Aleksandar Simic

Seed germination and seedling vigour of italian ryegrass, cocksfoot and timothy following harvest and storage

During post-harvest maturation, different species vary in the length of dormancy breaking or germination increases. Seed dormancy and slow seedling development often limit establishment of forage grass stands. Seed germination and seedling vigour of Italian ryegrass (Lolium italicum A. Braun, Synonym Lolium multiflorum L.), cocksfoot (Dactylis glomerata L.) and timothy (Phleum pretense L.) were observed after harvest and storage. After harvest in June, seeds were stored under standard storage conditions and sampled every 30 days after harvest (DAH), up to 270 DAH, and then every 60 days up to 990 DAH. At each date, seeds were tested for final germination percentage and for seedling vigour traits. Timothy seeds had a maximum germination (88%) and the best seedlings vigour at 90 DAH, which implies that early autumn (September-October) is the best sowing period for freshly harvested seeds of timothy. Timothy seed germination was poor from 270 DAH (73%). The best germination and vigour of Italian ryegrass and cocksfoot seedlings were between 270 and 330 DAH, which equates to spring sowing time (March-April) in the succeeding year. Cocksfoot and Italian ryegrass seeds maintained satisfactory germination levels up to 630 DAH (81%) and 810 DAH (81%), respectively. The data can serve for the determination of a proper storage duration management between harvest and sowing of the tested species under ambient conditions of south-eastern Europe.

The effect of vegetation area size on grass seed yield

This paper surveys sowing norms (row spacing and seed rate) in both our country and the world, as well as the optimal seed rates in grass seed production. It gives a short overview of row spacings and seed rates applied in our and some other countries. Earlier, grass cultivated for the purpose of seed production was grown on small vegetation area. According to some researches, high seed yields can be achieved by cultivating grass on large vegetation area. Based on the results obtained, it can be concluded that the highest cocksfoot, timothy, meadow fescue, tall fescue seed yield was achieved with plants grown in 50 cm spaced rows employing lower seed rates (8 and 4 kg/ha of seeds). The highest Italian ryegrass and perennial ryegrass seed yield was achieved with plants grown in 20 cm spaced rows employing 20 kg/ha of seeds.

Dry Matter Production and Nutritive Value of Perennial Ryegrass Cultivars Collection

Perennial ryegrass (Lolium perenne L.) is one of the most important perennial cool-season forage grasses. It is highly productive, with the highest nutritive value among forage grasses, adapted for frequent defoliation and grazing. Market demands focus interest of perennial ryegrass breeders to production of cultivars with high, stable yield and good dry matter quality, tolerant to drought, frost and other stressful environmental conditions, with different maturity. According to that, initial breeding material must be heterogeneous, with a range of different genotypes, either cultivars or wild populations. In this article the diversity in a collection of perennial ryegrass cultivars has been investigated at the beginning of the breeding process. The collection consisted of 21 genotypes which originated from Europe and USA. Within a 2-year period time of tillering, crop height in first and regeneration in second cut, annual yield and nutritive value of dry matter were investigated. The data were analysed by ANOVA on the basis of 2-year mean values and all traits showed great level of variability. Highest annual dry matter yield of about 14tha−1 was achieved by cultivars Mara and K-11, both being intermediate diploid varieties.

Minimally invasive surgery for benign esophageal disorders: first 200 cases

SummaryBackgroundTo evaluate the method of introduction, feasibility, and early results of a laparoscopic surgery for benign foregut disorders in a single high volume center.MethodsA retrospective clinical study included consecutively laparoscopically operated patients due to benign foregut disorders. The study was conducted at the Department of Esophagogastric Surgery, First Surgical University Hospital, School of Medicine, University of Belgrade from March 2010 until July 2014. Complete preoperative diagnostics data, details of surgical procedures, and follow-up results are included.ResultsOverall, 200 consecutive patients were enrolled in the study. GERD and achalasia were the most common indications for laparoscopic surgery, with 81 and 72 patients respectively. Due to giant hiatal hernia, 37 patients were operated on, while the rest were less common indications. There were no conversions to open procedures. In three patients, pneumothorax resulted from intraoperative pleural lesion. One mucosal perforation occurred in an achalasia patient. One reoperation was conducted due to excessive port site bleeding. Short term follow-up results are highly satisfactory, and are presented in detail for every patient group.ConclusionIntroduction of laparoscopy in a foregut surgery high volume center for the treatment of benign foregut disorders can be obtained with low incidence of complications, and satisfactory short term functional results.

Assessment of AquaCrop model in the simulation of seed yield and biomass of Italian ryegrass

ABSTRACT Given that the optimal sowing rate and inter-row spacing of Italian ryegrass raised for seed have not been determined, the objective of this research was to assess the effect of crop density on biomass and seed yields under different climate conditions, applying the AquaCrop model. The data came from experiments conducted under moderate continental climate conditions at Stitar (Serbia) and Mediterranean climate conditions at Cukurova (Turkey). At Stitar, there were three different inter-row spacings (high (Sd), medium (Sm) and low (Sw) crop densities), while at Cukurova there was only high crop density (Sn). In the calibration process, the initial canopy cover, canopy expansion and maximal canopy cover were adapted to each crop density, while the other conservative parameters were adjusted to correspond to all climate conditions. Calibration results showed a very good match between measured and simulated seed yields; the values of the coefficient of determination (0.922). The biomass simulation was very good for Cukurova (R2 = 0.97), but somewhat poorer for Stitar (R2 = 0.72). Other statistical indicators were high such as Willmott index of agreement of both the calibrated and validated data sets, for both study areas >0.916 and normalized root mean square error in the range from 9–18%. The AquaCrop model was found to be more reliable for Italian ryegrass biomass and seed yield predictions under mild winter climate conditions, with adequate water supply, compared with moderate climate and water shortage conditions.

Yield and nutritional value of permanent grassland forage under simulated rotational grazing

A cutting experiment was conducted to test the changes in botanical composition, yield and nutritional value of forage, obtained in conditions of simulated rotational spring grazing on permanent grassland. The experiment was carried out on permanent pasture in vicinity of Šabac, Serbia in 2015 included three cuttings as a simulated rotational spring grazing. The highest share of grasses was noted in the first cut and decreased in the second and third cut, with increased forbs participation, and relatively constant percentage of legumes. The highest dry matter (DM) yield was obtained for the first harvest, followed by the second cut, and the lowest forage production was determined for the third harvest, with only 11.04 and 17.42% of the first and second cut yield. There were not found the significant differences between cuts for herbage DM and crude protein content. Markedly lower value for non-protein N concentration (p<0.05) was determined in the third cut. The fiber content increased during the grazing season (p<0.05), with the highest value determined in the herbage obtained in the second cut. The highest energy values (p<0.05) had the herbage produced in the first cut (DM basis), wherein the lowest values were found in the forage from the second harvest. These results indicate that especially herbage yield of analyzed grassland as chemical composition and nutrition value are highly variable during the growing season. The accurately defined optimal period for using is necessary to provide the high-quality forage for grazing animals.

Alternative therapies for GERD: a way to personalized antireflux surgery

Gastroesophageal reflux disease (GERD) is a common disorder, known to affect about 20% of the Western population. Although conventional medical or surgical treatment has proven effective, there is certainly room for improvements. As only 10% of GERD patients are finally treated by antireflux surgery, a large therapeutic window exists. This treatment gap consists of patients who are not effectively treated with proton pump inhibitor but do not want to run the potential risks of conventional surgery. During the last two decades, several novel and intriguing options for the surgical treatment of GERD have been introduced and found their way into clinical use. The following summary will give an update of certain alternative therapeutic options to treat GERD or its pathological consequences.

The performance of perennial ryegrass in binary mixtures with lucerne and red clover under N fertilization

Perennial ryegrass is a very important and widespread grass species used for livestock nutrition, in particularly ruminants. As a species that is most commonly used on grasslands, it is grown in mixtures with other types of grasses and legumes. The objective of the research was to investigate the performance of perennial ryegrass at various proportions in the mixtures with red clover and lucerne, and how different levels of N fertilization affect its competitiveness. Ryegrass achieved the highest yield with lucerne at seeding rate 50:50 and with red clover at seeding rate 70:30. Relative grass yield (RYg) of mixtures ranged from 1.01 to 1.55 respectively, which means that ryegrass in mixtures achieved 0.1-55% greater yield than pure ryegrass crop. N fertilization increased DMY and RYg, leaf : steam ratio, specific leaf area (SLA), leaf area ratio (LAR) and leaf area index (LAI) in both years thus increasing the competitive capability of perennial ryegrass.

APPLICATION OF FARMYARD MANURE IN GRASSLAND PRODUCTION

This experiment aimed at determining the effect of farmyard manure (FYM) applicationon a natural pasturein Western Serbia, with a 30 t ha-1treatment in comparison to control (no fertilizer added) during two years (2012-2014).The FYM was applied in the autumn of 2012 and the trial plots were harvested twice a year. Dry matter (DM) yield and forage quality - content of crude protein (CP), nonprotein N (%CP), neutral detergent fiber (NDF), acid detergent fiber (ADF) and net energy for lactation(NEL), were estimated for each production year. Treatment with manure gave a higher DM yield compared to control plots in both experimental years (5.91 t ha-1 vs. 3.01 t ha-1 in 2013, and 2.76 vs. 2.03 t ha-1 in 2014). As expected,the yield in the second cuts of both years was much lower than in the first cuts. The FYM application did not affect chemical composition and net energy concentration of forages, whereas significant effects of different cuts were found, but were inconsistent between the first and second experimental year. In general, it can be concluded that application of FYM did not have a significant effect on forage quality ina permanent grassland, whereas chemical composition was significantly affected by different cuts and experimental years. Based on the results, a grassland may have a good DM yield response if FYM is used as a fertilizer, while the effect on forage qualitymay be much weaker.

Yield and morphological traits in alfalfa varieties of different origin

The study was conducted to examine variability of green forage yield (GFY) and morphological traits (tiller length, internodes length, internodes-stem diameter, leaf width and length) in nine alfalfa varieties from USA and six varieties from Europe. The trials were carried out in Central Serbia during the second (2006-A1) and third year (2007-A2) of alfalfa exploitation. In unfavourable environmental conditions (A1), varieties from the USA had higher coefficient of variability (CV, %) in all cuttings (I CV=16.93, II CV=17.13, III CV=13.00, IV CV=21.29), as well as total yield variability (CV=14.33), compared to varieties from Europe (I CV=7.45, II CV=6.47, III CV=10.65, IV CV=19.51, for total yield CV=6.43). In the favourable agro-ecological conditions (A2) genetic potential of varieties was manifested, which caused similar yield variability. Variety origin (USA or Europe) had a low effect on variability of the morphological traits. The highest correlation (P £ 0.001) was achieved between yield and tiller length, regardless of variety origin.