Polyethylene Glycol Induced Osmotic Stress Affects Germination and Seedling Establishment of Wheat Genotypes (original) (raw)
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Bangladesh Agronomy Journal, 2023
Germination characteristics, early seedling growth and seed metabolic efficiency of four wheat genotypes (BARI Gom 28, BARI Gom 29, BAW 1177 and ESWYT 29) were evaluated under 15% polyethylene glycol (PEG-6000) induced osmotic stress (-3 bar). Germination characteristics (germination rate, coefficient of germination and germination vigor index), shoot and root length, shoot and root dry weight, and seed metabolic efficiency decreased under osmotic stress induced by PEG than control treatment. But the degree of reduction was different for various wheat genotypes. Genotype BAW 1177 showed the highest performance in respect to germination and early seedling traits at both control and PEG induced osmotic stress than other three genotypes. So, genotype BAW 1177 can be considered as relatively drought tolerant genotype.
Journal of Crop Science and Biotechnology, 2019
Seed germination and seedling growth establishment are the most critical growth stages, and drought stress imposed at these stages highly limits crop productivity. In this regard, a hydroponic water culture experiment was conducted with the aim to assess the potential of 20 wheat genotypes against drought stress at the seedling stage. Water deficit was induced through polyethylene glycol (PEG-6000), by maintaining two osmotic potentials in water culture medium, i.e.-0.7 MPa (medium water stress) and-1.0 MPa (high water stress). After seed germination, drought stress was applied for 8 days. Seedlings shoot and root length and biomasses were restricted with an increase in osmotic deficit. Photosynthetic pigments and nitrate reductase activity (NRA) of wheat seedlings were reduced, while proline, total soluble sugars, total phenolics, and mineral ions (K + and Ca 2+) were augmented with the rise in water deficiency in most of the genotypes. On the basis of growth and biochemical attributes, six genotypes (NIA-AA-01, NIA-AA-08, NIA-AA-09, NIA-AA-13, NIA-AA-12, and NIA-AA-14) were categorized as drought tolerant, and three as medium tolerant. These genotypes exhibited better growth by showing the least reduction in root and shoot length, and fresh and dry biomasses, as well as modulation in biochemical processes to survive under water deficit. All studied traits indicated tolerance potential of these genotypes against moderate and extreme drought stress, which could also give better growth in arid and semi-arid regions of the country that facing water scarcity.
Caderno de Pesquisa série Biologia, 2010
Sixteen wheat genotypes including local varieties were tested in completely randomized design with three repeats. Data were recorded at four different moisture levels by using polyethylene glycol (PEG) 6000 on germination percentage, germination rate index, shoot length, root length, fresh weight of shoot, dry weight of shoot, fresh weight of root, dry weight of root, shoot/root ratio and analysed for significance. The genotypes differ significantly in response to the moisture stress. There were highly significant differences for all traits. PK-18199 gave the maximum germination percentage, germination rate index, shoot length root length, coleoptile length, fresh shoot weight, dry shoot weight, fresh root weight, dry root weight and root/shoot ratio under all four moisture stresses. PK-18175 showed maximum resistance against moisture stress while WAFAQ 2001 showed minimum resistance. AS-2002 and KC033 also gave the better performance under all four moisture levels for most of the traits at seedling stage. 99FJ03 gave maximum root/shoot length ratio while PK 18199 gave minimum value of root/shoot length ratio showing resistance against water stress.
Performance of wheat genotypes under osmotic stress at germination and early seedling growth stage
Sixteen wheat genotypes including local varieties were tested in completely randomized design with three repeats. Data were recorded at four different moisture levels by using polyethylene glycol (PEG) 6000 on germination percentage, germination rate index, shoot length, root length, fresh weight of shoot, dry weight of shoot, fresh weight of root, dry weight of root, shoot/root ratio and analysed for significance. The genotypes differ significantly in response to the moisture stress. There were highly significant differences for all traits. PK-18199 gave the maximum germination percentage, germination rate index, shoot length root length, coleoptile length, fresh shoot weight, dry shoot weight, fresh root weight, dry root weight and root/shoot ratio under all four moisture stresses. PK-18175 showed maximum resistance against moisture stress while WAFAQ 2001 showed minimum resistance. AS-2002 and KC033 also gave the better performance under all four moisture levels for most of the traits at seedling stage. 99FJ03 gave maximum root/shoot length ratio while PK 18199 gave minimum value of root/shoot length ratio showing resistance against water stress.
Effects of osmotic stress on germination and germinationindices of synthetic wheat
2012
In order to investigate the synthetic wheat genotype reactions to drought stress in germination stage and to determine the resistant genotypes to osmotic stress, an experiment consisting of 12 genotypes from synthetic wheat through factorial experiment in Complete Random Design (CRD) with three repetitions has been conducted. The first factor was considered as poly ethylene glycol density (PEG) with osmotic potentials of 0, -4/0, -8/0, and -2/1 mp and the second factor was 12 types of synthetic wheat. During conduction of the experiment germination indices including: germination rate (GR), germination index (GI), mean of emergence time (MET), final germination percentage (FGP), and germination rate index (GRI) were calculated. The analysis of variance for germination indices showed that there was a significant difference between different levels of osmotic potentials and genotypes for all the investigated characteristics. The mutual effects of variance in the amount have been observ...
A study was carried out to compare the appreciable differences between various durum wheat genotypes during the germination and seedling stages. Twenty promising spring durum wheat genotypes were tested under four (0.0,-0.3,-0.6 3 and-0.9 MPa) osmotic stresses conditions laid out in factorial experiments based on a completely randomized design (CRD) with three replications. Osmotic potentials were produced using different concentrations of polyethylene glycol (PEG 6000) at 20°C. Results revealed that all the recorded traits were significantly (P<0.01) affected by osmotic stress treatments. There were remarkable decreases in germination percentage, coleoptile, root and shoot length, shoot dry weight, seedling dry weight with increasing osmotic stress. However the germination rate showed a slight increase under low osmotic stress condition. The highest germination percentage was 93.5%, observed in D1 (control) treatment whilst the lowest (42%) was seen in the D4 (-0.9 MPa) treatment. Furthermore, root dry weight, root to shoot length ratio and root to shoot dry weight ratio also increased under low osmotic stress, although severe osmotic stress caused a sizeable decrease in their values. The genotypic effects on germination percentage and rate were highly significant (P<0.01), whilst its effects on coleoptile, root length and root dry weight were significant (P<0.05). Genotype four (G4) exhibited the highest germination percentage (84.17%) whilst G17 showed the lowest value (62.92%). Correlation studies amongst the different traits showed that the highest correlation coefficient was between seedling dry weight and shoot dry weight (r = 0.96), whilst the lowest value was between germination rate and root to shoot dry weight (r =-0.13).
A study was conducted in the Department of Plant Breeding and Genetics, Sindh Agriculture University, Tandojam, Pakistan during the year 2009. Sixteen spring wheat cultivars (Triticum aestivum L.) were screened under osmotic stress with three treatments i.e. control-no PEG (polyethylene glycol), 15 percent and 25 percent PEG-6000 solution. The analysis of variance indicated significant differences among treatments for all seedling traits except seed germination percentage. Varieties also differed significantly in germination percentage, coleoptile length, shoot root length, shoot weight, root/shoot ratio and seed vigour index. However, shoot and root weights were non-significant. Significant interactions revealed that cultivars responded variably to osmotic stress treatments; hence provided better opportunity to select drought tolerant cultivars at seedling growth stages. The relative decrease over averages due to osmotic stress was 0.8 percent in seed germination, 53 percent in coleoptile length 62.9 percent in shoot length, 74.4 percent in root length, 50.6 percent in shoot weight, 45.1 percent in root weight, 30.2 percent in root/shoot ratio and 68.5 percent in seed vigour index. However, relative decrease of individual variety for various seedling traits could be more meaningful which indicated that cultivar TD-1 showed no reduction in coleoptile length, while minimum decline was noted in Anmol. For shoot length, cultivar Sarsabz expressed minimum reduction followed by Anmol. However, cultivars Anmol, Moomal, Inqalab-91, and Pavan gave almost equally lower reductions for root length suggesting their higher stress tolerance. In other words, cultivars Anmol, Moomal, Inqalab-91, Sarsabz, TD-1, ZA-77 and Pavan had relatively longer coleoptiles, shoots and roots, and were regarded as drought tolerant. Correlation coefficients among seedlings traits were significant and positive for all traits except germination percentage which had no significant correlation with any of other trait. The results indicated that increase in one trait may cause simultaneous increase in other traits; hence selection for any of these seedling attributes will lead to develop drought tolerant wheat cultivars. KEYWORDS: Triticum aestivum; cultivars; seedlings; osmotic pressure; stress; Pakistan. *Department of Plant Breeding and Genetics, Sindh Agriculture University, Tan
Cereal Research Communications, 2010
Literature confirms that using polyethylene glycol (PEG) as an osmotic agent to imitate water shortage was not so easy in practice, due to PEG toxicity effects and frequent contaminations. Two new approaches were developed to alleviate those problems, one using a raft covered with a membrane to prevent PEG entry in roots, and one using solidified PEG media. The raft trials were done on corn, hexaploid and tetraploid wheat, rye, triticale, oats, barley, Agrotricum; those in solid media, with corn, hexaploid and tetraploid wheat, barley, sorghum and pearl millet. Different species respond differently to PEG-induced osmotic stress. In our trials, the most sensitive cereal was corn, and this finding correlates with the lower osmotic pressure of the sap (a constitutive trait in corn seedlings). Corn responded to osmotic stress by a very poor rate of elongation of the coleoptile, especially when the highest stress (32% PEG) was used. This behavior was also observed in the field in dry years, for example in the Sahel area. Compared to this sensitive cereal species, all other cereals tested were more resistant. Hexaploid and tetraploid wheat, triticale, and Agrotricum kept capacity to elongate roots when submitted to a high osmotic stress, but the higher stress reduced root length considerably. Barley kept rooting ability like other cereals, but was able to develop more aerial biomass, seminal roots, and ramifications. Barley root hair was also longer and covered a higher proportion of the root. Those adaptive features likely explain part of the good adaptation of barley to dry Mediterranean areas. Preliminary results on solid media also showed relationships between drought resistance and the osmoresistance response, at least when comparing species. Roots of species adapted to hot climate, like pearl millet and sorghum, had few seminal roots but displayed a strong gravitropism under osmotic stress. The ease of use of solidified PEG media shows promise for future larger scale trials. Applications of solidified PEG media for research beyond cereal crops is envisioned.
Effect of Polyethylene GLYCOL-6000 on Wheat (Triticum Aestivum L.) Seed Germination
2013
The response of twenty-five wheat (Triticum aestivum L.) varieties to different water stress levels were studied in a series of experiments conducted in the laboratory on Polyethylene glycol-6000. The experiments on germination with twenty-five wheat varieties were conducted in a growth cabinet maintained at 30/25 0 C day/night temperature with 16 hours photoperiod. Seeds were germinated in glass tray lined with filter paper moistened with polyethylene glycol (PEG-6000) solutions of 0.0,-0.25,-0.50,-0.75 and-1.0 MPa osmotic potential. Germination percentage decreased with decrease in water potential of the medium. The water uptake reached at a peak value within 48 hours in all the genotypes under all the water stress conditions. The varieties Sarsabz and Kiran-95 showed comparatively better performance of germination under water stress than other wheat varieties.
Biology and Life Sciences Forum
Wheat is an important cereal crop that often suffers from osmotic stress under various growing conditions. The objective of this study was to investigate the effects of PEG-induced osmotic stress at the phytomer level on root growth and root hair morphology of 22 hydroponically grown wheat varieties. Two treatments, 0% and 10% PEG, were imposed on 20-day old wheat seedlings for a duration of 15 days. PEG stress significantly reduced plant height, number of live leaves per tiller, chlorophyll content, shoot dry weights, number of root bearing phytomers and roots per tiller. By contrast, PEG stress significantly increased leaf injury scores, root dry weight, main axis length and diameter of developed roots, length and diameter and density of both first and second order lateral roots, and the density and length of root hairs. An increase in root dry weight in PEG stress tolerant wheat genotypes was achieved through an increase in the length and diameter of main axis and lateral roots.