Volume 28 (2020): Edizione 1 (June 2020)

The root system architecture (RSA) displays complex morphological characteristics because of diverse root growth behaviors. Recent studies have revealed that swarming behavior among roots is particularly important for RSA to adapt to environmental stimuli. However, few models are proposed to simulate RSA based on swarming behavior of roots. To analyze plasticity of RSA affected by swarming behavior, we propose viewing it as a swarm of single roots. A swarming behavior model is proposed by considering repulsion, alignment, and preference of individual single roots. Then, the swarming behavior model is integrated into a simple and generic RSA model (called ArchiSimple). Lastly, characteristics of RSA affected by swarming behavior model and non-swarming behavior model are compared and analyzed under three different virtual soil sets. The characteristics of RSA (such as primary root length, lateral root length, lateral roots, and resource uptake) are significantly promoted by swarming behavior. Root system distributions can also be greatly affected by swarming behavior. These results show that root foraging and exploration in soil can be regarded as collective behavior of individual single root.

Thrips tabaci Lindeman is a cosmopolitan and polyphagous insect pest. It is known worldwide and recorded on more than 300 plant species. T. tabaci is a key pest of onion and several other crops, and its control is vital to the production and profitability of crops. If onion thrips population is not controlled, damage can reduce yield volume and quality. In addition to direct damage to the host plants, T. tabaci has been characterized as an asymptomatic vector of three devastating tospovirus species, such as Tomato spotted wilt virus, Iris yellow spot virus, and Tomato yellow ring virus. For this reason, several synthetic insecticides were used for control. However, these insecticides bring unwanted effects, like pesticide resistance, elimination of nontarget species, environmental pollution, and threats to human health. To solve the negative consequences of insecticides, biopesticides, such as plant secondary metabolites, entomopathogenic viruses, bacteria, fungi, and nematodes, have been recognized as effective alternatives. The use of plant-based insecticides and entomopathogenic control methods gained more attention in integrated pest management. Their strong side is lack of residues, saving beneficial insects and minimizing air and water pollution. Plant-derived compounds and entomopathogenic biological control agents offered a variety of biological modes of actions against onion thrips, such as repellency, feeding deterrence, anti-oviposition, fecundity deterrence, metamorphosis inhibition, and parasiting the host’s body.

The present study aimed to investigate whether adult males could fertilize immature female pupae in the leek (L1) and tobacco-associated (T) Thrips tabaci lineages and to investigate the potential effects of mother to son inbreeding on the appearance of deuterotokous females in the T lineage. To confirm the pupal insemination, a single female pupa was exposed to a single adult male for 24 hours. The removal of a male from the tube that contained the female pupa was made before the female pupa emerged to adulthood. Emerged female adults were isolated and reared individually and the sex of their progeny was determined in the larval stages. To examine a mother and son inbreeding, a single female adult was exposed to her son for 48 hours, and for two consecutive generations, the mode of reproduction was determined by identifying the sex of the progeny. This result showed that pupal insemination was not successful; thus, all the tested females produced only male progeny. Virgin inbred females produced both male and female progeny that refers to deuterotokous reproduction mode. Three virgin females produced a total of 20 females and 75 males in two consecutive generations. A study concluded that deuterotokous mode of reproduction is not a persistent mode of reproduction in the T lineage but is a result of irregularity in the mode of reproduction, and it might be changed because of brother and sister inbreeding and need further studies.

Cut rose stems were pretreated for 24 h with various compounds before being stored in Chrysal solution. Two experiments were conducted to study the effects of different concentrations of aluminum sulphate, ethanol and sucrose in preservative solutions and their combination on flower longevity and post-harvest physiological properties of rose (Rosa hybrida L.) cut flowers cultivars ‘Red Sky’ and ‘Blizzard’. The first experiment aimed to determine the optimum concentration of aluminum sulphate used as a biocide (0, 0.5, 1, 1.5 g·dm⁻³), ethanol used as a biocide and anti-ethylene factor (0, 4, 8, 12%) and sucrose used as a source of energy (0, 10, 20, 30 g·dm⁻³). In the second experiment, the most effective concentrations were cumulated in combinations of pretreatment solutions. Single use of chemicals: 0.5 g·dm⁻³ aluminum sulphate, 4% ethanol and 20 g·dm⁻³ sucrose extended the longevity of both cultivars by 17, 18 and 19%, respectively as compared to deionized water. In the second experiment, the preservative solution containing all three chemicals at optimal concentrations extended cut flower longevity by 30% compared to deionized water. ‘Blizzard’ has lost its commercial value by 6.6% of the time earlier than ‘Red Sky’. Generally, using a biocide, anti-ethylene and source of energy in a pretreatment solution can maintain the high quality of the cut rose flowers and their vase life.

Postharvest senescence is a critical problem of carnation cut flowers, limiting their transportation and subsequent marketing chain. This study was designed to assess whether the application of 1-methylcyclopropene (1-MCP), silver nanoparticles (AgNPs), and nitric oxide (NO) released from donor sodium nitroprusside (SNP) could prolong the vase life of cut carnations through an influence on the physiological and biochemical mechanisms involved in aging process. 1-MCP was used in the concentrations of 0, 100, 200, and 300 mg·m⁻³; AgNPs in the concentrations of 0, 50, 100, and 150 mg·dm⁻³; and SNP in the concentrations of 0, 0.1, 0.2, 0.3, and 0.4 mM. All treatments significantly extended the cut flower life compared with untreated flowers, more so with 300 mg·m⁻³ of 1-MCP, 100 mg·dm⁻³ of AgNPs, or 0.3 mM of SNP. All these chemical compounds were able to considerably improve the relative water content (RWC), reduce the malondialdehyde (MDA) content and increase the membrane stability index (MSI) in petals and, therefore, maintain the membrane integrity. In addition, they decreased the activities of acetyl-CoA synthetase (ACS) and nitric oxide synthase (NOS) and, hence, depressed the production of ethylene in carnation cut flowers through downregulating the ethylene production, what prolonged the vase life. Altogether, the application of exogenous 1-MCP, AgNPs, or SNP may provide a promising avenue to improve the postharvest performance of carnation cut flowers.

A detailed, species-specific comprehension of plant water behavior can be a central tool to improve water management in nursery production and irrigated landscapes. Potted plants of Nerium oleander, Pittosporum tobira, and Ligustrum japonicum ‘Texanum’ were exposed to controlled increasing drought conditions in greenhouse. Water use, gas exchange, and foliar thermoregulation were monitored along the trial. N. oleander showed the most efficient response to increasing water stress, maintaining high levels of gas exchange and evapotranspiration rate during the whole trial, whereas L. japonicum emerged as the most sensitive species, with a significant drop in physiological performances already from the second day. The more aggressive water behavior of N. oleander can be compared to the one of anisohydric plants, whereas L. japonicum displays an isohydric strategy. P. tobira showed intermediate characteristics between the two other species. This work comes to provide useful tools for the management of irrigation in plant nursery and for decision making in the use of ornamental shrubs for landscape applications.

Understanding how bees use the resources provided by crops of massive flowering is essential to develop meaningful agricultural management of plans to maximize the potential of pollination service. We assessed the effect of the pollination carried out by native species Bombus pauloensis and Apis mellifera on the production and quality of blueberry fruits. In this context, we tested the prediction that pollinator assemblages benefit fruit yield. Four treatments were performed: open pollination, B. pauloensis pollination, A. mellifera pollination, and autogamy. For each treatment, the frequency of floral visitors, fruit setting, yield, and quality were evaluated. The results showed that Vaccinium corymbosum L. ‘Emerald’ is highly dependent on entomophilous pollination to obtain optimal production and high-quality fruit, and that pollination with A. mellifera generated the highest proportion of fruit setting (0.80 ± 0.03). The highest seed number was found in open pollinated fruits. This study highlights the effect of the interactions among wild and managed pollinators on the productivity of commercial blueberry fields, and is the first report of B. pauloensis use in blueberry pollination.

Citrus genus includes a wide number of species that have been long cultivated and well adapted in Tunisia. It is represented by small number of plantations and considered as underutilized in Tunisia. Our goal was to genetically characterize Tunisian lime genotypes to obtain data useful for gene conservation and breeding purposes. The survey of genotypes was conducted in the Cap Bon region, where citrus cultivation is the most spread. Sixteen quantitative and 19 qualitative parameters were evaluated. The observed accessions belonged to three different species: Citrus limetta, Citrus latifolia (limes Byrsa), and Citrus limettioides (limes of Palestine) according to Tanaka classification. Principal component analysis confirmed these classifications. Four-cell analysis (FCA) was used to determine the most threatened genotypes. Quantitative traits were evaluated and allowed the discrimination between genotypes. Many quantitative traits of fruit and juice were highly positively and significantly correlated. Phenotypic diversity was determined using Shannon–Wiener diversity index (H’). The highest value of diversity index was observed for both vesicle thickness and thickness of segment walls (H’ = 0.98). Intermediate values were observed for both fruit axis (H’= 0.49) and pulp firmness (H’ = 0.43). However, fruit shape (H’ = 0.24), shape of fruit apex (H’ = 0.24), and vesicle length (H’ = 0.33) presented the lowest values of diversity index. Current findings will be useful to conserve threatened genotypes ex situ and on farm and also will guide strategic conservation on Citrus genetic resources for future breeding programs.

The effect of gibberellic acid (GA₃), forchlorfenuron (CPPU), and abscisic acid (ABA) on the parameters of yield of ‘Flame Seedless’ grapes was investigated. The clusters of 8-year-old grapevines were sprayed with solutions: GA₃ at 25 mg·dm⁻³, CPPU at 10 mg·dm⁻³, and ABA at 300 mg·dm⁻³, alone or in combinations. GA₃ and CPPU treatment increased yield, cluster weight and length, berry weight and diameter, as well as fruit firmness, but reduced the total soluble solids (TSS) and intensity of berry color. Anthocyanin content of berries treated with GA₃ and CPPU increased significantly by ABA treatment. Shelf life was increased by GA₃ and CPPU treatments, as they decreased the percentage of weight loss, shattering, and unmarketable berries after storing at 20 °C for 7 days. Thus, it can be concluded that the combined use of GA₃, CPPU, and ABA may be an efficient practice for fruit enlargement, coloration, and keeping quality in ‘Flame Seedless’ grape.

A field experiment was conducted at Landmark University Omu-Aran, Nigeria from June to November 2017 and repeated at the same time in the year 2018 on a nematode infested soil to evaluate the effects of different amounts of Siam weed compost on the performance of root-knot nematode (RKN) infested tomato. The compost was applied a week before planting as soil amendment at the amount of 0.0, 0.5, 1.5, and 2.0 t·ha⁻¹, while carbofuran was applied at the rate of 3.0 kg·ha⁻¹. Four weeks old tomato seedlings cultivar ‘Roma VF’, which is susceptible to RKN, was transplanted to already prepared soil. Results of the experiment showed that the compost, especially in the amount 2 t·ha⁻¹ and carbofuran at 3 kg·ha⁻¹, brought about significant reduction of the population of RKN in soil and roots, and a significant increase in the growth and yield of tomato. The result of the experiment showed that Siam compost can be used for the managing root-knot nematodes in tomato cultivation, as an environmentally safe factor.

The study was conducted to assess the effect of 1-methylcyclopropene (1-MCP) treatment on the storage ability of fresh-cut pepper fruit. The cut fruit of pepper ‘Yecla F1’ were treated immediately after cutting and ‘Roberta F₁’ before cutting. The 1-MCP at the concentrations of 1.0 μl·dm⁻³, 3.0 μl·dm⁻³, and 5.0 μl·dm⁻³ was applied to gas-tight containers with fruit for 20 hours at 20 °C. Peppers were stored at two temperatures: 0 °C and 5 °C, for up to 8 days. The treatment applied immediately after cutting slowed down the softening of pepper a little when fruit was stored at 0 °C, as well as during subsequent shelf life. The treatment applied before cutting did not reduce the softening, discoloration as well as rotting of pepper strips in cold conditions and shelf life. The sensory evaluation showed that 1-MCP treatment, applied before or after cutting, did not improve the quality of fresh-cut pepper during short term storage. The ethylene concentration after 4 days of cold storage was higher inside the bags with treated fresh-cut pepper, as compared to the bags with untreated samples. These results can give important direction for pepper fruit storage.

Melon (Cucumis melo L.) is a high-value fruit in Thailand, usually grown in plastic houses where light could become a major limiting growth factor. This study used melon cultivar ‘#120’ (orange flesh) grown in a plastic house under natural daylight (NDL, control) and with supplementary lighting using light emitting diodes (LEDs) of a combination of red 630 nm, red 660 nm, blue 450 nm, blue 460 nm, white 14000 K, UV 410 nm and IR 730 nm (LED1) or a combination of red 630 nm, red 660 nm, blue 450 nm and blue 460 nm (LED2) applied for 12 h from 6:00 pm to 6:00 am. These lighting treatments were combined with NPK fertilization using complete fertilizer 15–15–15 (N–P₂O₅–K₂O) at 5 g, 7 g (recommended rate) or 9 g per plant. Results showed that LED2 combined with 9 g 15–15–15 was the most effective in increasing plant height, chlorophyll content (SPAD index), fruit size and mass, and peel and flesh thickness. The fruit also developed the desired lighter color (higher L* and lower a* coordinates) and were the firmest and sweetest (highest soluble solids content and lowest titratable acidity) among all treatments.

The impact of regulated drip-irrigation on productivity and fruit quality of tomato ‘Tofane’ has been studied under a warm dry desert climate in southern Algeria. Yield, fruit weight and size, water content and parameters of fruit quality – total soluble solids, phenolic compounds, carotenoids, vitamin C, pH and titratable acidity were determined. Two irrigation treatments were applied in 2012 and 2013: T1, optimal irrigation (100% evapotranspiration – ET_c) during the whole growth period (growth stages I, II and III); T2, optimal irrigation during I and II stages, and regulated deficit irrigation (67% ET_c) during stage III (from fruit set to full fruit maturity of first and second bunch). T1 treatment during the whole season showed the highest values of soil water potential (Ψ_soil), between −0.02 MPa and −0.06 MPa, on depths of 0.3 and 0.6 m, respectively. During stage III, regulated deficit irrigation caused the lowest Ψ_soil values, which were between −0.1 MPa and −0.12 MPa on a soil depth of 0.3 and 0.6 m, respectively. Deficit irrigation caused significant decrease of water content in fruits and not significant decrease of fruit weight and size, as well as fruit yield while water saving for irrigation amounted to 10%. Comfort-irrigated tomato plants produced fruits containing significantly higher titratable acidity, total soluble solids and vit. C content. There was a tendency to decrease carotenoid content and increase phenolic content in both years of the study. Due to the possibility of water saving with not significant yield decrease, it seems that the reduction of water use in growth stage III would be an adequate strategy for tomato cultivation in hot, dry climate.

The aim of the study was evaluation of water from geothermal source Uniejów for spontaneous fermentation of red beetroot, assuming that beetroot values in combination with highly mineralized water will lead to innovative products with excellent organoleptic properties and potentially higher pro-health activity in comparison to the products available in the market. In the result, the use of geothermal water allowed to obtain fermented beet cubes and juice characterized by high sensory quality, unique mineral aftertaste, very good flesh firmness and viscosity. A significant impact on the physicochemical characteristics and sensory quality had the original quality of cultivar, which was evaluated higher for ‘Wodan F₁’ than for ‘Alto F₁’. There were no significant differences in the contents of the selected compounds depending on the type of water, except for cubic texture, which was higher evaluated after fermentation in geothermal water.