The aim of this study was to develop a protocol for the
The sweet potato [
The root is a valuable food for human consumption because it is considered to be a good source of energy, minerals, and vitamins. The branches and roots can also be fed to cattle, pigs, poultry, and other domestic animals. The roots of this vegetable crop also have great potential for the production of biomass in biofuel production [
Due to the enormous commercial interest in the sweet potato, the conservation of the germplasm of this species is needed. The diversity contained in a germplasm must be protected against losses; the basis of all genetic improvement lies in genetic diversity, which is reflected in the creation of plants with resistance/tolerance to various biotic and abiotic factors, ensuring increased productivity.
The slow growth
Therefore, the aim of this study was to develop a protocol for the
Stecklings were produced from stem cuttings and planted in plastic pots containing a mixture of sand + cattle manure at a ratio of 2 : 1 and grown in a greenhouse with 50% shade screen, irrigation, and intermittent nebulization located IN the Department of Agronomical Engineering of the Federal University of Sergipe, Brazil.
The trials were conducted at the Laboratory of Tissue Culture and Plant Breeding of the Department of Agronomical Engineering. We used MS culture medium [
The plant material was kept in a growth room with a photoperiod of 12 hours light and luminous intensity of 60
The apical segments of the young plants grown in the previous step were used as an explant source for establishing sweet potatoes
The plant material was cut into segments of approximately 2 cm. The segments were placed in 250 mL flasks containing 25 mL of semisolid MS medium containing sucrose (30 g·L−1) and agar (7 g·L−1). After inoculation, the material was kept in a growth room with a controlled temperature of
The explants used in this experiment were apical segments of plants already established
We used a completely randomized design, in a
Every three months, we quantified the survival (%) as well as the height of the shoots using the following rating scale:
We used a completely randomized design, in a
Every three months, we evaluated the survival (%), shoot height, and color of the shoots (from the rating scales used in Experiment 1).
All of the data were subjected to analysis of variance with the
Genotype IPB-007 showed a higher survival rate at 18°C (56%). At 25°C, however, there was not a significant difference between genotypes, with survival rates between 58.40% (IPB-007) and 64.80% (IPB-137) (Table
Survival of sweet potato plant shoots after 180 days of
Genotype | ||
---|---|---|
IPB-007 | IPB-137 | |
Temperature (°C) | ||
18 | 56.00aA | 31.20bB |
25 | 58.40aA | 64.80aA |
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ABA (mg·L−1) | ||
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0,0 | 64.00A | 78.00A |
1,0 | 58.00A | 58.00A |
2,0 | 78.00A | 44.00B |
4,0 | 42.00A | 42.00A |
8,0 | 44.00A | 18.00B |
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Equation ( |
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CV (%) | 34.85 |
The means followed by the same lowercase letters in the same column and uppercase letters in the same line do not significantly differ according to a Tukey test at a 5% probability.
The effect of different ABA concentrations on the IPB-007 genotype is represented by a cubic equation, with the highest average survival obtained with 2.0 mg·L−1 ABA. For genotype IPB-137, the different concentrations of ABA are represented by a linear decreasing equation, where the highest average survival rate was obtained at the lowest concentration of the regulator (0.0 mg·L−1—78%).
Analyzing the ABA treatment concentrations at 18°C, the variations in shoot height can be demonstrated by a cubic equation, where the lowest average value was obtained at the highest concentration of the regulator (8.0 mg·L−1) in genotype IPB-007 (Table
Height of sweet potato plant shoots after 180 days of
ABA | Genotype | |
---|---|---|
(mg·L−1) | IPB-007 | IPB-137 |
Temperature 18°C | ||
0 | 3.83bA | 2.02bB |
1.0 | 1.13bA | 0.85aA |
2.0 | 1.10aA | 1.10aA |
4.0 | 1.40aA | 0.60aA |
8.0 | 0.90aA | 0.60aA |
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Equation ( |
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Temperature 25°C | ||
0 | 6.00aA | 6.00aA |
1.0 | 3.80aA | 1.65aB |
2.0 | 1.93aA | 1.40aA |
4.0 | 0.90aA | 1.03aA |
8.0 | 0.40aA | 0.70aA |
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Equation ( |
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CV (%) | 34.92 |
The means followed by the same uppercase letters in the same line and lowercase letters between temperatures do not significantly differ according to a Tukey test at a 5% probability.
The different temperatures combined with each concentration of ABA revealed no significant differences in the shoot height variable, with the exception of two genotypes in the absence of the regulator and genotype IPB-007 at a concentration of 1.0 mg·L−1 of ABA, which produced a lower mean at a temperature of 18°C.
Independently of temperature, only two conditions showed a significant difference between genotypes at the different concentrations of ABA: in the absence of ABA, genotype IPB-137 (2.02) had a lower mean, and, under a concentration of 1.0 mg·L−1 at 25°C, genotype IPB-137 (1.65) had lower shoot heights compared to genotype IPB-007 (3.80).
Regarding ABA within each genotype, the results are represented by a cubic equation where the lowest coloration was obtained with 1.0 mg·L−1 (IPB-007) and 4.0 mg·L−1 (IPB-137) (Table
Coloration of sweet potato plant shoots after 180 days of
ABA | Genotype | |
---|---|---|
(mg·L−1) | IPB-007 | IPB-137 |
0 | 3.20A | 2.53B |
1.0 | 2.24A | 2.83A |
2.0 | 2.84A | 3.09A |
4.0 | 2.25A | 2.35A |
8.0 | 3.15A | 2.75A |
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Equation ( |
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Temperature (°C) | ||
18 | 25 | |
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0 | 2.25B | 3.48A |
1.0 | 2.00B | 3.07A |
2.0 | 2.24B | 3.69A |
4.0 | 1.95B | 2.65A |
6.0 | 1.80B | 4.10A |
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Equation ( |
ns |
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CV (%) | 26.25 |
The means followed by the same uppercase letters in the same lines do not significantly differ according to a Tukey test at a 5% probability.
Analyzing the effect of ABA within each temperature under 18°C revealed that the concentrations of the regulator did not result in any significant effects on shoot coloration. The 25°C condition was represented by a cubic equation, with the lowest average (2.65) obtained when we used 4.0 mg·L−1 of ABA.
At all concentrations of ABA, we observed the lowest means for shoot coloration under 18°C. There are several reports in the literature highlighting the impact of low temperatures on the
Because it blocks the action of auxin and gibberellins [
As demonstrated by the data transcripts, the responses of the different genotypes to the addition of ABA to the culture medium and different temperatures are as diverse as possible.
In choosing the best treatment for
Regarding MS salt concentrations, we noted that a 50% concentration of the MS culture medium provided a greater survival rate for microplants of genotypes IPB-007 (94.44%) and IPB-052 (88.9%) (Table
Survival of sweet potato microplants at 180 days of
Genotypes | ||||
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IPB-007 | IPB-052 | IPB-072 | IPB-137 | |
Concentration of MS (%) | ||||
50 | 94.44aA | 88.89aA | 68.89aB | 64.44aB |
75 | 72.22bA | 77.78bA | 54.44aB | 65.56aAB |
100 | 68.89bA | 70.00bA | 32.22bB | 61.11aA |
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Sucrose (g·L−1) | ||||
10 | 77.78aA | 80.00aA | 41.11bB | 53.33bB |
20 | 74.44aAB | 81.11aA | 58.89aB | 60.00bB |
30 | 83.33aA | 75.56aA | 55.55abB | 77.78aA |
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CV (%) | 27.70 |
The means followed by the same uppercase letters in the same line and lowercase letters in the columns do not significantly differ according to a Tukey test at a 5% probability.
At 180 days, there was no significant difference between genotypes IPB-007 and IPB-052 in terms of the sucrose concentrations tested. For genotype IPB-072, a better survival rate was achieved with 20 g·L−1 (58.89%) of sucrose (Table
Similar results were obtained for
There was no significant difference between the MS salt concentration variations in genotypes IPB-052 and IPB-137 in terms of shoot coloration (Table
Coloration of sweet potato plant shoots after 180 days of
Genotypes | ||||
---|---|---|---|---|
IPB-007 | IPB-052 | IPB-072 | IPB-137 | |
Concentration of MS (%) | ||||
50 | 1.16bB | 1.49aB | 1.72bAB | 2.41aA |
75 | 1.81aB | 2.04aB | 3.07aA | 2.30aAB |
100 | 1.07bC | 1.94aB | 3.47aA | 2.34aB |
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Sucrose (g·L−1) | ||||
10 | 1.06aC | 1.79aB | 3.36aA | 2.64aA |
20 | 1.51aB | 1.84aAB | 2.31bA | 2.57abA |
30 | 1.57aB | 1.84aAB | 2.59bA | 1.85bAB |
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CV (%) | 44.25 |
The means followed by the same uppercase letters in the same line and lowercase letters in the columns do not significantly differ according to a Tukey test at a 5% probability.
At 270 days of storage
Survival of sweet potato plants at 270 days of
Genotypes | ||
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IPB-007 | IPB-137 | |
Concentration of MS (%) | ||
50 | 74.44aA | 51.11aB |
75 | 53.33bA | 53.33aA |
100 | 60.00bA | 47.78aB |
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Sucrose (g·L−1) | ||
10 | 60.00aA | 41.11bB |
20 | 62.22aA | 44.44bB |
30 | 65.56aA | 66.67aA |
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CV (%) | 27.34 |
The means followed by the same uppercase letters in the same line and lowercase letters in the same column do not significantly differ according to a Tukey test at a 5% probability.
Regarding the concentration of MS salts, we found that higher survival was obtained in genotype IPB-007 (74.44%) with 50% MS salts. For genotype IPB-137, no significant difference between treatments was observed, with survival rates ranging between 47.78 and 53.33%. Comparing the genotypes within each concentration of MS salts, it was observed that IPB-007 showed overall higher survival rates that were indistinguishable from IPB-137 only at the 75% MS salts treatment level. After the same period of
There was no significant difference in the survival of genotype IPB-007 at 270 days between the sucrose concentrations, with rates varying between 60.00 and 65.56%. For the genotype IPB-137 (66.67%), a greater survival rate was achieved at higher concentrations of sucrose (30 g·L−1). Comparing the genotypes within each sucrose concentration, it was observed that IPB-007 showed higher survival rates that differed from IPB-137 at all sucrose levels except the treatment with 30 g·L−1.
In terms of shoot height, there was an interaction between MS salt concentration × sucrose (Table
Height of sweet potato plant shoots at 270 days of
Concentration of MS (%) | Sucrose (mg·L−1) | ||
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10 | 20 | 30 | |
50 | 3.15aA | 3.07aA | 3.07aA |
75 | 3.31aA | 3.11aA | 2.82aA |
100 | 1.93bB | 2.56aAB | 3.26aA |
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CV (%) | 27.94 |
The means followed by the same lowercase letters in the same column and uppercase letters in the same line do not significantly differ according to a Tukey test at a 5% probability.
At 270 days of cultivation, there was no significant interaction between the sources of variation tested for shoot coloration (Table
Coloration of sweet potato plant shoots at 270 days of
Genotype | Color of shoots |
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IPB-007 | 2.65b |
IPB-137 | 2.97a |
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Sucrose (g·L−1) | |
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10 | 3.01a |
20 | 3.12a |
30 | 2.30b |
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CV (%) | 28.28 |
The means followed by the same lowercase letters in the same columns do not significantly differ according to a Tukey test at a 5% probability.
Reducing the levels of MS salts is one of the most popular strategies for the
Variations in sucrose concentration have been successfully tested for the
In the literature, there are reports of the
In this work, the genotypes IPB-007 and IPB-137 could be kept for nine months with an average survival rate of 74.44% and 66.67%, respectively.
Here we show the successful
The authors declare that there is no conflict of interests regarding the publication of this paper.
The authors wish to acknowledge CNPq, FAPITEC/SE, and CAPES for supporting funds.