- Email: [email protected]
Effect of γ-ray irradiation on the germinating characteristics of wheat seed
Radiation Physics and Chemistry 81 (2012) 463–465
Contents lists available at SciVerse ScienceDirect
Radiation Physics and Chemistry journal homepage: www.elsevier.com/locate/radphyschem
Technical Note
Effect of g-ray irradiation on the germinating characteristics of wheat seed Jun Wang n, Yong Yu, Xiaojing Tian Department of Biosystems Engineering, Zhejiang University, 866 Yuhangtang Road, Hangzhou 301129, PR China
a r t i c l e i n f o
abstract
Article history: Received 7 November 2010 Accepted 18 December 2011 Available online 28 December 2011
Few researches have been reported on the long-term germination characteristics and the effect of high gamma radiation dose on cereal seeds. In this paper, to observe the effects of gamma irradiation (0–3 kGy) on the germination of wheat seed in long-term (within 20 months), wheat seed was dried after irradiation and the germination experiment during storage time was conducted. It was found that the lengths of buds of irradiated wheat seeds diminished, the roots of irradiated wheat seeds disappeared, and no germinations in irradiated wheat seed was found. The influence of g-ray irradiation on roots was more significant than that on buds. After long-term storage, the germination of irradiated wheat seeds increased. & 2011 Elsevier Ltd. All rights reserved.
Keywords: Germination Irradiation Wheat Seed stimulation
1. Introduction The germination of grain seeds is affected by many factors. Some factors belong to properties of grain seeds, such as a and b amylase activity (Nandi et al., 1995; Das and Sen-Mandi, 1992; Wang et al., 2005). The extent of amylase activity probably determines germination ability of cereal seeds. Some factors belong to environmental conditions during germination, such as temperature, CO2 concentration, ethanol, kinetin, dehusking, cigarette smoke, steeping and so on. CO2 concentration can affect both seedling establishment and grain quality of crops (Bai et al., 2003), ethanol and kinetin have stimulatory effects on the germination of dehusked seeds of indica and japonica rice under aerobic and anaerobic conditions (Miyoshi and Sato, 1997a, 1997b), dehusking stimulates the germination of seeds of indica rice but strongly inhibits that of japonica rice (Miyoshi et al., 1996), and cigarette smoke inhibits germination of many kinds of plant seeds including wheat seeds (Noble, 2001). Besides, other factors belong to the processing method for grain seeds before and/or during germination. It has been demonstrated that sound field with 400 Hz and 106 dB is the best condition for germination of rice. Electric field has no significant effects on the germination of rice (Cao et al., 2004), but for other plants (e.g. tomato), electric and magnetic field enhance its germination significantly (Moon and Chung, 2000). The optimum germination conditions for high amylose rice seeds were steeping for 24 h at 25 1C (or 16 h at 35 1C) and germinated for 3 days at 30 1C (Capanzana and Buckle, 1997).
n
Corresponding author. Tel.: þ86 571 86971881; fax: þ 86 571 86971139. E-mail address: [email protected] (J. Wang).
0969-806X/$ - see front matter & 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.radphyschem.2011.12.024
The potential application of ionizing radiation in food processing is based mainly on the fact that ionizing radiations damage the bio-molecules very effectively, deactivating living cells, thereby preventing microorganisms, insect gametes, etc. from reproducing. One of the major advantages of radiation treatment is that it causes no rise in temperature in the product even after packaging thus avoiding re-contamination or re-infection of sterilized sample. Gamma ray possess high penetrating characteristics, thus it can be effectively used for decontamination of seed surface affected with fungi. Sterilization by gamma irradiation also helps in preserving the quality of processed food/seed as no or very negligible degradation is observed compared to other techniques, thus reducing the risk for the consumers (Maity et al., 2009; WHO, 1999). Gamma irradiation is one kind of processing methods, which could affect the germination of grain. Cells of rice and wheat could be destroyed by gamma irradiation (Yu and Wang, 2005, 2006), this is the reason that irradiation affect the germination of rice and wheat seed. There are many surveys describing inhibition of germination by treatment by ionizing radiation, for example, the effects of gamma irradiation on the germination of wheat seeds and gamma germination inhibits the germination of wheat seeds (Barros et al., 2002; Wang and You, 2000). However, in these reports, the germination experiments were finished within 3 months after low dose irradiation (0–1.0 kGy). Few studies have been reported on the long-term germination characteristics and the effects of high gamma radiation dose on cereal seeds. In this paper, to observe the effects of gamma irradiation (0–3 kGy) on the germination of wheat seeds in long-term (within 20 months), wheat seed was dried after irradiation and the germination experiment during storage time was conducted.
464
J. Wang et al. / Radiation Physics and Chemistry 81 (2012) 463–465
2. Materials and methods 2.1. Wheat seeds Wheat (Zhenong 1) harvested in June, 2004, from the experimental farm of Agronomy, Zhejiang University, was used for this experiment. The initial moisture content of wheat seed was 25.0% (dry basis), which was determined by drying five samples at 105 1C (GB/T 5497–1985, National Standard of China). After irradiation, the samples were dried and packed in polyethylene bags and stored in refrigerator at 5 1C (resembling seed lowtemperature storage). 2.2. Gamma irradiation Wheat seeds samples were exposed to 60Co source at an ambient condition at the Institute of Nuclear-agriculture Sciences, Zhejiang University. The samples were divided into 5 sets (500 g each sample) and irradiated at the doses 0 kGy (non-irradiation), 0.6 kGy, 1.5 kGy, 2.4 kGy, and 3 kGy, respectively, with dose rate of 1 kGy/h. 2.3. Air drying Irradiated samples were symmetrically placed on a sifter dried with an air velocity of 0.5 70.1 m/s at low drying temperature of 50 1C. The samples were dried until it reached the final moisture content of 14.5 70.1% (dry basis), which represented the safe moisture value for wheat storage. 2.4. Germination test After dipped into water for 1 h, one hundred wheat seeds were symmetrically placed on two pieces of filter paper. Seeds were incubated under 12 h light and 12 h darkness for 14 day in growth chambers at 30 1C (GB/T 3543.4–1995, National Standard of China). Seeds germination was checked daily and the length of root and sprout were measured at the 14th day. The first set of germination tests was commenced immediately after irradiation, and the other sets of tests were done at intervals of three months. Seeds were considered to be germinated when the roots were longer than 5 mm (Bai et al., 2003). Experiment for each sample had two replications.
14th day). It was evident that the germination rate of wheat seeds was significantly affected by gamma irradiation, and the germination rates decreased to 0% when radiation dose was equal to or higher than 0.6 kGy. The effects of different radiation doses on germination characteristics were represented in bud occur rate (the percentage of wheat grain owning bud). With increasing radiation dose, the average value of bud occur rates decreased from 85% to 50%, and the average length of buds decreased from 5.7 cm to 1.3 cm. Compared with non-irradiated wheat sample (93%, 11.2 cm), the bud occur rate and average length of bud of irradiated wheat samples decreased evidently. However, the occur rate and average length of root decreased to 0% and 0 cm when radiation dose was equal to or higher than 0.6 kGy. The influence of g-ray irradiation on roots may be more significant than that on buds (Table 1). Because seeds were not considered as germinated until the roots were 5 mm long, the effects of g-ray irradiation on germination rate were mainly due to the effects on roots.
3.2. Effect of radiation dose on long-term germination rate of wheat seeds The long-term germination experiments were carried out and the results were shown in Fig. 1 (data measured at 14th day). It showed the changes in germination rates of wheat samples with the increasing storage time. The germination rates of irradiated wheat samples would increase after different storage time. The germination rates were prolonged with increasing radiation dose. The time when germination rates of samples irradiated reach a peak value were about 4, 6, 10 and 12 months under 0.6 kGy, 1.5 kGy, 2.4 kGy and 3 kGy, respectively. After the germination rate reaching a peak value, the germination rates of irradiated wheat samples decreased like non-irradiated wheat sample, and the peak germination rate was comparatively high. For example, the germination rate of wheat samples irradiated at 0.6 kGy, 1.5 kGy, 2.4 kGy and 3 kGy increase to 88%, 85%, 80% and 76% in 20 months. After long-term storage, some germination rates of irradiated wheat samples were higher than that of non-irradiated wheat sample. For example, after 12 months storage, the germination rates of wheat samples non-irradiated and irradiated at 0.6 and 1.5 kGy were 73%, 80% and 86%, respectively. Those changes of germination rates of irradiated wheat samples were assumably due to the self-repair function of irradiated organism.
3. Results and discussion 3.1. Effect of radiation dose on short-term germination rate of wheat seed The results of germination experiment carried out immediately after irradiation, were shown in Table 1 (data measured at Table 1 Results of germination experiment commenced immediately after irradiation (measured at 14th day).
Germination rate (%) Bud occur ratea (%) Average length of bud (cm) Root occur rateb (%) Average length of root (cm)
0 kGy
0.6 kGy
1.5 kGy
2.4 kGy
3 kGy
92 93 11.2 91 8.6
0 85 5.7 0 0
0 71 2.6 0 0
0 62 1.6 0 0
0 50 1.3 0 0
The data were average values of two replications. a b
Bud occur rate: the percentage of wheat grain owning bud. Root occur rate: the percentage of rice wheat owning root.
Fig. 1. Germination rate of long-term germination experiment.
J. Wang et al. / Radiation Physics and Chemistry 81 (2012) 463–465
465
These changes of germination velocity curves of irradiated wheat samples were assembly due to the conjunct effect of respiration and self-repair of wheat seeds (Boubriak et al., 1997).
4. Conclusions (1). The lengths of buds of irradiated wheat seed minished with increasing radiation dose, the roots of all irradiated wheat disappeared, and no germinations of irradiated wheat seed was found. (2). The germination rates were prolonged with increasing radiation dose, but the germination rates of irradiated wheat seed would increase within definite storage time.
Acknowledgments
Fig. 2. Effect of store time on germination characteristics of non-irradiated wheat.
The authors acknowledge the financial support of Chinese National Foundation of Nature and Science through project 3047000 and the project was supported by China Postdoctoral Science Foundation 20060400320. References
Fig. 3. Effect of store time on germination characteristics of 1.5 kGy irradiated wheat.
3.3. Effect of storage time on germination characteristics of irradiated wheat seed The effects of storage time on germination characteristics of nonirradiated wheat samples and 1.5 kGy irradiated wheat samples were shown in Figs. 2 and 3 (other figures were omitted). The germination amount (the amount of germinating seeds in each day in the 14 day germination experiments) of each wheat sample was obvious in these figures. For the non-irradiated wheat samples, it was evident that, with increasing of storage time from 0 to 20 months, the peak amount of germinating seeds decreased and the time needed to reach the peak amount increased (Fig. 2). These changes in germination velocity curves of non-irradiated wheat samples were assembly due to the effect of respiration of wheat seeds. For the 1.5 kGy irradiated wheat samples, with the increasing of storage time from 8 to 12 months, the peak amount of germinating seeds increased and the time needed to reach the peak amount decreased (Fig. 3). With increasing storage time from 16 to 20 months, the peak amount of germinating seeds decreased, and the germination velocity curves may be similar to that of non-irradiated wheat samples if store time prolonged.
Bai, Y., Tischler, C.R., Booth, D.T., Taylor, E.M., 2003. Variations in germination and gain quality within a rust resistant common wheat germplasm as affected by parental CO2 conditions. Environ. Exp. Bot. 50, 159–168. Barros, A.C., Freund, M.T.L., Villavicencio, C.H., Delincee, H., Arthur, V., 2002. Identification of irradiated wheat by germination test, DNA comet assay and electron spin resonance. Radiat. Phys. Chem. 63, 423–426. Boubriak, I., Kargiolaki, H., Lyne, L., Osborne, D.J., 1997. The requirement for DNA repair in desiccation tolerance of germinating embryos. Seed Sci. Res. 7, 97–105. Cao, W., Nishiyama, Y., Koide, S., Lu, Z.H., 2004. Drying enhancement of rough rice by an electric field. Biosyst. Eng. 87, 445–451. Capanzana, M.V., Buckle, K.A., 1997. Optimisation of germination conditions by response surface methodology of a high amylose rice (Oryza sativa) cultivar. LWT- Food Sci. Technol. 30, 155–163. Das, G., Sen-Mandi, S., 1992. Utilisation of free fatty acids during germination of unaged and differentially aged wheat embryos. Indian J. Exp. Biol. 30, 299–301. Maity, J.P., Chakraborty, S., Kar, S., Panja, S., JeanJ., -S., Samal, A.C., Chakraborty, A., Santra, S.C., 2009. Effects of gamma irradiation on edible seed protein, amino acids and genomic DNA during sterilization. Food Chem. 114, 1237–1244. Miyoshi, K., Sato, T., 1997a. The effects of ethanol on the germination of japonica and indica rice (Oryza sativa L.) under anaerobic and aerobic conditions. Ann. Bot. (Lond) 79, 391–395. Miyoshi, K., Sato, T., 1997b. The effects of kinetin and gibberellin on the germination of dehusked seeds of indica and japonica rice (Oryza sativa L.) under anaerobic and aerobic conditions. Ann. Bot. (Lond.) 80, 479–483. Miyoshi, K., Sato, T., Takahashi, N., 1996. Differences in the effect of dehusking during formation of seeds on the germination of seeds of indica and japonica rice (Oryza sativa L.). Ann. Bot. (Lond.) 77, 599–604. Moon, J.D., Chung, H.S., 2000. Acceleration of germination of tomato seed by applying AC electric and magnetic fields. J. Electrostat. 48, 103–114. GB/T 3543.4–1995. 1995. Rules for agricultural seed testing-germination test. National Standard of China. GB/T 5497–1985. 1985. Methods for determination of moisture content for grain and oilseeds. National Standard of China. Nandi, S., Das, G., Sen-mandi, S., 1995. b-Amylase activity as an index for germination potential in rice. Ann. Bot. (Lond.) 75, 463–467. Noble, R.E., 2001. Effect of cigarette smoke on seed germination. Sci. Total Environ. 267, 177–179. Wang, Z., You, R., 2000. Changes in wheat germination following g-ray irradiation: an in vivo electronic paramagnetic resonance spin-probe. Environ. Exp. Bot. 43, 219–225. Wang, A.X., Wang, X.F., Ren, Y.F., Gong, X.M., Bewley, J.D., 2005. Endo-betamannanase and beta-mannosidase activities in rice grains during and following germination, and the influence of gibberellin and abscisic acid. Seed Sci. Res. 15, 219–227. WHO, 1999. High-Dose Irradiation: Wholesomeness of Food Irradiated with Doses above 10 kGy. WHO Technical Report Series 890. World Health Organization, Geneva. Yu, Y., Wang, J., 2005. Effect of g irradiation pre-treatment on drying characteristics and qualities of rice. Radiat. Phys. Chem. 74, 378–383. Yu, Y., Wang, J., 2006. Effect of gamma-ray irradiation on drying characteristics of wheat. Biosyst. Eng. 95, 219–225.
Contents lists available at SciVerse ScienceDirect
Radiation Physics and Chemistry journal homepage: www.elsevier.com/locate/radphyschem
Technical Note
Effect of g-ray irradiation on the germinating characteristics of wheat seed Jun Wang n, Yong Yu, Xiaojing Tian Department of Biosystems Engineering, Zhejiang University, 866 Yuhangtang Road, Hangzhou 301129, PR China
a r t i c l e i n f o
abstract
Article history: Received 7 November 2010 Accepted 18 December 2011 Available online 28 December 2011
Few researches have been reported on the long-term germination characteristics and the effect of high gamma radiation dose on cereal seeds. In this paper, to observe the effects of gamma irradiation (0–3 kGy) on the germination of wheat seed in long-term (within 20 months), wheat seed was dried after irradiation and the germination experiment during storage time was conducted. It was found that the lengths of buds of irradiated wheat seeds diminished, the roots of irradiated wheat seeds disappeared, and no germinations in irradiated wheat seed was found. The influence of g-ray irradiation on roots was more significant than that on buds. After long-term storage, the germination of irradiated wheat seeds increased. & 2011 Elsevier Ltd. All rights reserved.
Keywords: Germination Irradiation Wheat Seed stimulation
1. Introduction The germination of grain seeds is affected by many factors. Some factors belong to properties of grain seeds, such as a and b amylase activity (Nandi et al., 1995; Das and Sen-Mandi, 1992; Wang et al., 2005). The extent of amylase activity probably determines germination ability of cereal seeds. Some factors belong to environmental conditions during germination, such as temperature, CO2 concentration, ethanol, kinetin, dehusking, cigarette smoke, steeping and so on. CO2 concentration can affect both seedling establishment and grain quality of crops (Bai et al., 2003), ethanol and kinetin have stimulatory effects on the germination of dehusked seeds of indica and japonica rice under aerobic and anaerobic conditions (Miyoshi and Sato, 1997a, 1997b), dehusking stimulates the germination of seeds of indica rice but strongly inhibits that of japonica rice (Miyoshi et al., 1996), and cigarette smoke inhibits germination of many kinds of plant seeds including wheat seeds (Noble, 2001). Besides, other factors belong to the processing method for grain seeds before and/or during germination. It has been demonstrated that sound field with 400 Hz and 106 dB is the best condition for germination of rice. Electric field has no significant effects on the germination of rice (Cao et al., 2004), but for other plants (e.g. tomato), electric and magnetic field enhance its germination significantly (Moon and Chung, 2000). The optimum germination conditions for high amylose rice seeds were steeping for 24 h at 25 1C (or 16 h at 35 1C) and germinated for 3 days at 30 1C (Capanzana and Buckle, 1997).
n
Corresponding author. Tel.: þ86 571 86971881; fax: þ 86 571 86971139. E-mail address: [email protected] (J. Wang).
0969-806X/$ - see front matter & 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.radphyschem.2011.12.024
The potential application of ionizing radiation in food processing is based mainly on the fact that ionizing radiations damage the bio-molecules very effectively, deactivating living cells, thereby preventing microorganisms, insect gametes, etc. from reproducing. One of the major advantages of radiation treatment is that it causes no rise in temperature in the product even after packaging thus avoiding re-contamination or re-infection of sterilized sample. Gamma ray possess high penetrating characteristics, thus it can be effectively used for decontamination of seed surface affected with fungi. Sterilization by gamma irradiation also helps in preserving the quality of processed food/seed as no or very negligible degradation is observed compared to other techniques, thus reducing the risk for the consumers (Maity et al., 2009; WHO, 1999). Gamma irradiation is one kind of processing methods, which could affect the germination of grain. Cells of rice and wheat could be destroyed by gamma irradiation (Yu and Wang, 2005, 2006), this is the reason that irradiation affect the germination of rice and wheat seed. There are many surveys describing inhibition of germination by treatment by ionizing radiation, for example, the effects of gamma irradiation on the germination of wheat seeds and gamma germination inhibits the germination of wheat seeds (Barros et al., 2002; Wang and You, 2000). However, in these reports, the germination experiments were finished within 3 months after low dose irradiation (0–1.0 kGy). Few studies have been reported on the long-term germination characteristics and the effects of high gamma radiation dose on cereal seeds. In this paper, to observe the effects of gamma irradiation (0–3 kGy) on the germination of wheat seeds in long-term (within 20 months), wheat seed was dried after irradiation and the germination experiment during storage time was conducted.
464
J. Wang et al. / Radiation Physics and Chemistry 81 (2012) 463–465
2. Materials and methods 2.1. Wheat seeds Wheat (Zhenong 1) harvested in June, 2004, from the experimental farm of Agronomy, Zhejiang University, was used for this experiment. The initial moisture content of wheat seed was 25.0% (dry basis), which was determined by drying five samples at 105 1C (GB/T 5497–1985, National Standard of China). After irradiation, the samples were dried and packed in polyethylene bags and stored in refrigerator at 5 1C (resembling seed lowtemperature storage). 2.2. Gamma irradiation Wheat seeds samples were exposed to 60Co source at an ambient condition at the Institute of Nuclear-agriculture Sciences, Zhejiang University. The samples were divided into 5 sets (500 g each sample) and irradiated at the doses 0 kGy (non-irradiation), 0.6 kGy, 1.5 kGy, 2.4 kGy, and 3 kGy, respectively, with dose rate of 1 kGy/h. 2.3. Air drying Irradiated samples were symmetrically placed on a sifter dried with an air velocity of 0.5 70.1 m/s at low drying temperature of 50 1C. The samples were dried until it reached the final moisture content of 14.5 70.1% (dry basis), which represented the safe moisture value for wheat storage. 2.4. Germination test After dipped into water for 1 h, one hundred wheat seeds were symmetrically placed on two pieces of filter paper. Seeds were incubated under 12 h light and 12 h darkness for 14 day in growth chambers at 30 1C (GB/T 3543.4–1995, National Standard of China). Seeds germination was checked daily and the length of root and sprout were measured at the 14th day. The first set of germination tests was commenced immediately after irradiation, and the other sets of tests were done at intervals of three months. Seeds were considered to be germinated when the roots were longer than 5 mm (Bai et al., 2003). Experiment for each sample had two replications.
14th day). It was evident that the germination rate of wheat seeds was significantly affected by gamma irradiation, and the germination rates decreased to 0% when radiation dose was equal to or higher than 0.6 kGy. The effects of different radiation doses on germination characteristics were represented in bud occur rate (the percentage of wheat grain owning bud). With increasing radiation dose, the average value of bud occur rates decreased from 85% to 50%, and the average length of buds decreased from 5.7 cm to 1.3 cm. Compared with non-irradiated wheat sample (93%, 11.2 cm), the bud occur rate and average length of bud of irradiated wheat samples decreased evidently. However, the occur rate and average length of root decreased to 0% and 0 cm when radiation dose was equal to or higher than 0.6 kGy. The influence of g-ray irradiation on roots may be more significant than that on buds (Table 1). Because seeds were not considered as germinated until the roots were 5 mm long, the effects of g-ray irradiation on germination rate were mainly due to the effects on roots.
3.2. Effect of radiation dose on long-term germination rate of wheat seeds The long-term germination experiments were carried out and the results were shown in Fig. 1 (data measured at 14th day). It showed the changes in germination rates of wheat samples with the increasing storage time. The germination rates of irradiated wheat samples would increase after different storage time. The germination rates were prolonged with increasing radiation dose. The time when germination rates of samples irradiated reach a peak value were about 4, 6, 10 and 12 months under 0.6 kGy, 1.5 kGy, 2.4 kGy and 3 kGy, respectively. After the germination rate reaching a peak value, the germination rates of irradiated wheat samples decreased like non-irradiated wheat sample, and the peak germination rate was comparatively high. For example, the germination rate of wheat samples irradiated at 0.6 kGy, 1.5 kGy, 2.4 kGy and 3 kGy increase to 88%, 85%, 80% and 76% in 20 months. After long-term storage, some germination rates of irradiated wheat samples were higher than that of non-irradiated wheat sample. For example, after 12 months storage, the germination rates of wheat samples non-irradiated and irradiated at 0.6 and 1.5 kGy were 73%, 80% and 86%, respectively. Those changes of germination rates of irradiated wheat samples were assumably due to the self-repair function of irradiated organism.
3. Results and discussion 3.1. Effect of radiation dose on short-term germination rate of wheat seed The results of germination experiment carried out immediately after irradiation, were shown in Table 1 (data measured at Table 1 Results of germination experiment commenced immediately after irradiation (measured at 14th day).
Germination rate (%) Bud occur ratea (%) Average length of bud (cm) Root occur rateb (%) Average length of root (cm)
0 kGy
0.6 kGy
1.5 kGy
2.4 kGy
3 kGy
92 93 11.2 91 8.6
0 85 5.7 0 0
0 71 2.6 0 0
0 62 1.6 0 0
0 50 1.3 0 0
The data were average values of two replications. a b
Bud occur rate: the percentage of wheat grain owning bud. Root occur rate: the percentage of rice wheat owning root.
Fig. 1. Germination rate of long-term germination experiment.
J. Wang et al. / Radiation Physics and Chemistry 81 (2012) 463–465
465
These changes of germination velocity curves of irradiated wheat samples were assembly due to the conjunct effect of respiration and self-repair of wheat seeds (Boubriak et al., 1997).
4. Conclusions (1). The lengths of buds of irradiated wheat seed minished with increasing radiation dose, the roots of all irradiated wheat disappeared, and no germinations of irradiated wheat seed was found. (2). The germination rates were prolonged with increasing radiation dose, but the germination rates of irradiated wheat seed would increase within definite storage time.
Acknowledgments
Fig. 2. Effect of store time on germination characteristics of non-irradiated wheat.
The authors acknowledge the financial support of Chinese National Foundation of Nature and Science through project 3047000 and the project was supported by China Postdoctoral Science Foundation 20060400320. References
Fig. 3. Effect of store time on germination characteristics of 1.5 kGy irradiated wheat.
3.3. Effect of storage time on germination characteristics of irradiated wheat seed The effects of storage time on germination characteristics of nonirradiated wheat samples and 1.5 kGy irradiated wheat samples were shown in Figs. 2 and 3 (other figures were omitted). The germination amount (the amount of germinating seeds in each day in the 14 day germination experiments) of each wheat sample was obvious in these figures. For the non-irradiated wheat samples, it was evident that, with increasing of storage time from 0 to 20 months, the peak amount of germinating seeds decreased and the time needed to reach the peak amount increased (Fig. 2). These changes in germination velocity curves of non-irradiated wheat samples were assembly due to the effect of respiration of wheat seeds. For the 1.5 kGy irradiated wheat samples, with the increasing of storage time from 8 to 12 months, the peak amount of germinating seeds increased and the time needed to reach the peak amount decreased (Fig. 3). With increasing storage time from 16 to 20 months, the peak amount of germinating seeds decreased, and the germination velocity curves may be similar to that of non-irradiated wheat samples if store time prolonged.
Bai, Y., Tischler, C.R., Booth, D.T., Taylor, E.M., 2003. Variations in germination and gain quality within a rust resistant common wheat germplasm as affected by parental CO2 conditions. Environ. Exp. Bot. 50, 159–168. Barros, A.C., Freund, M.T.L., Villavicencio, C.H., Delincee, H., Arthur, V., 2002. Identification of irradiated wheat by germination test, DNA comet assay and electron spin resonance. Radiat. Phys. Chem. 63, 423–426. Boubriak, I., Kargiolaki, H., Lyne, L., Osborne, D.J., 1997. The requirement for DNA repair in desiccation tolerance of germinating embryos. Seed Sci. Res. 7, 97–105. Cao, W., Nishiyama, Y., Koide, S., Lu, Z.H., 2004. Drying enhancement of rough rice by an electric field. Biosyst. Eng. 87, 445–451. Capanzana, M.V., Buckle, K.A., 1997. Optimisation of germination conditions by response surface methodology of a high amylose rice (Oryza sativa) cultivar. LWT- Food Sci. Technol. 30, 155–163. Das, G., Sen-Mandi, S., 1992. Utilisation of free fatty acids during germination of unaged and differentially aged wheat embryos. Indian J. Exp. Biol. 30, 299–301. Maity, J.P., Chakraborty, S., Kar, S., Panja, S., JeanJ., -S., Samal, A.C., Chakraborty, A., Santra, S.C., 2009. Effects of gamma irradiation on edible seed protein, amino acids and genomic DNA during sterilization. Food Chem. 114, 1237–1244. Miyoshi, K., Sato, T., 1997a. The effects of ethanol on the germination of japonica and indica rice (Oryza sativa L.) under anaerobic and aerobic conditions. Ann. Bot. (Lond) 79, 391–395. Miyoshi, K., Sato, T., 1997b. The effects of kinetin and gibberellin on the germination of dehusked seeds of indica and japonica rice (Oryza sativa L.) under anaerobic and aerobic conditions. Ann. Bot. (Lond.) 80, 479–483. Miyoshi, K., Sato, T., Takahashi, N., 1996. Differences in the effect of dehusking during formation of seeds on the germination of seeds of indica and japonica rice (Oryza sativa L.). Ann. Bot. (Lond.) 77, 599–604. Moon, J.D., Chung, H.S., 2000. Acceleration of germination of tomato seed by applying AC electric and magnetic fields. J. Electrostat. 48, 103–114. GB/T 3543.4–1995. 1995. Rules for agricultural seed testing-germination test. National Standard of China. GB/T 5497–1985. 1985. Methods for determination of moisture content for grain and oilseeds. National Standard of China. Nandi, S., Das, G., Sen-mandi, S., 1995. b-Amylase activity as an index for germination potential in rice. Ann. Bot. (Lond.) 75, 463–467. Noble, R.E., 2001. Effect of cigarette smoke on seed germination. Sci. Total Environ. 267, 177–179. Wang, Z., You, R., 2000. Changes in wheat germination following g-ray irradiation: an in vivo electronic paramagnetic resonance spin-probe. Environ. Exp. Bot. 43, 219–225. Wang, A.X., Wang, X.F., Ren, Y.F., Gong, X.M., Bewley, J.D., 2005. Endo-betamannanase and beta-mannosidase activities in rice grains during and following germination, and the influence of gibberellin and abscisic acid. Seed Sci. Res. 15, 219–227. WHO, 1999. High-Dose Irradiation: Wholesomeness of Food Irradiated with Doses above 10 kGy. WHO Technical Report Series 890. World Health Organization, Geneva. Yu, Y., Wang, J., 2005. Effect of g irradiation pre-treatment on drying characteristics and qualities of rice. Radiat. Phys. Chem. 74, 378–383. Yu, Y., Wang, J., 2006. Effect of gamma-ray irradiation on drying characteristics of wheat. Biosyst. Eng. 95, 219–225.