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.

Impact of gamma irradiation pretreatment on the growth of common vetch (Vicia sativa L.) seedlings grown under salt and drought stress.

It has been generally accepted that the morphology, physiology and biochemistry of plants are differentially affected by low-dose gamma ionizing radiation that is associated with the tolerance of plant species under biotic/abiotic stress. Therefore, the aim of this study is to investigate the protective role of low gamma irradiation pretreatment against salt and drought stress. For this aim, irradiated (100 Gy) and non-irradiated seeds of common vetch were cultured on an MS medium with separate addition of concentrations of NaCl (100 mM) and PEG-6000 (100 g/l) under in vitro conditions. Morpho-physio-biochemical analyses were carried out on 14-day-old seedlings. The findings of this study clearly show that exposure to gamma irradiation pretreatment (100 Gy), alone or in combination with salt stress and drought stress, led to significant increases (p < .01) in dry matter accumulation, CAT, SOD and APX activities, proline contents and decreases in relative water content. However, alone, gamma irradiation pretreatment caused increased chlorophyll contents while decreasing MDA contents. Overall, these results suggested that low-dose gamma irradiation pretreatment can enhance the tolerance of common vetch seedlings against stress due to salt and drought.

Effect of magnetic field on in vitro seedling growth and shoot regeneration from cotyledon node explants of Lathyrus chrysanthus boiss.

The stimulatory effects on germination of seeds and growth of plants of static magnetic field (MF) pre-treatments depending on MF intensity, exposure time periods, signal form, flux density, and source frequencies on plants are reported. Seed germination frequency is low due to dormancy in Lathyrus chrysanthus Boiss. from Fabaceae family, consisting of 187 taxa. Tissue culture protocol for this plant has already been optimized. This plant is also used as a model for developing alternative methods to overcome dormancy. This study was conducted to determine the effects of MF on in vitro seed germination, seedling growth, and shoot regeneration capacity of cotyledon node explants in Lathyrus chrysanthus Boiss. to obtain healthy seedlings in large quantities. The seeds of an ecotype (Diyarbakir) were subjected to 125 mT MF strength for different exposure time periods (0-untreated, 24, 48, and 72 h). Sterilized seeds were germinated on growth basal medium in Magenta vessels. Seed germination and seedling growth percentages were recorded after 7 and 14 days of culture initiation, whereas seedling and root lengths were noted 28 days after culture initiation. At the end of the culture, shoot regeneration percentage, shoot number per explant, highest shoot height per explant, and total shoot number per petri dish were recorded. According to the results, it could be concluded that MF treatment could clearly be used to improve germination by breaking dormancy not only in Lathyrus chrysanthus Boiss. but also other plant species. Bioelectromagnetics. 39:547-555, 2018.© 2018 Wiley Periodicals, Inc.

Physiological responses of the M1 sainfoin (Onobrychis viciifolia Scop) plants to gamma radiation.

Effects of gamma radiation on physiological responses of the M1 sainfoin plants were investigated. Seeds of sainfoin ecotype 'Koças' were exposed to 0, 400, 500 and 600Gy from a 60Co source at a dose rate of 0.483 kGyh-1. Irradiated and unirradiated seeds were sown into culture vessels containing MS-basal medium to be cultured for 30 days under in vitro conditions. At the end of this period, seedlings, which germinated from the radiated and unirradiated seeds, were transferred into pots in a growth chamber for 30 days more. Chlorophyll contents, activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR), as well as contents of monodehydroascorbate reductase (MDA) and proline were examined in unirradiated and irradiated 60-day-old seedlings. Overall, the activities of the antioxidant enzymes (SOD, CAT and GR) and contents of chlorophyll and proline in the leaves tended to increase after irradiation in a dose-dependent manner. By contrast, the activity of APX decreased. The lipid peroxidation characterized by the MDA content remained unchanged, except after irradiation to 500Gy. The highest CAT activity and the highest proline content were observed after irradiation to the highest dose of 600Gy. The highest SOD and GR activities were observed after irradiation to the lowest tested dose of 400Gy. This is the first study that provided basic information on the impact of gamma radiation on physiological responses of sainfoin and its radiosensitivity. These findings will be useful in development of a mutation breeding program of sainfoin.

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.