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Eleven plum cultivars (Prunus domestica L.) for processing grafted on semidwarf rootstock ‘Wangenheim Prune’ and vigorous rootstock ‘Myrobalan’ were densely planted (1000, 1250, 1666, 2500 trees ha-1) and trained to central leader spindle tree. A new training system was applied to obtain trees suitable for mechanical harvesting. The leader was not headed after planting and summer training procedures were performed in May/June. From the third year onwards, renewal pruning was carried out after fruit harvesting. The new training and pruning systems resulted in very fast tree growth, abundant branching, fruit bud formation on young wood and early bearing. The plum trees appeared to be suitable for hand and mechanical harvesting within 3 years from planting. The self propelled straddle combine harvester was able to harvest 2-3 tons of plums per hour compared to 30 kg with hand picking. Harvesting effectiveness was 90-95%. The quality of mechanically harvested plums was a little worse than of those hand picked, but fruits were suitable for processing. The ‘Common Prune’ and the prune type small plums were the most suitable fruit for mechanical harvesting.

Plant productivity in protected cultivation is highly influenced by air temperature and humidity. The conditions relating to the moisture content of the air in protected plant cultivation are preferably defined by vapour pressure deficit (VPD), which describes the difference between the maximal and actual water vapour pressure (kPa). VPD is widely used as the parameter describing the climate conditions favourable for the development of fungal diseases and for highlighting conditions unfavourable for plant development. In protected cultivation, both the air temperature and the humidity are influenced by heating systems, and one such system is a heat accumulator, which may store the excessive heat produced during the day by converting the solar energy inside the plastic tunnel, and using it when plant heating is required. The tunnel equipped with a heat accumulator maintained an optimal level of humidity for a longer period, and significantly reduced the time of excessive air humidity. The longest time with an optimal VPD was recorded in August in a tunnel with an accumulator – 30.5% of total time vs. 22.3% of time for control tunnel. The highest difference of total time where the VPD was too low (below 0.2 kPa) was recorded in July – 12.4% of time in a tunnel with an accumulator vs. 39.1% of time for control tunnel. The highest difference of total time with an excessive VPD (over 1.4 kPa) was recorded in May – 12.1% of time in a tunnel with an accumulator vs. 17.9% of time for control tunnel. However, a situation beneficial for plant growth occurred every month during the investigated season.

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Orchard location had a slight effect on the mean initial colour value, indicating differences in development stage, most probably due to differences in assessing the harvest date. The magnitude of the variation in these colour values was, however, the same for all three orchards. The behaviour of the green colour aspect (a* value) has been reported separately, as this represents the major change in perceived colour. The changes in b* and L* values are rather small, while the biological variation between the individual fruit is at least of the same magnitude. The model presented here is, as far as known, the first model on b* and L* values for green-coloured products. Analysing b* and L* data using this model provides additional information with respect to the stage of maturity at harvest in a batch or for an orchard of Granny Smith apples. All the variation in the yellow colour aspects could be attributed exclusively to the initial level of yellow compounds.

The aim of this study was to evaluate the effect of heated soil on the population of bacteria, fungi and nematodes inhabiting the soil of tomato cultivar "Tamaris" growing in peat and coconut substrates. In addition, these media were tested in two different containers: cylinders and slabs. The total number of bacteria and fungi was significantly higher in the peat substrate than in the coconut substrate. A much higher number of beneficial bacteria producing spores were noted in the coconut soil. The total number of bacteria and fungi was modified by the heating levels. In all the experimental treatments, most of the identified individuals belonged to the group of nematodes that feed on bacteria and it was the most diverse group of species. The highest total number of nematodes was recorded for the second heating level, with the exception of cultivation carried out in peat slabs, where the most of nematodes were found at the control level. The highest first crop was produced by plants growing on the peat slabs supplied with the highest soil temperature. Tomato roots of all the control treatments showed the highest root morphological parameters.

This paper presents the results of the analysis of thermal issues and energy efficiency of three types of accumulators; namely stone-bed; water and phase change. Research experiments were carried out during April–October 2013 in a standard commercial semi-cylindrical high plastic tunnel with tomato cultivation of 150 m2. A stone-bed accumulator; with an area of almost 75 m2 was installed in the tunnel below ground level; while a water accumulator with a volume of 4 m3 was installed outside the tunnel. A phase change material (PCM) accumulator, with a volume of 1 m3 containing paraffin, was located inside the tunnel. The heat storage capacity of the tested accumulators and the energy efficiency of the process were determined based on the analyses of the 392 stone-bed charging and discharging cycles, the 62 water accumulator charging cycles and close to 40 PCM accumulator charging and discharging cycles. Dependencies in the form of easily measurable parameters; have been established to determine the amount of stored heat; as well as the conditions for which the effectiveness of these processes reaches the highest value. The presented analysis falls under the pro-ecological scope of replacing fossil fuels with renewable energy. As a result of the analysis; it was found that; in the case of a stone-bed; such an accumulator shows higher efficiency at lower parameters; that is, temperature difference and solar radiation intensity. In turn; a higher temperature difference and a higher value of solar radiation intensity are required for the water accumulator. The energy storage efficiency of the PCM accumulator is emphatically smaller and not comparable with either the stone-bed or the water accumulator.