The process of mutation breeding for strawberry varieties entailed subjecting runner sections to irradiation, specifically utilizing three unique dosages of 60Co-gamma rays. The present study was carried out at Lovely Professional University, wherein strawberry runners belonging to the cv. Chandler were subjected to varying dosages of acute gamma radiation. The irradiation therapy was conducted at Punjab Agriculture University using the 60Co source. Different concentrations, namely 20 Gy, 30 Gy, 40 Gy, and 0 Gy, were administered at a consistent dosage rate of 1.52 Gy per minute. The physiological effects arising from irradiation were evaluated by the LD50 analysis, which was measured 30 days post-transplantation, serving as a benchmark for three distinct levels of irradiation dosages. The highest mortality rate was recorded in the group exposed to the maximal dosage of irradiation, which was 40 Gy. In addition to the control group, it was noted that the irradiated dose of 20Gy yielded the greatest plant height, fruit length, and diameter, while the lowest results were obtained from the 40 Gy treatment. Furthermore, the 20 Gy dose exhibited the largest leaf area index, number of leaves, and chlorophyll levels, whereas the 40 Gy treatment yielded the lowest outcomes. The occurrence of early flower bud formation was documented at a dose of 30 Gy, while late flower bud formation was observed at a dose of 20 Gy. Additionally, early flowering was noted at a dose of 40 Gy, with late flowering occurring at a dose of 20 Gy. Furthermore, early fruit set was found at a dose of 40 Gy, while late fruit set was observed at a dose of 20 Gy. In our observation of yield, we recorded the largest number of buds, flowers, and fruits at a radiation dose of 20 Gy. Conversely, we noticed a lesser number of buds with a radiation dose of 40 Gy. The results indicate that the maximum values for primary secondary root length and root number were recorded in the 30 Gy treatment, while the lowest values were observed in the 40 Gy treatment. Additionally, a greater number of deformed fruit and leaves were observed in the 40 Gy treatment of gamma irradiation dose. These findings would be beneficial in future endeavours aimed at producing potential mutants in the strawberry plant.
Research Article
Standardization of suitable Gamma irradiation doses 60 Co for mutagenesis in strawberry (Fragaria × annanasa Duch) cv. Chandler
https://doi.org/10.21203/rs.3.rs-3643574/v1
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Gamma irradiation
60Co
strawberry runners
chandler
different doses
The strawberry (Fragaria x ananassa Duch) is highly popular among consumers in various parts of the world (Fan et al., 2021). In commercial production, cultivars of Fragaria × ananassa have taken over the woodland strawberry (Fragaria vesca), which was the initially cultivated strawberry species in the early 17th century. Strawberry is cultivated throughout much of the US, Canada, Europe, Southern and Eastern Africa, New Zealand, Australia, and Japan. The US produces 30% of global supplies. In the early sixties, NBPGR Regional Research Station, Shimla (Himachal Pradesh) introduce the crop to India (Anonymous, 2019) In India, strawberries are grown extensively for commercial purposes in several states, such as Himachal Pradesh, Uttarakhand, Uttar Pradesh, Punjab, Haryana, Karnataka, Tamil Nadu, and Maharashtra. In India, the cultivation of this crop spans across a 1000-hectare region, resulting in a combined yield of 8000 metric tons (NHB,2021-22).
Generating novel strawberry germplasm through various breeding techniques is of utmost importance. Mutation breeding has been a pivotal factor in improving global food security. The development of new crop varieties through the use of different mutagens has substantially increased crop production. In recent times, physical mutagens have played a crucial role in generating desirable traits in crop breeding. Among these, gamma irradiation has proven to be an especially effective tool for inducing new traits in various crop plants (Yasmin et al.,2022). The application of gamma irradiation causes artificial induction of mutations, leading to physiological, biochemical, and agronomic changes in plant growth by altering the cellular makeup (Sarkar et al., 2018). Consequently, gamma irradiation emerges as a potent tool for driving genetic alterations and enhancing crops through the generation of advantageous mutants (Yasmin et al. 2020).
Gamma irradiation serves as a widely utilized physical mutagen and proves highly efficient in introducing genetic variations in several fruits, including Strawberry (El Oualkadi et al. 2019), Guava (Singh S et al. 2018), citrus (Pérez-Jiménez et al. 2020), Mango (Arthur et al. 2021), Grape (Surakshitha et al. 2017), Papaya (Chaudhari et al. 2022), Pear (Predieri et al. 2000), and Kiwifruit (Yook et al. 2009). Two factors influence the impact of gamma rays on plant growth characters. The first factor pertains to plant characteristics, including species, genus, and growth stage. The second factor is associated with the irradiation process, encompassing aspects such as the source of irradiation, dose level, and dose rate (Jan et al. 2012).
Considering this, the primary objectives of the current research were to experiment with exposing strawberry runner plants to varying doses of 60Co-gamma rays. The purpose was to investigate the impact of irradiation on factors such as lethality, growth, development, and productivity. The ultimate goal was to determine the sensitivity of strawberries to irradiation and identify the optimal dosage for strawberry cultivar Chandler. Additionally, the study aimed to offer valuable insights for strawberry mutation breeding using 60Co-gamma rays as a physical mutagen.
The commercially grown strawberry cultivars selected for this study were Chandler. The runner plants of these strawberry cultivars were used as the experimental planting materials. The runner plants were dug and collected from the strawberry field at ICAR Regional Station Shimla, Himachal Pradesh in mid-October 2022. Subsequently, they were irradiated immediately with 60Co-gamma rays (Fig. 1) at Punjab Agriculture University, Ludhiana, Punjab.
The doses administered during the experiment were categorized into four groups: 0 Gy (Control), 20 Gy, 30 Gy, and 40 Gy, and they were applied at a rate of 1.52 Gy per minute. Each treatment of the Chandler variety consisted of 25 runner plants, and all treatments were replicated once. follows the irradiation treatment, the runner plants were immediately transplanted into plastic pots filled with a mixture of sand, cocopeat, and vermicompost in a 1:1:1 ratio, with a total weight of 5 kg. This transplantation took place in a polytunnel (Fig. 2) at Lovely Professional University's Agriculture farm, located in Phagwara, Punjab. In the experiment, a complete randomized design (CRD) was used, comprising five replications, with each replication consisting of five plants of the Chandler variety. The study involved four different treatments. A commercially cultivated strawberry variety was collected for this study. The plants were pruned, removing runners, dead leaves, and flowers before subjecting them to mutagen treatment plants were then divided into three groups, and each group received a different dose of the mutagen. Each set of 25 plants was carefully placed in a container for irradiation. The duration of radioactive decay was observed and recorded during the experiment.
After treatment the strawberry runners to physical mutagenesis through Gamma irradiation, two sets of plants were established: one group consisted of 75 treated runners, while the other group had 25 untreated (control) runners. The planting of these runners occurred promptly within 24 hours, with each of them placed in separate plastic pots. Immediately after planting, light irrigation was administered, followed by subsequent irrigations based on the soil's moisture levels. The individual growth of plants (one plant per pot) took place under controlled conditions at temperatures of 28°C during the day and 20°C during the night. The relative humidity was maintained between 60% and 75%, and the photoperiod was set at 14 hours of light and 10 hours of darkness. Throughout the cultivation process, three rounds of manual weeding followed by hoeing were carried out, the first after 20 days and the second after 25 days from the transplanting date. Observations were made on five randomly chosen plants from each replication of both treatments at intervals after the plants had recovered from the initial transplanting shock.
Growth related observations
The LD50 doses of radiation will be determined using the probit analysis method, which involves analyzing the mortality percentages at 15 and 30-day intervals after treatment. The calculation of the LD50 dose through Probit analysis will be based on the observations of sprouting percentage and survival rate, following the methodology outlined by Sharma in 1998.
The number of shoots exhibiting the growth with non-browning shoots will be taken at 15, 20 and 30 days of treatment. The calculation will be performed utilizing a specific formula.
The height of each plant in every pot was measured in centimetre using a meter scale, and then the average height was calculated. The number of leaves on each plant in each pot was counted, and the average leaf count was determined. The Leaf Area Index (measured in millimetre) was obtained using a destructive method with the CL-202 Leaf Area Meter (USA). The measurement involved mature leaves, and their values were expressed in millimetres. Chlorophyll content was non-destructively measured using a SPAD meter on mature leaves of each plant in each pot. Observations were made to record the number of days taken for flower bud initiation, flowering, and fruiting from the date of strawberry plant transplantation until the end of the experiment. Additionally, the primary and secondary root lengths, Crown diameter of each strawberry plant under different treatments were measured in centimetres using a meter scale, and the number of primary and secondary roots was counted.
Yield related observation
The number of flower buds, flowers, and fruits per plant was determined by tallying the total number of leaves and counting the number of flower buds, open flowers, and mature fruits on each plant in every pot. Subsequently, the average value was calculated. Fruit quality related observation: Fruit length and diameter were assessed with the Digital Calliper − 515 (DC-515) in millimetres (mm). The average value was determined for each treatment. Brix percentages will be determined using a portable digital refractometer from ERMA, Tokyo, Japan.
Statistical analysis
The data analysis was conducted using SPSS-21 software (SPSS, Chicago, IL). The significance of differences between treatments for the various observed parameters was assessed using one-way ANOVA. The analyzed data employed the least significant difference (LSD) test to ascertain the statistical significance of the disparity between the two means, with a significance level of 5 percent (Gomez and Gomez, 1984). The statistical significance of the treatment effects was evaluated using a significance level of 5%.
LD50 lethal dose
To determine the best dose, LD50 analyses were conducted. The treatment of various doses of gamma radiation shows different results that the number of surviving runners decreased as the dose of irradiation increased. The LD50 analysis was taken 30 days after irradiation and served as the reference for selecting three irradiation levels of 20 Gy, 30 Gy, and 40 Gy to potentially create mutant plants. Exposure to radiation up to 30 Gy had no effect on the survival rate of runners, whereas the treatment with 40 Gy resulted in a reduced survival rate. During this experiment, the observations were taken 30 days after transplanting, and the results for the Chandler variety of plants treated with different levels of irradiation were found out of 25 treated plants exposed to 20 Gy of irradiation, 9 plants were observed to have been killed. Similarly, among the 25 treated plants exposed to 30 Gy of irradiation, 10 plants were found to have been killed. The highest number of killed plants 12, was recorded in the dose exposed to 40 Gy of irradiation. On the other hand, the dose not subjected to any irradiation (0 Gy) control had 3 killed plants (Table 2).
| Treatments | Dose rate | Time of radioactive decay. |
|---|---|---|
| T1 | 20 Gy | 10 min 14 sec |
| T2 | 30 Gy | 15 min 22 sec |
| T3 | 40 Gy | 20 min 29 sec |
| T0 | 0 Gy | Control |
| Concentration | Total no. of plant | Killed plant | No of survived | % of Survival |
|---|---|---|---|---|
| 20 Gy | 25 | 9 | 17 | 68% |
| 30 Gy | 25 | 10 | 16 | 64% |
| 40 Gy | 25 | 12 | 14 | 56% |
| 0Gy | 25 | 8 | 21 | 84% |
The survival percentage of plants showed no variation between the control 0 Gy and the dose exposed to 20 Gy of radiation. However, a higher number of plants had been found to be killed when exposed to 40 Gy of radiation, while the minimum number of killed plants had been observed in the 20 Gy dose. Based on the findings, it was determined that the survival percentage of 30 days strawberry runner plantlets was reduced when they were exposed to doses of gamma irradiation, as compared to the control. The plantlets that didn't receive any gamma irradiation shows the highest survival percentage at 90%. Following this, the plantlets exposed to a dose of 20 Gy exhibited a good survival percentage. In contrast, the plantlets exposed to 40 Gy of gamma irradiation showed the lowest survival percentage. The highest survival percentage was noted in the plantlets treated with a 20 Gy dose of irradiation. These results were presented in the (Table 2).
Growth Attributes
The plant runners' survival significantly improved when they were transplanted into plastic pots. Nevertheless, their plant height, leaf count, leaf area index (mm), and chlorophyll content underwent alterations compared to the control. However, the extent of these changes varied depending on the dosage of irradiation. At different irradiation doses, the height of the plant was maximum at a dose of 20 Gy. The minimum plant height was recorded with the irradiation dose of 40 Gy. The number of leaves for each plant in every pot is a crucial factor for photosynthesis and varies between 10.9 to 15.7. among the gamma irradiation-treated runner plant 20 Gy dose shows the maximum number of leaves, whereas the minimum leaf count was observed at the 40 Gy dose. Among the different irradiation doses the maximum LAI was recorded in 20 Gy of dose and the minimum LAI was recorded in 40 Gy of Gamma irradiation dose.
Chlorophyll was measured to check the greenness of the plant. It differed with irradiation dosage, with the maximum chlorophyll being observed at 20 Gy, followed by the minimum observed at 40 Gy (Table 3). In our study on the leaf-related traits of treated strawberry runners, among the gamma irradiation doses observed that the application of a 20 Gy dose of Gamma irradiation resulted in the maximum leaf number, leaf area index (mm), and increased chlorophyll content in strawberry plants. Conversely, when using a 40 Gy dose of gamma irradiation, minimum values were recorded for these leaf characteristics.
| Dosage | Plant Height | Leaf Number | Leaf Number | LAI (mm) | Chlorophyll | Leaf Abnormalities |
|---|---|---|---|---|---|---|
| 20Gy | 25.94b (5.19) | 14.74b (3.96) | 14.74b (3.96) | 28.29a (5.41) | 48.46a (7.03) | Normal trifoliate leaf |
| 30Gy | 18.66c (4.43) | 11.84c (3.58) | 11.84c (3.58) | 21.292b (4.72) | 47.88a (6.98) | Narrow rugose leaf, trifoliate leaf |
| 40Gy | 15.654d(4.08) | 10.9d (3.44) | 10.9d (3.44) | 15.93c (4.11) | 46.08a (6.86) | Wrinkled leaf, Trifoliate leaf |
| 0Gy | 28.08a (5.39) | 15.76a (4.09) | 15.76a (4.09) | 20.71b (4.66) | 48.5a (7.05) | Normal Trifoliate leaf |
| C.D. | 1.36 (0.142) | 0.589 (0.077) | 0.589 (0.077) | 1.34 (0.146) | N/A | |
| SE(m) | 0.462(0.047) | 0.195 (0.025) | 0.195 (0.025) | 0.446 (0.048) | 0.952 (0.069) | |
| SE(d) | 0.653(0.067) | 0.276 (0.036) | 0.276 (0.036) | 0.63 (0.068) | 1.346 (0.098) | |
| C.V. | 4.674(2.207) | 3.273 (1.506) | 3.273 (1.506) | 4.623 (2.285) | 4.58 (2.223) | |
| The values show in the table represent the average of five replications. Distinct letters within the same column indicate significant variances at a significance level of P < 0.05, determined by the Ducan Multiple Range Test. Values in the brackets are transformed. | ||||||
Yielding attributes
The time taken for the first bud to initiate was measured from the day of transplanting, and the results varied based on the different dosages. The among the irradiation doses earliest bud initiation was observed in the 30 Gy dosage. The greater number of days required for the first flower bud initiation was recorded at the 20 Gy dose (Table 4). The number of days it took for flowering to occur after transplanting was noted follow the emergence of buds. The treated dose of 40 Gy plant resulted in the observation of early first flowering with the 20 Gy treatment causing a delay in flowering. After observing the flower bud and flowering stages, we proceeded to count the number of days It took for fruit setting to occur after transplanting, varying the treatment dosages. Among the irradiation dose the earliest fruit setting was observed in plants exposed to a 40 Gy dose. while the greater number of days taken for fruit setting in irradiation dose 20 Gy (Table 5).
| Dosage | Days to flower bud | Number of flower bud | Days to flowering | Number of flowers | Number of flowers |
|---|---|---|---|---|---|
| 20Gy | 61.6a (7.91) | 30.84a (5.64) | 63.9a (8.05) | 30.58 a (5.61) | 30.58 a (5.61) |
| 30Gy | 35.16c (6.01) | 28.94b (5.47) | 57.66b (7.65) | 28.68b (5.44) | 28.68b (5.44) |
| 40Gy | 43.94b (6.70) | 15.14d (4.01) | 50.98c (7.20) | 15.1d (4.01) | 15.1d (4.01) |
| 0Gy | 26.08d (5.20 | 19.34c (4.51) | 31.32d (5.68) | 18.66C (4.43) | 18.66C (4.43) |
| C.D. | 2.39 (0.195) | 1.349 (0.148) | 3.444 (0.224) | 1.401 (0.151) | 1.401 (0.151) |
| SE(m) | 0.793 (0.065) | 0.446 (0.049) | 1.139 (0.074) | 0.463 (0.05) | 0.463 (0.05) |
| SE(d) | 1.121 (0.091) | 0.631 (0.069) | 1.611 (0.105) | 0.655 (0.071) | 0.655 (0.071) |
| C.V. | 4.25 (2.234) | 4.234 (2.223) | 4.997 (2.318) | 4.454 (2.296) | 4.454 (2.296) |
| The values show in the table represent the average of five replications. Distinct letters within the same column indicate significant variances at a significance level of P ≤ 0.05, determined by the Ducan Multiple Range Test. Values in the brackets are transformed. | |||||
| Dosage | Days to fruit set | Number of fruits | Fruit Length | Fruit Diameter | Fruit Abnormalities |
|---|---|---|---|---|---|
| 20Gy | 82.5a (9.13) | 32.24a (5.76) | 39.17a (6.33) | 28.78b (5.47) | Conical, Cordate, wedged |
| 30Gy | 76.24b (8.78) | 25.9b (5.18) | 35.03a (6.00) | 25.3c (5.12) | Obloid, Globose |
| 40Gy | 59.58c (7.78) | 15.18d (4.02) | 19.82b (4.56) | 18.21d (4.38) | Rhomboid, Cylindrical, wedged |
| 0Gy | 77.88ab (8.87 | 18.74c (4.43) | 40.02a (6.40) | 31.03a (5.65) | Conical, Globose |
| C.D. | 4.978 (0.277) | 1.548 (0.157) | 1.761 (0.051) | 1.66 (0.161) | |
| SE(m) | 1.646 (0.092) | 0.512 (0.052) | 0.582 (0.051) | 0.551 (0.053) | |
| SE(d) | 2.328 (0.13) | 0.724 (0.074) | 0.824 (0.072) | 0.779 (0.075) | |
| C.V. | 4.971 (2.37) | 4.974 (2.398) | 3.886 (1.955) | 4.771 (2.311) | |
| The values show in the table represent the average of five replications. Distinct letters within the same column indicate significant variances at a significance level of P ≤ 0.05, determined by the Ducan Multiple Range Test. | |||||
| Values in the brackets are transformed. | |||||
During our observation of fruit-related parameters, we noticed that when plant bear flower buds the treated plant of 30 Gy irradiation dose shows early flower bud apart from other treated doses, flowering commenced earlier in 40 Gy of gamma dose, with 40 Gy of gamma irradiation dose early fruit set was observed as compared with other treated doses. The maximum number of buds was observed in the dose exposed to a radiation of 20 Gy. On the other side, the minimum number of buds was recorded in the 40 Gy dose. These observations were taken at 71 days, and a final average was calculated (Table 4). After calculating the number of buds, we recorded observations related to yield in terms of the number of flowers at 81 days. The maximum number of flowers was observed at a dose of 20 Gy. The minimum number of flowers was recorded at a dose of 40 Gy (Table 4). Following the appearance of healthy flowers, fruit production was monitored. The maximum number of fruits was observed at a radiation dose of 20 Gy, while the minimum number of fruit was recorded at a dose of 40 Gy. In our observations related to yield, we found that the highest count of flower buds, flowers, and fruits was recorded at a gamma irradiation dose of 20 Gy. Conversely, a lower number of flower buds, flowers, and fruits were observed at a dose of 40 Gy.
Quality attributes
Among the irradiation doses Gamma radiation dose with 20 Gy shows maximum fruit thickness. The minimum fruit thickness was observed at a radiation dose 40 Gy (Table 5). During the observation of treated strawberry plants shows in fruit quality, we observed that the fruit's length and diameter were significantly reduced at a 40 Gy dose of Gamma irradiation. Conversely, the most substantial length and diameter of fruit were noted at a 20 Gy dosage.
During the harvesting period, we observed various fruit abnormalities that resulted from different gamma irradiation doses, as shown in (Table 5). At a dose of 20 Gy, the fruits exhibited conical, cordate, and wedged shapes. With a 30 Gy dose, obloid and globose shapes were observed, while a dose of 40 Gy led to rhomboid, cylindrical, and wedged fruit shapes. The untreated group (0 Gy) showed conical and globose fruit forms, as depicted in (Fig. 4).
Various leaf abnormalities were noted when subjected to varying doses of Gamma irradiation. At a dosage of 20 Gy, the leaves appeared normal with three leaflets. However, at 30 Gy, the leaves were narrow and had a wrinkled appearance with three leaflets. Further, at a dosage of 40 Gy, the leaves displayed a wrinkled pattern with three leaflets. Meanwhile, in the control (0 Gy), normal trifoliate leaves were observed (Table 3). Prior investigation that criticized the leaf irregularities observed in plants exposed to radiation.
Root length and Number of root
The root serves as the site for plant growth, and an increase in root length is expected to enhance the strength and vitality of the plants. In a study involving strawberry runners exposed to different doses of Gamma irradiation (20 Gy, 30 Gy, 40 Gy, and 0 Gy), (Table 6) the root length varied across the doses, with the maximum primary and secondary root length observed in 30 Gy (Fig. 5). Conversely, the minimum root length was observed at 40 Gy.
| Dosage | Primary root length | Secondary root length | Number of primary with secondary root | Crown/ Stem Diameter (mm) |
|---|---|---|---|---|
| 20Gy | 26.52b (5.24) | 4.86a (2.42) | 32.8b (5.81) | 12.27b (3.64) |
| 30Gy | 28.22a (5.40) | 5.14a (2.47) | 40.4a (6.43) | 14.17a (3.89) |
| 40Gy | 16.08d (4.13) | 3.2c (2.04) | 31bc (5.60) | 10.27c (3.5) |
| 0Gy | 24.56c (5.05) | 4.28b (2.29) | 30.4c (5.65) | 10.44d (3.83) |
| C.D. | 1.567 (0.162) | 0.289 (0.063) | 2.006 (0.175) | 0.807 (0.114) |
| SE(m) | 0.518 (0.054) | 0.096 (0.021) | 0.663 (0.058) | 0.267 (0.038) |
| SE(d) | 0.733 (0.076) | 0.135 (0.029) | 0.938 (0.082) | 0.377 (0.053) |
| C.V. | 4.859 (2.413) | 4.894 (2.011) | 4.4 (2.197) | 4.957 (2.333) |
| The values show in the table represent the average of five replications. Distinct letters within the same column indicate significant variances at a significance level of P < 0.05, determined by the Ducan Multiple Range Test. Values in the brackets are transformed | ||||
In our own observation related to crown diameter, among the irradiation doses we found that the highest crown diameter was observed at gamma irradiation doses of 30 Gy and while the minimum crown diameter was seen at 40 Gy. Crown diameter of strawberry plants cv. 'Pircinque' using a digital Vernier caliper, recording the measurements in millimeters. The study revealed that plants with larger crown diameters demonstrated better productive performance and improved the quality of harvested fruits compared to less vigorous plants. Plants with crown diameters of 15 and 17 mm resulted in higher yields and precocity values, along with fruits of high physical-chemical quality.
The main aim of induced mutation studies is to ascertain the optimal dosage for a particular cultivar. The reported decrease in growth found in strawberry runners that have been exposed to radiation is typically regarded as a sign of genetic harm inflicted upon the plant. In order to ascertain the optimal dosage for the purpose of generating mutations, it is imperative to establish the LD50 dose. In the conducted experiment, the LD50 value of papaya cultivars was seen to be improved. In general, it was observed that the germination, survival, and growth rate of papaya exhibited a downward trend as the gamma irradiation dosages were raised. According to Ravi et al. (2022), Significantly, the findings of this study are consistent with previous research conducted by Zamir et al. (2003), which also reported that the percentage of sprouting was greater at lower concentrations of irradiation doses compared to higher concentrations in Guava plants. This observation indicates that the trend observed in the sprouting buds could perhaps be attributed to the carcinogenic impact of irradiation on chromosome abnormalities. The lethal dosage for 50% of the buds (LD50) was established at 30 Gy, leading to a lethality rate of 78.95% for bud survival (Preuss and Britta, 2003). According to the paper, the observed suppression of growth resulting from exposure to elevated levels of radiation can be attributed to the halt of the cell cycle at the G2/M phase during somatic cell division, as well as the potential infliction of harm upon the entirety of the genome.
The findings of this study are consistent with previous research conducted by Gupta et al. (2011) on the strawberry variety Chandler. The effects of gamma irradiation were observed to differ across different doses of irradiation. An experiment was conducted in Banana Cv. Bhimkol, whereby gamma irradiation was employed at different doses. According to Soorianathasundaram et al. (2022), the findings demonstrated a gradual decline in the percentage of germination as the dose of gamma irradiation dose.
Based on the findings of the previous study, which involved the examination of plantlet mortality percentage and growth performance, it was recommended that a dosage range of 20 to 30 Gy exhibited a death rate of approximately 50%. This finding is consistent with prior research conducted on citrus crops (Arisah et al., 2017). The administration of a precise dosage was taken into account as a therapeutic intervention for inducing mutations in strawberry explants by the utilization of gamma rays. At the specified dosage, the researchers hypothesized that genetic modifications would occur, even in the absence of observable morphological alterations. Furthermore, Gupta et al. (2018) recommended the utilization of lower dosages for this objective. The positive influence of a modest dosage of gamma irradiation on growth characteristics can be characterized as the advantageous mutational effect, including processes such as DNA repair, the activation of endogenous hormones, and the stimulation of enzymes involved in germination and plant development (Majeed et al., 2018). The key factor that may contribute to the enhancement of antioxidant capabilities and the establishment of a positive connection among endogenous hormones within irradiated cells is the presence of low amounts of gamma irradiation. The alterations described in the study conducted by Wi et al. (2007) have been found to have a positive influence on the growth parameters. The potential association between a low dosage of gamma radiation and its influence on the genetic regulation of diverse characteristics, as well as its capacity to induce hormonal responses, activate germination-related enzymes, and expedite DNA repair, has been observed. Furthermore, it has been observed that in the process of plant germination, the application of modest levels of gamma radiation can potentially have advantageous effects by accelerating cell division in meristematic tissues (Dhakshanamoorthy et al., 2011).
The correlation between the increase in plant height and the utilization of low levels of gamma irradiation may be attributed to its ability to induce cell division and enhance essential processes associated with nucleic acid synthesis (Arthur, 2021). In a previous investigation conducted by Kovacs and Keresztes (2022), it was observed that there was a drop in the average height of plants as the irradiation dose was raised. The study conducted on Guava plants revealed an inverse relationship was seen between the escalating levels of gamma ray doses and the height of the plantlets. According to Sarkar and Kundagrami (2018), the application of a 10 Gy treatment resulted in the most significant drop in plant height, whilst the treatments with 20 and 30 Gy exhibited the least pronounced decrease in plant height.
The utilization of gamma rays has demonstrated a positive effect on the vegetative growth of Red Radish. According to Dhakshanamoorthy et al. (2011), it was observed that the doses of 10 Gy demonstrated the most notable stimulation, leading to an increased number of leaves per plant.
In a similar vein, Fagherazzi et al. (2021) reported that the utilization of small amounts of gamma rays led to an augmented accumulation of photosynthetic pigments. The observed phenomenon is plausibly ascribed to the capacity of gamma rays to elicit advantageous genetic alterations, resulting in modifications to cellular morphology and vital physiological mechanisms, such as the augmentation of thylakoid membranes and the enhancement of photosynthetic efficiency. The aforementioned alterations finally played a role in the cumulative mass of pigments, hence exerting an impact on the chromatic properties of plant foliage. This discovery is consistent with a previous study that examined the effects of modest dosages on photosynthetic pigments. According to Aly et al. (2021), the red radish leaves that were subjected to low doses of gamma radiation demonstrated the most elevated levels of chlorophyll and carotenoids. Previous studies conducted by David et al. (2018) and Surakshitha and Soorianathasundaram (2017) were centered around the establishment of standardized dosages of Gamma irradiation for the strawberry cultivar. The experiment revealed that the plants exhibited varying responses based on the dosage of irradiation administered to the particular strawberry variety.
In the majority of instances, when the dosage is beyond the recommended thresholds, it results in the mortality of a significant number of plants. This phenomenon arises due to the direct imposition of deleterious effects on plant tissues by physical mutagens, resulting in the occurrence of multiple mutations. The main cause of this phenomenon is the suppression of cellular proliferation, leading to cellular demise, hence affecting the developmental trajectory and modifying the overall morphology of the organism. The observed consequences are a result of cytological alterations, such as chromosomal damage, suppressed mitotic division, nucleus degradation, and cellular expansion, as reported by Jan et al. (2012).
The occurrence of diverse flowering patterns may be associated with seed metabolism and the initiation of DNA synthesis following exposure to gamma rays (Sarkar and Kundagrami, 2018). The study conducted by Raina et al. (2016) demonstrated that the application of a Gamma irradiation dose of 40 Gy effectively induced early blooming in bananas. In a similar vein, Sarkar and Kundagrami (2018) conducted a study whereby Capsicum annum plants were subjected to a uniform irradiation dose of 40 Gy. The findings of their research revealed that these treated plants similarly displayed premature flowering, hence suggesting the efficacy of irradiation in stimulating early flowering in many plant species. Furthermore, a study conducted by Daniel et al. (2014) revealed that the utilization of 40 Gy Gamma irradiation had a substantial effect on the agro-morphological traits of Solanum aethiopicum L., namely the duration till the initial flowering stage.
The utilization of gamma rays has demonstrated a positive effect on the vegetative growth of Red Radish. According to Dhakshanamoorthy et al. (2011), it was observed that the doses of 10 Gy demonstrated the most notable stimulation, leading to an increased number of leaves per plant.
In a similar vein, Fagherazzi et al. (2021) reported that the utilization of small amounts of gamma rays led to an augmented accumulation of photosynthetic pigments. The observed phenomenon is plausibly ascribed to the capacity of gamma rays to elicit advantageous genetic alterations, resulting in modifications to cellular morphology and vital physiological mechanisms, such as the augmentation of thylakoid membranes and the enhancement of photosynthetic efficiency. The aforementioned alterations finally played a role in the cumulative mass of pigments, hence exerting an impact on the chromatic properties of plant foliage. This discovery is consistent with a previous study that examined the effects of modest dosages on photosynthetic pigments. According to Aly et al. (2021), the red radish leaves that were subjected to low doses of gamma radiation demonstrated the most elevated levels of chlorophyll and carotenoids. Previous studies conducted by David et al. (2018) and Surakshitha and Soorianathasundaram (2017) were centered around the establishment of standardized dosages of Gamma irradiation for the strawberry cultivar. The experiment revealed that the plants exhibited varying responses based on the dosage of irradiation administered to the particular strawberry variety.
In the majority of instances, when the dosage is beyond the recommended thresholds, it results in the mortality of a significant number of plants. This phenomenon arises due to the direct imposition of deleterious effects on plant tissues by physical mutagens, resulting in the occurrence of multiple mutations. The main cause of this phenomenon is the suppression of cellular proliferation, leading to cellular demise, hence affecting the developmental trajectory and modifying the overall morphology of the organism. The observed consequences are a result of cytological alterations, such as chromosomal damage, suppressed mitotic division, nucleus degradation, and cellular expansion, as reported by Jan et al. (2012).
The occurrence of diverse flowering patterns may be associated with seed metabolism and the initiation of DNA synthesis following exposure to gamma rays (Sarkar and Kundagrami, 2018). The study conducted by Raina et al. (2016) demonstrated that the application of a Gamma irradiation dose of 40 Gy effectively induced early blooming in Banana. In a similar vein, Sarkar and Kundagrami (2018) conducted a study whereby Capsicum annum plants were subjected to a uniform irradiation dose of 40 Gy. The findings of their research revealed that these treated plants similarly displayed premature flowering, hence suggesting the efficacy of irradiation in stimulating early flowering in many plant species. Furthermore, a study conducted by Daniel et al. (2014) revealed that the utilization of 40 Gy Gamma irradiation had a substantial effect on the agro-morphological traits of Solanum aethiopicum L., namely the duration till the initial flowering stage.
The objective of the experiment was to investigate the impact of several doses of Gamma-irradiation on the strawberry variety Chandler. Specifically, dosages of 20 Gy, 30 Gy, and 40 Gy were utilized. The findings of the study revealed that doses of 20 Gy and 30 Gy exhibited favorable outcomes in terms of early fruit set, enhanced bud, flower, and fruit quantities, as well as longer and healthier root systems, which permitted improved water and nutrient uptake from the soil. Nevertheless, the administration of a high dosage of 40 Gy resulted in a range of anomalies in the morphology of fruits and leaves, a decrease in the viability of runners, and an impact on the stature of plants and features associated with leaves. However, it has been shown that irradiation doses have prompted early blooming and fruit development. In the final analysis, it was determined that the most effective dosages for inducing possible mutations in the chandler cultivar of strawberries were 20 Gy and 30 Gy. The study also emphasized the significance of conducting dose determination studies before to embarking on large-scale experiments, as a result of the found variations in radiation sensitivity among various cultivars.
Acknowledgments The author would like to express their gratitude to the Chhatrapati Shahu Maharaj National Research Fellowship (CSMNRF-2022) under the Government of Maharashtra, India, for providing the necessary support as a Doctoral Fellowship.
Authors’ contributions I/we declare that the contribution of particular Authors to the publication is as follows: Developing the concept, the methods and the assumptions: Rajni Rajan; conducting the research and sta tistical analyzes of data: Rahul R. Rodge; Sunny Sharma and Tanya Singh contributed to the drafts in collection of necessary information and all authors gave final approval for publication .
Funding The authors receive financial support as a Doctoral Fellowship Chhatrapati Shahu Maharaj National Research Fellowship (CSMNRF-2022) and author also thankful to Lovely Professional University for providing necessary requirements.
Data availability All data generated or analyzed during this study are included in this published research paper.
Conflict of interest The authors declare no conflict of interest.
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No competing interests reported.