COMPARATIVE EFFICACY OF MAGNETIC FIELD SEED TREATMENT AND PRIMING IN IMPROVING GROWTH AND PRODUCTIVITY OF OKRA

K. Ziaf^1*, M. Amjad¹, M. A. Ghani¹, I. Ahmad¹, M. Ayub¹, M. Sarwar², Q. Iqbal³ and M. A. Nawaz¹

¹Institute of Horticultural Sciences, University of Agriculture, Faisalabad 38040, Pakistan

²Institute of Agricultural Sciences, University of the Punjab, Lahore, Pakistan

³Fiblast, LLC. 1602 Mizell Road Tuskegee, Alabama 36083, USA 

*Corresponding Author’s email: khurramziaf@uaf.edu.pk

ABSTRACT

Seed priming (halo- and hydro-priming) and magnetic seed treatments have been used to invigorate seeds. Primed seeds cannot be stored for long duration due to start of gemination processes, although dried to initial seed moisture content at the end of lag phase of germination. On the other hand, magnetic seed treatment invigorates the seeds without starting germination processes and so considered safe for storage of seeds. The comparative evaluation as well as their impact on various physiological aspects of okra plant has been scarcely evaluated. A field experiment was conducted to compare the impact of seed priming (hydro-priming and halo-priming) and magnetic field seed treatments, on growth, photosynthesis related attributes and yield of two okra cv. Sabz Pari and Super Green during summer 2016. Seeds of both cultivars, primed in water (hydro-priming), salt solution (halo-priming using NaCl 1%, ZnSO₄ 0.1%, CuSO₄ 0.1%, H₃BO₃ 1%, KNO₃ 1% and 2%), or exposed to magnetic field of 100 or 200 mT for 10 or 20 minutes, were sown in field according to randomized complete block design under factorial arrangements. Results revealed that magnetic field seed treatment, specifically 100 mT for 20 minutes, improved emergence (25-34% over control), seedling fresh and dry weight, leaf weight, pod length, number of fruits per plant and fruit yield per plant (27-38% over control). Chlorophyll contents of both okra cultivars were highest in response to seed priming with 1% KNO₃. Transpiration rate and net photosynthetic rate of both okra cultivars were also high for plants grown using 100 mT for 20 minutes treated seeds of both cultivars. While, sub-stomatal conductance of cv. Sabz Pari and Super Green was highest in response to 100 mT for 10 minutes and 1% NaCl, respectively. However, water use efficiency of Sabz Pari and Super Green was highest for plants raised using seeds primed in 1% KNO₃ and 1% H₃BO₃, respectively. It may be inferred that pre-sowing magnetic field treatment of seed (100 mT for 20 minutes) can be effectively used to improve okra crop stand establishment, growth and yield followed by seed priming in 1% KNO₃. Moreover, magnetic seed treatment, being less damaging to seed, is more suitable than priming; the later one decreases storage life of seed.

Key words:Abelmoschus esculentus, Halopriming, Hydropriming, Magnetic field seed treatment, Seedling traits, Gas exchange attributes

https://doi.org/10.36899/JAPS.2022.1.0405
Published online June 14, 2021

INTRODUCTION

Okra (Abelmoschus esculentus L.), also known as ladyfinger, belongs to family Malvaceae, is a well-known summer vegetable crop. It is a rich source of vitamins A, B, and C as well as a good source of iodine and protein. Its stem is a source of fiber that is used in paper industry (Gupta et al. 2019). Okra seeds are hard and emergence is spread over a wide period of time after sowing, depending upon temperature and soil conditions (Demir and Ermis 2004). Uniform crop stand ensures uniform maturity and high yield (Sarwar et al. 2017). Several pre-sowing treatments have been reported to increase uniform germination and emergence in various agronomic and horticultural crops viz., magnetic seed treatment, humidification, soaking, and various types of priming (sand, halo-priming, hydro-priming, and hormonal priming). Priming allows some of the important metabolic processes to occur before actual germination to get started, such as synthesis or activation of some enzymes that catalyze the mobilization of storage reserves in seed, and weakening of endosperm (Farooq et al. 2008).

Physical pre-sowing seed treatments are considered eco-friendly as compared to chemical ones (Iqbal et al. 2012). Among physical seed treatments, Magnetic Field (MF) pre-sowing seed treatment is safer and inexpensive method to advance the seed germination and seedling growth (Podlesny et al. 2005), without any degradation/alteration in the chemical composition of seed. Magnetic seed treatment enhanced seed germination, seedling growth, fresh and dry weight, activities of some enzymes and seed yield in wheat (Gholami and Sharafi 2010). Similarly, pea seeds exposed to magnetic field exhibited increased germination and vigour (Iqbal et al. 2012). Okra seeds exposed to 99 mT for 11 minutes showed significant increase in leaf area, number of fruits per plant and pod yield per plant (Naz et al. 2012). Photosynthesis, stomatal conductance and chlorophyll content increased in corn plants exposed to static MFs of 100 and 200 mT, compared to control under irrigated and mild stress condition (Anand et al. 2012). Previously, it has been mentioned in literature that magnetic field increase mobility of ions in seed that may in turn improve nutrient availability to the growing axis in the seed. But, there was scarcity of comparative studies on use of priming and magnetic seed treatment. Moreover, impact of magnetic seed treatments on photosynthetic rate, stomatal conductance, transpiration rate and water use efficiency have not been studied in previous studies in okra. Therefore, this study was planned to compare the impact of hydro-priming, halo-priming and magnetic field treatment of okra seed on improvement of seed vigour, photosynthetic rate, water use efficiency, transpiration rate and ultimate plant growth and productivity of two okra cultivars.

MATERIALS AND METHODS

Site, Seed Source and Seed Treatments: This study was conducted at experimental field of Institute of Horticultural Sciences, University of Agriculture Faisalabad, Pakistan. Mean minimum and maximum temperature during the study period was 23.5 °C and 35.5 °C, respectively. Total rainfall during the study period was 69 mm. Seeds of okra cultivars Super Green and Sabz Pari were collected from Siddique Sons (A registered seed merchant) and Vegetable Seed Lab, Institute of Horticultural Sciences, University of Agriculture Faisalabad, Pakistan. Seeds were subjected to various treatments, selected on the basis of literature review, as mentioned in the following section. For the magnetic field treatment of okra seeds, seeds were exposed to magnetic field developed by the electromagnet of different strengths (100 mT or 200 mT) and durations (10 or 20 minutes), in the Physics department, University of Agriculture, Faisalabad, Pakistan, essentially as reported earlier by Naz et al. (2012). Seeds (2 g) were primed either in 50 mL of distilled water (hydro-priming) or in 50 mL solutions of various salts (NaCl 1%, ZnSO₄ 0.1%, CuSO₄ 0.1%, H₃BO₃ 1%, KNO₃ 1% and 2%) for 12 hours. Seeds were primed at 25±2 ^°C in darkness using aquarium air pump. After priming, seeds were dried to their initial moisture content and used for sowing in field.

Sowing, Cultural Practices and Experimental Layout: Treated and untreated (control) seeds of both okra cultivars were sown during March 2018 in Vegetable Area of Institute of Horticultural Sciences, University of Agriculture, Faisalabad. There were 12 seed treatments (Seeds primed in water [hydro-priming], salt solution [halo-priming using NaCl 1%, ZnSO₄ 0.1%, CuSO₄ 0.1%, H₃BO₃ 1%, KNO₃ 1% and 2%], or exposed to magnetic field of 100 or 200 mT for 10 or 20 minutes) including control and each treatment was replicated three times. Experiment was laid out according to the randomized complete block design under factorial arrangements because study was conducted in field conditions. Each experimental plot was of 25 ft² area. Seeds were sown on both sides of ridge at one feet plant to plant distance, at alternate position. Recommended dose of phosphorus (50 kg/acre) and potash (30 kg/acre) along with one third dose of total nitrogen (50 kg/acre) was applied at the time of land preparation, before ridge preparation. Remaining two third dose of nitrogen was applied in two splits at 20 and 35 days after sowing. Hoeing and manual weeding was done to keep soil loose and weed free. Imidacloprid was applied two times to control sucking insects and Match (a.i. lufenuron) was sprayed once to control chewing insects. Irrigation was done as per requirement, mostly at weekly interval, keeping in view rainfall.

Seedling Emergence, Growth and Yield Related Traits: The seeds producing normal seedlings were counted after seven days and emergence percentage was calculated. Mean emergence time (days) was determined according to the formula by Ellis and Roberts (1981). Fresh weight (mg) of five randomly selected seedlings from each replication of a treatment was recorded after one month. These seedlings were sundried followed by drying at 65-70 ^°C for 72 hours in a laboratory oven (UNB-500, Memmert, Germany) and their dry weight (mg) was measured. Number of leaves per plant was counted after 65 days of sowing. Pods were harvested at marketable maturity stage, starting 35 days after sowing, usually 5-7days after fruit setting, and their length (cm) and weight (g) was measured. Total weight of the pods per plant harvested periodically till 65 days after sowing, was expressed as yield per plant (g).

Physiological Attributes: Three young fully developed and healthy leaves per plant (two plants per replicate) were selected to measure photosynthesis rate (Pn), transpiration rate (E) and stomatal conductance (g_s). These selected leaves were placed one by one in the chamber of portable Infra-Red Gas Analyzer (IRGA) (Analytical Development Company, Hoddesdon, England). Readings of these physiological attributes were taken from 10.00 to 12.00 a.m. Ambient temperature ranged from 24.5 to 33.9 ^°C, atmospheric pressure 99.9 kPa, water vapor pressure in chamber ranged from 6.0 to 8.9 mbar, and at 403.3 mmol m^-2s^-1 flow of air per unit leaf area. Maximum PAR at leaf surface was up to 1711 µmol m^-2 s^-1, while leaf temperature ranged from 28.4 to 32.4 ^°C, and ambient CO₂ concentration was 352 µmol mol^-1. WUE was calculated as the ratio between photosynthesis (Pn) and the amount of water transpired (E).

Statistical Analysis: Experiment comprised of two factors, i.e., cultivars and seed treatments. Therefore, two-way ANOVA was used for statistical analysis of the data in statistical package “Statistix 8.1”. The statistical difference among treatment means was checked using the Tukey’s (HSD) Test (P≤0.05).

RESULTS AND DISCUSSION

Seedling Traits: Both okra cultivars (Sabz Pari and Super Green) showed highest seedling emergence (100%) when grown from seeds treated with 100 mT for 20 minutes. While, seeds of Super Green, primed in distilled water (hydro-priming), H₃BO₃ (1%) or NaCl (1%), showed the least emergence. These treatments were statistically similar to seeds of Sabz Pari primed in H₃BO₃ (1%), i.e., 62.5% in all these treatments (Table 1). It is also obvious that all magnetic treatments excelled over priming treatments and control in cv. Super Green, while NaCl (1%) and KNO₃ (1%) treatments were better than magnetic treatments except 100 mT for 20 minutes for okra cv. Sabz Pari. Both okra cultivars took minimum time to emergence (6.14 days) when grown from seeds treated with 100 mT for 20 minutes. While, maximum mean emergence time for Sabz Pari (7.54 days) and Super Green (7.53) was recorded for seeds primed with NaCl (1%) and 100 mT for 10 minutes, respectively (Table 1). This improvement in germination related parameters can be attributed to more uptake of water (Soltani et al. 2006) at enhanced rate (Garcia and Arza 2001) in magnetically treated seeds, as well as to increased synthesis of protein or enzyme activities (Afzal et al. 2012). Our results are in confirmation to the findings of Naz et al. (2012) who recorded significant increase in germination of okra cv. Sabz Pari seeds exposed to 99 mT for 11 minutes. Moreover, all seed priming treatments also increased emergence of both okra cultivars to variable extent; higher for KNO₃ or NaCl than others, which is line with the observations of other researchers (Afzal et al. 2011). Superiority of magnetic field seed treatment over halo-priming was also in accordance to the findings of Soltani et al. (2006).

Okra cv. Super Green showed highest seedling fresh weight (55.28 g) when grown from seeds treated with 100 mT for 20 minutes (Table 1). While, untreated Super Green seeds produced seedlings with minimum seedling fresh weight (24.03 g). Moreover, seeds treated with 200 mT for 10 minutes showed decreased seedling fresh weight of both cultivars in comparison with other magnetic treatments; more in Sabz Pari as compared to Super Green. Furthermore, seed priming with 1% NaCl, 1% H₃BO₃, 0.1% CuSO₄, and 1% KNO₃ significantly decreased seedling fresh weight as compared to hydro-priming, 2% KNO₃ and magnetic seed treatments. Seedling fresh weight of Super Green in response to hydro-priming was statistically at par with most of magnetic seed treatments. It can be visualized from results (Table 1) that okra cv. Super Green showed highest seedling dry weight when grown from seeds treated with 100 mT for 20 minutes (19.68 g). While, untreated Super Green seeds produced minimum seedling dry weight (5.25 g). Furthermore, seed priming with 0.1% ZnSO₄, 1% NaCl, 1% H₃BO₃, 0.1% CuSO₄, and 1% KNO₃ significantly decreased seedling dry weight as compared to hydro-priming, 2% KNO₃ and magnetic seed treatments. However, hydro- and halo-priming (with 1% and 2% KNO₃) enhanced seedling fresh and dry weight, although less than 100 mT for 20 minutes, yet higher than control, i.e. 39-48% and 64-68% higher fresh and dry weight than control, respectively. Early germinated seeds may have also grew faster and accumulated more photosynthates resulting in more fresh and dry weight of seedlings. Augmented fresh and dry weight of seedlings due to magnetic field seed treatment has also been recorded in asparagus (Soltani et al. 2006) and marigold (Afzal et al. 2012), which strengthen our findings.

Plant Growth and Yield Related Traits: Okra cv. Super Green showed highest leaf weight when grown from seeds treated with 200 mT for 10 minutes (161.5 g), statistically similar to Sabz Pari raised using seed exposed to 100 mT for 10 and 20 minutes (161.25 g in both). Seed of Super Green primed in H₃BO₃ (1%) showed lowest leaf weight per plant (97.5 g), even lower than unprimed seeds (106.25 g) (Fig. 1). Hegazi (2014) also stated that seed priming enhanced the growth and development of plant, which was evident as increased leaf weight of okra in this study.

Results depicted that okra cv. Super Green showed highest pod length (11.4 cm) when grown from seeds treated with 100 mT for 20 minutes that was statistically at par with Super Green seeds primed in 2% KNO₃ (11.32 cm) while, NaCl (1%) treated seeds of Super Green produced pods of minimum length (8.3 cm). Further, it is clear

Table 1. Effect of different seed treatments on emergence and seedling traits of two okra cultivars.

from results that seed treated with NaCl (1%), CuSO₄ (0.1%), 100 mT for 10 min and 200 mT for 10 min decreased pod length of both cultivars as compared to other seed treatments (Fig. 2). Highest pod weight (14.7 g) was recorded for okra cv. Super Green in response to seed priming in 1% KNO₃ while minimum pod weight (11.1g) was noticed in cv. Super Green grown from seeds treated with 200 mT for 20 minutes. Further, it is clear from results that seed treated with KNO₃ (2%) decreased pod weight of both cultivars, more in Sabz Pari compared to Super Green (Fig. 3). Increased pod length and pod weight due magnetic field treatment of seed was in accordance to the findings of earlier research on okra (Naz et al. 2012), peas (Podlesny et al. 2005) and tomato (De Souza et al. 2006).

It can be visualized from results that okra cv. Sabz Pari showed highest number of fruits per plant (11.75) when grown from seeds treated with 100 mT for 20 minutes (Fig. 4), statistically similar to fruit number in Super Green in response to 100 mT for 20 minutes (11.5) and 1% KNO₃ (11.5).

While, seeds of Sabz Pari treated with KNO₃ (2%) produced minimum number of fruits. Further, it is clear from results that seed treated with H₃BO₃ (1%) decreased number of fruits of both cultivars, more in Super Green as compared to Sabz Pari. Increased number of okra pods per plant due magnetic field treatment of seed has also been reported in earlier studies on peas (Podlesny et al. 2005), okra (Naz et al. 2012), and tomato (De Souza et al. 2006).

Okra cv. Super Green produced highest fruit yield per plant when grown from seeds treated with 100 mT for 20 minutes (467.5 g), statistically at par with 1% KNO₃ (458.7 g) for same cv. (Fig. 5). While, hydro-primed Super Green seeds produced minimum yield per plant (315 g). Improvement of yield due to seed priming with 1% KNO₃ can be due to improved chlorophyll contents, photosynthetic rates and water use efficiency. Sharma et al. (2014) reported up to 55% increase in okra yield due to priming that strengthen findings of this study. Priming has also been reported to improve yield of some horticultural and agronomic crops (Dabrowska et al. 2000; Srivastava et al. 2010).

Chlorophyll Contents and Physiological Attributes: It is evident from results (Table 2) that both cultivars showed highest chlorophyll contents in response to priming with KNO₃ (1%); higher in Sabz Pari (61.95 CCI) than Super Green (61.45 CCI), but were statistically similar. Moreover, chlorophyll contents of 100 mT for 20 minutes treated seed were statistically at par or statically similar or at par with 1% KNO₃. Super Green cv. of okra showed minimum chlorophyll contents when grown from seeds treated with 200 mT for 10 min (31.72 CCI). Negative effect of magnetic field treatments on chlorophyll contents was more pronounced in Super Green than Sabz Pari. Recently, Anwar et al. (2020) also reported enhancement in chlorophyll contents of cucumber seedlings due to seed priming with KNO₃. They also stated that seed priming increased nitrogen and magnesium contents of leaves that are required for chlorophyll synthesis. Increase in chlorophyll contents of okra cultivars Sabz Pari and Arka Anamika due to seed priming in water and ascorbic acid were also reported by Hussain et al. (2017), which affirm results of this study.

Okra cv. Sabz Pari showed highest stomatal conductance when grown from seeds treated with 100 mT for 10 minutes (551 µmol m^-2s^-1). While, stomatal conductance of Super Green was highest for 1% NaCl (542 µmol m^-2s^-1). Moreover, it is evident that prolonged exposure (20 minutes) of seed to both (100 and 200 mT) magnetic field seed treatments decreased sub-stomatal conductance of both okra cultivars to less than the control (Table 2). Okra seeds treated with 100 mT for 20 minutes induced highest transpiration rate in Super Green (1.35 mmol H₂O m^-2s^-1) followed by Sabz Pari (1.16 mmol H₂O m^-2s^-1). While, Super Green seeds treated with H₃BO₃ (1%) showed minimum transpiration rate (0.53 mmol H₂O m^-2s^-1) (Table 2). It is obvious that all priming and magnetic seed treatments increased photosynthetic rate of both cultivars compared to control (untreated seeds) (Table 2). Seed treatment 100 mT for 20 minutes induced highest net photosynthetic rate in okra cv. Sabz Pari (6.55 µmol CO₂ m^-2s^-1) and Super Green (6.37 µmol CO₂ m^-2s^-1). Okra cv. Super Green showed highest water use efficiency when grown from seeds treated with H₃BO₃ (1%) while, Sabz Pari exhibited highest water use efficiency in response to priming in 1% KNO₃ (Table 2).

Anwar et al. (2020) stated improvement in photosynthetic activities including stomatal conductance, transpiration rate and rate of photosynthesis in cucumber seedlings grown by using seeds primed in KNO_3­ and attributed this increase in photosynthetic activities to increased chlorophyll contents as recorded in this study on okra. Previously, Iqbal and Ashraf (2005) also asserted that pre-sowing seed treatments significantly increased photosynthesis activity in wheat plants, which support these results in okra.

Table 2. Effect of different seed treatments on physiological traits of two okra cultivars.

Conclusion: It can be concluded that magnetic field treatment of 100 mT for 20 minutes and 1% KNO₃ enhanced vegetative growth, photosynthesis and yield compared to all other treatments; former was superior to the later one in almost all traits, but the difference in most of the cases was non-significant. Moreover, magnetic seed treatment, being less damaging to seed, is more suitable than seed priming that decreases the storage life of seed.

REFERENCES

1. Afzal, I., Hussain, B., Basra, S.M.A. and Ullah, S.H. (2011). Halopriming triggers higher germination potential and early seedling growth of tomato. Journal of Agriculture and Social Sciences, 7, 105-108.
2. Afzal, I., Mukhtar, K., Qasim, M., Basra, S.M.A., Shahid, M. and Haq, Z. (2012). Magnetic stimulation of marigold seed. International Agrophysics, 26, 335-339.
3. Anwar, A., Yu, X. and Y. Li. (2020). Seed priming as a promising technique to improve growth, chlorophyll, photosynthesis and nutrient contents in cucumber seedlings. Notulae Botanicae Horti Agrobotanici Cluj-Napoca, 48, 116-127.
4. Anand, A., Nagarajan, S., Verma, A., Joshi, D., Pathak, P. and Bhardwaj, J. (2012). Pre-treatment of seeds with static magnetic field ameliorates soil water stress in seedlings of maize (Zea mays). Indian Journal Biochemical Biophysics, 49, 63–70.
5. Dabrowska, B., Suchorska, K. and Capecka, E. (2000). Value of matrically conditioned seeds of hot pepper (Capsicum annum) after one year of storage Part II. Yield and quality of crude product. Annals of University of Mariae Curie Sklodowska, 8, 369-375.
6. Demir, I. and Ermis, S. (2004). Improvement of okra seed germination by drying within the fruit during development and after-ripening treatment. Acta Agriculturae Scandinavica, Section B- Soil & Plant Science, 54, 38-41.
7. De Souza, A., Garcia, D., Suerio, L., Liccea L. and Porras E. (2006). Pre-Sowing magnetic treatment of tomato seeds increase the growth and yield of plants. Journal of Bioelectromagnetics, 27, 247-257.
8. Ellis, R.A. and Roberts, E.H. (1981). The quantification of ageing and survival in orthodox seeds. Seed Science & Technology, 9, 373-409.
9. Farooq, M., Basra, S.M.A., Rehman, H. and Saleem, B.A. (2008). Seed priming enhances the performance of late sown wheat by improving chilling tolerance. Journal of Agronomy and Crop Science, 194, 152-
10. Garcia, R.F. and Arza, P.L. (2001). Influence of a stationary magnetic field on water relations in lettuce seeds. Part I: theoretical considerations. Bioelectromagnetic, 22, 589-595.
11. Gholami, A. and Sharafi, S. (2010). Effect of magnetic field on seed germination of two wheat cultivars. World Academy of Science, Engineering Technology, 62, 279-282.
12. Gupta, P.K., Patra, S. and Samanta, K.K. (2019). Potential of okra for application in textiles: A review. Journal of Natural Fibers, https://doi.org/10.1080/15440478.2019.1697997
13. Hegazi, A.Z. (2014). Influence of seed priming on growth and seed yield of okra under water stress. Egyptian Journal of Agricultural Research, 92, 197-217.
14. Hussain, I., Siddique, A., Ashraf, M.A., Rasheed, R., Ibrahim, M., Iqbal, M., Akbar, S. and Imran, M. (2017). Does exogenous application of ascorbic acid modulate growth, photosynthetic pigments and oxidative defense in okra (Abelmoschus esculentus (L.) Moench) under lead stress? Acta Physiologia Plantarum, 39, 144.
15. Iqbal, M. and Ashraf, M. (2005). Changes in growth, photosynthetic capacity and ionic relations in spring wheat (Triticum aestivum) due to pre-sowing seed treatment with polyamines. Plant Growth Regulation, 46, 19-30.
16. Iqbal, M., Haq, Z.U., Jamil, Y. and Ahmad, M.R. (2012). Effect of pre-sowing magnetic treatment on properties of pea. International Agrophysics, 26, 25-31.
17. Naz, A., Jameel, Y., Haq, Z.U., Iqbal, M., Ahmad, M.R., Ashraf, M.I. and Ahmad, R. (2012). Enhancement in germination, growth and yield of okra (Abelmochus esculentus) using pre sowing magnetic treatment of seeds. Indian Journal of Biochemistry & Biophysics, 49(2), 211-214.
18. Podlesny, J., Pietruszewski, S. and Podlesna, A. (2005). Influence of magnetic stimulation of seeds on the formation of morphological features and yielding of the pea. International Agrophysics, 19, 61-68.
19. Sarwar, M., Amjad, M. and Ayyub, C.M. (2017). Alleviation of salt stress in cucumber (Cucumis sativus) through seed priming with triacontanol. International Journal of Agriculture Biology, 19, 771-778.
20. Sharma, A.D., Rathore, S.V.S., Srinivasan, K. and Tyagi, R.K. (2014). Comparison of various seed priming methods for seed germination, seedling vigour and fruit yield in okra. Scientia Horticulturae, 165, 75-81.
21. Soltani, F., Kashi, A. and Arghavani, M. (2006). Effect of magnetic field on Asparagus officinalis seed germination and seedling growth. Seed Science & Technology, 34, 349-353.
22. Srivastava, A.K., Lokhande, V.H., Patade, V.Y., Suprasanna, P., Sjahril, R. and D’ Souza S.F. (2010). Comparative evaluation of hydro-, chemo-, and hormonal priming methods for imparting salt and PEG stress tolerance in Indian mustard (Brassica juncea ). Acta Physiologia Plantarum, 32, 1135-1144.