1 Introduction

Vegetables that are often grown in the tropics of Latin America, Africa, and Asia under dry agroecological conditions are known as cowpeas (Vigna unguiculata (L.) Walpers) or black eye peas. This legume is a member of the Fabaceae family, tribe Phaseoleae, genus Vigna, and section Catiang of the genus Vigna. Unguiculata is a subspecies of cowpea that people grow for food. There are five groups of cultivars: Unguiculata, Sesquipedalis, Textilis, Biflora, and Melanophthalmus (Boukar et al., 2019). In terms of micronutrients and amino acids, cowpeas outperform or complement cereals, making them ideal candidates for solving the global shortage of micronutrients. Legumes include a variety of micronutrients, including carotenoids, which have been shown to enhance human health. Consumption of these foods has been shown to increase cellular differentiation and reproduction, reduce the risk of vision impairment, cancer, cardiovascular disease, and newborn mortality, and contribute to the body's antioxidant defense system. Carotenoids present in legume crops include α- and β-carotenes, as well as hydroxylated versions of these compounds (lutein, zeaxanthin, violaxanthin, etc.). Even though all carotenoids have isoprene units in common, their structural and functional characteristics vary (Sodedji et al., 2022). Therefore, cowpea seed is regarded as an important source of additional protein in cereals and as a means of extending the shelf life of animal protein sources (Rangel-Montoya et al., 2022). It's one of eight grain legume crops that the Consultative Group for International Agricultural Research (CGIAR) wants to improve. Cowpea species is one of them (Salinas-Gamboa et al., 2016). Most of the research on cowpea is devoted to promoting active breeding in underdeveloped nations in order to alleviate poverty. In sustainable farming, this plant is used because of its ability to withstand drought and water deficiency, as well as high temperatures and high salinity. In many areas, it serves as a stress-tolerant, low-cost, and environmentally friendly source of protein, making it especially important for vegetarians (Jayawardhane et al., 2022).

Studies explored the use of plant growth regulators to boost plant growth and production. Because it reduces soil oxygen levels, waterlogging stress can cause hypoxia and anoxia in plants. In waterlogging-sensitive crops, such as cowpeas, lower diffusion rates of gases that can induce cell and tissue death are signs of a hypoxic environment, as is plant anaerobic respiration (Olorunwa et al., 2022). Gibberellic acid at 50 and 75 ppm was observed to improve G. arborum's photosynthetic activity and, as a result, the total amount of photosynthetic metabolites, soluble sugars, and proteins. Foliar spraying of 50 or 100 ppm gibberellic acid to Vicia faba plants improved seed yield, pod yield, and harvest index (Choudhury et al., 2013). The utilization of Indole acetic acid (IAA) and gibberellic acid (GA₃) can be used to manage a variety of agricultural growth and development phenomena. IAA has been proven to increase plant height, leaf number per plant, fruit size, and seed yield in a variety of species, including groundnuts, cotton, cowpeas, and rice. Flowers and fruit set increase, as well as the amount of dry matter in a crop. A similar effect was seen with GA₃, which promoted stem lengthening, dried matter accumulation, and an increase in overall yield (Sarkar et al., 2002). Previous research found that soaking carrot roots in IAA at 100 ppm increased seed output and harvest index. The effects of soaking soybean seeds in IAA at various concentrations were studied using soybean and Seseamum plants (50, 75, and 100 ppm). Another study found that IAA treatment boosted blooming stage endogenous auxin and gibberellin activity (Khandaker et al., 2018; Prajapati et al., 2015).

Kinetin foliar applications at 100 and 200 ppm were sprayed on wheat leaves, and the plants' shoot fresh weight increased considerably. Helioanthus annus grew taller, had more chlorophyll, and had a larger leaf area when it was given Kinetin. According to previous studies, wheat plants' fresh and dry weights were dramatically boosted when kinetin was applied. Soybean seeds that had been soaked in various growth hormones exhibited a considerable increase in the amount of protein and oil in the final product compared to untreated plants. It was hoped that this study will examine theeffect of growth bioregulators on cowpea plant yield and yield characteristics. Seed yields were also tested for total protein and total soluble sugar content.

2 Materials and methods

3 Results

4 Discussion

The goal of this study was to explore at the involvement of growth bioregulators in yield and yield qualities of cowpea plants, as well as the levels of complete protein and soluble sugars in yielding seeds. This study employed methodologies such as plant and growth conditions analysis, yield and yield component analysis, calculation of total soluble sugars and proteins in yielding seeds, and endogenous hormone determination. In this experiment, three growth regulators were utilized to increase the physiological activity and production of cowpea plants. When compared to untreated control plants, seed presoaking in various concentrations of IAA, GA₃, and kinetin appeared to enhance various yield parameters such as 100-seed weight and relative growth yield, pod weight, pod length number, and total amount of seeds/pots of cowpea plants. One of the causes again for increase in production of cowpea is the increased rate of transpiration and photosynthetic transfer from leaves to developing seeds produced by hormone treatments (Khandaker et al., 2018; Ayyub et al., 2013). This study found that growth regulators utilized in this study had a positive influence on the growth of cowpea plants, which in turn led to an increase in the quality of the plant's output as a result of increased leaf area, pigment production, and photosynthetic activity (Prajapati et al., 2015; Weiming and Aiwu, 1999; Vamil et al., 2010).

To treat persistent boils, ground up cowpea seeds mixed with oil is utilized. To satisfy thirst, a jelly prepared from cowpea starch is utilized. According to some medical professionals, spiced seeds and their boiling liquid may be a therapeutic cure for the common cold. Poultices made from the leaves and seeds can be used to treat swellings and infections, the leaves are chewed to treat tooth ailments, powdered carbonized seeds can be applied to insect stings, and the root is used as an antidote for snakebites as well as to treat epilepsy,$chest pain, constipation, $and dysmenorrhea. Many other biological actions are also demonstrated, such as effects on cellular signaling and animal infertility prevention. They are also expected to serve a preventative function in oxidative stress-related disorders such as cancer, cardiovascular disease, cataracts, age-related macular degeneration, central neurodegenerative diseases, and diabetes mellitus. A seed infusion can be used to cure amenorrhea, and powdered roots can be mixed into porridge to treat menstrual cramps, epilepsy, and chest pain.$Traditional healers use it to treat urinary shistomiasis$ (bilharzias). On relieve pain, the leaves can be put to burns and snuffed. Emetics derived from the plant are used to cure fevers. Tocopherols are the most important lipophilic antioxidants. Even though cowpea seed does not contain oil, it can be crushed and utilized to manufacture edible oils. Lipoproteins and membrane polyunsaturated fatty acids are protected from oxidation (Zia-Ul-Haq et al., 2010).

In this study, kinetin application was determined to be the most effective growth regulator for raising yield and yield components in cowpea plants when compared to other growth regulators. El-Saeid et al found that IAA boosted cowpea plant growth metrics, which is consistent with our findings (El-Saeid et al., 2010). IAA and GA₃ have been shown to increase tomato yield through changes in carbohydrate metabolism enzyme activity, (Choudhury et al., 2013). Cowpea seeds produced from this experiment had significantly higher levels of total soluble sugars than those produced without the growth regulators. Khandaker et al also found that floral$injection of IAA at 30 and 90 mg/L increased$ Abelmoschusesculentus' total soluble sugars (Khandaker et al., 2018). Furthermore. Soluble carbohydrate content and activity of the acid invertase enzyme were considerably boosted by the use of Kinetin (8, 19). Furthermore. The kinetin therapy, according to Prajapati et al, caused an excessive buildup of lemna minor starch (Prajapati et al., 2015).

The results of this study show that the protein content of growing cowpea seeds was greatly boosted by the use of growth regulators. Several researchers found that IAA elevated levels of protein and other nitrogenous substances in a variety of plant types when tested (Sarkar et al., 2002; Prajapati et al., 2015; Vamil et al., 2010). Before, it was reported that spraying 50 ppm IAA on the leaves of maize, bean, and cowpea plants increased their total nitrogen content, primarily protein. In addition, it was discovered that the protein content of the harvested cowpea seeds increased considerably when GA₃ was applied. In addition, the findings of Ayyub et al. and Choudhury et al. support these findings (Choudhury et al., 2013; Ayyub et al., 2013). Furthermore, kinetin was found to be the most effective hormone for protein modification in growing seeds of cowpea plants (Prajapati et al., 2015; Weiming and Aiwu, 1999; El-Saeid et al., 2010; Al-Humaid, 2002). Because kinetin increases chlorophyll content, stomatal conductance, and the accumulation of dry matter within developing seed$, the apparent increase in seed protein content after kinetin application may be explained by the fact that kinetin enhances mobilization centers, which in turn directs the migration and accumulation of compounds into developing seeds (Khandaker et al., 2018; El-Saeid et al., 2010). In addition, Exogenous applications of some phytohormones (e.g., GA₃, IAA, ABA, and kinetin), have the potential to offset the adversities of salinity stress up to a certain limit in rice plants (Prajapati et al., 2015; Ayyub et al., 2013). Cytokinins indirectly affect tuberization by enhancing the activation of starch-synthesizing enzymes to support continuing starch deposition (Shah, 2011). Applications of exogenous kinetin in vitro stimulated accumulation of starch, possibly by activation of ADP glucose phosphorylase and pyrophosphorylase during tuberization (El-Saeid et al., 2010). Cytokinin activity can create a nutrient sink and that both ¹⁴C-labelled sucrose and amino acids are mobilized to localized sites of high cytokinin accumulation. Local synthesis of cytokinins in axillary buds of transgenic tobacco resulted in an increase in starch accumulation in the lateral shoots that formed (Ayyub et al., 2013).

An increase in endogenous auxin and gibberellin activity in cowpea seeds was clearly observed in this study. An increase in gibberellin biosynthesis gene expression and polysaccharide production was detected (Prajapati et al., 2015); who discovered that foliar treatment of IAA caused similar results. The generation of secondary messengers by IAA activates preexisting H⁺-ATPases and increases the activation of various growth and development related genes. IAA also starts a signal transduction pathway (Sarkar et al., 2002; Khandaker et al., 2018; Shah, 2011). When seeds were presoaked in GA₃ at varying concentrations, auxins, gibberellins, and cytokinin levels rose significantly. The concentration of abscisic acid was found to be decreasing. GA₃ was shown to stimulate proteolytic enzymes that may be predicted to release tryptophan, a precursor to IAA (El-Saeid et al., 2010). After kinetin treatment, there was a significant rise in auxins, gibberellins, and cytokinins in cowpea seeds. The induction of some metabolites, particularly sugars, into seeds may have led to this increase (Shah, 2011). An increase in osmotic water uptake ensued, leading to a rapid rise in fresh weight for the seed and, ultimately, to an increase in the seed's extractable gibberellin activity. Furthermore, kinetin treatment increased the cytokinin content of the cowpea seeds that were harvested. Because of an increase in seed division, the amount of cytokinin in the seeds produced may be higher than normal (Vamil et al., 2010; Al-Humaid, 2002).

5 Conclusion

The data reported here show that seed presoaking with varied doses of IAA, GA3, or kinetin increased yield quality of cowpea plants by generating a significant rise in yield components as well as increases in protein content and total soluble sugars in produced seeds. Kinetin treatment, according to the findings of this study, is the most effective hormone for raising productivity and endogenous auxins, gibberellin, and cytokinin in cowpea plants. Furthermore, more research is needed to better understand how growth bio-regulators alter cowpea plants' metabolic pathways, molecular analyses, and enzymes.