https://orcid.org/0000-0001-7929-968X
Abstract
The cyanobacteria may contribute significantly to sustainable agriculture by enhancing plant growth, productivity and environmental quality. Tuberose is ranked among the ten most significant cut flowers in the world. In this regard, this study intends to improve the tuberose plant’s growth, flowering, corms, and concrete oil under sandy soil conditions by employing a sufficient amount of N fertilizer or/and Spirulina platensis extract. N was added to the pot at a rate of 2, 4 g and the control treatment (without adding; 0). S. platensis extract was foliar sprayed at concentrations of 10, 15 %, and distilled water. Results showed that N or S. platensis increased the leaves dry weight, no. of florets/spike, spike dry weight, corms and cormels dry weight, total chlorophyll, and concrete oil. Ultimately, a combination of 2 g N/plant with a 15% concentration of S. platensis extract proved to be the most successful treatment for all the features under investigation.
Reviewing editor:
1. Introduction
Polianthes tuberosa L. is a perennial decorative bulb plant native to Mexico and classified as a member of the Amaryllidaceae (Agavaceae) family Benschop (Citation1993). Tuberose is among the most significant bulbs that have a high economic value for the cut flower and volatile oil markets (Alan et al., Citation2007). Among the ornamental bulbous plants, tuberose occupies an advanced position, as it is appreciated by lovers of the quiet beauty of attractive flowers. Its spikes are excellent for vases; they stay in them for ten to fifteen days and it is included in other floral decorations (Suseela et al., Citation2016).
There are three classes of algae according to their content of pigments, namely green, brown and red algae. It has been indicated that using algae in its various forms on plants has a positive effect on growth and productivity (Spinelli et al., Citation2009; Abdel-Mawgoud et al., Citation2010). In addition to the fact algae is a naturally active substance that is safe for humans, animals and the environment, it is rich in protein, fats, vitamins, carbohydrates and minerals. They are rich in N, phosphorus (P), potassium (K) and microelements such as Co, B, Mo, Zn and Cu which are present in soluble forms and can be easily assimilated by leaves and roots (Chapman & Chapman, Citation1980). Foliar application with algae extract was suggested for enhancing the development and production of many plants (Awad et al., Citation2006; Nour et al., Citation2010; Pramanick et al., Citation2013; Shalaby & El-Ramady, Citation2014). Spraying pea plants with either a 10% or 15% algae extract grew the yield along with vegetative development more than the control (Nawar Dalia & Ibraheim Sabree Kh, Citation2014).
Sandy soil has a restricted capacity for natural production as a result of restricting soil properties like high water infiltration, low water retention, low fertilizer and high susceptibility to erosion (Zhang et al., Citation2020). Nitrogen (N) is one of the major limiting nutrients for sustainable and profitable plant production in sandy soil; hence N fertilizer is usually added in higher quantities to improve productivity in all parts of the world (Sainju et al., Citation2006). N fertilization is one of the determinations of canopy formation in the plants, and its deficiency negatively affects the photosynthesis process (Thomas & Thorne, Citation1975). It is a vital element in different crucial metabolic compounds such as proteins, amino acids, DNA, enzymes and photosynthesis pigments, and is also necessary for plants to use carbohydrates. The effect of N fertilizer rates on P. tuberosa cv. Double was reported by Mahmoodinezhadedezfully et al. (Citation2012). Their results indicated that the addition of 100 kg N/ha improved stem and spike length, florets number/spike and quality of flowers compared to other rates. The results of Attia et al. (Citation2018) suggested that applying of 100% mineral N registered a higher plant height, number of florets/spikes and number of leaves/plants of tuberose plants. Furthermore, Sendhilnathan and Manivannan (Citation2019) studied the nutritional requirements of tuberose plant for N and indicated that the highest florets number per spike, flower yield, number of bulbs number per plant and dry matter production were registered with 150 kg N/ha. Hence this work has been done to evaluate the effect of N-rich fertilizer and algal extract levels on the development and production of tuberose cv. Double in sandy soil.
2. Materials and methods
In a private nursery in Damanhour, Beheira Governorate, Egypt, a pot trial was carried out in two succeeding growing seasons (2020/2021 and 2021/2022) to investigate the influence of N fertilization levels and algal extract on tuberose cv. Double-grown in sandy soil. Tuberose bulbs with a diameter of 30–35 mm and a weight of 25–30 g were obtained from a commercial nursery in Al-Qanatir Al-Khairya, Qualubya Governorate, Egypt. Corms were planted on May 20 for the two growing seasons, in pots 30 cm in diameter filled with a mixture of sand and organic compost at 3:1 (v/v) at 8 cm depth. Pots (30 cm in diameter) were packed with a mixture made up of sand and organic compost at 3:1 (v/v). Analyses of the chemical features of organic compost () as well as sandy soil physical and chemical characteristics () were carried out according to Page et al. (Citation1982). Data on temperature, rainfall, daylight and relative humidity, as average of both seasons of study are listed in . Three replications and five corms per experimental unit were arranged in the randomized complete block design (RCBD) experiment in a factorial design. The N fertilizer supplied at rates (0, 2 and 4 g/pot), where the algae extract concentrations were applied at (0%, 10% and 15%). Equal amounts of ammonium nitrate (33.5% N), which was utilized as a N source, were top-dressed after 30, 45, 60 and 75 d of planting. Spirulina platensis algae was attained from the Algal Biotechnology Unit, NRC, Egypt. It is a type of multicellular, photosynthetic blue-green algae that may thrive in a variety of fresh, marine and brackish waters (Marrez et al., Citation2014). Using an immersion blender, one kilogram of the fresh algal material was eliminated after being catted into tiny pieces. After being blinded, the materials were filtered over two layers of cotton cloth to get rid of any debris and were given a 100% concentration designation. After adding distilled water, various concentrations were made and then refrigerated between 0 °C and 4 °C until used (Pise & Sabale, Citation2010). Forty and seventy days after planting, algae extract concentrations were sprayed on foliage in the morning till the run-off point. Irrigation and other routine practices were carried out during the investigation whenever necessary. Nutritional requirements of P, K and micronutrients were applied on tuberose plants according to the recommendation of Selim et al. (Citation2006).
Table 1. Chemical features of the organic compost.
Table 2. Sandy soil physical and chemical characteristics.
Table 3. Temperature, rainfall, daylight and relative humidity of Damanhour, Egypt, as average of two seasons 2020/2021 and 2021/2022 (Meteorological station in Damanhour, Egypt).
2.1. Agronomic parameters
Plant growth characteristics of tuberose were evaluated: plant height (cm) from the stem base (at soil surface) to the highest plant part by a tape measure, leaf area (cm2) by measuring the leaves length and width and leaves dry weight (g) was measured by using an electric balance for oven-dried leaves at 80 °C until a constant dry weight (Huang et al., Citation2019). Floral characteristics included flowering time (number of days from planting date to first flower), flowering duration (days from 1st flower till flowering end), No. of florets/spike was measured as the number of florets in each spike, floret dry weight (g), floret and spike diameter (cm), as well as spike dry weight (g). Corms characteristics involved corm diameter (cm) and corms and cormels dry weight (g).
2.2. Biochemical parameters
The total chlorophyll content of leaves (mg/100 g FW) was determined according to Moran and Porath (Citation1980). Volatile oil percentage determination: the extraction of the scents of tuberose flowers was by Hexane. 100 g of the fresh flowers were soaked in solvent (1 l) for 1 h. After getting rid of the debris, the solvent volatilizes and the concrete remains. Then, tuberose absolute extracted from the concrete samples using alcohol as reported by Rakthaworn et al. (Citation2009).
2.3. Statistical analysis
Using the SAS software (statistical software; Cary, NC), the acquired data went through a two-way analysis of variance (ANOVA; SAS Institute, Citation2002), and the means of the values were compared using Tukey’s test at the 0.05 LSD level (Snedecor & Cochran, Citation1974). In addition, a heatmap was made to summarize the findings on agronomic and biochemical aspects using the online tool ClustVis (https://biit.cs.ut.ee/clustvis/).
3. Results
3.1. Agronomic parameters
Regarding the vegetative characteristics, the recorded data presented in indicated that a significant influence of N rates, algae concentrations and their combinations was registered on all the growth characteristics of tuberose during both seasons. Higher values of the tested growth traits were detected with increasing N levels up to 4 g/plant and algae extract concentrations up to 15%. When N fertilizer was added along with spraying algae extract, the growth parameters increased. The recommended dose of 2 g/plant of N fertilizer in combination with 15% algae extract had pronounced effects on the tuberose vegetative outgrowth characteristics including plant height (88.71 and 88.57 cm), leaves dry weight/plant (21.22 and 21.70 g) and leaf area/plant (3686.38 and 3717.96 cm2) in both season, respectively. The obtained results clearly show that, compared to the control, the application of N fertilization increased the tuberose plants’ growth characteristics in terms of plant height, dry weight of leaves per plant and leaf area per plant in both seasons. Compared to 4 g N/plant, applying 2 g N/plant level showed superior development features.
Table 4. P. tuberosa L. cv. Double growth characteristics as influenced by N and algae extract levels during 2020/2021 and 2021/2022 seasons.
Regarding the flowering characteristics, the pertaining data to the flowering time (days), flowering duration (days) and number of floret/spikes are shown in (). The data indicated that significant influences with highest trends for flowering duration (25.14 and 26.09 d), number of floret/spike (23.83 and 23.92) and least days from planting till opening of the first floret or flowering time (111.17 and 111.17 d) were produced with an application of 2 g N/plant + 15% algae extract in the 1st and 2nd seasons, respectively. The data concerning to the flowering parameters like florets diameter, dry weight of florets, tuberose spike diameter and dry weight of spike are displayed in . The noted data proved that significant influences with highest values for florets diameter (5.74 and 5.72 cm), florets dry weight (3.20 and 3.19 g), spike diameter (0.88 and 0.87 cm) and spike dry weight (8.79 and 8.86 g) were recorded with the combination of 2 g N/plant + 15% algae extract in the first and second seasons, respectively.
Table 5. P. tuberosa L. cv. Double Floral characteristics as influenced by N and algae extract levels during 2020/2021 and 2021/2022 seasons.
Table 6. P. tuberosa L. cv. Double Corms characteristics as influenced by the N and algae extract levels during 2020/2021 and 2021/2022 seasons.
In the concern of corms characteristics, analysis of variance revealed that corm diameter and dry weight of corms and cormels were significantly impacted by N fertilizer, algal extract and their combination ( and ). The maximum diameter of corm registered being (3.20 cm) was obtained in tuberose plants treated with 2 g N/plant + 15% algae extract as an average of the both seasons. Moreover, the highest dry weight of corms and cormels (59.00 g) was achieved in plants applied with 2 g N/plant with 15% algae extract as average of both seasons compared to the other treatments.
Figure 1. Corm diameter (cm) of P. tuberosa L. cv. Double as influenced by N fertilizer and algae extract concentrations during the 2020/2021 and 2021/2022 seasons.
Figure 2. Corms and cormels dry weight (g) of P. tuberosa L. cv. Double as influenced by N fertilizer and algae extract concentrations during the 2020/2021 and 2021/2022 seasons.
3.2. Biochemical analysis
Significant variations in the application of N levels, algae concentrations and their interaction were found in the data pertaining to the total chlorophyll in tuberose leaves (). On average during the two seasons, tuberose plants fertilized with a combination of 2 g N/plant and 15% algal extract showed the superior value of total chlorophyll content (77.76 mg/100 g FW). This means that adding 15% algal extract with 2 g N/plant resulted in a more effective increase in the chlorophyll content of tuberose leaves.
Figure 3. Total chlorophylls content (mg/100 g) in P. tuberosa L. cv. Double leaves as influenced by N fertilizer and algae extract concentrations during the 2020/2021 and 2021/2022 seasons.
Regarding the percentage of concrete oil, the data regarding the effects of N levels, concentrations of algae and their interaction showed notable variations for the percentage of tuberose concrete oil (). The percentage of essential oils increased when plants were fertilized with N at a rate of 2 g N/plant and 15% algal extract. In this concern, results indicated that the application of 2 g N/plant in combination with 15% algae extract recorded a greater oil percentage (0.317%), while the least one (0.224%) was produced with untreated plants in the average of both seasons.
Figure 4. Concrete oil (%) of P. tuberosa L. cv. Double as influenced by N fertilizer and algae extract concentrations during the 2020/2021 and 2021/2022 seasons.
To provide a graphical assessment of the effects determined by the experimental conditions on the tuberose plant, a heat-map analysis of the data was conducted for all parameters evaluated (). Two dendrograms made up the heat-map output: Dendrogram 1, which was positioned at the top and included all nine experimental combinations (3 N fertilizer rates × 3 Algae extract concentrations), and Dendrogram 2, which was positioned on the left and included all agronomic and biochemical characteristics that affected this distribution. Two primary clusters were shown in Dendrogram 1: the first, contained N1A2 (N2 at 2 g + alga extract at 15%) and was primarily grouped based on greater amounts of agronomic and biochemical parameters. The treatments of N2A2 (N2 at 4 g + alga extract at 15%), N2A1 (N2 at 4 g + alga extract at 10%) and N1A1 (N2 at 2 g + alga extract at 10%) were grouped in the first sub-group of the second cluster. The N2A0 (N2 at 4 g + alga extract at 0%), N0A2 (N2 at 0 g + alga extract at 15%), N1A0 (N2 at 2 g + alga extract at 0%) and N0A1 (N2 at 0 g + alga extract at 10%) made up the majority of the second sub-grouping (). The control treatment N0A0 (control) was a part of the second main cluster. The control treatment was grouped based on the analyzed parameters’ tendentially lowest values.
Figure 5. Cluster heat map analysis summarizing the responses of phenotypic and physiological parameters of tuberose subjected to different levels of N2 (g/plant) and Algae (%) treatments during two seasons. The color bands reveal the differential association of traits. Heatmap was realized via the online program ClustVis, https://biit.cs.ut. ee/clustvis/(accessed on 20/11/2023). Where, N0A0; control, N0A1; N2 (0 g) + A (10%), N0A2; N2 (0 g) + A (15%), N1A0; N2 (2 g) + A (0%), N1A1; N2 (2 g) + A (10%), N1A2; N2 (2 g) + A (15%), N2A0; N2 (4 g) + A (0%), N2A1; N2 (4 g) + A (10%), N2A2; N2 (4 g) + A (15%).
4. Discussion
Tuberose plants’ vegetative development was substantially affected by N fertilization (Mahmoodinezhadedezfully et al., Citation2012). Compared with unfertilized plants, higher values of the growth characters were registered by N fertilization up to 200 kg/ha. Nevertheless, after the crop production reaches its optimum, it may drop or stay the same with additional increases in N rates. These findings were in conformity with those reported by Yadav et al. (Citation2003), Patel (Citation2005), Sultana et al. (Citation2006), Khalaj and Edrisi (Citation2007) and Sharma and Yadav (Citation2007). According to Sainju (Citation2014), barley and pea growth, yield and C content peaked at 80 kg N/ha and subsequently started to decrease as the N rate rose to 120 kg N/ha. Furthermore, Sainju et al. (Citation2013) asserted that malt barley production, growth and N uptake increased from 0 to 40 kg N/ha before declining with additional N rate increases. Moreover, the positive influence of N in increasing chlorophyll content was previously obtained by Khalaj et al. (Citation2012) on tuberose; Attia et al. (Citation2005) on Gladiolus grandiflorus and Attia et al. (Citation2018) on tuberose.
The increment in the growth traits by N fertilization may be due to the N role in forming the chlorophyll, phospholipids, some co-enzymes, nucleotides and nucleic acid that are critical to plant metabolism, whereas a deficiency of N causes auxins to decrease and consequently growth characters (Kadu et al., Citation2009; Attia et al., Citation2018; Castañeda-Saucedo et al., Citation2023). According to Khalaj et al. (Citation2012), N fertilizer can enhance tuberose growth and flowering features such as bulb weight, stalk height of flower and stalk diameter. These findings agree with those obtained by Patel (Citation2005), Attia et al. (Citation2005), Khalaj et al. (Citation2012), Ali et al. (Citation2014), Kumar et al. (Citation2016) and Attia et al. (Citation2018).
Additionally, the obtained results pointed out that the tuberose plant treated with 15% algae extract registered the greatest increase in the vegetative development characteristics compared to the other treatments. The ability of algae extract to fix atmospheric N and increase root growth, production and proliferation-promoting hormones was thought to make it an essential group of microorganisms (Ghalab & Salem, Citation2001; Yassen et al., Citation2018). The presence of regulators of plant growth such as auxins, cytokines, amino acids, gibberellins and vitamins in algae extract may have a stimulating effect on growth characteristics. These regulators enhance growth characteristics by promoting cell division and differentiation, enzymatic activity, photosynthesis capacity and leaf development (Sayed et al., Citation2018; El-Naggar Noura et al., Citation2020). Foliar spraying with algae extract resulted in significant effects on the productivity of Freesia hybrida plants (Al-Shareefi et al., Citation2019; Khalaf & Abdul Kareem, Citation2020). Also, an induction in tuberose flowering can be explained as algae extract improves the vegetative and flowering characteristics of tuberose by the physiological and biological activities of seaweed extract (Khalid et al., Citation2013; Mohamed, Citation2015; Abdulraheem, Citation2009; Al-Shatri et al., Citation2020).
The number of inflorescences and florets/inflorescence, the diameter of the flower, the inflorescence stem length, the flowering period and the early date for freesia plant blossoming were all increased by spraying algal extract at a rate of 1.5 ml/l (Khalaf & Abdul Kareem, Citation2020). Moreover, spraying 15% of algae extract on tuberose plants increased corms’ productivity. These results were in coincidence with those reported by Khalaf and Abdul Kareem (Citation2020), who found that spraying algae extract at 1.5 ml/l improved the corm productivity of freesia plants. This could be because algae extract has been employed as a bio-stimulator and it is a rich basis of organic materials, carbohydrates and growth regulators such as auxins, cytokines and gibberellins (Spinelli et al., Citation2009; Jothinayagi & Anbazhagan, Citation2009).
On the other side, spraying algae extract improved chlorophyll contents in tuberose. The current findings concur with those attained by Enan et al. (Citation2016) and Yassen et al. (Citation2018). Enan et al. (Citation2016) discovered that applying algae extract topically to sugar beet led to noticeably greater levels of photosynthetic pigments and vegetative growth indices. Furthermore, the leaf content of chlorophyll and carotenoids was improved in freesia plants by spraying plants with algae extract at the rate of 1.5 ml/l as discussed by Khalaf and Abdul Kareem (Citation2020). The present results are in conformity with those obtained by El-Naggar et al. (2020). These findings were in harmony with those obtained by Attia et al. (Citation2018) on tuberose; Soliman et al. (Citation2009) on volatile French basil. Likewise, the stimulating and antioxidant properties of algal extract may be responsible for the significant effects on the oil content of tuberose flowers. This could be because algae are high in natural antioxidants and a variety of minerals, including Fe, Mg, K and Ca. These findings were validated by Yassen et al. (Citation2018), who disclosed that the seaweed extract’s stimulating impact on the chemical composition of onion bulbs might be attributed to its microelements, organic matter, fatty acids, vitamins and growth regulators like gibberellins auxin and cytokinin.
5. Conclusions
Through this study, we can conclude that it is possible to produce tuberose cv. Double in sandy soil with the addition of N fertilizer and seaweed extract. To obtain superior tuberose plants in regards of vegetative growth, flowering, corms, as well as volatile oil, N fertilizer is added at a rate of 2 g/plant with algae extract at a concentration of 15%.
Ethical approval statement
This study does not involve experiments involving human or animal.
Consent to publish
All the authors consented to the publication of this study.
Consent to participate
All the authors have consented for participation in this submission.
Author contributions
Conceptualization, E.A.S., A.A. and M.A.A.A.; methodology, E.A.S., A.A. M.A.A.A. and H.M.E.; software, E.A.S., M.A.A.A., A.R.O. and S.M.Y.; formal analysis, E.A.S., M.A.A.A., A.A., A.R.O. and E.A.E.; investigation, M.T. and E.A.S.; resources, E.A.S., M.A.A.A., M.T. and H.M.E.; writing—original draft preparation, E.A.S., M.A.A.A. and A.A.; writing—review and editing, M.T., H.M.E., S.M.Y., A.R.O. and E.A.E. All authors provided critical feedback and helped shape the research, analysis and manuscript. Also, all authors discussed the results and contributed to the final manuscript. All authors read and approved the final manuscript.
Acknowledgments
None declared.
Disclosure statement
No potential conflict of interest was reported by the authors.
Data availability statement
All data generated or analyzed during this study are included in this published article.
Additional information
Funding
Notes on contributors
Mohamed A. A. Ahmed
Mohamed A. A. Ahmed, have a permanent position as assistant professor of Medicinal and Aromatic Plants at Department of Plant Production, Faculty of Agriculture (Saba Basha), Alexandria University, Egypt. I did one post-doctoral study in China from December 2022 until now. I am interested in the research areas of Medicinal and Aromatic Plants, Ornamental Plants and Horticulture, and Ornamental Plants biotechnology. I am highly motivated to increase my knowledge and experience in these research areas, which will be useful in my career.
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