tank (initial oil concentration of 5066 mg/dm(3)). Wool-based sorbents showed higher sorption capacity (5.56 g/g for NWF and 5.48 g/g for RWNM) compared to sepiolite (0.19 g/g) in case of sorption in batch tank. The study on sorption in continuous tubular contractor suggested that volume of oily wastewater strongly affected oil removal. The results indicated that the combination of extractive-gravimetric and FTIR spectrophotometric methods can be recommended for precise determination of oil concentration, being suitable as a controlling tool for oil detection.