Tomislav Jemrić

Pollen germination and pollen tube growth in Fraxinus pennsylvanica

With regard to adaptation of green ash (Fraxinus pennsylvanicaMarshall) to ecological conditions in Croatia, pollen germination and pollen tube length after 2, 4 and 6 hours were examined in vitro at 10, 15, 20 and 25°C during two years 2001 and 2002. Narrow leaved ash (F. angustifoliaVahl) pollen served as a control in 2002. The year, time and temperature, and the interaction between time and temperature were significant for both germination percentage and pollen tube length. Interactions year × temperature and year × time were significant for pollen tube length only. The highest germination percentage (17.86% in 2001 and 19.40% in 2002) of green ash pollen was at 15°C after 6 hours. The pollen tube length was greatest at 20°C (393.46 µm) in 2001 and 25°C (899.50 µm) in 2002 after 6 hours. Narrow leaved ash pollen had the highest germination percentage (19.22%) at 20°C after 6 hours and was significantly reduced at 25°C. The pollen tube length was greatest at 25°C (518.90 µm) after 6 hours. It can be concluded that green ash pollen has satisfactory germination in ecological conditions in Croatia and that the optimum temperature for pollen germination is higher than 20°C.

Development and evaluation on a wireless multi-gas-sensors system for improving traceability and transparency of table grape cold chain

A WGS2 for table grape cold chain was developed and evaluated.The key traceability indicators include temperature, humidity, CO2, O2, and SO2.The shelf life model was built to predict the quality indicators.Tested and analyzed in two sample table grapes cold chains in China.Improving the traceability and transparency of the table grape cold chain. There is increasing requirement to improve traceability and transparency of table grapes cold chain. Key traceability indicators including temperature, humidity and gas microenvironments (e.g., CO2, O2, and SO2) based on table grape cold chain management need to be monitored and controlled. This paper presents a Wireless Multi-Gas-Sensors System (WGS2) as an effective real-time cold chain monitoring system, which consists of three units: (1) the WMN which applies the 433MHz as the radio frequency to increase the transmission performance and forms a wireless sensor network; (2) the WAN which serves as the intermediary to connect the users and the sensor nodes to keep the sensor data without delay by the GPRS remote transmission module; (3) the signal processing unit which contains embedded software to drive the hardware to normal operation and shelf life prediction for table grapes. Then the study evaluates the WGS2 in a cold chain scenario and analyses the monitoring data. The results show that the WGS2 is effective in monitoring quality, and improving transparency and traceability of table grape cold chains. Its deploy ability and efficiency in implantation can enable the establishment of a more efficient, transparent and traceable table grape supply chain.

The effects of postharvest application of lecithin to improve storage potential and quality of fresh goji (Lycium barbarum L.) berries

To enhance storage life and post-storage quality of fresh goji berries, three treatments with lecithin (1, 5, 10g·L-1) and two storage times (8, 16days) were evaluated. The significant effects on the physiological and biochemical parameters were varied. 1g·L-1 lecithin showed its main effects after 8days of storage by reduction in total weight loss and decay, SSC/TA ratio (also at 16days), and chlorophyll content and with highest scores of sensory attributes (also at 16days). 5g·L-1 lecithin showed its main effects after 16days of storage: highest SSC, highest TA (also at 8days), highest TPC, only significant reduction in DPPH antioxidant activity, and highest total flavonoid content. 10g·L-1 lecithin showed its main effects after 8days of storage with highest SSC, chlorophyll content, total flavonoid, DPPH, and ABTS antioxidant activity (also at 16days), but with least scores of sensory attributes.

Effects of Ocimum spp. essential oil on Monilinia laxa in vitro

One of the most important postharvest diseases of peach and nectarine is brown rot caused by the fungus Monilinia laxa. Increasing concern related to the toxic effect of the pesticide residues on fruits has enhanced the interest for the control of postharvest pathogenic fungi using biologically active constituents of plants such as essential oils. Species from genus Ocimum are known to possess essential oils with antifungal and fungicidal properties. The present paper reports the results of essential oil composition of four basil taxa and preliminary screening of their antifungal activity against M. laxa. The greatest effectiveness was achieved by the essential oils from Ocimum basilicum var. purpurascens and Ocimum tenuiflorum, whose activity was high throughout the testing period of twenty-three days.

First Report of Tilletiopsis pallescens Causing White Haze on Apple in Croatia

During 2014, apples ‘Pink Lady®’, showing white haze (WH) symptoms, were harvested in an orchard near Vratisinec (Croatia). Fungi were isolates from symptomatic epidermal tissue on Rose Bengal Chloramphenicol agar. After 7 days of incubation in the dark at 26°C, from whitish to cream colonies with irregular margin, single spore were isolated and transferred on Potato dextrose agar (PDA). Pathogenicity was tested on 20 apples ‘Pink Lady®’ and the pathogen was inoculated by aerosol diffusion on the sterilized surface. Symptoms occurred and T. pallescens was reisolated from inoculated fruit on PDA. Control fruits were symptomless. After 7 days at 26°C, the colonies and the morphology of conidia were the same as those of the original isolates. PCR amplification was carried out, from single spore DNA extraction, using universal primers ITS1 and ITS4. Two amplified sequences (AN KR269863 and KR269864) were blasted in Genbank obtaining 100% homology with strains of Tilletipsis pallescens. To confirm the species DNA sequences were aligned with CLUSTAL W with closely related species of Tilletiopsis (T. pallescens GQ281316.1, DQ317636.1 ; T. washingtoniensis DQ025483.1 ; T. lilacina AB025683.1, AB025689.1T ; T. cremea AB025690.1 ; and an undefined species Tilletiopsis sp. GQ281313.1) and a phylogenetic analysis with the Neighbor Joining method based on Maximum Composite Likelihood model (bootstrap 1, 000) was performed (supplementary material). The phylogenetic tree confirmed the identity of the isolates to the species Tilletiopsis pallescens. To our knowledge, this is the first report of Tilletiopsis pallescens causing postharvest white haze on apple in Croatia.

In vitro pollen germination and pollen tube growth differences among Quercus robur L. clones in response to meteorological conditions

Abstract The impact of meteorological conditions on in vitro pollen germination and pollen tube growth during the initial phases of the development of male flowers in the Pedunculate Oak, Quercus robur, is studied. Phenological observations of male flowers and pollen sampling were performed on the field trial established with grafted Pedunculate Oak clones. During the investigation, weather conditions (absolute minimum and maximum daily air temperature, minimum absolute relative humidity of air and amount of precipitation) were recorded by an automatic meteorological station installed at the field trial. Influence of meteorological conditions on pollen germination and pollen tube growth was studied in the following stages of male flower: (I) during the last ten days of flower bud dormancy, (II) during swelling of the buds, (III) during bud burst and beginning of male catkins elongation, (IV) during the final stage of male flower catkins elongation. High temperatures and low relative air humidity during the bud burst and beginning of the male catkins elongation reduced pollen germination and pollen tube growth. Weather conditions did not significantly affect pollen germination and pollen tube growth during the swelling of flower buds, or in the final stage of male catkins elongation.

Colouration of Apple cv. ‘Braeburn’ Grown Under Anti-Hail Nets in Croatia

Abstract Four anti-hail and anti-insect nets (red, white and yellow anti-hail and Stop Drosophila Normal) were used on apple cv. ‘Braeburn’ grown in northern Croatia in order to evaluate their effect on fruit colouration that was measured with the colorimeter (expressed as: L* – lightness, a* – yellow/blue b* – green/red) on two sides of fruit (“green” side and “red” side), and also they were used in order to evaluate their effect on the coloured surface percentage, apart from their anti-hail and pest damage protection properties. The fruits were harvested on 12th October 2015. Most differences were found between the fruit grown under the white anti-hail net and the fruit grown without the anti-hail net. Colour value “a*” was lower on the red side of the fruit under the white net in comparison with the red net. On the green side, “a*” value was lower and “L*” value was higher under the white net in comparison with control fruit. Different net colour had no influence on total colour difference. Regarding to the colouration, differences among the nets are found in classes 0–25% and 50–75% of skin coloured fruit. The fruit grown under the white nets had the higher percentage of fruit in class 0–25% than those grown without the net. The lower share of fruit in class 50–75% of skin colouration was recorded under the white net than under the red net or in the control fruit. Colouration index was lower in the fruit grown under the white net than in the control fruit. It can be concluded that the white anti-hail net promotes ripening, but at the same time it decreases red colouration. No significant differences in fruit colour have been found in the fruit grown under the red, yellow and Stop Drosophila Normal nets. Some accepted colour parameters such as a*/b* ratio are not appropriate for describing colour changes in ‘Braeburn’ apple in this study.