Ammonia–Nitrate Mixture Dominated by NH4+–N Promoted Growth, Photosynthesis and Nutrient Accumulation in Pecan (Carya illinoinensis)

Although ammonia–nitrogen (NH4+–N) and nitrate–nitrogen (NO3−–N) are the two main forms of N absorbed and utilized by plants, the preferences of plants for these forms are still unclear. In this study, we analyzed the growth, photosynthesis, and nutrients of pecan under different NH4+:NO3− ratios (0/0, 0/100, 25/75, 50/50, 75/25, 100/0) by indoor aerosol incubation. The results showed that additions of different N forms promoted the growth and development of pecan seedlings. When NO3−–N was used as the sole N source, it significantly promoted the ground diameter growth of pecan and increased the leaf pigment content and photosynthetic rate. The NH4+:NO3− ratio of 75:25 and NH4+–N as the sole N source significantly increased the soluble sugars in stems and roots, starch in leaves, stems and roots, soluble protein in leaves and stems, and soluble phenols in stems and roots. Additionally, the NH4+:NO3− ratio of 75:25 increased plant height, leaf number, root soluble protein, and leaf soluble phenol contents. In conclusion, regarding the physiological aspects of pecan growth, pecans are more inclined to use NH4+–N. Considering that the NH4+–N as the only N source may lead to nutrient imbalance or even toxicity, the NH4+:NO3− ratio of 75:25 was most favorable for the growth and development of pecan seedlings.

Evaluation of different antioxidants during in vitro establishment of allspice (Pimenta dioica L. Merrill): a recalcitrant species

Objective: To evaluate the effect of different antioxidant agents during in vitro establishment of allspice (Pimenta dioica L. Merrill). Design/methodology/approach: The effect of different antioxidant agents (Methylene blue, L-cysteine, and silver nanoparticles [AnNPs]) added to Murashige and Skoog culture medium at different concentrations were studied during axenic establishment of P. dioica. A completely randomized experimental design was used. All trials were performed in triplicate. The percentage of survival, oxidation, contamination was determined, the phenols content, antioxidant capacity and lipid peroxidation. Results: The highest survival occurred with the addition of L-cysteine. The lowest percentages oxidation were observed in explants treated with L-cysteine. Treatments with 100 and 200 mg L-1 AgNPs had the lowest contamination values. L-cysteine and 50 and 100 mg L-1 AgNPs resulted in an increase in the content of soluble phenols. The highest contents of cell wall-linked phenols were obtained in treatments with 200 mg L-1 methylene blue, L-cysteine, and 200 mg L-1 AgNPs. In this study, all treatments had a reaction of scavenging/reduction mechanisms free radicals. The highest content of malondialdehydes was observed in the control treatment and 200 mg L-1 methylene blue. The highest content of malondialdehydes was observed in the control treatment and 200 mg L-1 methylene blue. Limitations on study/implications: The highest percentage of oxidation was observed in the control treatments, 100 and 200 mg L-1 methylene blue, causing cell death. Findings/conclusions: The addition of L-cysteine to the culture medium is alternative to reduce oxidation during in vitro introduction of P. dioica.

Bioconversion of lignin and methane production from Corn cobs (Zea mays) treated by lignin-degrading bacteria

Corn cobs are one of the potential feedstocks consisting of cellulose, hemicellulose and lignin, which provide potential lignocellulose biomass to be converted into renewable energy such as biogas through anaerobic digestion (AD). However, the recalcitrant structure of corn cobs lignocellulose makes it resistant to microbial access to the cell wall, and therefore the effective pre-treatment needs to be conducted. The biological pre-treatment using lignin-degrading bacteria is one of the promising bioconversion processes which will help to break down the lignocellulose structure. This study aims to analyse the ability of bacteria, Agrobacterium sp., Lysinibacillus sphaericus and Paenibacillus sp. in degrading lignin of corn cobs and therefore will enhance the methane released from AD. The ability of bacteria to degrade lignin was observed by analysis of total reducing sugar, total soluble phenols, lignin content, and weight loss, while the methane production was determined by the biochemical methane potential (BMP). The percentage of lignin content of untreated and pre-treated corn cobs with bacteria Agrobacterium sp., L. sphaericus and Paenibacillus sp. is 18.34%; 9.66%; 11.48% and 9.06%, respectively. The methane concentration (specific methane production) produced by using inoculum of Agrobacterium sp., L. sphaericus and Paenibacillus sp. with the addition of pre-treated corn cobs are 1.79%; 1.16% and 2.51%, respectively. These results were higher than the inoculum with the addition of untreated corn cobs.

Bulk and nanoparticles of zinc oxide exerted their beneficial effects by conferring modifications in transcription factors, histone deacetylase, carbon and nitrogen assimilation, antioxidant biomarkers, and secondary metabolism in soybean

Nanoscience paves the way for producing highly potent fertilizers and pesticides to meet farmer’s expectations. This study investigated the physiological and molecular responses of soybean seedlings to the long-time application of zinc oxide nanoparticles (ZnO NPs) and their bulk type (BZnO) at 5 mg L-1 under the two application methods (I- foliar application; II- soil method). The ZnO NPs/BZnO treatments in a substance type- and method-dependent manner improved plant growth performance and yield. ZnO NPs transactionally upregulated the EREB gene. However, the expression of the bHLH gene displayed a contrary downward trend in response to the supplements. ZnO NPs moderately stimulated the transcription of R2R3MYB. The HSF-34 gene was also exhibited a similar upward trend in response to the nano-supplements. Moreover, the ZnONP treatments mediated significant upregulation in the WRKY1 transcription factor. Furthermore, the MAPK1 gene displayed a similar upregulation trend in response to the supplements. The foliar application of ZnONP slightly upregulated transcription of the HDA3 gene, while this gene showed a contrary slight downregulation trend in response to the supplementation of nutrient solution. The upregulation in the CAT gene also resulted from the nano-supplements. The concentrations of photosynthetic pigments exhibited an increasing trend in the ZnONP-treated seedlings. The applied treatments contributed to the upregulation in the activity of nitrate reductase and the increase in the proline concentrations. ZnO NPs induced the activity of antioxidant enzymes, including peroxidase and catalase by averages of 48.3% and 41%, respectively. The utilization of ZnO NPs mediated stimulation in the activity of phenylalanine ammonia-lyase and increase in soluble phenols. The findings further underline this view that the long-time application of ZnO NPs at low concentrations is a safe low-risk approach to meet agricultural requirements.

Effect of the dehydration method of Hibiscus sabdariffa L. calyces on the quality of their aqueous extracts

Hibiscus sabdariffa L. is a plant from tropical climates, which produces, among other products, deep red calyces used to prepare refreshing drinks. The high humidity (85-87%) of the calyces at the time of harvest must be reduced to about 12% for handling and storage. The aim of the work was to evaluate the effect of the dehydration method of the calyces (sun drying, SD; air-drying, AD, at three temperatures: 50, 60 and 70 ºC) of three varieties of Hibiscus sabdariffa L. on the quality of their aqueous extracts. The quality was measured as a function of color), and chemical variables (titratable acidity, TA, total soluble phenols, TSP; total anthocyanins content TAC, and organic acids). The varieties used were Negra Quiviquinta (NQ) with dark red calyces, UAN-9 with light red calyces, and UAN-16, with white calyces. The dehydration method affected the quality of the extracts. The SD was the one that most affected the color and chemical variables. The color of the extracts was darker than that of the control while titratable acidity (TA) was reduced on average 40.6%. No effect of AD treatments was observed on these variables. On chemical composition, SD reduced TSP on average 15.3%, the most affected variety was UAN-16. In the varieties with red calyces, the average TAC reduction was 36.9%. Of the organic acids, the most affected were malic and succinic. As observed in physical variables, AD treatments showed little influence on chemical composition of calyces. Of the dehydration methods evaluated, the AD70°C rendered the best quality aqueous extract, in base of the variables evaluated.

The relationships between selected soil properties and caesium-137 identify organic carbon, nitrogen and water soluble phenols as indicators of soil erosion processes in different forest stands

In the last few decades, the use of environmental radionuclides, particularly caesium-137 (137Cs), represented one of the most valid methods for estimating soil erosion. However, the cost associated with the use of the equipment needed for radiometric analyses is still high and, for this reason, finding more easily measurable indicators can be useful. There is a strong correlation between 137Cs, organic carbon (OC), nitrogen (N) and water soluble phenols (WSP) exists, indicating the latter parameters as possible early indicators of soil erosion. Based on the above assumptions, the main purpose of this work is to identify specific soil chemical parameters able to indicate early triggering of soil erosion. Specifically, several soil parameters such as pH, electric conductivity (EC), WSP, OC, N and C/N have been evaluated against 137Cs and on a comparative basis. In addition, since the rate of soil erosion depends on the degree of coverage and canopy structure, two different tree species (Pinus nigra laricio Poir. and Fagus sylvatica L.) have been considered in this contribution in which ten different scenarios of forest management have been analysed. The results show that the reduction in tree cover of managed sites triggers erosion and nutrient loss processes. It has been observed that the loss of 137Cs, compared to the control areas, is closely correlated with those of WSP, OC and N. These parameters (WSP, OC and N), more easily assessable, can be a valid tool to understand easily, triggering of erosive phenomena.

The effect of weed management method on weeds infestation, yield, storage ability and nutritional value of leek (Allium porrum L.)

In the years 2012–2014, at The National Institute of Horticultural Research in Skierniewice, research was carried out on determining the impact of various methods of weeding on leek yield, its storage stability and nutritional value after harvest and storage. In the field experiments the following methods were compared: mechanical treatments, mechanical treatments + growth stimulator, soil mulching with polypropylene and black foil and hand weeding. After harvest the leek were storage at the temperature 0°C for 124–150 days depending on the year and after the storage it was sorted as: marketable leeks and plants with diseases symptoms and rotten plants, and also leek’s natural weight loss was determined. After harvest and after storage, the content of dry matter, total sugars and soluble phenols in leeks was determined. The highest marketable yield immediately after harvest was obtained from plants mulched with black materials. After storage, the most marketable leeks were obtained from the control and hand weeded during cultivation. Chemical composition of leek was analysed after harvest and after the storage period. After harvest the highest yield from leek grown in black mulch were obtained and after the storage from control and hand weeding. Chemical analyses showed that the highest dry matter and total sugars contents were found in leek weeded by hand, and after storage mulched with black and polypropylene foil. After harvest, the highest content of soluble phenols was recorded in leek weeded mechanically and treated additionally with a growth stimulator, and after the storage – in mechanically weeded leeks.

Shelf life of pitaya [ Stenocereus pruinosus Otto ex Pfeiff.) Buxb.] fruit affected by temperature and guar gum, beeswax, oleic acid, and thyme essential oil coatings

Pitaya [Stenocereus pruinosus Otto ex Pfeiff.) Buxb.] produces fruit with high commercialization potential, but its shelf life is limited to few days. The objective of this study was to apply biopolymeric coatings to extend the shelf life of pitaya fruits at 25 °C and under refrigeration at 12 °C. The following variables were handled at each temperature: fruits without any treatment (Control), fruits coated with 1,000 ppm emulsion of thyme essential oil, and fruits coated with 1% emulsion of guar gum, 7.5% beeswax, and 7.5% oleic acid, without essential oil, and with 1,000 ppm of thyme essential oil. Shelf life was 6 d at 25 °C, without the beneficial effect of coatings, but increased to 15 d with refrigeration and coatings based on guar gum, beeswax, and oleic acid, since fungal growth was delayed, and weight loss was reduced. This allowed fresh appearance without significant modification of color, firmness, pH, total soluble solids, titratable acidity, contents of soluble phenols and betalains, and antioxidant capacity.