Studies the effects of low dose of gamma rays on the behaviour of chickpea under various conditions

X-radiation of Lotus corniculatus L. seeds improves germination and initial seedling growth

PURPOSE

Lotus corniculatus L. (bird's foot trefoil, BFT) is a valuable perennial legume forage species due to its high nutritive value, persistence under grazing, and condensed tannin content that improves ruminant production and prevents bloating. However, it is less preferred by farmers compared with other perennial forage legumes such as alfalfa because of slow germination, slow establishment and low seedling vigor. This study was conducted to determine whether X-ray seed priming could improve these deficiencies.

MATERIALS AND METHODS

Seeds of L. corniculatus cv. 'AC Langille' were irradiated at 0, 100, and 300 Gy. Non-irradiated and irradiated seeds were sown on Murashige and Skoog/Gamborg medium under in vitro conditions and cultured for 21 days. Germination percentage, mean germination time (MGT), germination rate index, length of shoot and root, fresh and dry weight of shoot and root, dry matter ratios of shoot and root, water content of shoot and root, and seedling vigor index were measured.

RESULTS

The results of this study demonstrated that X-ray seed priming significantly increased the germination percentage of L. corniculatus, increased the germination rate and thereby shortened the MGT, and improved seedling growth. However, X-ray pretreatment also decreased seedling shoot and root biomass.

CONCLUSIONS

In this study, it is reported for the first time that X-ray seed pretreatment has the potential to address important seedling establishment issues in L. corniculatus.

Hormesis effects of gamma radiation on growth of quinoa (Chenopodium quinoa)

PURPOSE

Quinoa is an annual plant that grows well in high altitude regions with high radiation and ultraviolet intensity. It has known that high-dose radiation damages living organisms, but low-dose radiation also has a beneficial effect. Therefore, the purpose of this study is to investigate the hormesis effect of gamma-ray on quinoa by growth analysis and hyperspectral imaging.

MATERIALS AND METHODS

Quinoa seeds were irradiated at 50, 100, and 200 Gy emitted by 60CO. Subsequently, the seeds were germinated and transplanted into pots, then conducted growth analysis and physiological evaluation every week, and hyperspectral imaging. Photosynthetic ability was measured at 35 days after transplanting (DAT), and the plants for each dose were divided into aerial and underground parts for biomass evaluation at 91 DAT. Various vegetation indices were estimated from 14 to 35 DAT by hyperspectral analysis, and the specific bands were extracted based on the PLS model using plant height, SPAD value, and chlorophyll fluorescence parameters.

RESULTS

We found that plant height and biomass were increased in quinoa plants treated with a low dose (50 Gy) as compared to control. Chlorophyll content and chlorophyll fluorescence were not different between doses at the early growth stage, but as growth progressed, the plant irradiated at 200 Gy began to be lower. The photosynthetic ability of the quinoa plant treated at 50 Gy was greater than other plants at 35 DAT. The vegetation indices related to the pigment status also were higher in the plants treated by irradiation at 50 Gy than the plants grown in other doses treatment units at the beginning of the growth. Using the PLS model we collected sensitive band wavelengths from hyperspectral image analysis. Among the collected bands, eight bands closely related to plant height, nine bands to chlorophyll content, and ten bands to chlorophyll fluorescence were identified.

CONCLUSION

Our results showed that the growth and physiological parameters of quinoa treated by low dose gamma irradiation to seeds were greater than that of control as well as the plant with higher doses. These findings confirm that the positive changes in the characteristics of quinoa with low dose radiation indicated that hormesis occurs at 50 Gy radiation.

Physio-biochemical and molecular mechanism underlying the enhanced heavy metal tolerance in highland barley seedlings pre-treated with low-dose gamma irradiation

Heavy metal pollution, as a consequence of rapid industrialization and urbanization, poses a threat to highland barley grown in Tibet. This study investigates the effect of different doses of gamma irradiation (50–300 Gy) on the physio-biochemical and molecular mechanism of highland barley under heavy metal stress. Growth data showed that 50-Gy gamma irradiation had the maximal beneficial effects on the highland barley seedlings under lead/cadmium stress. The results of oxidative parameters demonstrated that 50-Gy gamma-irradiated seedlings had lower hydrogen peroxide and malondialdehyde contents under lead/cadmium stress compared to non-irradiated seedlings. Moreover, the activities of antioxidant enzyme and proline levels in 50-Gy gamma-irradiated seedlings were drastically higher than those in non-irradiated seedlings under lead/cadmium stress. Additionally, transmission electron microscopy results revealed that the 50-Gy gamma-irradiated seedlings exhibited improved chloroplasts ultrastructure compared with non-irradiated seedlings exposed to lead/cadmium stress. Notably, transcriptional expression analysis showed that 50-Gy gamma irradiation could significantly affect the expression of genes related to heavy metal transport and abscisic acid metabolism under lead/cadmium stress. Collectively, these results provide insights into the physio-biochemical and molecular mechanisms of low-dose-gamma-irradiation-enhanced heavy metal tolerance in highland barley seedlings, thus proposing gamma irradiation as a potential technology to mitigate heavy metal toxicity in crops.

The effect of gamma radiation on seed germination and seedling growth of Lathyrus chrysanthus Boiss. under in vitro conditions

The effects of radiation at different doses (0, 50, 100, 150, 200 and 250 Gy) of radioactive cobalt (⁶⁰Co) γ rays on seed germination and seedling growth of Lathyrus chrysanthus were investigated under in vitro conditions. The results showed that irradiated seeds had increased seed germination percentage, seedling and root lengths, seedling fresh weight, seedling dry matter content and total chlorophyll content in the leaves of seedlings. However, at higher doses stress was evident and significant decreases in all parameters were observed. The highest seed germination percentage was recorded as 62.4%, 7 days after study initiation when seeds were irradiated with 150 Gy gamma dose, while 100 Gy gamma dose was ranked in second order. Fourteen days after culture initiation, the best shoot growth initiation was again obtained from 150 Gy gamma dose as 75.7% and this was followed by 100 Gy gamma radiation as 74.6%. Gamma doses over 150 Gy resulted in sharp decreases in all parameters examined. On the 14th day, the highest shoot and root lengths were recorded from 150 Gy gamma dose as 1.2 and 2.9 cm, respectively. Twenty eight days after study initiation, the highest values of seedling and root lengths, seedling fresh weight, seedling dry matter content and total chlorophyll content were noted from 50 Gy gamma radiation as 9.7 and 6.3 cm, 0.39, 0.09 g (23.08%) and 471.6 μg/g fresh tissue, respectively. This study is important from the aspect of showing that stimulatory effect of low gamma doses for germination and seedling growth may not be the same.

Dose-dependent effects of gamma radiation on lettuce (Lactuca sativa var. capitata) seedlings

Abstract Purpose: The objectives of this study were to determine the effects of gamma radiation on lettuce growth and development, as well as on the content of photosynthetic pigments in 28 days lettuce leaf.

MATERIALS AND METHODS

Lettuce dry seeds were exposed to a (60)Co [Cobalt-60] gamma source at doses ranging from 2-70 Gray (Gy). The photosynthetic pigment content was determined spectrophotometrically.

RESULTS

Our results showed that an irradiation dose between of 2-30 Gy enhanced the growth parameters (final germination percentage, germination index, root and hypocotyl length) as compared to untreated plants. Seed germination test revealed that 30 Gy irradiation dose induced the highest increase of growth parameters, while at 70 Gy a significant decrease of plant vegetative growth was recorded. The results indicated that exposing the seeds at doses ranging from 2-30 Gy enhanced the photosynthetic pigments (chlorophyll a, chlorophyll b, carotenoids) content, while at higher doses (70 Gy)) the decrease of the assimilatory pigments was noticed.

CONCLUSION

The present results suggested that seed treatment with gamma radiations (0-30 Gy) was effective in stimulating plant growth and development, as well as the content of assimilatory pigments. At a higher dose of 70 Gy, there was a drastic reduction in the length of shoots and roots and also in the total chlorophyll content. These observations confirm that ionizing radiation stimulates physiological parameters up to certain low doses, and then it inhibits these parameters at higher doses.

Anti-oxidant modulation in response to gamma radiation induced oxidative stress in developing seedlings of Psoralea corylifolia L

The seeds of Psoralea corylifolia L., an important medicinal herb in Indian and Chinese Pharmacopeia were exposed to gamma rays (2.5, 5, 10, 15 and 20 kGy) from Co(60) source at dose rate of 1.65 kGy h(-1). Enzymatic and non-enzymatic anti-oxidant responses were verified according to the developmental stages and gamma dose applied. Plants grown from seeds exposed to higher gamma doses exhibit higher activity of the antioxidants such as [Ascorbate peroxidase (APX, 1.11.1.1), superoxide dismutase (SOD, 1.15.1.1), glutathione reductase (GR, 1.6.4.2) and MDA content till flowering and declined thereafter. In contrast, CAT (1.11.1.6) activity declined in dose and age dependent manner. The correlation of gamma dose applied and oxidative stress was inferred from the increased enzymes activities and depression in total glutathione pool in seedlings developed from irradiated seeds. Nevertheless, the maintenance of high anti-oxidant capacity, psoralen accumulation seems to be an important strategy during acclimation of P. corylifolia to gamma radiation stress. Pronounced accumulation of psoralen following 15 and 20 kGy at post-flowering stage where oxidative stress is triggered modulates lipid peroxidation and proline accumulation. Further, in psoralen producing plants an increase in psoralen content can be used as a biomarker which specifies plant is under stress.