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Induction of Physical Mutations in Gladiolus grandiflorus L. through Gamma Irradiation
Abstract
Gladiolus is one of the most popular cut flowers cultivated in India, and it is excellent for inducing physical mutagenesis. The present study was carried out to determine the optimal lethal dose for gamma rays and to induce mutations through gamma irradiation in two gladiolus varieties, Arka Amar and Arka Thilak. The corms of both varieties were irradiated with gamma ray of doses 25, 40, 55 and 70 Gy using a gamma chamber with 60Co as the radiation source. The mortality rate of the plants increased significantly with increasing radiation doses, with Arka Thilak showing higher sensitivity. The LD50 (lethal dose) values were determined as 58.22 Gy for Arka Amar and 58.31 Gy for Arka Thilak through probit analysis. Based on the LD50, the effective doses were fixed as 45, 50, 55, 60 and 65 Gy, along with a control, for both varieties. Corms of gladiolus varieties were then treated with the selected doses of gamma radiation to induce physical mutation. Six treatments of each variety were evaluated in factorial completely randomized design with three replications. The characters like number of leaves per plant, length and diameter of the floret, and plant height were highest in Arka Thilak treated with 45 Gy. The number of spikes per plant and spike length were highest in the same variety treated with 50 Gy. In Arka Amar, the length of leaf blade and field life were maximum at 45 Gy, and a greater number of florets per spike was observed at 50 Gy. Among the treatments, lower doses promoted better growth, whereas higher doses had detrimental effects. Attractive colour mutants were obtained in Arka Amar at higher doses. The study suggest the ability of gamma irradiation to induce beneficial mutations in gladiolus, creating opportunities for breeding new varieties with improved ornamental traits.
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An experiment was conducted at Sam Higginbottom University of Agriculture Technology And Sciences, Allahabad in the year 2017-2018 to check the effect of different doses of Gamma radiation (0kR, 1.5kR, 3kR, 4.5kR, and 6kR) on corms of three different gladiolus cultivars namely Praha, Tiger flame, and Snow Princess, it was established that till 3 kR most of the characters were stimulated but started to sink from 4.5kR. However, 6kR treated corms produced leathery and narrower leaves with shorter plant height (57.41 cm), less leaf number (6.75), less sprouts/corm (1.57), and least spikes/plant (1.14) with an abnormal spike. While 1.5 kR treatment proved the most beneficial for various growth parameters including Plant height (87.21cm), the number of leaves (10.76), early sprouting (14.40 days), Early flowering (72.37 days), Longest flower spike (75.41 cm) and more spikes per plant (2.90). Among the Cultivars Tiger flame and Praha were found to respond well to lower doses of gamma radiation and consider being more suitable for gamma treatment. Moreover, discolor basal floret was found in Praha in 1.5kR treated corms, and Chimera was found on Tiger Flame variety at 3kR
This investigation was carried out to determine the effects of gamma radiation on germination characteristics of gladiolus corms. This experiment was conducted through a factorial design in randomized complete block with three replications. Two factors included cultivars of gladiolus (Red Advance, White Prosperity, Amsterdam, and Rose Supreme) and doses of gamma radiation (0, 15, 25, 35, 45, 55, 65, and 75 Gy). The results showed that corm weight, corm size, and number of daughter corms decreased with increasing radiation doses, however, low dose (15 Gy) stimulated them. High doses of gamma irradiation (75 Gy) showed the lethal effects on various vegetative traits. The low yield at high doses can be due to the reduced vegetative growth as a result of gamma treatments. The results of this study suggest a dose of 40-65 Gy as the optimal dose to improve the vegetative traits of gladiolus.
Gladiolus, the queen of bulbous ornamentals is very popular perennial cut flower owing to its marvelous beauty, striking colours, various sizes and shapes of flower, variable spike length and long vase life. In this experiment corms of eight varieties of gladiolus (Yellow Golden, Nathan Red, White Friendship, Jester Gold, American Beauty, Red Majesty, Purple Flora and Algarve) were treated with gamma rays and the frequency and spectrum of morphological mutations observed up to three generations at Model Floriculture Centre, G.B. Pant University of Agriculture and Technology during2012-2015. Uniform and healthy corms of eight gladiolus varieties were taken and irradiated with different doses (0, 25, 40, 55 and 70 Gy) of gamma rays from 60 Co source and planted in open field condition in Randomized Block Design (RBD) with factorial concept. The outcomes indicated that the plant survival decreased after gamma irradiation and minimum survival (77.11%) was recorded at 70 Gydose. Differences in varietal response to different mutagen doses were clearly evident as all the varieties differed in the spectrum and frequency of induced mutations. In vM1generation maximum flower colour mutation frequency was recorded in variety Purple Flora followed by Algarve and White Friendship. Irrespective of varieties, among different doses maximum mutation frequency was recorded at 55 Gy. In vM1 generation, maximum mutation frequency (18.52%) was recorded in Purple Flora variety at 55 Gy gamma rays irradiation. Most of the mutants were in the form of chimera in vM1 and few disappeared in vM2 whereas most of the mutants isolated in vM2 generation were solid mutants. A wide spectrum of colour was observed in treated plants and in general variants were lighter in colour than the original variety. Sixteen mutants, isolated from three varieties of gladiolus (White Friendship, Purple Flora and Algarve) were planted to raise vM3generation and out of these twelve were found stable for their colour.
ABSTRACT
Gladiolus is grown all over the world for cut flower production for floriculture trade. Extensive
research has already been done on gladiolus to generate basic knowledge on multidisciplinary
aspects. Efforts in germplasm collections, characterisation, cytology, tissue culture, disease
management, classical improvement and induced mutation are worth mentioning. Despite significant
technological advances, we are still repeating some of our experiments as routine activities. Selective
breeding is now most essential to develop varieties as per requirement of the trade. This will be
possible in two ways-utilising all available knowledge as guidelines and identification and wise
selection of parents having desirable genes prior to cross-breeding.
The experiment was carried out on gladiolus variety ‘Psittacinus Hybrid’ to know the best
mutagen between physical mutagen (Gamma rays) and chemical mutagen (DES). The
experiment was carried out at Floriculture Research Farm, ASPEE college of Horticulture
and Forestry, Navsari during the year 2013-2014.The corms of gladiolus were treated with
different doses of gamma rays viz. 5.5 kR, 6.0 kR, 6.5 kR, 7.0 kR, 7.5 kR and 8.0 kR and
different concentrations of DES 0.1%, 0.2%, 0.3%, 0.4% and 0.5%. Different vegetative
and flowering characters were taken under study. It was observed that there was negative
correlation of sprouting and survival per cent with the different treatments and it was also
noticed that survival per cent of DES treated corms was less compared to gamma rays.
Looking at vegetative characters it was found that DES had more pronounced effect on
vegetative characters similarly for flowering characters DES produced larger spikes and
with more no. of florets as compared to Gamma rays. Plants were more responsive to treatment of DES as compared to gamma rays.
Genetic variability is the prerequisite for any crop to be improved. Mutation breeding is a best method identifed to enhance the genetic variability in crops within short time. Knowing the limited variability in tuberose (Polianthes tuberosa), present investigation was undertaken for the improvement in this crop by utilizing the cultivars Phule Rajani and Prajwal. To induce variation, gamma radiation (2.5-15 Gy) was applied and the effect on flower and bulb characters were assessed in M 1 generation. With increase in doses of gamma irradiation, gradual reduction in number of spikes, flower number, number of bulb, weight of bulb and bulb diameter was observed. In some cases lower dose was found simulative, while higher dose had inhibitory effect on morphological variation. Various macro mutations were scored for uniform flowering, reduced number of bulbs and spike number in M1 population. The mutants of VM 1 generation not found stable in VM2 generation. But we could able to fnd the some more mutants from the maintained gamma irradiated population of VM1 generation related to change in flower shape. In general, freshly harvest tuberose bulbs of cv. Prajwal and Phuel Rajani responded more to gamma irradiation. From this study, it has found that gamma irradiation level, 7.5 Gy and 10.0 Gy were found optimal for mutation induction in these two tuberose cultivars.
