PERTANIKA JOURNAL OF TROPICAL AGRICULTURAL SCIENCE

Sweet basil is one of the most popular culinary, medicinal, and fragrance herbs in Mediterranean, Asian, and Western countries. This study aims to increase the growth performance of sweet basil via different concentrations of chitosan, which is applied at three growth stages. The study was arranged in a factorial randomized complete block design with four replications. The plants were divided into three growth stages, which were the vegetative stage (S1), the reproductive stage (S2), and both the vegetative and reproductive stages (S1 + S2). Those plants were then treated with four different concentrations of chitosan (0, 2, 4, and 6 ml/L) either on S1, S2, or S1 + S2. The results indicated that plants treated with chitosan at S1 showed greater performance. Chitosan concentration of 4 ml/L produced greater plant height (55.09 ± 1.75 cm/plant), stem diameter (11.08 ± 0.89 mm/plant), and a number of leaves (296.57 ± 11.61 leaves/plant). It is also interesting to observe that the lowest chitosan concentration was non-significantly different, with 4 ml/L at S1 in some parameters. Plants in those treatments showed the highest average length of internode, number of branches, total root length, average root diameter, total root volume, and total root surface area. Besides, correlation analysis proved that all the parameters significantly correlated positively. As the concentration of 4 ml/L showed a superior effect, especially on the number of yields, thus it is recommended for growers to apply chitosan at 4 ml/L during S1.

• Acemi, A. (2020). Chitosan versus plant growth regulators: A comparative analysis of their effects on in vitro development of Serapias vomeracea (Burm. f.) Briq. Plant Cell, Tissue and Organ Culture, 141, 327-338. https://doi.org/10.1007/s11240-020-01789-3

• Acemi, A., Bayrak, B., Çakır, M., Demiryürek, E., Gün, E., El Gueddari, N. E., & Özen, F. (2018). Comparative analysis of the effects of chitosan and common plant growth regulators on in vitro propagation of Ipomoea purpurea (L.) Roth from nodal explants. In Vitro Cellular & Developmental Biology-Plant, 54, 537-544. https://doi.org/10.1007/s11627-018-9915-0

• Acharya, T. P., Reiter, M. S., Welbaum, G., & Arancibia, R. A. (2020). Nitrogen uptake and use efficiency in sweet basil production under low tunnels. HortScience, 55(4), 429-435. https://doi.org/10.21273/HORTSCI14515-19

• Anusuya, S., & Sathiyabama, M. (2016). Effect of chitosan on growth, yield and curcumin content in turmeric under field condition. Biocatalysis and Agricultural Biotechnology, 6, 102-106. https://doi.org/10.1016/j.bcab.2016.03.002

• Atait, M., & Qureshi, U. S. (2020). Efficacy of different primers on growth and yield of tulip (Tulipa gesneriana L.). World Journal of Biology and Biotechnology, 5(2), 31-35.

• Avestan, S., Naseri, L., & Barker, A. V. (2017). Evaluation of nanosilicon dioxide and chitosan on tissue culture of apple under agar-induced osmotic stress. Journal of Plant Nutrition, 40(20), 2797-2807. https://doi.org/10.1080/01904167.2017.1382526

• Baddeley, J. A., & Watson, C. A. (2005). Influences of root diameter, tree age, soil depth and season on fine root survivorship in Prunus avium. Plant and Soil, 276, 15-22. https://doi.org/10.1007/s11104-005-0263-6

• Berliana, A. I., Kuswandari, C. D., Retmana, B. P., Putrika, A., & Purbaningsih, S. (2020). Analysis of the potential application of chitosan to improve vegetative growth and reduce transpiration rate in Amaranthus hybridus. In IOP Conference Series: Earth and Environmental Science (Vol. 481, No. 1, p. 012021). IOP Publishing. https://doi.org/10.1088/1755-1315/481/1/012021

• Boonlertnirun, S., Boonraung, C., & Suvanasara, R. (2008). Application of chitosan in rice production. Journal of Metals, Materials and Minerals, 18(2), 47-52.

• Bouma, T. J., Nielsen, K. L., & Koutstaal, B. A. S. (2000). Sample preparation and scanning protocol for computerised analysis of root length and diameter. Plant and Soil, 218, 185-196. https://doi.org/10.1023/A:1014905104017

• Bouteillé, M., Rolland, G., Balsera, C., Loudet, O., & Muller, B. (2012). Disentangling the intertwined genetic bases of root and shoot growth in Arabidopsis. PLOS One, 7(2), e32319. https://doi.org/10.1371/journal.pone.0032319

• Brian, P. W. (1958). Gibberellic acid: A new plant hormone controlling growth and flowering. Journal of the Royal Society of Arts, 106(5022), 425-441.

• Bufalo, J., Cantrell, C. L., Astatkie, T., Zheljazkov, V. D., Gawde, A., & Boaro, C. S. F. (2015). Organic versus conventional fertilization effects on sweet basil (Ocimum basilicum L.) growth in a greenhouse system. Industrial Crops and Products, 74, 249-254. https://doi.org/10.1016/j.indcrop.2015.04.032

• Chamnanmanoontham, N., Pongprayoon, W., Pichayangkura, R., Roytrakul, S., & Chadchawan, S. (2015). Chitosan enhances rice seedling growth via gene expression network between nucleus and chloroplast. Plant Growth Regulation, 75, 101-114. https://doi.org/10.1007/s10725-014-9935-7

• Choudhary, R. C., Kumaraswamy, R. V., Kumari, S., Sharma, S. S., Pal, A., Raliya, R., Biswas, P., & Saharan, V. (2017). Cu-chitosan nanoparticle boost defense responses and plant growth in maize (Zea mays L.). Scientific Reports, 7, 9754. https://doi.org/10.1038/s41598-017-08571-0

• Ciriello, M., Formisano, L., El-Nakhel, C., Corrado, G., Pannico, A., De Pascale, S., & Rouphael, Y. (2021). Morpho-physiological responses and secondary metabolites modulation by pre-harvest factors of three hydroponically grown Genovese basil cultivars. Frontiers in Plant Science, 12, 671026. https://doi.org/10.3389/fpls.2021.671026

• Corrado, G., Chiaiese, P., Lucini, L., Miras-Moreno, B., Colla, G., & Rouphael, Y. (2020). Successive harvests affect yield, quality and metabolic profile of sweet basil (Ocimum basilicum L.). Agronomy, 10(6), 830. https://doi.org/10.3390/agronomy10060830

• Davis, A. S., & Jacobs, D. F. (2005). Quantifying root system quality of nursery seedlings and relationship to out planting performance. New Forests, 30(2), 295-311. https://doi.org/10.1007/s11056-005-7480-y

• Delbeke, S., Ceuppens, S., Jacxsens, L., & Uyttendaele, M. (2015). Microbiological analysis of pre-packed sweet basil (Ocimum basilicum) and coriander (Coriandrum sativum) leaves for the presence of Salmonella spp. and Shiga toxin-producing E. coli. International Journal of Food Microbiology, 208, 11-18. https://doi.org/10.1016/j.ijfoodmicro.2015.05.009

• Divya, K., Vijayan, S., Nair, S. J., & Jisha, M. S. (2019). Optimization of chitosan nanoparticle synthesis and its potential application as germination elicitor of Oryza sativa L. International Journal of Biological Macromolecules, 124, 1053-1059. https://doi.org/10.1016/j.ijbiomac.2018.11.185

• Dwyer, P. J., Bannister, P., & Jameson, P. E. (1995). Effects of three plant growth regulators on growth, morphology, water relations, and frost resistance in lemonwood (Pittosporum eugenioides A. Cunn). New Zealand Journal of Botany, 33(3), 415-424. https://doi.org/10.1080/0028825X.1995.10412968

• El-Amerany, F., Rhazi, M., Wahbi, S., Taourirte, M., & Meddich, A. (2020). The effect of chitosan, Arbuscular mycorrhizal fungi, and compost applied individually or in combination on growth, nutrient uptake, and stem anatomy of tomato. Scientia Horticulturae, 261, 109015. https://doi.org/10.1016/j.scienta.2019.109015

• Elhindi, K. M., Al-Amri, S. M., Abdel-Salam, E. M., & Al-Suhaibani, N. A. (2017). Effectiveness of salicylic acid in mitigating salt-induced adverse effects on different physio-biochemical attributes in sweet basil (Ocimum basilicum L.). Journal of Plant Nutrition, 40(6), 908-919. https://doi.org/10.1080/01904167.2016.1270311

• Fahmy, A. A., & Nosir, W. S. (2021). Influence of chitosan and micronutrients (Fe + Zn) concentrations on growth, yield components and volatile oil of lavender plant. Scientific Journal of Flowers and Ornamental Plants, 8(1), 87-100. https://doi.org/10.21608/sjfop.2021.155941

• Farouk, S., Mosa, A. A., Taha, A. A., & El-Gahmery, A. M. (2011). Protective effect of humic acid and chitosan on radish (Raphanus sativus L. var. sativus) plants subjected to cadmium stress. Journal of Stress Physiology and Biochemistry, 7(2), 99-116.

• Fattahi, B., Arzani, K., Souri, M. K., & Barzegar, M. (2019). Effects of cadmium and lead on seed germination, morphological traits, and essential oil composition of sweet basil (Ocimum basilicum L.). Industrial Crops and Products, 138, 111584. https://doi.org/10.1016/j.indcrop.2019.111584

• Genc, Y., Huang, C. Y., & Langridge, P. (2007). A study of the role of root morphological traits in growth of barley in zinc-deficient soil. Journal of Experimental Botany, 58(11), 2775-2784. https://doi.org/10.1093/jxb/erm142

• Ghasemzadeh, A., Ashkani, S., Baghdadi, A., Pazoki, A., Jaafar, H. Z., & Rahmat, A. (2016). Improvement in flavonoids and phenolic acids production and pharmaceutical quality of sweet basil (Ocimum basilicum L.) by ultraviolet-B irradiation. Molecules, 21(9), 1203. https://doi.org/10.3390/molecules21091203

• Goudarzian, A., Pirbalouti, A. G., & Hossaynzadeh, M. (2020). Menthol, balance of menthol/menthone, and essential oil contents of Mentha × Piperita L. under foliar-applied chitosan and inoculation of Arbuscular mycorrhizal fungi. Journal of Essential Oil Bearing Plants, 23(5), 1012-1021. https://doi.org/10.1080/0972060X.2020.1828177

• Govindaraju, S., & Arulselvi, P. I. (2018). Effect of cytokinin combined elicitors (l-phenylalanine, salicylic acid and chitosan) on in vitro propagation, secondary metabolites and molecular characterization of medicinal herb Coleus aromaticus Benth (L). Journal of the Saudi Society of Agricultural Sciences, 17(4), 435-444. https://doi.org/10.1016/j.jssas.2016.11.001

• Gruber, B. D., Giehl, R. F., Friedel, S., & von Wirén, N. (2013). Plasticity of the Arabidopsis root system under nutrient deficiencies. Plant Physiology, 163(1), 161-179. https://doi.org/10.1104/pp.113.218453

• Guerrero-Lagunes, L. A., Ruiz-Posadas, L. M., Rodríguez-Mendoza, M. N., & Soto-Hernández, M. (2020). Quality and yield of basil (Ocimum basilicum L.) essential oil under hydroponic cultivation. Agro Productividad, 13(9), 89-94. https://doi.org/10.32854/agrop.vi.1616

• Guo, S., Zhang, S., Jia, L., Xu, M., & Wang, Z. (2020). Root growth of eleuthero (Eleutherococcus senticosus [Rupr. & Maxim.] Maxim.) seedlings cultured with chitosan oligosaccharide addition under different light spectra. Notulae Botanicae Horti Agrobotanici Cluj-Napoca, 48(2), 626-635. https://doi.org/10.15835/nbha48211634

• Guttridge, C. G., & Thompson, P. A. (1959). Effect of gibberellic acid on length and number of epidermal cells in petioles of strawberry. Nature, 183, 197-198. https://doi.org/10.1038/183197b0

• Haase, D. L., & Rose, R. (1994). Effects of soil water content and initial root volume on the nutrient status of 2+0 Douglas-fir seedlings. New Forests, 8, 265-277. https://doi.org/10.1007/BF00025372

• Hafez, Y., Attia, K., Alamery, S., Ghazy, A., Al-Doss, A., Ibrahim, E., Rashwan, E., El-Maghraby, L., Awad, A., & Abdelaal, K. (2020). Beneficial effects of biochar and chitosan on antioxidative capacity, osmolytes accumulation, and anatomical characters of water-stressed barley plants. Agronomy, 10(5), 630. https://doi.org/10.3390/agronomy10050630

• Hanachi, P., Fakhrnezhad, F. R., Zarringhalami, R., & Orhan, I. E. (2021). Cytotoxicity of Ocimum basilicum and Impatiens walleriana extracts on AGS and SKOV-3 cancer cell lines by flow cytometry analysis. International Journal of Cancer Management, 14(3), e102610. https://doi.org/10.5812/ijcm.102610

• Harnafi, H., Ramchoun, M., Tits, M., Wauters, J. N., Frederich, M., Angenot, L., Aziz, M., Alem, C., & Amrani, S. (2013). Phenolic acid-rich extract of sweet basil restores cholesterol and triglycerides metabolism in high fat diet-fed mice: A comparison with fenofibrate. Biomedicine and Preventive Nutrition, 3(4), 393-397. https://doi.org/10.1016/j.bionut.2013.03.005

• Hassnain, M., Alam, I., Ahmad, A., Basit, I., Ullah, N., Alam, I., Ullah, I., Khalid, M. A., Shair, M., & Ain, N. (2020). Efficacy of chitosan on performance of tomato (Lycopersicon esculentum L.) plant under water stress condition. Pakistan Journal of Agricultural Research, 33(1), 27-41. https://doi.org/10.17582/journal.pjar/2020/33.1.27.41

• Heidari, J., Amooaghaie, R., & Kiani, S. (2020). Impact of chitosan on nickel bioavailability in soil, the accumulation and tolerance of nickel in Calendula tripterocarpa. International Journal of Phytoremediation, 22(11), 1175-1184. https://doi.org/10.1080/15226514.2020.1748564

• Hidangmayum, A., Dwivedi, P., Katiyar, D., & Hemantaranjan, A. (2019). Application of chitosan on plant responses with special reference to abiotic stress. Physiology and Molecular Biology of Plants, 25(2), 313-326. https://doi.org/10.1007/s12298-018-0633-1

• Hutchings, M. J., & John, E. A. (2003). Distribution of roots in soil, and root foraging activity. In H. de Kroon & E. J. W. Visser (Eds.), Root ecology (Vol. 168, pp. 33-60). Springer. https://doi.org/10.1007/978-3-662-09784-7_2

• Ibrahim, M. F. (2020). The role of vermicompost and chitosan nanoparticles as foliar application to enhancing growth, yield and oil of black cumin (Nigella sativa L.) plants. Archives of Agriculture Sciences Journal, 3(2), 205-223. https://doi.org/10.21608/aasj.2020.178054

• Iglesias, M. J., Colman, S. L., Terrile, M. C., Paris, R., Martín-Saldaña, S., Chevalier, A. A., Álvarez, V. A., & Casalongué, C. A. (2019). Enhanced properties of chitosan microparticles over bulk chitosan on the modulation of the auxin signaling pathway with beneficial impacts on root architecture in plants. Journal of Agricultural and Food Chemistry, 67(25), 6911-6920. https://doi.org/10.1021/acs.jafc.9b00907

• Incrocci, L., Carmassi, G., Maggini, R., Poli, C., Saidov, D., Tamburini, C., Kiferle, C., Perata, P., & Pardossi, A. (2019). Iodine accumulation and tolerance in sweet basil (Ocimum basilicum L.) with green or purple leaves grown in floating system technique. Frontiers in Plant Science, 10, 1494. https://doi.org/10.3389/fpls.2019.01494

• Jiao, J., Gai, Q.-Y., Wang, X., Qin, Q. P., Wang, Z.-Y., Liu, J., & Fu, Y.-J. (2018). Chitosan elicitation of Isatis tinctoria L. hairy root cultures for enhancing flavonoid productivity and gene expression and related antioxidant activity. Industrial Crops and Products, 124, 28-35. https://doi.org/10.1016/j.indcrop.2018.07.056

• Khan, W., Costa, C., Souleimanov, A., Prithiviraj, B., & Smith, D. L. (2011). Response of Arabidopsis thaliana roots to lipo-chitooligosaccharide from Bradyrhizobium japonicum and other chitin-like compounds. Plant Growth Regulation, 63(3), 243-249. https://doi.org/10.1007/s10725-010-9521-6

• Klintham, P., Tongchitpakdee, S., Chinsirikul, W., & Mahakarnchanakul, W. (2018). Two-step washing with commercial vegetable washing solutions, and electrolyzed oxidizing microbubbles water to decontaminate sweet basil and Thai mint: A case study. Food Control, 94, 324-330. https://doi.org/10.1016/j.foodcont.2018.07.025

• Ljung, K., Bhalerao, R. P., & Sandberg, G. (2001). Sites and homeostatic control of auxin biosynthesis in Arabidopsis during vegetative growth. The Plant Journal, 28(4), 465-474. https://doi.org/10.1046/j.1365-313X.2001.01173.x

• Lopez-Moya, F., Suarez-Fernandez, M., & Lopez-Llorca, L. V. (2019). Molecular mechanisms of chitosan interactions with fungi and plants. International Journal of Molecular Sciences, 20(2), 332. https://doi.org/10.3390/ijms20020332

• Mahmoody, M., & Noori, M. (2014). Effect of gibberellic acid on growth and development plants and its relationship with abiotic stress. International Journal of Farming and Allied Sciences, 3, 717-721.

• Marschener, H. (1998). Role of root growth, Arbuscular mycorrhiza, and root exudates for the efficiency in nutrient acquisition. Field Crops Research, 56(1-2), 203-207. https://doi.org/10.1016/S0378-4290(97)00131-7

• Meng, S., Jia, Q., Zhou, G., Zhou, H., Liu, Q., & Yu, J. (2018). Fine root biomass and its relationship with aboveground traits of Larix gmelinii trees in Northeastern China. Forests, 9(1), 35. https://doi.org/10.3390/f9010035

• Mirzajani, Z., Hadavi, E., & Kashi, A. (2015). Changes in the essential oil content and selected traits of sweet basil (Ocimum basilicum L.) as induced by foliar sprays of citric acid and salicylic acid. Industrial Crops and Products, 76, 269-274. https://doi.org/10.1016/j.indcrop.2015.06.052

• Mondal, M. M. A., Rana, M. I. K., Dafader, N. C., & Haque, M. E. (2011). Effect of foliar application of chitosan on growth and yield in Indian spinach. Journal of Agroforestry and Environment, 5(1), 99-102.

• Mondal, M., Puteh, A. B., & Dafader, N. C. (2016). Foliar application of chitosan improved morphophysiological attributes and yield in summer tomato (Solanum lycopersicum). Pakistan Journal of Agricultural Sciences, 53(2), 339-344.

• Monfared, B. B., Noormohamadi, G., Rad, A. H. S., & Hervan, E. M. (2020). Effects of sowing date and chitosan on some characters of canola (Brassica napus L.) genotypes. Journal of Crop Science and Biotechnology, 23, 65-71. https://doi.org/10.1007/s12892-019-0177-0

• Mosadegh, H., Trivellini, A., Maggini, R., Ferrante, A., Incrocci, L., & Mensuali, A. (2021). In-vivo in-vitro screening of Ocimum basilicum L. ecotypes with differential UV-B radiation sensitivity. Horticulturae, 7(5), 101. https://doi.org/10.3390/horticulturae7050101

• Mukta, J. A., Rahman, M., Sabir, A. A., Gupta, D. R., Surovy, M. Z., Rahman, M., & Islam, M. T. (2017). Chitosan and plant probiotics application enhance growth and yield of strawberry. Biocatalysis and Agricultural Biotechnology, 11, 9-18. https://doi.org/10.1016/j.bcab.2017.05.005

• Oosterhuis, D. M. (1990). Growth and development of a cotton plant. In W. N. Miley & D. M. Oosterhuis (Eds.), Nitrogen nutrition of cotton: Practical issues (pp. 1-24). American Society of Agronomy. https://doi.org/10.2134/1990.nitrogennutritionofcotton.c1

• Osei-Akoto, C., Acheampong, A., Boakye, Y. D., Naazo, A. A., & Adomah, D. H. (2020). Anti-inflammatory, antioxidant, and anthelmintic activities of Ocimum basilicum (sweet basil) fruits. Journal of Chemistry, 2020, 2153534. https://doi.org/10.1155/2020/2153534

• Pandey, P., Singh, S., & Banerjee, S. (2019). Ocimum basilicum suspension culture as resource for bioactive triterpenoids: Yield enrichment by elicitation and bioreactor cultivation. Plant Cell, Tissue and Organ Culture, 137, 65-75. https://doi.org/10.1007/s11240-018-01552-9

• Patriani, P., Hellyward, J., Hafid, H., & Apsari, N. L. (2021). Application of sweet basil (Ocimum basilicum) on physical and organoleptic qualities of chicken meatballs. In IOP Conference Series: Earth and Environmental Science (Vol. 782, No. 2, p. 022083). IOP Publishing. https://doi.org/10.1088/1755-1315/782/2/022083

• Rahman, M., Mukta, J. A., Sabir, A. A., Gupta, D. R., Mohi-Ud-Din, M., Hasanuzzaman, M., Miah, G., Rahman, M., & Islam, M. T. (2018). Chitosan biopolymer promotes yield and stimulates accumulation of antioxidants in strawberry fruit. PLOS One, 13(9), e0203769. https://doi.org/10.1371/journal.pone.0203769

• Salehi, S., Rezayatmand, Z., & Pirbalouri, A. G. (2017). The effect of foliar application of chitosan on yield and essential oil of savory (Satureja isophylla L.) under salt stress. Journal of Medicinal Herbs, 8(2), 101-108.

• Sari, S. G., Selvia, E., Nisa, C., & Junaidi, A. B. (2020). Pengaruh pemberian komposit kitosan asap cair terhadap pertumbuhan cabai rawit merah Capsicum frutescens Linn. [The effect of liquid smoke and chitosan composition on the growth of red cayenne pepper Capsicum frutescens Linn.]. Biotropika Journal of Tropical Biology, 8(1), 8-12. https://doi.org/10.21776/ub.biotropika.2020.008.01.02

• Sathiyabama, M., & Parthasarathy, R. (2016). Biological preparation of chitosan nanoparticles and its in vitro antifungal efficacy against some phytopathogenic fungi. Carbohydrate Polymers, 151, 321-325. https://doi.org/10.1016/j.carbpol.2016.05.033

• Scagel, C. F., Lee, J., & Mitchell, J. N. (2019). Salinity from NaCl changes the nutrient and polyphenolic composition of basil leaves. Industrial Crops and Products, 127, 119-128. https://doi.org/10.1016/j.indcrop.2018.10.048

• Sharif, R., Mujtaba, M., Ur Rahman, M., Shalmani, A., Ahmad, H., Anwar, T., Tianchan, D., & Wang, X. (2018). The multifunctional role of chitosan in horticultural crops; A review. Molecules, 23(4), 872. https://doi.org/10.3390/molecules23040872

• Sun, J., Wang, M., Lyu, M., Niklas, K. J., Zhong, Q., Li, M., & Cheng, D. (2019). Stem diameter (and not length) limits twig leaf biomass. Frontiers in Plant Science, 10, 185. https://doi.org/10.3389/fpls.2019.00185

• Tagliavini, M., Veto, L. J., & Looney, N. E. (1993). Measuring root surface area and mean root diameter of peach seedlings by digital image analysis. American Society for Horticultural Science, 28(11), 1129-1130. https://doi.org/10.21273/HORTSCI.28.11.1129

• Tanimoto, E. (2005). Regulation of root growth by plant hormones — Roles for auxin and gibberellin. Critical Reviews in Plant Sciences, 24(4), 249-265. https://doi.org/10.1080/07352680500196108

• Turk, H. (2019). Chitosan-induced enhanced expression and activation of alternative oxidase confer tolerance to salt stress in maize seedlings. Plant Physiology and Biochemistry, 141, 415-422. https://doi.org/10.1016/j.plaphy.2019.06.025

• Ullah, N., Basit, A., Ahmad, I., Ullah, I., Shah, S. T., Mohamed, H. I., & Javed, S. (2020). Mitigation the adverse effect of salinity stress on the performance of the tomato crop by exogenous application of chitosan. Bulletin of the National Research Centre, 44, 181. https://doi.org/10.1186/s42269-020-00435-4

• Waly, A. A., El-Fattah, A., Hassan, M. A. E., El-Ghadban, E. M., & Abd Alla, A. S. (2020). Enhancing growth, productivity and essential oil percentage of Thymus vulgaris L. plant using seaweeds extract, chitosan and potassium silicate in sandy soil. Scientific Journal of Flowers and Ornamental Plants, 7(4), 549-562. https://doi.org/10.21608/sjfop.2020.148056

• Wang, Y., Zhao, J., Lu, W., & Deng, D. (2017). Gibberellin in plant height control: Old player, new story. Plant Cell Reports, 36(3), 391-398. https://doi.org/10.1007/s00299-017-2104-5

• Went, F. W. (1935). Auxin, the plant growth-hormone. The Botanical Review, 1(5), 162-182.

• Xu, C., & Mou, B. (2018). Chitosan as soil amendment affects lettuce growth, photochemical efficiency, and gas exchange. American Society of Horticultural Science, 28(4), 476-480. https://doi.org/10.21273/HORTTECH04032-18

• Yang, J., Kloepper, J. W., & Ryu, C.-M. (2009). Rhizosphere bacteria help plants tolerate abiotic stress. Trends in Plant Science, 14(1), 1-4. https://doi.org/10.1016/j.tplants.2008.10.004

• Zulfiqar, F., Chen, J., Finnegan, P. M., Younis, A., Nafees, M., Zorrig, W., & Hamed, K. B. (2021). Application of trehalose and salicylic acid mitigates drought stress in sweet basil and improves plant growth. Plants, 10(6), 1078. https://doi.org/10.3390/plants10061078