Volumen 23 (2015): Edición 2 (December 2015)

Mutation breeding is an established method used for crop improvement and has played a major role in the development of many new flower color/shape mutant cultivars in ornamentals. The present study is aimed at inducing mutations in Delphinium malabaricum using chemical mutagens ethyl methane sulfonate (EMS), sodium azide (SA) and physical mutagen (gamma rays). It was observed that D. malabaricum manifested specific reactions to the treatments with EMS, SA and gamma rays. Identification and selection of mutations were carried out in the second generation (M₂). A variety of chlorophyll deficient mutants and high percentage of the flower color and morphological mutants were recorded. The maximum frequency of chlorophyll and flower color and morphological mutations were recorded in EMS treated plants when compared to the other two mutagens. The frequency values for the individual mutant types were varied and randomly distributed at different mutagenic treatments. The highest percentage of color mutants arose after treatments with 0.25% of EMS and the lowest at 20 kR of gamma rays. The mutants were quite distinct, as compared to the control and often had more attractive ornamental features compared to the starting material. The major commercial benefit of the application of this technology has so far been obtaining of novel flower mutants that can be used as an initial material for further breeding of new cultivars.

An experiment was conducted in order to investigate the effects of exogenous polyamines (PAs) on the development of mycorrhizae in roots, nutrient uptake and vegetative and reproductive growth of Freesia hybrida ‘Golden Wave’. Corms of freesia were inoculated with Rhizophagus intraradices at sowing time and treated once a week by one of three PAs, putrescine (Put), spermidine or spermine, in concentrations of 0.05 and 0.1 mM each as foliar application or soil drench. Application of PAs, especially as soil drench, increased mycorrhizal colonization as well as the growth and development of inoculated plants. Among the three PAs, Put in 0.1 mM concentration was the most effective in increasing colonization, enhancing floral stem length and diameter, floral spike length, floret number on main and lateral spikes and increasing corm and cormlet weight, corm diameter and cormlet number. Sole application of arbuscular mycorrhizal fungi had no significant effect on the flowering time but soil drench with 0.1 mM Put accelerated flowering by about 17 days. Application of PAs elevated leaves N, P, K, Mg, Fe and Zn and corms’ P, K, Ca, Fe and Zn concentration of inoculated plants. Our results suggest that soil drench application of PAs, especially Put, positively influenced mycorrhizal inoculation and nutrient uptake, which leads to improving growth, flower and corm production and quality of mycorrhizal plants of freesia.

In this study, the effects of compounds providing Fe in chelated (NaFeEDTA and Fe(III)AC) and non-chelated (FeSO₄·7H₂O) forms as components of culture media, on in vitro shoot multiplication and rooting of Magnolia soulangeana ‘Alexandrina’, Magnolia grandiflora and Prunus cerasifera ‘Nigra’ were comparatively evaluated. Each of the tested chemicals was used as a single Fe source in the basal salt medium. In the stages of shoot multiplication and rooting plant response was scored by biometrical indices (number of shoots, leaves and roots, shoot and root length, percent of rooted plants and root hairs). The occurrence of physiological disorders was estimated by visual observations. In presence of FeSO₄, symptoms of chlorosis, hyperhy-dricity, early senescence and specific morphology of roots, suggesting Fe deficiency, were observed. These deteriorations were entirely prevented at the application of Fe chelates of which, in this experimental systems, Fe(III)AC was tested for the first time. The addition of Fe(III)AC positively affected the plant quality to extent comparable to that of NaFeEDTA. The obtained data suggest that both applied Fe chelates are more appropriate than non-chelated Fe form and can be alternatively used in the optimization of nutrient media for micropropagation of Magnolia and Prunus cerasifera genotypes.

The development of a papaya cultivar for unripe or green consumption that has resistance to papaya ringspot virus (PRSV) began in 2004 by crossing red-fleshed ‘Red Krang’ cultivar with yellow-fleshed Sai Nampeung cultivar. Numerous diverse hybrids that were obtained were selected in a recurrent selection until 2010. The ’Yellow Krang’ line was selected because of the early and high yielding, elongated fruit shape, is yellow and crispy flesh when unripe and suitable for consumption as green papaya, and tolerance to PRSV. From 2010 to 2015 the ‘Yellow Krang’ line was refined through pure line selection. It was evaluated in four growing areas in Thailand for 3 years. The field trial showed that ‘Yellow Krang’ can be classified as dwarf, reaching a height of 110-150 cm, early bearing, with mean 105 days to first flower anthesis; an average of 100 flowers and 206 fruits per plant, mean fruit weight 1.2 kg, mean fruit thickness 2.4 cm, mean fruit firmness 7.15 Newtons; high yielding, with mean fresh weight yield of 134.606 kg/hectare; and 24.86% incidence of PRSV.

The spotted wing drosophila (Drosophila suzukii) (SWD) monitoring was carried out between 2012-2014 in eight locations. In order to determine the presence of Drosophila suzukii, several types of traps and baits were used. In 2014, Polish (prototype of Drosinal) and Spanish (Cera Trap) traps and baits were used in our study. In each year, traps were placed on the plantations of blueberry, strawberry, raspberry and at a wholesale market at the beginning of July, and monitored once or twice a week until mid-December. During 2012 and 2013 there were no flies of the spotted wing drosophila in traps. First flies of this species were captured in 2014 in two locations: Września (3^rd week of October) and Brzezna (1^st week of December) – western and southern Poland respectively, in both types of the traps. However, Polish traps were more effective in trapping D. suzukii. In addition, the Polish product has small holes and therefore captures less no target and beneficial insects than Spanish traps. Despite detection of SWD in Poland, damaged fruits were not found.

The purpose of the study was to assess the storability of unripe hazelnuts in the husk of four cultivars: ‘Hall’s Giant’, ‘Catalan’, ‘Webb’s Prize Cob’ and ‘Cosford’. The nuts were stored in normal and controlled atmospheres, and in Xtend® bags for three months. A quality assessment was performed based on the following parameters: weight of the nut in the husk and without the husk, weight of the kernel, percentage of nuts with husk attached, dry matter content in kernels, infection with fungal diseases, and the presence of physiological disorders. The study demonstrated that hazelnuts stored in Xtend® bags and under a controlled atmosphere had a higher weight for the nut in the husk and without the husk, as well as a higher weight of the kernel and water content when compared to batches of hazelnuts stored in a normal atmosphere. The percentage of nuts remaining in the husk was also higher when stored under such conditions. For the majority of investigated cultivars the storage in Xtend® bags, and to a lesser extent under normal atmosphere conditions, resulted in a substantial increase in nuts infected with fungal and abiotic diseases. Among investigated cultivars, ‘Hall’s Giant’ turned out to be the most resistant to storage diseases.

The relation of hand-harvesting cost in plum and prune production to the total costs amounts to 25-40%. Mechanical harvesting makes it possible to cut drastically both the harvesting and total costs. To test the suitability of plum and prune species to be mechanically harvested, an experimental grove (area 0.8 ha) was established in 2008. Three plum cultivars and one prune cultivar grafted on semi-dwarf and vigorous rootstocks were planted at high density (1250; 1666; 2500 trees·ha⁻¹). During the span of full yielding (2012-2014), fruits were harvested mechanically with a canopy contact, straddle harvester in continuous motion, designed at the Institute of Horticulture in Skierniewice, to harvest tart cherry, and later adapted to harvesting plums and prunes. Trees grafted on semi-dwarf rootstock (‘Wangenheim Prune’) appeared to be more suitable for mechanical harvesting than strong-growing trees grafted on Prunus cerasifera clone ‘Myrobalan’. Cumulative yield per ha (years 2012-2014) was the highest at the highest planting density. Trees grafted on the semi-dwarf rootstock had a higher productivity index than trees grafted on the vigorous rootstock. There was no significant difference in fruit quality related to planting distance. Mechanical harvesting was nearly 40 times more efficient than hand picking. The efficiency of mechanical harvest was from 85% to 90%. Over 5% of fruits were lost on the ground and from 1 to 5% of fruits were left on the tree. Up to 18% of the plums and no more than 10% of the prunes harvested mechanically showed some damage. They can be fully acceptable for processing, for up to 10 days, providing the potential deterioration processes are inhibited by cold storage. The large-fruited cultivars seem to be more susceptible to bruising than the small-fruited ones. For the latter, the share of marketable quality fruits within the mechanically harvested crop amounted to about 80%, which could be a good prognostic justifying further trials on the prune harvester.

The quality of cloudy juices produced from two plum cultivars varied in chemical characteristics and native polyphenol oxidase (PPO) activity, and was studied in relation to specific pectinolytic activity of enzyme preparations used for fresh fruit maceration before pressing. Process effectiveness expressed as juice yield, turbidity and the rate of transfer of anthocyanins and polyphenols were determined for five different enzyme preparations, whose activity was also analysed. Juice yields obtained after 1 hour mash maceration (50 ºC, 100 g·t⁻¹) were between 86.6 and 95.4%. The anthocyanins content of the obtained juices strongly depended on the cultivar and ranged from 26 to 50 mg·L⁻¹ for ‘Promis’, and from 269 to 289 mg·L⁻¹ for ‘Čačanska Najbolja’, which could be related to the differences in the measured PPO activity (175.4 and 79.8 nkat·g⁻¹, respectively). The type of enzyme preparation strongly affected the degradation rate of anthocyanins during juice processing. Peonidin-3-rutinoside proved to be the most stable during plum juice production in contrast to cyanidin-3-glucoside. Irrespectively of the cultivar, the juice prepared with the mixture of Rohapect PTE + Rohament PL (2 : 1) showed the highest turbidity among the investigated combinations. The results suggest that for the production of cloudy plum juice use of a preparation with low pectin methyl esterase and polygalacturonase activities and high pectin lyase activity could be recommended.

Studies realized in 2008 and 2009 proved that Neo Arbolin Extra (10 g GA₄₊₇ and 50 g BA in 1 l of solution) and Neo Arbolin (18 g GA₄₊₇ and 18 g BA in 1 l of solution) applied separately or with Algamino Plant (18% extract from seaweeds and 10% of potassium salt of amino acids) stimulated the development of axillary buds on apple maiden trees of ‘Ligol’, ‘Golden Delicious’ and ‘Mutsu’ cultivars grafted on M.9 rootstock, thus enhancing the number of feathers longer than 10 cm. Preparations were applied twice, from the middle of June to July 9. Results differed between years, which may be related to different weather courses during the growing seasons. Neo Arbolin Extra at a concentration 30 ml·l⁻¹ with adjuvant addition (Adpros 5 ml·l⁻¹) gave the best results in branching of maiden trees of three examined cultivars. Trees treated with those preparations twice produced more than 10 feathers (> 10 cm) in the year highly favoring maiden tree growth and more than 6 feathers in the less favorable year. Algamino Plant did not influence apple tree branching.

Scallop squash fruit may be harvested and supplied to the fresh market at different stages of maturity. However, small size and immature fruit, preferred by the consumers and food industry, have only a limited storage life, which duration, among others, depends on cultivar characteristic. The objective of the study was to evaluate the storage ability and pre- and postharvest nutritional value of small size fruit of ‘Disco’, ‘Polo F₁’, ‘Sunny Delight F₁’, ‘Gagat’ and ‘Okra’ scallop squash cultivars. Fruit with diameter 3-6 cm, harvested at the time of maximum fruiting, were placed in the storage room with temperature 7 ºC, and relative humidity > 95% for the period of 1 or 2 weeks. Results of the study showed that prolonged up to 14 days period of fruit storage caused a drastic, within 9.95% – 13.95% weight loss, which was associated with visual symptoms of wilting and significant decrease of dry matter, sugars, vitamin C, carotenoids and nitrates contents. Among examined cultivars, the best suitable for the short storage, lasted no longer than 7 days, appeared to be ‘Disco’ and ‘Okra’. ‘Sunny Delight F₁’, the only one cultivar with yellow color of skin, containing high amounts of vitamin C and polyphenols and showing low tendency to nitrates accumulation, similarly as ‘Gagat’ and ‘Polo F₁’, were less suitable for short period of cold storage.

Six fruit body derived lines (pfle FB) generated from six fruiting pfle somatic hybrid mushroom lines showed genetic diversity analysed by fruit body morphology and inter simple sequence repeat (ISSR) markers. Stipe length, pelius diameter and bioefficiency % (BE%) of all the strains showed variations between each other with respect to Pleurotus florida parent. Hybrid pfle 1v and pfle 1q showed the highest value of stipe length and pelius diameter, respectively, compared with parent P. florida. Four ISSR primers amplified a total of 47 reproducible fragments with 82.9% polymorphism in which primer ISSR-03 produced the highest number of amplicons. Unweighted pair group method with arithmetic mean (UPGMA) based dendrogram exhibited two major groups in which hybrids pfle 1r and pfle 1q showed genetical closeness to parents P. florida and Lentinula edodes, respectively. Tissue culture generated line from fruit body of pfle 1r hybrid showed maximum BE% compared with the other hybrids and P. florida parent. For identification of this line, a pair of hybrid strain-specific SCAR marker (RFB₂F and RFB₂R) was developed based on an unique 813 bp RAPD amplicon.

Tomato fruit cv. ’Faustine’ F₁ were harvested at mature green and full-red stages and treated with 1 or 2 µl·l⁻¹ of 1-methylcyclopropene (1-MCP) at 20 °C and 85-90% RH, for 21 hours to investigate the ability to delay ripening. Treated and control fruit were stored at 12.5 and 20 °C and 85-90% RH. Ethylene production, rate of respiration, weight loss, market value and storage life were determined after 4-week storage. Exposure of tomato fruit to 1-MCP reduced ethylene production and respiration rate of the fruit harvested at mature-green and full-red stages of maturity. Storage life and market value of tomato fruit depended on the treatment with 1-MCP, stage of maturity and storage temperature. Untreated fruits were characterized by the shortest storage life in comparison with the fruit treated with 1-MCP. The lowest market value was observed for tomato fruit harvested as a mature green, untreated with 1-MCP and stored at 20 °C. Treatment of tomato fruit with 1-MCP resulted in the reduction of natural weight loss during storage. These results suggest that 1-MCP treatment can be used in a commercial storage and trading system for tomatoes due to its ability to delay fruit ripening.

Thin cell layers (TCLs), which contain a small number of cells or tissues, are explants excised from different organs (stems, leaves, roots, inflorescences, flowers, cotyledons, hypocotyls/epicotyls, and embryos). After almost 45 years of research, this culture system has been used for several monocotyledonous and dicotyledonous plants of commercial importance, and for model plants. The limited amount of cells in a TCL is of paramount importance because marker molecules/genes of differentiation can be easily localized in situ in the target/responsive cells. Thus, the use of TCLs has allowed, and continues to allow, for the expansion of knowledge in plant research in a practical and applied manner into the fields of tissue culture and micropropagation, cell and organ genetics, molecular biology, biochemistry, and development. Starting from a brief historical background, the actual and potential uses of the TCL system are briefly reviewed.