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Screening of Chickpea (Cicer arietinum L.) Genotypes for Germination and Early Seedling Growth under PEG 6000 Induced Drought Stress
First Online 04-08-2021|
Methods: Effect of drought stress on germination and early seedling growth of thirty three chickpea genotypes was studied under four different concentrations of PEG 6000 (-0.3, -0.6, -0.9 and -1.2 MPa) along with control and hydration under laboratory conditions during 2018-19.
Result: Significant variation was observed among the genotypes for germination, root length, shoot length and seedling vigour index under different concentrations of PEG 6000. Complete inhibition of germination was observed in most of the genotypes at -1.2 MPa. Based on the results obtained, JG 11 and NBeG 3 were considered as tolerant since they showed comparatively higher germination, root length, shoot length and seedling vigour even at -1.2 MPa, while NBeG 723 and NBeG 833 were considered as susceptible genotypes because of their poor germination and seedling growth even at lower levels of drought stress.
Screening of the genotypes for drought tolerance can be done both in field as well as laboratory. But field experiments related to water stress are labour intensive, time consuming and difficult to handle due to uncontrolled atmospheric conditions, soil heterogeneity and significant interaction with biotic, abiotic and other environmental factors. Moreover creation and maintenance of a pure and uniform water potential in the field is a difficult job. Hence, in vitro screening method by creation of water stress using different osmotic materials is considered as one of the best methods to study the effects of drought stress during early seedling growth and select drought tolerant genotypes. The osmotically active substances or osmolytes increases the solute concentration, thereby decreases the water potential in the substrate making it unavailable to the plant. Various osmolytes that are used to induce drought stress include sugars, sodium chloride, mannitol, sorbitol, polyethylene glycol etc. However to obtain accurate results and inter-experimental compatibility, special importance should be given to biologically inert polymeric osmolytes. Polyethylene glycol (PEG) is considered as non-toxic, non-permeable and most commonly used as drought simulator. PEG solutions mimic dry soil moisture more closely than solutions of low molecular osmotic compounds, which infiltrate the cell wall with solutes (Verslues et al., 1998). The present investigation was carried out to screen the chickpea genotypes and identify elite genotypes that could withstand different levels of PEG induced water deficit conditions during germination and early seedling growth.
MATERIALS AND METHODS
Four replicates of 100 seed from each PEG-induced drought stress treatment along with hydrated and control seed were sown in sand with uniform spacing. Equal volume of different concentrations of polyethylene glycol (PEG) 6000 solution was used to moisten the sand in respective treatments. For hydration treatment and control equal volume of distilled water was used to moisten the sand. All the samples were incubated at 25±2°C for 8 days. Data on germination and seedling vigour index were recorded/computed as per the details mentioned below:
Normal seedlings were counted and expressed as germination (%) as per the following formula:
Root and shoot lengths were measured at the end of test period by randomly selecting ten normal seedlings from every replication in each treatment. The root length was measured from the tip of the primary root to the base of the hypocotyl and the mean root length was expressed in centimeters. Shoot length was measured from the tip of the primary leaf to the base of the hypocotyl and the mean shoot length was expressed in centimeters. The root length and shoot length were added to calculate the seedling length (cm).
Seedling vigour index was computed by adopting the following formula suggested by Abdul-Baki and Anderson (1973) and was expressed in whole number.
Data were analyzed in factorial completely randomized design (FCRD) with four replications by using SPSS (version 16.0) software after subjecting the obtained data to proper transformations. The differences among the genotypes and treatment means were compared by using Duncan’s multiple range test at 5% level of probability.
RESULTS AND DISCUSSION
Mean germination of chickpea genotypes ranged from 71.58% (JG 11) to 29.00% (NBeG 723) with an overall mean of 47.42% (Table 2).
Increase in PEG concentration caused a gradual and highly significant decline in germination. Untreated seed (control) recorded significantly highest mean germination (93.77%). The reduction in mean germination upon hydration (90.35%) over control might be due to differential response of the chickpea genotypes. PEG induced drought stress drastically reduced the germination at all the levels. However, the per cent decrease in germination over control was highest (98.12%) and lowest (41.12%) at -1.2 MPa and -0.3 MPa, respectively (Fig 1).
Germination potential diminished gradually with increase in water stress and was completely inhibited in majority of the genotypes at -1.2 MPa. NBeG 3, NBeG 738, JG 11, KAK 2, NBeG 119, NBeG 399 and NBeG 829 exhibited germination even at -1.2 MPa while, NBeG 723 and NBeG 833 showed lowest germination even at -0.3 MPa. In addition to these two genotypes, NBeG 785 and NBeG 805 did not show germination at -0.6 Mpa.
The reduction in germination with decrease in osmotic potential was earlier reported by Yucel et al., (2010) and Awari and Mate (2015) in chickpea. The decline in germination under different stress levels may be due to reduced imbibition by seed (Rauf et al., 2006). Pratap and Sharma (2010) reported that during water deficit condition seed forces themselves to undergo dormancy as an adaptive strategy to prevent germination under stressful conditions. The decrease in water potential gradient between seed and media will prevent the seeds to absorb the desired amount of water (Achakzai, 2009). Shamim et al., (2016) earlier pointed out that PEG creates an osmotic barrier, hinders water uptake leading to reduction in cell division and cell enlargement and ultimately effects the protein synthesis along with mobilization of reserved resources (Farooq et al., 2009; Osorio et al., 2014) due to the activation of stress inducible genes which expresses themselves under specific stress conditions (Foolad et al., 2003).
Plants with better growth of root system under stress conditions can be considered as tolerant genotypes (Allah et al., 2010; Basha et al., 2015) since they can explore moisture and nutrients from the deeper layers of the soil. Significantly superior root growth was noticed in JG 11 (12.87 cm) followed by NBeG 3 (11.66 cm). In contrast lowest mean root length was recorded in NBeG 723 (4.26 cm) and NBeG 833 (4.82 cm). Increased levels of drought stress showed repressing effect on root length. Highest mean root length was expressed for hydration treatment (14.64 cm) followed by control (13.54 cm) (Table 3). The per cent decrease in mean root length over control was more (92.76%) at -1.2 MPa (Fig 2).
Reduction in root growth is a good indicator of drought susceptibility of cultivars (Macar et al., 2009). Smita and Nayyar (2005) earlier observed reduction in root length of chickpea seedlings under water stress and opined that detrimental effects could be due to distortion and reduction in root hair diameter and plasmolysis. Root growth inhibition under PEG induced drought stress is the result of less turgor pressure created on the cell wall by the vacuole which ultimately inhibits cell division and/or elongation (Awari and Mate, 2015). Shahriari and Hassan (2005) attributed the decrease in root length under stress conditions to the decreased divisions in meristematic cells which ultimately affect the cell growth.
Highest mean shoot length was recorded by JG 11 (13.55 cm) followed by NBeG 3 (12.35 cm) and lowest was observed in NBeG 723 (4.47 cm) followed by NBeG 833 (5.23 cm). Progressive decrease in shoot length was observed with increase in PEG concentration. Hydration treatment showed highest mean shoot length (18.52 cm) when compared to control (17.62 cm) (Table 4). At lower PEG concentration (-0.3 MPa) 43.47% decrease in shoot length was observed over control, while at -1.2 MPa, 97.78% decrease was observed (Fig 2).
Severe effect of drought on shoot length was also reported by Macar et al., (2009) in chickpea. Kravic et al., (2012) earlier reported that decline in shoot length in response to drought might be due to decrease in cell elongation resulting from the inhibitory effect of water shortage on growth promoting hormones which in turn led to decrease in cell turgor, cell volume and eventually cell growth (Banon et al., 2006). Fathi and Tari (2016) found that the prevention of shoot growth during drought stress was due to modification of biochemical changes occurring in cell wall during growth.
For testing drought tolerance under laboratory conditions, seedling development can be taken as an advisable parameter (Bayoumi et al. 2008). Effect of drought stress was observed more in seedling length when compared to germination (Macar et al., 2009; Petrovic et al., 2016). Lack of sufficient soil moisture effects the establishment of the seedlings leading to seedling mortality. Seedling growth varied significantly among the genotypes with highest in JG 11 (26.43 cm) followed by NBeG 3 (24.01 cm) and lowest in NBeG 723 (8.74 cm) followed by NBeG 833 (10.05 cm) (Table 5).
Similar variation among the genotypes for seedling growth was earlier reported by Dharanguttikar et al., (2015) in chickpea. Gradual decrease in seedling growth was observed with increase in PEG concentration. Seed subjected to hydration recorded better mean seedling growth (33.16 cm) compared to control (31.70 cm). The per cent decrease in seedling growth was highest at -1.2 MPa (95.62%) whereas lowest decrease was noticed at -0.3 MPa (12.50%). Amador et al., (2002) earlier reported that decrease in seedling growth was due to reduction in uptake of water which inhibits mobilization of cotyledon reserves to the growing embryonic axis. The inhibition of growth under stress condition is due to inhibition of cell division and/or cell elongation (Farooq et al., 2009). In the present study, shoot length of chickpea genotypes under drought stress was more inhibited when compared to root length (Fig 2), which could be due to the fact that root emerges first from the seed and hence exhibit faster growth than shoot (Awari and Mate, 2015). Seedling growth is impaired due to decline in growth rate (Soltani et al., 2006). Suboptimal moisture availability drastically affects the seedling dry weight, plumule length and radicle length (Ajirloo et al., 2011).
Seedling vigour being sensitive to the availability of moisture reflects better response of genotypes to drought during germination and early seedling growth. Seedling vigour index of all the genotypes in the present study ranged from 644 (NBeG 723) to 2125 (JG 11) (Table 6)
NBeG 3 (1937) exhibited superior seedling vigour next to JG 11. NBeG 833 (806) recorded slightly more seedling vigour than NBeG 723. With the increase in drought stress, seedling vigour index decreased drastically. Highest seedling vigour index was observed in hydration (3000) which was at par with control (2986). Even at lower concentration of PEG (-0.3 MPa) 56.36% of decrease in seedling vigour over control was observed. Highest percent reduction (99.53%) in seedling vigour index over control was observed at -1.2 MPa (Fig 1). Gong et al., (2000) suggested that improvement of the seedling vigour index was associated with the enhancement of activated oxygen metabolism in seedlings.
- Abdul-Baki, A.A and Anderson, J.D. (1973). Vigour determination in soybean seed by multiple criteria. Crop Science. 13: 630-633
- Achakzai, A.K.K. (2009). Effects of water stress on imbibitions, germination and seedling growth of maize cultivars. Sahrad Journal of Agriculture. 25(2): 165-172.
- Ajirloo, A.R., Mohammadi, G.R and Ghobadi, M. (2011). The effect of priming on seed performance of chickpea (Cicer arietinum L.) under drought Stress. J. Agric. Sci. Technol. 1: 1349-1351.
- Allah, A.A.A., Badawy, S.A., Zayed, B.A and Gohary, A.A.E. (2010). The role of root system traits in the drought tolerance of rice (Oryza sativa L.). World Academy of Science, Engineering and Technology. 44: 1388-1392.
- Amador, B.M., Aguilar, R.L., Kaya, C., Mayoral, J.L and Hernandez, A.F. (2002). Comparative effects of NaCl and polyethylene glycol on germination, emergence and seedling growth of cowpea. Journal of Agronomy and Crop Science. 188: 235-247.
- Awari, V.R and Mate, S.N. (2015). Effect of drought stress on early seedling growth of chickpea (Cicer arietinum L.) genotypes. Life Sciences International Research Journal. 2(2): 356 -361.
- Banon, S.J., Ochoa, J., Franco, J.A., Alarcon, J.J and Sanchez- Blanco, M.J. (2006). Hardening of oleander seedlings by deficit irrigation and low air humidity. Environmental and Experimental Botany. 56: 36-43.
- Basha, P.O., Sudarsanam, G., Reddy, M.M.S and Sankar, N.S. (2015). Effect of PEG induced water stress on germination and seedling development of tomato germplasm. International Journal of Recent Scientific Research. 6(5): 4044-4049.
- Bayoumi, T.Y., Manal, H.E. and Metwali, E.M. (2008). Application of physiological and biochemical indices as a screening technique for drought tolerance in wheat genotypes. African Journal of Biotechnology. 7(14): 2341-2352.
- Dharanguttikar, V.M., Bharud, R.W and Borkar, V.H. (2015). Physiological responses of chickpea genotypes for drought tolerance under induced moisture stress. International Journal of Scientific and Research Publications. 5(9): 1-6.
- Farooq, M., Wahid, A., Kobayashi, N., Fujitha, D and Basra, S.M.A. (2009). Plant drought stress: Effects, mechanisms and management. Agronomy for Sustainable Development. 29: 185-212.
- Fathi, A and Tari, D.B. (2016). Effect of drought stress and its mechanisms in plants. International Journal of Life Scieneces. 10(1): 1-6.
- Foolad, M.R., Subbaiah, P., Kramer, G., Hargrave, G and Lin, G.Y. (2003). Genetic relationships among cold, salt and drought tolerance during seed germination in an interspecific cross of tomato. Euphytica. 130: 199-206.
- Gong, P.G.U., Guo, R.W.U., Chang, M.I and Chang, F.Z. (2000). Effects of PEG priming on vigor index and activated oxygen metabolism in soybean seedlings. Chinese Journal of Oil Crop Sciences. 22(2): 26-30.
- Harris, D., Tripathi, R.S and Joshi, A. (2002). On-farm seed priming to improve crop establishment and yield in dry direct- seeded rice. Direct seeding: Research Strategies and Opportunities, International Research Institute, Manila, Philippines. 231-240.
- Kravic, N., Vuletic, M., Nikolic, A., Babic, V., Ristic, D., Peric, V and Andelkovic, V. (2012). The effect of osmotic stress on physiological parameters in different maize genotypes. Journal of Plant Physiology. 133: 1-5.
- Macar, T.K., Turan, O and Yasemin, E. (2009). Effects of water deficit induced by PEG and NaCl on chickpea (Cicer arietinum L.) cultivars and lines at early seedling stages. Gazi University Journal of Science. 22(1): 5-14.
- Michel, B.E. and Kaufmann, M.R. (1973). The osmotic potential of polyethylene glycol 6000. Plant Physiology. 51: 914-916.
- Osorio, S., Yong-Ling, R and Fernie, A.R. (2014). An update on source to sink carbon partitioning in tomato. Frontiers in Plant Science. 5: 1-11.
- Pratap, V. and Sharma, Y.K. (2010). Impact of osmotic stress on seed germination and seedling growth in black gram (Vigna mungo). Journal of Environmental Biology. 31(5): 721-726.
- Petrovic, G., Jovicic, D., Nikolic, Z., Tamindzic, G., Ignjatov, M., Milosevic, D. and Milosevic, B. (2016). Comparative study of drought and salt stress effects on germination and seedling growth of pea. Genetika. 48(1): 373-381.
- Rauf, M., Munir, M., Hassan, M., Ahmad, M. and Afzal, M. (2006). Performance of wheat genotypes under osmotic stress at germination and early seedling growth stage. African Journal of Biotechnology. 6: 971-975.
- Shahriari, R and Hassan, P.D. (2005). Measuring the length of coleoptiles in native and promising genotypes of wheat in vitro using mannitol as the osmotic stress factor. Acta Botanica Boreali- Occidentalia Sinica. 22(3): 561-565.
- Shamim, F., Khan, K. and Khalid, S. (2016). Comparision among twelve exotic accessions of tomato (Solanum lycopersicum L.) for root and shoot growth under polyethylene glycol induced water stress. Pakistan Journal of Phytopathology. 28(2): 161-171.
- Sleimi, N., Guerfali, S and Bankaji, I. (2013). Biochemical indicators of salt stress in Plantago maritima: Implications for environmental stress assessment. Ecological Indicators. 48: 570-577.
- Smita and Nayyar, H. (2005). Carbendazim alleviates effects of water stress on chickpea seedlings. Biologia Plantarum. 49: 289-291.
- Soltani, A., Gholipoor, M and Zeinali, E. (2006). Seed reserve utilization and seedling growth of wheat as affected by drought and salinity. Environ. Exp. Bot. 55: 195-200.
- Verslues, P.E., Ober, E.S and Sharp, R.E. (1998). Root growth and oxygen relations at low water potentials: Impact of oxygen availability in polyethylene glycol solutions. Plant Physiology. 116: 1403-1412.
- Vessal, S., Palta, J. A., Atkins, C. A and Siddique, K. H. M. (2012). Development of an assay to evaluate differences in germination rate among chickpea genotypes under limited water content. Funct. Plant Biol. 39: 60-70.
- Yucel, D.O., Adem E.L., Durdane, M and Celal, Y. (2010). Effects of drought stress on early seedling growth of chickpea (Cicer arietinum L.) genotypes. World Applied Sciences Journal. 11(4): 478-485.
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