Enhancing growth and yield parameters of Sinapis alba through optimized seed priming techniques

Abstract

Early seed germination significantly influences crop growth and production, prompting the exploration of seed priming as a pivotal technique. Despite the acknowledged importance of faster germination and emergence for successful seedling establishment, oilseed crops like Sinapis alba have received limited attention concerning seed priming methods, unlike cereal and grain crops. This study aimed to bridge this gap by subjecting S. alba seeds to six priming treatments: T1 = control, T2 = distilled water, T3 = NaCl (0.5%), T4 = KNO₃ (0.5%), T5 = CaCl₂ (0.5%), and T6 = Moringa leaf extract at a 1:30 ratio (30 times diluted), to assess their impact on various growth and yield parameters. The data analysis revealed significant effects of seed priming on various parameters, with exceptions in plant height unaffected by seed soaking. Seed priming notably enhanced germination percentage, germination rate index, and seedling vigor index, while reducing mean germination time to emergence significantly. Furthermore, primed seeds exhibited significant increases in seedling fresh and dry weights, crop growth rate, net assimilation rate, root and shoot lengths, leaf area, chlorophyll content, early flowering, branch numbers, pod counts, and 1000-seed weight compared to non-primed seeds. The biological yield was relatively higher in treated seeds. Additionally, seed yield and oil content were found to be higher in primed seeds compared to the control. Among the treatments, KNO₃ along with Moringa, displayed the most desirable outcomes across overall seedling parameters, suggesting their recommendation for effective priming treatments to improve the growth and yield of S. alba.

Abbreviations
• CGR
• crop growth rate
• DAE
• days after emergence
• GRI
• germination rate index
• MLE
• Moringa leaf extract
• NAR
• net assimilation rate
• VI
• vigor index

INTRODUCTION

Oil seeds are very highly sensitive to drastic environmental variations. The contents oxidize readily, resulting in deterioration of physical condition of the seed during storage (T. Mahmood & Basra, 2009; Taylor, 2020). Faster germination and emergence is very essential for early and successful establishment of seedling and overall crop productivity (Gardarin et al., 2016; Harris et al., 1999). Several techniques have been used to speed up the rate of germination, emergence, and seedling establishment, among which seed priming is the most important (Basra et al., 2003; de Oliveira & Gomes-Filho, 2016; Singh et al., 2015). Priming treatments imbibe the seed with water, causing sufficient hydration of the seed and increasing all the metabolic processes needed for seed germination (Ashraf & Foolad, 2005). Priming enhances the rate of seed germination, emergence, seedling growth, and tolerance to harsh and stressed environmental conditions (Harris et al., 1999; Kaya et al., 2006) (allowing water uptake and leading germination metabolism to a definite point at which the germination just starts prior to radicle emergence (Bradford, 1986).

Seed priming is carried out by various methods, like hydro-priming, osmo-priming, using growth regulators, and solid matrix priming (Capron et al., 2000); however, on-farm priming reduced the time of germination and escaped seedling from deteriorating the physical condition of the soil (Rashid et al., 2006).

Seed soaking has been effectively utilized for enhancing the rate of seed germination and the uniformity of emergence in many types of seeds, including those of crops and vegetables (Arif et al., 2008; Harris et al., 2007), and it works better even in worst field conditions (Kant et al., 2004). Primed seeds emerge 12 h earlier than untreated seeds, which could be attributed to the early activation of amylases, proteases, and lipases that provide energy to the growing embryo (Dell'Aquila & Tritto, 1990). Seed soaking induces DNA replication, enhances synthesis of RNA and proteins, improves embryo development, maintains weakened seed portions, and diminishes the escape of metabolites from the seed (McDonald, 2000).

Primed seeds of improved Brassica crop establish quickly in wet and cold soil conditions (Rao et al., 1987). Treating canola seeds with NaCl solution improved germination rate, germination percentage, and seedlings dry weight as compared to untreated seeds of the crop (G. Mohammadi, 2009). Raising the NaCl solution concentration to 200 mM decreases seed germination, relative water content, and growth parameters of lentil cultivars (Sidari et al., 2007). Seed priming decreases germination time and improves final germination percentage, early development, quantity, and quality of grains in sunflower (Wahid et al., 2008). Seed soaking with CaCl₂ enhances germination, results in enhanced seedling emergence of rice, and increases seed and straw yields as compared to traditional seed soaking (Farooq et al., 2007). Priming treatments enhance biological yield and grain production of the rape seed by improving seedlings establishment (Jabbarpour et al., 2012).

The important advantages of seed priming in all types of crops are rapid emergence of the crop, improved and uniform crop stands, more vigorous plants, tolerance to harsh environmental conditions, early flowering of crops, early harvest, and maximum seed yield of crops (Harris et al., 2007). Various studies have shown that seed priming techniques significantly enhance the germination and early growth of numerous oil seed species, including safflower (Jocković et al., 2018) and Aeluropus macrostachys (Nejad, 2013). Techniques such as hydro-priming and osmo-priming have demonstrated their efficacy by augmenting water absorption and activating crucial metabolic processes within seeds, resulting in improved germination parameters in these species.

Core Ideas

• Enhanced Sinapis alba germination and emergence through diverse seed priming techniques.
• Optimized seed priming notably boosts S. alba seedling vigor and growth.
• Improved S. alba yield and seed quality via targeted seed priming methods.
• KNO₃ and Moringa seed priming emerge as effective solutions for enhancing S. alba growth.
• Priming treatments showcase substantial potential in elevating S. alba biological yield.

However, despite the advancements in seed priming techniques and their positive impacts on several oil seed varieties, the direct effects of these methods on the germination and growth of Sinapis alba seeds have not been specifically investigated. S. alba, an oil seed crop, remains relatively understudied in the context of seed priming. Given the diverse responses of different oil seed species to priming techniques, further research is warranted to ascertain the most effective priming approach tailored to the unique characteristics of S. alba seeds.

This study aims to bridge this knowledge gap by evaluating the influence of various priming techniques on the germination, growth, and development of S. alba. Moreover, it seeks to explore the effects of different chemical priming agents on the field performance, yield, and quality of S. alba, providing insights into optimizing seed priming strategies for this specific oil seed crop.

MATERIALS AND METHODS

The laboratory and field experiments were carried out at Pir Mehr Ali Shah Arid Agriculture University, Rawalpindi, Pakistan, to evaluate the effects of seed priming on S. alba during Rabi season, 2012. The laboratory experiment was laid out in a complete randomized design (CRD), while the field experiment was carried out in a randomized complete block design (RCBD) with three replications and six treatments each. In laboratory experiment, seeds were placed in petri dishes with filter papers properly moistened with distilled water, while in field experiment, seeds were sown in plots of 2.2 m × 4 m in size each. S. alba, at a seed rate of 5 kg ha⁻¹, was sown in four rows spaced at 30 cm in each plot. Soil was plowed with cultivator and properly planked at the end of rainy season. At the time of plowing, 75:50:0 kg ha⁻¹ NPK (where N, P, and K denote nitrogen, phosphorus, and potassium, respectively)was applied to the soil by the broadcast method. The sowing was done by the Pora method using hand on November 17, 2012. The treatments used for priming were NaCl, CaCl₂, and KNO₃ at the rate of 0.5% solution, Moringa leaf extract (MLE) at the ratio of 1:30 (Yasmeen et al., 2013), and distilled water, while the untreated seeds were taken as control. In total, there were 18 plots with six treatments and three replications.

Laboratory experiment

The following parameters were studied in the laboratory experiment:

• Daily germination count was performed until no further germination occurred. The germination percentage was calculated by the following formula: [Image Omitted. See PDF]

• Germination rate index (GRI) was determined by the following formula: [Image Omitted. See PDF]

• The seedling vigor index (VI) was determined by the following formula: [Image Omitted. See PDF]

• Seedling root length and shoot length were measured for the randomly selected seedlings after 10 days of germination.

Field experiment

During field experiment, the parameters studied were as follows:

• Note that, 50% emergence was determined by calculating seedling emergence by selecting a 1 m² area randomly in each plot from the sowing date until 50% of the seedlings emerged.

• Seedling fresh and dry weights were taken by selecting five normal seedlings randomly collected from each treatment and all the replications at 15-day intervals from the emergence of the crop. After taking fresh weight, the seedlings were oven-dried at 60°C for 24 h, and then the dried seedlings were weighed in grams by using an electrical balance.

• Data regarding crop growth rate (CGR) were recorded by taking samples randomly from each treatment and all replications at a 15-day interval from the emergence of the crop. CGR was determined by using the following formula: [Image Omitted. See PDF]

• The net assimilation rate (NAR) was determined by taking samples randomly from each treatment and all replications at a 15-day interval from emergence of the crop. NAR was determined from the accumulated dry matter by the following formula: [Image Omitted. See PDF]

where W₁ and W₂ are the total dry weights, and LogeL1 and LogeL2 are the natural logs of total leaf areas L1 and L2 at time T₁ and T₂, respectively.

• Leaf area, plant height, number of branches per plant, number of pods per plant, seeds per pod, and 1000-seed weight were measured by selecting 10 plants randomly from each treatment and all replications.

• The leaf chlorophyll content was recorded by taking 10 randomly selected leaves from each treatment and all replications by using a SPAD (Soil Plant Analysis Development) chlorophyll meter.

• Days to flowering were counted by observing plants daily for flowering. The day on which 50% of plants showed flowers was considered as 50% flowering. Then, days to flowering were calculated from the sowing date to the day on which 50% of the plants completed flowering.

• Biological yield of the crop was taken by harvesting all plants from the net plot from each treatment and all replications and was expressed in kg ha⁻¹.

• Seed yield per hectare was taken by harvesting all the mature pods from the net plot (2.2 m × 4 m) in each treatment from all replications and the seeds were separated, weighed in kilograms, and then converted into kg ha⁻¹.

• Data concerning harvest index were recorded by taking the ratio of seed yield to the biological yield using the following formula: [Image Omitted. See PDF]

• Oil contents (oleic acid, linolenic acid, and erucic acid) were determined by using the Near-Infrared Spectroscopy (NIRS) system at The Nuclear Institute for Food and Agriculture (NIFA), Peshawar, Pakistan.

Statistical analysis

Data were statistically analyzed using analysis of variance technique suitable for CRD and RCBD. The means of the data were compared using the least significant difference test at a 5% probability level (Montgomery, 2001).

RESULTS Laboratory experiment Germination percentage

Analysis of the data showed significant differences (≤0.05) among treatments (Table 1). The maximum germination percentage (97.50%) was recorded for the seeds primed with KNO₃ solution, followed by seeds primed in water (96.67%), MLE (95.83%), CaCl₂ (95.00%), and NaCl (90.83%). The minimum germination percentage (83.33%) was observed in unprimed seeds of the crop.

TABLE 1 Germination percentage and germination rate index as influenced by seed priming.

Treatments	Germination (%)	Germination rate index
Control	83.33C	7.68D
Water	96.67AB	12.23AB
NaCl	90.83B	10.82C
KNO3	97.50A	13.39A
CaCl2	95.00AB	12.06B
Moringa	95.83AB	13.27AB
Cv % LSD (0.05)	4.00 6.63	5.94 1.22

Note: Two means in the columns not sharing any letter differ significantly at 0.05 probability level.

Abbreviation: Cv, coefficient of variation; LSD, least significant difference.

Germination rate index

Data concerning GRI given in Table 1 showed significant differences (≤0.05) among treatments. Maximum GRI was observed in the seeds primed with KNO₃ (13.39), followed by seeds primed with MLE (13.27), while the minimum germination rate (7.68) was observed in unprimed dry seeds.

Seedlings vigor index

Data about seedlings VI shown in Table 2 exhibited significant differences (≤0.05) among treatment means. The highest seedling VI was observed in the seeds treated with KNO₃ (1292.0), which was at par with the seeds primed with MLE (1153.8), while the minimum seedling VI (582.3) was recorded in untreated seeds of the crop.

TABLE 2 Seedlings vigor index (VI), seedlings root length, and seedlings shoot length as influenced by seed priming.

Treatments	Seedlings vigor index	Seedlings root length (cm)	Seedlings shoot length (cm)
Control	582.33C	4.57C	2.43D
Water	1088.8AB	7.23AB	4.00BC
NaCl	997.0B	7.22AB	3.73C
KNO3	1292.0A	8.33A	4.90A
CaCl2	954.0B	6.27B	3.77C
Moringa	1153.8AB	7.30AB	4.73AB
Cv % LSD (0.05)	11.45 205.93	12.86 1.56	12.22 0.85

Note: Two means in the column not sharing any letter differ significantly at 0.05 probability level.

Abbreviation: Cv, coefficient of variation; LSD, least significant difference.

Seedlings root length

Data regarding seedlings' root length given in Table 2 revealed significant differences (≤0.05) among treatments. Maximum seedlings' root length was observed in the seeds soaked in KNO₃ (8.33 cm), followed by MLE (7.30 cm); however, the minimum seedlings' root length (4.57 cm) was observed in non-soaked dry seeds.

Seedlings shoot length

Data concerning seedlings' shoot length shown in Table 2 revealed significant differences (≤0.05) among treatments. The maximum seedlings shoot length was observed in the seeds treated with KNO₃ (4.90 cm), followed by the seeds treated with MLE (4.73 cm). The minimum seedlings shoot length (2.43 cm) was observed in unprimed seeds of the crop. This might be due to the instigation of metabolic behavior in embryos caused by priming.

Field experiment Days to 50% emergence

The emergence of a crop is the appearance of seedlings above the surface of the soil. Suitable soil, oxygen, available water, and temperature are the essential requirements for sufficient emergence. Data concerning days to emergence (Table 3) revealed significant differences (≤0.05) among treatments. The minimum number of days to emergence was estimated in the seeds treated with KNO₃ (5.67), followed by seeds treated with MLE (7.00). The maximum number of days to emergence (13.00) was observed for unprimed dry seeds.

TABLE 3 Days to 50% emergence and plant height, as influenced by seed priming.

Treatments	Days to 50% emergence	Plant height (cm)
Control	13.00A	150.67 NS
Water	7.00BC	153.73
NaCl	8.33B	153.27
KNO3	5.67C	157.93
CaCl2	7.67BC	153.87
Moringa	7.00BC	157.57
Cv % LSD (0.05)	16.79 2.48	2.53NS

Note: Two means in the column not sharing any letter differ significantly at 0.05 probability level.

Abbreviations: Cv, coefficient of variation; LSD, least significant difference; NS, nonsignificant.

Seedling fresh weight

Data concerning seedling fresh weight presented in Figure 1 revealed significant differences (≤0.05) among treatments. In all priming agents, seedlings' fresh weights were significantly improved as compared to the control. The highest seedlings' fresh weights were recorded 75 days after emergence (DAE) of the crop. The lowest seedlings fresh weights were observed in 15 DAE of the crop. Maximum seedlings' fresh weights were observed in the seeds primed with KNO₃ at all growth stages, which were statistically at par with the seeds primed in water and MLE, followed by the seeds treated with NaCl and CaCl₂. The minimum seedlings' fresh weights at all stages were observed in unprimed seeds.

FIGURE 1. Seedlings fresh weight as influenced by seed priming. MLE, Moringa leaf extract.

Seedling dry weight

Data about seedling dry weight presented in Figure 2 showed significant differences (≤0.05) among treatments. All priming agents effectively increased seedlings' dry weights as compared to control. The graph showed that the maximum seedlings' dry weights were attained at 75 DAE of the crop, while the lowest seedlings' dry weights were observed at 15 DAE of the crop. The seeds primed with KNO₃ showed the highest seedlings dry weights at all growth stages, which were statistically at par with the seeds primed in water and MLE, followed by the seeds treated with CaCl₂ and NaCl. The minimum seedlings' dry weights at all growth stages were recorded in untreated seeds.

FIGURE 2. Seedlings dry weight as influenced by seed priming. MLE, Moringa leaf extract.

Crop growth rate

Data concerning CGR presented in Figure 3 showed significant differences (≤0.05) among treatments. All priming agents effectively increased CGR as compared to control. The maximum CGRs were recorded in each treatment at 60 DAE, while the lowest crop growth rates were observed at 15 DAE of the crop. It is also observed that CGR was reduced at 75 DAE of the crop in each treatment. The seeds primed with KNO₃ showed the highest CGR at all growth stages, which were statistically at par with the seeds primed with water and MLE, followed by the seeds treated with CaCl₂ and NaCl. Minimum CGR at all growth stages was observed in control.

FIGURE 3. Crop growth rate (CGR) as influenced by seed priming. MLE, Moringa leaf extract.

Net assimilation rate

Data pertaining to the NAR presented in Figure 4 showed significant differences (≤0.05) among treatments. All priming agents effectively increased NAR as compared to control. The maximum NARs were observed in each treatment at 60 DAE, while the lowest NARs were observed at 15 DAE of the crop. It is also observed that NAR was reduced at 75 DAE. The seeds primed with KNO₃ attained the highest NAR at all growth stages, which were statistically at par with the seeds primed with water and MLE, followed by the seeds treated with CaCl₂ and NaCl. Minimum NAR at all growth stages was observed in unprimed seeds.

FIGURE 4. Net assimilation rate (NAR) as influenced by seed priming. MLE, Moringa leaf extract.

Leaf area

Data concerning leaf area represented in Figure 5 revealed significant differences (≤0.05) among treatments. All priming agents effectively increased leaf area as compared to control. Maximum leaf area was observed in each treatment at 60 DAE, while the lowest leaf area was recorded at 15 DAE of the crop. It is also observed that the leaf area was reduced at 75 DAE. The seeds primed with KNO₃ attained the highest leaf areas at all growth stages that were statistically at the same level as the seeds treated with water and MLE. The minimum leaf area at all growth stages was observed in control.

FIGURE 5. Leaf area as influenced by seed priming. MLE, Moringa leaf extract.

Leaf chlorophyll content

Data pertaining to leaf chlorophyll content is shown in Figure 6. Analysis of the data revealed significant differences (≤0.05) among treatments. All priming agents effectively increased leaf chlorophyll content compared to untreated seeds. The highest leaf chlorophyll content was observed in each treatment at 60 DAE, while the minimum leaf chlorophyll contents were recorded at 15 DAE of the crop. It is also observed that the leaf chlorophyll contents were reduced at 75 DAE in each treatment. The seeds primed with KNO₃ attained the highest leaf chlorophyll content at all growth stages which was statistically at the same level as the seeds treated with water and MLE, followed by the seeds treated with CaCl₂ and NaCl. The minimum leaf chlorophyll content at all growth stages was observed in untreated seeds.

FIGURE 6. Leaf chlorophyll contents as influenced by seed priming. MLE, Moringa leaf extract.

Plant height

It is clear from the data that there were statistically nonsignificant differences (≤0.05) among treatments for plant height (Table 3). It revealed that priming did not influence plant height. These results are in conformity with the results of Hussain et al. (2006), who observed non-considerable effects in treated sunflower seeds. It might be a genetically controlled trait. Similar observations were recorded by Basra et al. (2003) in primed canola seeds.

Number of branches per plant

The number of branches per plant is the outcome of the combined effects of planting geometry and the genetic makeup of crops. They play an essential role in establishing seed yield. For the number of branches per plant, significant differences (≤0.05) were observed among treatments (Table 4). The highest number of branches per plant was recorded from the seeds primed with KNO₃ (13.39), followed by seeds primed in MLE (13.27), water (12.23), CaCl₂ (12.06), and NaCl (10.82). The minimum number of branches per plant (7.68) was observed in unprimed dry seeds.

TABLE 4 Days to 50% flowering and number of branches per plant as influenced by seed priming.

Treatments	Days to 50% flowering	No. of branches per plant
Control	115.33A	12.4C
Water	102.67CD	16.4AB
NaCl	108.33B	15.0B
KNO3	101.33D	18.3A
CaCl2	107.00BC	15.2B
Moringa	103.33BCD	16.6AB
Cv % LSD (0.05)	2.91 5.64	6.81 1.94

Note: Two means in the column not sharing any letter differ significantly at 0.05 probability level.

Abbreviation: Cv, coefficient of variation; LSD, least significant difference.

Days to 50% flowering

Data about days to flowering, shown in Table 4, revealed significant differences (≤0.05) among treatments. The minimum days to flowering were observed in the seeds primed with KNO₃ (101.33), which were statistically at par with water (102.67) and MLE (103.33)-treated seeds, followed by seeds primed with CaCl₂ (107.00) and NaCl (108.33). The maximum days to 50% flowering of 115.33 were recorded in control plots.

1000-Seed weight

The seed weight of a crop expresses the degree of seed development which is an essential yield-determining component. It plays an important role in showing off the yield potential of a crop. The maximum 1000-seed weight was observed in the seeds primed in KNO₃ (4.69 g), which was statistically at par with MLE (4.62 g) and water (4.59 g), followed by seeds treated in CaCl₂ (4.49 g) and NaCl (4.35 g). The minimum 1000-seed weight (3.95 g) was observed in unprimed dry seeds of the crop (Table 6).

Biological yield

Biological yield is an important index of crop growth. The overall growth performance of a crop during its life cycle is determined by the weight of its total biomass. It is the combination of grain and straw yield. Data concerning biological yield given in Table 6 revealed significant differences (≤0.05) among treatments. Maximum biological yield was observed in the seeds primed with KNO₃ (11,818.5 kg), which was statistically at par with water (10,833.7 kg) and MLE (10,682.8 kg), followed by seeds primed in CaCl₂ (10,265.2 kg) and NaCl (10,076.3 kg). Minimum biological yield (6591.4 kg) was recorded in untreated seeds.

Seed yield

Economical yield of crops is the result of the combined outcomes of different yield-contributing factors. The number of pods per plant, branches per plant, planting density, and the number of seeds per pod are all factors contributing to the seed yield (Table 5). Data regarding seed yield (Table 7) revealed that the data were significantly different (≤0.05) among treatments. Maximum seed yield was found in the seeds treated with KNO₃ (1447.0), followed by seeds primed with water (1178.0), which was at par with MLE (1162.9), CaCl₂ (1102.3), and NaCl (1068.2). Minimum seed yield (560.6) was observed in untreated dry seeds.

TABLE 5 Number of pods per plant and number of seeds per pod as influenced by seed priming.

Treatments	Pods per plant	Seeds per pod
Control	984.8D	3.80C
Water	1615.2ABC	4.40AB
NaCl	1473.8BC	4.20BC
KNO3	1676.3AB	4.80A
CaCl2	1421.9C	4.13BC
Moringa	1696.5A	4.53AB
Cv % LSD (0.05)	8.1 217.8	6.32 0.49

Note: Two means in the column not sharing any letter differ significantly at 0.05 probability level.

Abbreviation: Cv, coefficient of variation; LSD, least significant difference.

TABLE 6 1000-Seed weight and biological yield (kg ha⁻¹) as influenced by seed priming.

Treatments	1000-Seed weight (g)	Biological yield(kg ha−1)
Control	3.95C	6591.4C
Water	4.59AB	10,833.7AB
NaCl	4.35B	10,076.3B
KNO3	4.69A	11,818.5A
CaCl2	4.49AB	10,265.2B
Moringa	4.62AB	10,682.8AB
Cv % LSD (0.05)	3.87 0.32	7.96 1453.9

Note: Two means in the column not sharing any letter differ significantly at 0.05 probability level.

Abbreviation: Cv, coefficient of variation; LSD, least significant difference.

TABLE 7 Seed yield (kg ha⁻¹) and harvest index as influenced by seed priming.

Treatments	Seed yield (kg ha−1)	Harvest index
Control	560.6C	8.52C
Water	1178.0B	10.83AB
NaCl	1068.2B	10.54B
KNO3	1447.0A	12.23A
CaCl2	1102.3B	10.71AB
Moringa	1162.9B	10.87AB
Cv % LSD (0.05)	12.60 249.04	4.0 1.58

Note: Two means in the column not sharing any letter differ significantly at 0.05 probability level.

Abbreviation: Cv, coefficient of variation; LSD, least significant difference.

Harvest index

Harvest index is the ability and physiological efficiency of crops to convert dry matter into economic yield. The higher the harvest index, the greater will be the conversion efficiency of dry matter into yield. The highest harvest index was observed in the seeds treated with KNO₃ (12.23), which was statistically at par with MLE (10.87), water (10.83), and CaCl₂ (10.71), followed by seeds primed in NaCl (10.54). The minimum harvest index (8.52) was observed in control (Table 7).

Oil contents

The ultimate goal of farmers is to grow seed crops rich in high-quality oil content. The data regarding seed oil contents, as shown in Table 8, revealed significant differences (≤0.05) among treatments. Seeds primed with KNO₃ (35.47%) accumulated the highest oil content, which was statistically at par with water (34.13%), followed by seeds primed with MLE (33.97%), NaCl (33.37%), and CaCl₂ (33.00%). The lowest oil content (32.33%) was recorded in untreated seeds.

TABLE 8 Oil contents and oleic acids as influenced by seed priming.

Treatments	Oil content (%)	Oleic acids (%)
Control	32.33C	55.07B
Water	34.13AB	59.90A
NaCl	33.37BC	58.80A
KNO3	35.47A	58.13A
CaCl2	33.00BC	59.63A
Moringa	33.97B	59.10A
Cv % LSD (0.05)	2.35 1.44	1.68 1.79

Note: Any two means in a column not sharing a letter differ significantly at 0.05 level of probability.

Abbreviation: Cv, coefficient of variation; LSD, least significant difference.

Fatty acids profile

White mustard is composed of various types of unsaturated and saturated fatty acids, such as oleic acid, linolenic acid, erucic acid, etc. In the present study, the concentration of these acids was determined.

Oleic acid

Oleic acid is an important fatty acid. Data regarding oleic acid given in Table 8 showed significant differences (≤0.05) among treatments for oleic acid. Maximum oleic acid was accumulated by seeds treated with water (59.90%), which was statistically at par with CaCl₂ (59.63%), MLE (59.10%), NaCl (58.80%), and KNO₃ (58.13%). The lowest oleic acid (55.07%) was observed in control. These results are in conformity with El-Saidy et al. (2011), who recorded maximum oleic acid percentage in sunflower cultivars primed with different priming agents as compared to control.

Linolenic acid

Linolenic acid of different treatments as influenced by seed priming is depicted in Table 9. Different treatments exhibited a significant response to linolenic acid. Seeds treated with KNO₃ (3.30%) accumulated the highest linolenic acid, which was statistically at par with MLE (3.23%), followed by seeds treated with water (2.20%), NaCl (1.07%), and CaCl₂ (0.93%). The lowest linolenic acid (0.17%) was recorded in control. Our results agree with El-Saidy et al. (2011), who found the highest linolenic acid percentage in primed sunflower seeds as compared to the control.

TABLE 9 Linolenic acids (%) and erucic acids (%) as influenced by seed priming.

Treatments	Linolenic acids (%)	Erucic acids (%)
Control	0.17D	19.70C
Water	2.20B	29.83AB
NaCl	1.07C	27.47AB
KNO3	3.30A	32.63A
CaCl2	0.93C	24.33BC
Moringa	3.23A	29.40AB
Cv % LSD (0.05)	8.93 0.29	13.55 6.71

Note: Two means in the column not sharing any letter differ significantly at 0.05 probability level.

Abbreviation: Cv, coefficient of variation; LSD, least significant difference.

Erucic acid

Data concerning erucic acid presented in Table 9 revealed significant differences (≤0.05) among treatments. Maximum erucic acid was accumulated by seeds treated with KNO₃ (32.63%), which was statistically at par with seeds treated with water (29.83%), MLE (29.40%), and NaCl (27.47%), followed by seeds treated with CaCl₂ (24.33%). The lowest erucic acid content (19.70%) was observed in untreated dry seeds of the crop.

DISCUSSION

It is revealed from the present study that priming seeds with different treatments enhances germination percentage in S. alba. The results support the previous investigations of Eskandari and Kazemi (2011), who observed the highest germination percentage in Cowpea hydro-primed seeds and osmo-primed seeds treated with NaCl and KNO₃ solutions. Similarly, the highest germination percentage in primed mustard seeds was observed as compared to unprimed dry seeds (Taherkhani et al., 2013). This might be due to the completion of all metabolic processes before germination caused by seed priming, making the seed prepared for rapid germination after sowing as compared to untreated dry seeds of the crop (Sadeghi et al., 2011).

A higher GRI was observed for the primed seeds as compared to the unprimed seeds, which supports the results of G. R. Mohammadi and Amiri (2010), who recorded the maximum mean germination rate in canola cultivars under drought stress conditions. It may be due to the liberation of different enzymes, which increased the preparation of soluble food nutrients. When these seeds are planted, developmental procedures start more quickly than unprimed dry seeds (Kattimani et al., 1999).

Primed seeds had relatively higher vigor levels. These results are in agreement with the conclusions of Shehzad et al. (2012), who observed the highest seedling VI in primed seeds of forage sorghum. Similarly, Eskandari and Kazemi (2011) reported higher seedling VI in primed seeds of cowpea.

The root length that significantly increased due to priming in the study is in agreement with the findings achieved by Taherkhani et al. (2013), who observed that seed priming increased the seedlings' root length of mustard under drought conditions. Similarly, Hassanpouraghdam et al. (2009) also observed that priming considerably enhanced seedlings root length of Brassica napus. An enhancement in root length might be due to the initiation of metabolic behavior in the embryo as a result of priming (Wahid et al., 2008). Seed priming enhances shoot length as compared to the unprimed seeds. Our findings support the earlier work reported for sunflower (Hamidi et al., 2013) and forage sorghum (Shehzad et al., 2012).

The priming of seeds significantly reduced the emergence time. These results support the observations of Farooq et al. (2007), who found that all the priming treatments reduced mean emergence time in melon seeds than the untreated seeds of the crop. Similarly, Alishavandi et al. (2014) revealed that priming rapeseed cultivars with water and KNO₃ significantly reduced emergence time as compared to control. This might be due to the completion of all metabolic processes before germination caused by priming (Sadeghi et al., 2011).

The seedling fresh weight was observed to be higher in primed seeds. These findings support the earlier work of Ayub et al. (2015), who found higher seedling fresh weight in seeds of Garden cress primed with different priming treatments. Similarly, Basra et al. (2011) observed maximum seedling fresh weight in primed seeds of hybrid maize. The seed priming techniques that resulted in enhanced seedling dry weight support the results of G. R. Mohammadi and Amiri (2010), who observed higher seedling dry weight in treated canola seeds as compared to untreated seeds. Similar results were obtained by Eskandari and Kazemi (2011) in cowpea as a result of hydro-priming and osmo-priming. Taherkhani et al. (2013) also observed higher seedlings' dry weights in treated mustard seeds under drought stresses.

The improved CGR of the treated seeds confirms the previous observations of Basra et al. (2003), who observed that seed soaking effectively improved CGR in treated canola seeds. Similarly, Arif et al. (2008) found higher CGR in treated soybean seeds as compared to untreated seeds (Arif et al., 2008). Zhao et al. (2007) also stated that treating seeds before crop sowing slightly improved the vegetative growth of crops.

The higher NAR observed for the treated seeds was in conformity with the results of I. Hussian et al. (2013), found increased NAR in osmo-primed wheat seeds. Similarly, Afzal et al. (2013) observed effectively higher NAR in primed seeds of hybrid maize as compared to control. Seed priming leads to a significant increase in leaf area (Hamidi et al., 2013), which could be due to stimulation of metabolic activities in the embryo caused by seed priming (Wahid et al., 2008). The enhanced chlorophyll concentration due to seed treatment confirms the results of Tabrizi et al. (2011), who recorded similar results in primed corn seeds. Similarly, Esmeili and Heidarzade (2012) observed higher chlorophyll content in primed rice seeds. The observed enhancement in the number of branches per plant in primed seeds might be due to better emergence, good establishment of root system, and higher seedling growth. These results are in agreement with the findings of Basra et al. (2003), who observed the highest number of branches per plant in osmo-primed seeds of Brassica napus as compared to the control. Similarly, Aymen et al. (2012) observed a maximum number of branches per plant in primed seeds of safflower.

Priming resulted in a lower time taken for 50% emergence. Our findings support the earlier work of Janmohammadi et al. (2013), who stated that seeds treated with KNO₃ and distilled water lower days to 50% emergence in chickpeas. This might be due to a prominent increase in plant development caused by seed soaking. The higher 1000-seed weight and improved biological yield support the observations of Basra et al. (2003), who observed higher seed weight and increased biological yield in treated canola seeds as compared to control. Similarly, Mahmood et al. (2013) observed higher seed weight and highest biological yield in primed fennel seeds.

The significant increase in seed yield and higher harvest index observed for primed seeds are in agreement with the results of Mahmood et al. (2013), who observed that soaking effectively improved grain yield and increased the harvest index of fennel crops. Similarly, Rashid et al. (2006) found considerable results of seed soaking on the grain yield of barley. Similar findings were obtained by Li et al. (2005).

The increased oil contents observed due to seed treatment support the earlier results of Irshad et al. (2016), who found higher oil percentage in primed seeds of linola (Linum usitatissimum L.). Similarly, Narayanareddy (2008) found that oil content was improved in sunflower seeds treated with CaCl₂, water, and GA3 as compared to untreated dry seeds of the crop. In contrast, M. Hussain et al. (2006) observed that hydro-priming and osmo-priming with KNO₃ and NaCl had no significant effects on the oil contents of hybrid sunflower. However, subsequent studies have shown that these priming methods can have positive effects on other aspects of sunflower growth. Pahoja et al. (2013) found that hydro-priming was more effective than osmo-priming in improving seed germination and seedling growth under salt stress. Čanak et al. (2014) reported that seed priming with 0.1% KNO3 improved germination parameters in sunflowers under in vitro drought conditions. Akram and Muhammad (2009) demonstrated that foliar application of KNO3 alleviated the adverse effects of salt stress on sunflowers, enhancing growth and yield. Ashraf and Sultana (2000) observed that the combination of NaCl salinity and nitrogen form had varying effects on mineral composition in sunflower plants. These studies suggest that while priming methods may not directly impact oil content, they can have significant effects on other aspects of sunflower growth and development.

CONCLUSION

In summary, this study underscores the transformative potential of seed priming techniques in enhancing S. alba growth and yield parameters. The comprehensive evaluation of six distinct priming treatments revealed significant enhancements across various germination, growth, and yield metrics. Despite the promising outcomes, limitations regarding the duration and broader environmental conditions like temperature, humidity, and soil composition could influence the efficacy of the priming methods. Moreover, the study evaluates specific growth and yield parameters, but other relevant aspects such as disease resistance, nutritional quality, or resilience to varying stressors remain unexplored and warrant further investigation. These findings strongly support the hypothesis that optimized seed priming positively influences S. alba, offering pathways for improved agricultural practices. While affirming the positive impacts of seed priming, the study prompts future research to delve deeper into the long-term effects and scalability of these techniques under diverse environmental contexts.

AUTHOR CONTRIBUTIONS

Zia Ur Rehman: Conceptualization; data curation; formal analysis; funding acquisition; investigation; methodology; project administration; resources; software; supervision; validation; visualization; writing—original draft; writing—review and editing. Rashid Ul Haq: Conceptualization; data curation; formal analysis; funding acquisition; investigation; methodology; project administration; resources; software; supervision; validation; visualization; writing—original draft; writing—review and editing. Safi Ullah: Conceptualization; data curation; formal analysis; investigation; methodology; project administration; resources; software; supervision; validation; visualization; writing—review and editing. Aamir Iqbal: Conceptualization; data curation; formal analysis; funding acquisition; investigation; methodology; project administration; resources; software; supervision; validation; visualization; writing—original draft; writing—review and editing. Amir Muhammad Khan: Conceptualization; data curation; formal analysis; investigation; methodology; project administration; resources; software; supervision; validation; visualization; writing—review and editing. Cedric Mankponse Antoine Assogba: Conceptualization; data curation; formal analysis; funding acquisition; investigation; methodology; project administration; resources; software; supervision; validation; visualization; writing—original draft; writing—review and editing. Muhammad Awais: Conceptualization; data curation; formal analysis; investigation; methodology; project administration; resources; software; supervision; validation; visualization; writing—review and editing.

ACKNOWLEDGMENTS

The authors would like to thank the Department of Agronomy at Pir Mehr Ali Shah Arid Agriculture University, Rawalpindi, Pakistan, for generously providing the opportunity to conduct this research, encompassing both laboratory and field experiments. The authors' sincere appreciation extends to the co-authors, each of whom contributed significantly to their designated roles, showcasing their expertise in both laboratory and field experimentation. It is important to note that no financial support was received for the research conducted.

CONFLICT OF INTEREST STATEMENT

The authors declare no conflicts of interest.