Effect of Pre-Sowing Chemical Treatment on Selected Seeds: For Enhancing Germination

In agriculture and ecological restoration, seed dormancy is an adaptive mechanism that inhibits germination in adverse environmental conditions presents a major obstacle. There are a number of dormancy mechanisms, such as physiological dormancy brought on by hormone imbalances and physical dormancy brought on by impermeable seed coats (Zalamea et al., 2015). Various pre-sowing treatments have been devised to improve seed germination in order to overcome these dormancy limits; chemical treatments have emerged as a popular and successful strategy (Chauhan et al., 2006).  To understand the principles behind seed dormancy and create efficient methods for breaking it, a great deal of research has been done. Using chemical treatments to improve seed germination is one such strategy. Gibberellic acid and potassium nitrate are two examples of chemical compounds that have been discovered to be useful in promoting the metabolic processes necessary for seed germination and breaking dormancy. (Bhatt et al., 2019). The application of chemical treatments to dormant seeds triggers a series of complex biochemical and physiological processes that ultimately stimulate germination (Farooq et al., 2019). Strong oxidizing agents like hydrogen peroxide (H₂O₂) have several uses in promoting seed germination (Kaur et al., 2020). H₂O₂ can weaken the seed coat, allowing water uptake and gas exchange, critical steps in the germination process (Kaur et al., 2020). Furthermore, hydrogen peroxide has the ability to function as a signalling molecule, activating germination-related genes (Farooq et al., 2019). Another capable chemical, nitric acid, efficiently scarifies the seed coat, especially in species whose seed coatings are rigid or impermeable (Kaur et al., 2020). This scarification process encourages the release of compounds that induce dormancy and improves water imbibition (Kaur et al., 2020). This, in turn, can lead to increased germination percentage, reduced mean germination time, and more synchronous germination across a population of seeds (Bhatt et al., 2019). Likewise, it has been noted that potassium nitrate improves germination in a number of desert plants, especially when paired with exposure to light (Bhatt and Santo, 2018). It seems that the generation of hydrogen peroxide activates antioxidant enzymes, especially in the plumule, which may enhance seed germination. Furthermore, the buildup of reactive oxygen species (ROS), including hydrogen peroxide, might create an "oxidative window," which is a condition where the seed can germinate effectively (Boucelha et al., 2019). potassium nitrate, has been demonstrated to enhance seed germination in a variety of species. It is thought to work by making the enzymes in the pentose phosphate pathway more active, which increases the synthesis of NADPH, a reductant that is essential for germination. Furthermore, potassium nitrate may impact the balance of plant hormones, such as gibberellins and abscisic acid, which play crucial roles in controlling seed dormancy and germination (Habib 2010; Sharma et al., 2013). Germination rate, seedling weight, shoot length, and sugar content have all been demonstrated to be greatly impacted by seed invigoration techniques like traditional soaking and hardening. Traditional soaking and seed hardening for 24 hours have been found to be the most successful in shortening germination times and raising shoot dry weight. Under etiolated conditions, nitric acid and potassium nitrate also play a role in the process of seed emergence. It has been demonstrated that potassium nitrate helps a variety of plant species, including those cultivated without light, germinate and grow their seedlings early. (Chakma et al., 2021). In contrast, nitric acid has been shown to promote the emergence of radicles and plumules in etiolated seedlings.

MATERIAL AND METHODS

• Seed sample collection

This study was conducted with four types of plant seed samples and three types of chemical solutions for treatment. Plant seeds were collected in January 2025 from different sources. Plant seeds that are used including, Maize seed (Zea mays L.), Cotton seed (Gossypium hirsutum L.), Bajri seed (Pennisetum glaucum L. R. Br.), Black gram seed (Vigna mungo L.).

• Preparation of solutions

First of all, make three separate solutions of 1000 ppm in 500 ml with distilled water. These are the chemicals used in the study: nitric acid, ascorbic acid, hydrogen peroxide, and a control beaker containing 500 ml of pure water. To make a 500-ml solution with 1000 ppm of H₂O₂. Mix 500 ml of distilled water with 1.5 ml of 30% w/v hydrogen peroxide. Give it a good shake. To make a 500-ml solution with 1000 ppm of HNO₃. Shake thoroughly after dissolving 514 μl of nitric acid in 500 ml of distilled water. To make a 500-ml solution with 1000 ppm of KNO₃. Take 500 ml of distilled water, dissolve 0.5 grams of potassium nitrate, and shake thoroughly. This experiment's methodologies were influenced by various scientists working with various chemicals. This is followed by gibberellic acid (GA₃) (Al-naber et al., 1988; Clor and Charchafchi, 1984). For hydrogen peroxide (H₂O₂) (Riffle, 1968), potassium nitrate (KNO₃) (Abu-Zanat & Samarah, 2005; Roberts, 1964). Through the measurement of radicle and plumule growth, this experiment illustrated a comparative analysis of seed germination. All that is required to successfully germinate such seeds is a chemical treatment and purified water.

• Layout of experiment

Each seed was prepared in five sets of petri dishes. Cover the petri dish with 125 mm of Wattman No. 1 filter paper. Pour 30 ml of a different chemical into each set of petri plates containing various seeds. Random number of seed are taken in each petri dish for study. Then, to ensure healthy germination, keep petri dishes in a large tray. Day-wise observation was taken for all seeds.

RESULT AND DISCUSSION

In this research, two seed varieties, including monocot and dicot, were chosen to conduct the chemical treatment experiment. Gossypium hirsutum L., Pennisetum glaucum L. R. Br., Vigna mungo L., and Zea mays L. are the seeds employed in this investigation. Each petri dish of seeds contains a random number of seeds. Chemical substances were weighed once using a weighing balance in order to prepare a solution. For the purpose of treating seeds, three solutions are made, H₂O₂, KNO₃ and HNO₃. Every chemical's concentration was maintained at 1000 parts per million. Throughout the six days of the experiment, constant observation was taken. When seeds are treated chemically, they produce favourable consequences. As a result of this experiment, seeds developed varying lengths of plumule and radicle in different solutions.

Table 4.1 - Day wise measured length of germinated seed’s plumule and radicle of Zea mays L. seeds.

Table 4.2 - Day wise measured length of germinated seed’s plumule and radicle of Gossypium hirsutum L. seeds.

Table 4.3 - Day wise measured length of germinated seed’s plumule and radicle of Pennisetum glaucum L.R. Br. seeds.

Table 4.4 - Day wise measured length of germinated seed’s plumule and radicle of Vigna mungo L. seeds.

The results of the growth of the radicle and plumule of different seeds as shown above can be shown in the form of a graph as follows.

Figure 3.1: Graphical data of length of plumule and radicle of Zea mays L. seed.

Figure 3.2: Graphical data of length of plumule and radicle of Gossypium hirsutum L. seed.

Figure 3.3: Graphical data of length of plumule and radicle of Pennisetum glaucum L. R. Br. seed.

It is demonstrated by the data in the above graph that the seeds utilized exhibit excellent germination outcomes when treated with hydrogen peroxide. Additionally, it can be observed from the graph below that Vigna Mungo L. seeds exhibit comparable germination outcomes across all chemical treatments. Nitric acid shows less results in all seeds.

Figure 3.3: Graphical data of length of plumule and radicle of Vigna mungo L. seed.