Volumen 26 (2018): Edición 2 (December 2018)

The experiment was conducted in anti-insect net house for three consecutive years (2013–2016) with the goal of improving the growth and biochemical contents in two F1 cultivars of cucumber, ‘Sevenstar’ and ‘KUK 9’. Treatment was given in the form of foliar spray containing different concentrations of gibberellic acid (GA₃) [0.005 g·dm⁻³ (G₁), 0.01 g·dm⁻³ (G₂), and 0.015 g·dm⁻³ (G₃)] and potassium [1.0 g·dm⁻³ (K₁), 2.5 g·dm⁻³ (K₂), and 5.0 g·dm⁻³ (K₃)] alone and as combinations. All the treatments significantly enhanced plant growth and yield over control. The combination K₂G₂ showed a marked increase in growth parameters (leaf area, flower number, total dry matter production, growth rate, net assimilation rate) and biochemical attributes (total sugar content, starch, protein). The cultivar ‘KUK 9’ had more increased parameter values than the ‘Sevenstar’. This study provides a direct evidence of the beneficial role of the application of potassium and gibberellic acid on growth, biochemical attributes, and yield of cucumber.

The article presents the results of research on the occurrence of beneficial groups of microorganisms in the rhizosphere of carrot, parsley and potato plants after the application of: (1) a commercial product EmFarma Plus (Probiotics Polska), (2) a consortium called Skierniewickie Microorganisms (MS) (containing three strains of Klebsiella oxytoca, Pseudomonas fluorescens, Pseudomonas sp.), and (3) Consortium MS together with EmFarma Plus. The study estimated the populations of microscopic fungi and bacteria, including the groups of microorganisms considered to be beneficial, i.e., spore-forming bacteria, fluorescent bacteria of the genus Pseudomonas, diazotrophs and actinomycetes. Applications of Consortium MS and, to a lesser extent, the preparation EmFarma Plus together with Consortium MS resulted in a significant increase in the total population of diazotrophs isolated from the rhizosphere soil of the vegetable species included in the study. There was no significant impact of the application of EmFarma Plus on the population size of the analyzed groups of microorganisms in the rhizosphere soil.

The influence of chilling period hours and accumulative photo-thermal unit at different base temperatures, 10, 11, 13, 15, and 18 °C, on the flowering of strawberry was examined in Sana’a University-Yemen during two seasons: 2006 and 2007. The randomized complete block design (RCBD) field experiment was designed with 5 chilling hours (CHs) periods (0, 360, 750, 1080, and 1440 CHs under 2 ± 1 °C), with four replicates each. Accumulative photo-thermal unit (PTU) was calculated for every treatment at different base temperatures for two stages: (i) from planting date to the flower opening (THA) and (ii) from planting date until the end of 2 months (THB). The results revealed that the plants treated with 1080 h of chilling produced flowers with about 55.12% and 61.97% earlier when compared with control (without chilling) in both the seasons, respectively. Stepwise multiple regression analysis showed that both CHs and the accumulative PTU THA13 (in the first season) and CH plus THA10 (in the second season) have significant effect on days until flower opening, in which the majority effect was related to the chilling period. The effect of chilling period and accumulative PTU at 18 °C (THB18) had s significant influence (p < 0.05) on the number of early flower per plant, with about r² = 0.250 and r² = 0.536 in both the seasons, respectively, and r² = 0.531 and r² =0.740 for the total effect of both CH and THB18, respectively. However, the exposure of plants to the long period of chilling (1080 and 1440 h) led the plants to produce runners and break up the flowering stage after 9 and 11 weeks in both the seasons, respectively. Meanwhile, plants that received 360-h chilling produced significantly highest (p < 0.05) total number of flowers (24.83 per plant), with about 71.2% higher than that produced by control plants. Moreover, in the second season, plants treated with 750-h chilling produced the significantly higher total number of flowers per plant, with about 50.3% higher than that of the control. Meanwhile, the 360-h and 750-h chilling periods have similar effect on the number of flowers per plant in the second season. The result showed that the starch level in the crown significantly positively correlated with the days to flower opening (r² = 0.415, p = 0.05) and negatively correlated with the number of early flower (r² = 0.587, p = 0.01). The data from this study might be used for the management of strawberry production.

The influence of foliar application of benzylaminopurine (BAP) and gibberellic acid (GA₃) alone and in combination on quantitative and qualitative yields of Solanum macrocarpon L. ‘Igbagba’ was investigated to increase the production of the vegetable. Treatments were arranged in randomized complete block design with three replicates. Analysis of variance showed that treatments had significant (p < 0.05) influence on all parameters measured. Foliar application of 20–40 mg·dm⁻³ of GA₃ alone doubled the shoot heights compared with other treatments. The highest leaf area, fresh shoot weight, dry weight and number of regrowth was observed on plants to which foliar application of 40 mg·dm⁻³ of BAP and 30 mg·dm⁻³ of GA₃ was applied. Combinations of 40 mg·dm⁻³ of BAP and 30–40 mg·dm⁻³ of GA₃ produced the highest quantities of chlorophyll a and chlorophyll b, carotenoids, total phenolics, soluble sugars and soluble protein. Highest moisture, crude protein, crude fat and ash contents were detected when 40 mg·dm⁻³ of BAP and 10–40 mg·dm⁻³ of GA₃ were applied. However, the application of GA₃ alone promoted crude fiber and carbohydrate synthesis. Leaf Na, P, Ca, Mg, Zn and Fe had highest quantities when 40 mg·dm⁻³ of BAP was combined with 30–40 mg·dm⁻³ of GA₃. Leaf K was promoted by the application of BAP alone and combination of 40 mg·dm⁻³ of BAP and 10–20 mg·dm⁻³ of GA_3. The highest number of re-growth was observed when 40 mg·dm⁻³ of BAP was combined with 30 mg·dm⁻³ of GA₃. Foliar application of 40 mg·dm⁻³ of BAP and 30 mg·dm⁻³ of GA₃ in combination was suggested for the enhancement of quantitative and qualitative yields of the vegetable.

Vegetable production may be the source of excessive residual nitrate that is prone to leaching to waters. To ascertain the risk of nitrate leaching in water collection area, the content of soil mineral nitrogen (N_min = N-NO₃⁻ + N-NH₄⁺) down to 120 cm depth was monitored in the years 2013–2016 on vegetable farms along lower Jizera river (in the Czech Republic). The risk of nitrate leaching below 30, 60, 90 and 120 cm during winter period was simulated with a simple model. The depths represent the limits of effective root depth and N depletion of groups of vegetables and field crops. The average autumn mineral nitrogen content in the fields, during experimental years, ranged from 101 kg to 134 kg N·ha⁻¹ in the 0–120 cm soil layer, 85 to 92% of which was in the form of nitrate. The calculated leaching of nitrate from the topsoil (0–30 cm) and shallow subsoil (0–60 cm) ranged from 27 to 41%, and from 7 to 14% of autumn content, respectively. The risk of leaching below 60 cm and 90 cm was near to none during the experimental years due to the exceptionally low precipitation. High nitrate content in subsoil layers below 60 cm constitutes risk of leaching and water pollution due to shallow root systems of many vegetables and potatoes in seasons with normal weather and higher water percolation.

The present study was designed to investigate the effects of two girdling dates (late April and early September) on fruit quality and carbohydrate accumulation in barberry shrubs (Berberis vulgaris L.) during the years 2016–2017. One year old shoots were ringed and fruit characteristics were monitored for two continues year. Data showed that the girdling caused a significant increase in the ascorbic acid content in fruit. Similarly, anthocyanin and total acidity were affected by girdling compared to control in 2017. September-girdled shrubs had the highest amount of fresh mass but the dry mass was not changed. It was shown that chlorophyll b increased in the girdled shrubs compared to control. September girdling reduced the carbohydrate content in leaves. In contrast, it increased the carbohydrate content in shoots. In addition, there was a significant difference between starch in the shoot and starch in leaf. Owing to the obtained results, early September girdling caused a broad range on fruit quality.

Gerbera is a very important plant widely grown for cut flowers. To check the influence of salinity and boron excess in nutrient solution, nine treatments as factorial combination of three sodium chloride (NaCl) (1, 15 and 30 mM) and three boron (B) (0.1, 1 and 2 mM) concentrations in the nutrient solution were applied during the gerbera cultivation. The effects of experimental treatments on gerbera growth, flowering and the interaction in morphological and nutritional aspects were tested. The formation of leaves, stems and flowers, flower dry mass and evapotranspiration (ET) were more negatively affected when plants were irrigated with 2 mM B than with 0.1 mM B concentration. High levels of boron (1 and 2 Mm) in nutrient solution resulted in leaf chlorosis and necrosis. The severity of leaf burn was correlated with leaf B content. Salinity acted as a protector against boron content in leaves and flowers at 1 Mm B. However, at the 2 Mm B in nutrient solution, leaf B accumulation was not reduced by the presence of NaCl but also increased with the increased levels of salinity. The external levels of boron used in this study, which were found to be the highest in the literature, and the high sensitivity of gerbera to boron, suggested that boron acted as the dominant factor. Lower external boron concentrations would be needed to establish to what extent salinity would be able to mitigate the negative effects of boron.

In this study, we investigated the effects of different-colored light-emitting diodes (LEDs) on the growth and quality of daughter cladodes of the edible cactus Nopalea cochenillifera. Cladodes were cultured hydroponically using the deep-flow technique under red, blue, or a combination of red and blue, or red, blue, and green light in an enclosed-type plant factory. We found that daughter cladodes developed from the mother cladodes in all the treatments, despite pH of the nutrient solution drastically decreasing over time. However, the elongation growth rate of the first daughter cladodes and the number of daughter cladodes produced were highest under red light and lowest under blue light, indicating that blue light suppresses daughter cladode development. The total fresh weight (FW) of the daughter cladodes emerging from a single mother cladode was also lowest under blue light. However, the average FW of the daughter cladodes was the highest under blue light, or under simultaneous irradiation with red and blue light. The number of spines, which is an undesirable characteristic in edible cacti, was significantly lower under red light than under blue light, while the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity of the daughter cladodes was the highest under blue light or under simultaneous irradiation with red and blue light. Our results show that light wavelength has a strong effect on daughter cladode development in N. cochenillifera, so controlling the light environment represents an effective approach for improving the growth and quality of this edible cactus.

Due to the common trend towards limitation of excessive use of chemicals in agriculture, there is a growth of interest in methods of seed quality improvement that would be safe for the environment. These include methods based on the effect of various physical factors, such as laser light, magnetic field, seed treatment with magnetized water, electric field. The work provides detailed information on the impact of seed stimulation of these factors on germination, growth, development and yielding of horticultural plants. Summarizing the results of the study, it can be concluded that the application of physical factors in appropriate doses can be an effective way to enhance many plant parameters that increase their productivity. The beneficial effects of seed stimulation are mainly related to the first stages of plant life, i.e. – germination, emergence and growth of seedlings. In many cases, the enhancement of these features is also the result of the increase of plant yields. The increase of yield is even several dozen percent. The results of the study encourage the implementation of these physical methods of seed quality improvement into agricultural and horticultural practice.

Natural weight losses, flesh and core browning, senescent breakdown and fruit rot, ethylene-production, firmness, soluble solids content, titratable acidity and taste of apple ‘Reinette Simirenko’ during storage, depending on the dose of postharvest treatment with 1-methylcyclopropene (1-MCP) were studied. Fruits were collected in harvesting maturity and treated with 1-MCP at the recommended dose of 1000 ppb (SmartFresh^TM 0.068 g·m⁻³) and experimental doses of 750 ppb (75% of the recommended dose) and 500 ppb (50%). Apples were stored at 2 ± 1 °C and air humidity 85–90%. After seven months of cold storage, irrespective of dose of 1-MCP, on the 20th day of shelf-life, ethylene production from the treated apples was 3.9–5.3 times lower than that of the untreated ones. During the seven months of storage, fruits with post-harvest treatment had high firmness – 8.8–9.0 kg without a significant difference in range of 500–1000 ppb 1-MCP. 1-MCP treatment provides 0.6–1.0% higher content of soluble solids (highest level is for the treatment of 750 and 1000 ppb). Content of titratable acidity was higher by 1.4–1.7 times (the highest acidity was at 1000 ppb and, respectively, 1.1 and 1.2 times lower when treated with doses of 750 and 500 ppb). There was no skin browning and senescent breakdown and no flesh browning at 750 and 1000 ppb, and no fruit rot at 1000 ppb. When smaller doses (as recommended) are applied, a more harmonious taste of apples without reducing storage ability is achieved.

Two-spotted spider mite (Tetranychus urticae, Koch) possess tremendous ability to develop resistance to pest control chemicals. Hence, although METI-acaricides are quite new group of pesticides, the resistance to this chemicals may shortly become a serious obstacle in two-spotted spider mite management. In presented study, molecular and phenotypic diversity of three laboratory strains and seven T. urticae populations collected from pest-protected apple orchards were analysed in reference to METI-acaricides resistance. The inter-population molecular diversity analysis with a set of RAPD markers revealed 6 populations to be in close relation to susceptible reference strain (GSS). Only one population turned out to be linked relatively close with METI-acaricides resistant strain (Akita). Simultaneously, the results of biological test showed similar relation among the analysed populations, according to the resistance incidence ratio. Obtained results suggest that METI-acaricides resistance trait in two-spotted spider mite is likely to be determined at genomic level and may be considered as an initial stage for developing molecular biology tools for early detection of METI-acaricides resistance in T. urticae populations.