EFFECT OF SALT STRESS (NaCl) ON MORPHOLOGICAL PARAMETERS OF ONION (Allium cepa L.) SEEDLINGS (original) (raw)
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Acta Horticulturae, 2016
This study was conducted to investigate the effects of salt stress on proline, chlorophyll-a, chlorophyll-b, total chlorophyll, carotenoids, sodium, calcium, potassium, chloride (Cl) contents of some onion (Allium cepa L.) cultivars. Seeds of 'Akgun-12', 'Besirli-77', 'Beyaz Bilek', 'Imrali Kirmasi', 'Kantartopu-3', 'Metan-88' and 'Texas Early Grano' were germinated in peat material and transferred to plastic pots after 21 days of sowing. The plants have been grown in vermiculite by substrate culture technique. The early plant stage (63 days old plant) was used for screening studies. Three different salinity levels (0-control, 50 mM and 125 mM NaCl) were tested under greenhouse conditions. After six weeks of transferring, leaf parts were isolated and studied for physiological and mineral analyses. Cultivars showed different responses to NaCI. Increased salinity levels resulted in decreased chlorophyll-and carotenoids, increased proline. The sodium (Na +), potassium (K +) and chloride (Cl-) contents of plants were significantly affected by salinity in all cultivars.
Germination and antioxidant defense system in onion (Allium cepa. L) cultivars under salt stress
Salinity is one of the major environmental aspects, which affects on plant growth, development and productivity of the agricultural crops worldwide. The aim of this study was to evaluate germination, initial growth parameters, antioxidant enzyme (CAT, APX and GR) activities and proline accumulation, Na + / K + content in seedlings of four onion cultivars Agrifound Rose, Bellary, Prema-178 and Nasik Red exposed to salt stress with different concentrations of NaCl (0, 50, 100, 150 and 200 mM). In all cultivars, morphological parameters and relative water content decreased with increasing NaCl concentrations, whereas antioxidant enzyme activities, proline accumulation and Na + / K + content increased. Bellary cultivar showed highest salt tolerance than the Agrifound Rose, Prema-178 and Nasik Red. Decrease in RWC was least in Bellary as compared to other cultivars. The results suggest that high NaCl concentrations have a negative effect on the physiological quality of onion seedlings, resulting in lower seedling growth rates and increased antioxidant enzyme activity and among four cultivars Bellary was found more tolerant to salt stress.
This study was conducted to investigate the effects of drought and salinity on four onion (Allium cepa L.) cultivars (Texas Early Grano, Kantartopu-3, Besirli-77 and Akgun-12) in the early plant growth phase. Seeds were germinated in peat material. After 21 days of sowing, seedlings were transferred to plastic pots (1.6 L). The plants have been grown in vermiculite by “substrate culture” technique. After ten days of transplanting, irrigation was stopped gradually for drought stress. For this aim, three different levels of irrigation were used. (D0 was 90% of field capacity, D1 was 70% of field capacity, and D2 treatment was 40% of field capacity). In order to determination of effects of salinity on onion plants, 0. 50 mM and 125 mM NaCl were added to nutrition solution. To determine the effect of salinity and drought stress factors, tolerance indexes based on plant neck diameter (mm), leaf diameter (mm), plant length (cm), amount of leaves, leaf water potential (%) and waxy on leaves were measured as morphological parameters. At the same time, amount of proline, the concentrations of total chlorophyll (μg/ml), chlorophyll-a (μg/ml), chlorophyll-b (μg/ml) carotenoids (μg/ml) and chlorophyll-a/b were investigated as physiological parameters. Cultivars showed different responses to drought and salinity. The significant varietal differences were observed for the proline amount, chlorophyll-a, leaf water potential index and leaf amount under drought stress; and for the proline amount, chlorophyll-a and leaf diameter under salinity stress.
Salt tolerance in tissue culture of onion (Allium cepa L.)
2000
The response of onion tissue cultures to salinity stress was investigated. Callus initiated from aseptic seedlings was exposed to different levles of salt mixture. Fresh weight and growth value of callus inoculms were decreased as salt mixture increased in culture medium. However, dry weight and dry matter increased as salt level increased up to 4000 ppm and then decreased. Total
Improvement of Abiotic Stress Tolerance in Onion: Selection Studies Under Salinity Conditions
Onion (Allium cepa L.) is one of the most important vegetable in Turkey, and often cultivated in arid and semiarid regions with salinity problems. In the first year of the study, three onion varieties were evaluated at various levels of salinity to identify susceptibility and tolerance levels. At the end of the experiment, “Akgun” determined more tolerant than the other varieties. At 9.6 dSm-1 condition, the survived individuals of this variety were selected as “candidate line”. Selected individuals were grown to maturity and self-pollinated to produce next generations. In the third year of the study, the plants have been grown in vermiculite by substrate culture technique. The early plant stage at the 250 mM NaCl was used for the second selection studies. The same selection procedures were repeated once more on the next season. At each selection stage, the individuals were selected based on plant mortality. At the last year of study, the selected line was evaluated for both seed germination and seedlings growth at three treatment levels of 0 (nonstress), 250 mM, and 350 mM NaCl and were compared with the unselected population. The results indicated that selections were effective at all two salt-stress levels.
Germination and Emergence Response of Some Onion Cultivars of Southern Iran to Salinity Stress
The onion plant is sensitive to salinity, but the reaction of various onion cultivars to salinity is different. The effect of different salinity levels (0.01, 1, 2, 3, 5, 7 and 9 ds/m) on the germination and emergence stages of six onion cultivars ('Bardsiri', 'Hendijani', 'Texas Early Grano', 'Ramhormozi', 'Sarkareh', and 'Behbahani') were evaluated. The effect of cultivar and salinity on all investigated attributes was significant (P<0.01). Also, the cultivar × salinity interaction on germination percentage (GP), germination rate (GR), and root length (LR) were significant, although it did not have any significant effect on shoot length (SL). With increasing salinity, GP, GR, RL, and SL decreased. 'Ramhormozi', 'Bardsiri', and 'Behbahani' were most tolerant (in this order) to salinity stress than other cultivars; 'Sarkareh', 'Texas Early Grano' and 'Hendijani' were most sensitive. Noteworthy is that the GP of 'Ramhormozi' did not change despite the increase in salinity levels.
Germination responses to salinity levels were evaluated for eight days using the most frequently cultivated onion (Allium cepa L.) cultivar in Tunisia 'Merveille de Pompeï', an early white European variety with a flat bulb and small neck. Five salt levels were used with electrical conductivities (EC) ranging from 1.21 to 9.51 dS.m-1. Germination percentage after 8 days was not significantly reduced at any salt level. These test results confirm that salt effects during germination are not related to later responses of the whole plant to salt. Screening onion for salt tolerance would best be done at the vegetative stage. In a second experiment, onion growth responses to salinity levels were evaluated in a greenhouse study in which the same range of salt levels was tested. Total number, height, fresh and dry weight of the leaves, fresh and dry weight of bulbs and fresh and dry weight of roots were measured during the growing season. Onion was sensitive to low salt levels. In the field, continuous irrigation of onion with water having electrical conductivities of 1.21, 1.45, 3.70, 6.21 and 9.51 dS.m-1 resulted in severe die-off of transplanted seedlings in the salinized plots during the first 60 days of growth and consequently, in reduced yields of bulbs. Significant differences in both foliage and bulb weight were found due to the interaction between treatments and plant age. Observations of plant morphological and physiological behaviour under saline conditions were used to explain the effects of brackish water irrigation on onion yield.
A rapid screening method for salt stress tolerance of onion genotypes
Salinity is one of the major limitations for onion growth and productivity all over the world. There are several methods to determine of salt stress tolerance of plants such as germination tests, pots trials, in vitro experiments etc. This study was conducted for optimisation of rapid and practical method to compare onion genotypes under salinity conditions. In the first stage of the study, three explant types and twenty one combinations of plant growth regulators were tested for optimization of callus protocol. Callus indicate percentage (%), callus fresh weight (mg) and callus dry weight (mg) were measured on the 31st day. According to results, the best medium (MS + 2 mg/L 2,4-D + 0,5 mg/L BAP) and explant type (mature zygotic embryo) for the proliferation of callus were determined. After choosing the best hormone and explant type, the effect of salinity on callus induction was tested using different level of NaCl. Akgun-12 consistently performed the best in callus culture. Responses of onion cultivars were different for different parameters. The proposed method was simple to perform, as no long time is required, and offers a possibility to screen genotypes in any time of year.
EFFECT OF SALT (NACL) STRESS ON GERMINATION AND EARLY SEEDLING GROWTH OF FOUR VEGETABLES SPECIES
2006
Due to increasing salinity problems, in this experiment four vegetables species were treated with different concentration of salt solution to study salt effect. Results indicated that salinity caused signifi cant reduction in germination percentage, germination rate, root and shoot lengths and fresh root and shoot weights. Liner relation was developed to fi nd relation between salt stress and plant growth and also between germination and rest of plant characters.
In Vitro Regeneration of Onion (Allium cepa L.) Genotypes under Salt Stress Condition
2021
Salinity is a major problem affecting crop production all over the world. Excessive soil salinity can reduce the productivity of many agricultural crops including many vegetables and spices. Onion is one of the most important spices in the Asiatic region which is now in high demand. The experiment was conducted to observe in vitro regeneration of onion (Allium cepa L.) under salt stress condition from September 2016 to July 2017. The experiment was conducted as two factorial (genotype and treatment) Completely Randomized Design (CRD) with 3 replications for each treatment. Shoot tip segments of three genotypes namely Faridpuri, Taherpuri and Pusa red (Indian) were cultured in MS (Murashige and skoog, 1962) media supplemented with 25, 50, 75 and 100 mM NaCl. The genotype Faridpuri gave maximum salt tolerance upto 100 mM salinity level with 10.60 cm shoot length and 1.94 cm root length having the highest relative shoot and root growth. Pusa red was found to be salinity sensitive genot...