الفهرس 
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Abstract
The 1st experiment (In vitro study)
This research was done at a Minia University, Egypt, tissue culture lab and experimental farm from 2017 to 2020. To study the response of three varieties of sweet potato plants Apis, Menofia 6 and American to grow in the presence of different growth regulators ”Indole Acetic Acid (IAA) at 0.5 mg L−1 , Gibberellic Acid (GA3) at 1.0 mg L−1 and Kinetin (kin) at 0.1 mg L−1 ” individually or in combinations as well as the control treatment and to determine the most effective optimum concentration of plant growth regulators, as well as the cultivar.
The following are the main findings of this investigation:
1. Abis cv. had the tallest plantlets (23.92 cm) when grown on control (MS medium without growth regulators), followed by American cv. (23.28 cm) on MS modified with IAA and Menofia 6 cv. (20.44 cm) in control treatments. The same treatment reduced American cv’s height (8.633cm).
2. The tallest plants were American cv. (7.650 cm) on MS with IAA treatment, Abis cv. (7.633 cm) on control treatment, Abis cv. (7.180 cm) on MS with added kin, and Menofia 6 (5.010 cm) on GA3 treatment. On the other hand, American cv. had the shortest shoot lengths when grown on the control (2.350 cm) and GA3 (2.837 cm) treatments, respectively.
3. When Menofia 6 cv. was grown on MS+IAA, its average root length was 16.37 cm. This was followed by 16.28 cm for Abis cv. and 16.00 cm for Menofia 6 cv. when they were grown on the control treatment. On the other hand, American cv. on hormone-free MS media had the shortest roots (6.39 cm), followed by the Menofia 6 on IAA+GA3 media (8.893 cm).
4. Abis cv. grew the most roots when it was grown on MS with IAA+GA3 (4.200) and MS with kin (4.0). American cv. grew the most roots when it was grown on MS with IAA (3.867). On the other hand, MS treated with GA3 gave Abis cultivar the fewest roots (2.100).
5. The average number of leaves produced by Abis cv. was 15.63 when the MS medium was combined with kinetin. This was followed by 14.93 when the MS medium was combined with IAA and 14.67 when the control treatment was used. On the other hand, under control treatment, American cv. grew the fewest leaves (4.83).
6. Under IAA+GA3 treatments, Abis cv. had the highest fresh weight of shoots (1174.0 mg). Then Menofia 6 with GA3 + kin (442.0 mg) and control treatment (380.7 mg), respectively. While American cv. (70.67 mg) and Menofia 6 (99.33 mg) had the least fresh weight of shoots when grown on MS media without growth regulators and IAA+ GA3, respectively.
7. Abis cv. had the heaviest roots fresh weight (314.0 mg) with control treatments, followed by American cv. (284.7 mg) and Menofia 6 (258.0 mg) with IAA+GA3+kin and control treatments, respectively. American cv. (64.00 mg) and Menofia 6 (80.67 mg) had less roots fresh weight when they were grown on MS media without growth regulators and IAA+GA3.
8. Menofia 6 cv. had the highest dry weight of shoots (17.20 mg) on MS with GA3 and kinetin added, followed by Abis cv. (16.10 mg) with IAA and GA3. On the other hand, when IAA+GA3 was used, American cv. had the lowest dry weight of its shoots (1.700 mg).
9. The roots of Menofia 6 cv. had the most dry weight (13.30 mg) on MS that had been given GA3 and kin. After that, Abis cv. (11.50 mg) was given with IAA + GA3. However, when control treatments were used, American cv. (3.700 mg) and Menofia 6 cv. (4.500 mg) roots had the least amount of dry weight.
10. Menofia 6 plantlets grown in MS with IAA and kin had the highest level of chlorophyll A (2.049), followed by American plantlets (2.033) and Abis plantlets (2.028) grown in MS with kin and GA3, respectively. With IAA treatment, Abis cv. had the lowest concentration of chlorophyll A (1.296).
11. IAA + kin yielded Abis cv. the greatest chlorophyll B content (2.775), followed by Menofia-6 (1.680) and American (1.675). On MS medium with IAA+ kin, the American cv had the least chlorophyll B (0.5310).
12. Abis and American plantlets had the greatest carotenoids level (0.6710) with IAA + GA3 + kin, followed by Abis cv. (0.6680) without growth regulators. American cv. in MS with GA3 + kin had the least carotenoids (0.5760).
The 2nd experiment
This research was conducted to study the effect of growth regulators on the root development of sweet potato cuttings, cultivars namely, Beauregard and Menofia 6. The cuttings were soaked in plant growth regulators (PGRs), either alone or in combinations. PGRs were IAA at 0.5 mg L−1 and/or kin at 0.1 mg L−1 for 12 hr sessions continued all night. All PGRS-treated cuttings were then soaked in water for 24, 72, and 120 hours and the root traits were recorded.
The following are the main findings of this investigation:
1. After 120 hours of soaking in water, Menofia 6 cv. with IAA treatment had the most roots (35.93), whereas after 24 hours of soaking in water it had the fewest (11.23).
2. Menofia 6 which treated kin treatment then 120 hours of soaking in water had the longest roots (12.60 cm) while with control and 24 hours of soaking in water produced the shortest (2.400 cm).
3. After 72 hours of soaking in water, the Beauregard cv. treated with IAA had the maximum number of roots (36.7%), whereas Menofia 6 cv. had the lowest (1.3%).
4. Root length increased by 69.4% in Menofia 6 cv. after 24 hours of soaking in water which previously treated with kin and decreased with longer soaking from 72 to 120 hours in water. Beauregard cv. with IAA treatment yielded the lowest percentage (5.9%) after 24 hours of soaking then it increased after 120 hours (59.4%).
The 3rd experiment (In vivo study)
During the growth season of 2021, two planting dates ”April 26th and June 13th” were used at the experimental farm of the Agricultural Research Center (ARC), Mallawi, El Minia, Egypt to study the effect of growth regulators ”IAA at 0.5 mg L−1 and kin at 0.1 mg L−1 ” individually or in combinations on the quantitative and qualitative characteristics of two sweet potato cultivars, Beauregard, and Menofia 6
The following are the main findings of this investigation:
Growth and yield characteristic
1. With the control treatment on the 2nd planting date and IAA on the 1st and 2nd planting dates, Beauregard cv. had a 100% survival rate for sweet potato cuttings. When using kin, Menofia 6 cv. in the 1st planting date showed the lowest values.
2. Menofia 6 cv. that was given 0.1 mg L−1 of kin grew the tallest vine. While Beauregard cv plants treated with IAA+kin at the 1st planting date had the shortest length.
3. Menofia 6 plants in the 2nd planting date recorded the highest and no. of vines stems plant-1 (4.967) being for the control treatment however, it showed the lowest number (3.00) when treated with kin.
4. Under control and kin treatments, the Menofia 6 cv. had the heaviest vine fresh weight (4.500 kg) in the 1st planting date. In the 2nd planting date, the Minofia 6 cv. had a lower vine fresh weight (1.833 kg) when IAA was sprayed on the leaves.
5. On the second planting date, Menofia 6 cv. had the maximum fresh root weight (2.800 kg) with foliar spraing of IAA + kin. While employing IAA treatments on the first planting date, Beauregard cv. produced the least amount of fresh roots (0.233 kg).
6. On the second planting date, Minofia-6 cv had the maximum fresh root weight (40.32 ton fed-1) with foliar spraing of IAA + kin. In contrast, the Beauregard cv (3.360 ton fed-1) produced the least fresh root weight when IAA treatments were used on the first planting date.
7. Biomass yield with the kin treatment in first planting date showed the highest values for biomass yield with Minofia 6 cv. (6.067 kg plant-1) however it gave and Beauregard cv. (2.433 kg plant-1).
Storage root characteristics
1. With kin treatments, the largest average number of storage roots plant-1 and were observed in Beauregard cv. (7.767) and Menofia 6 cv. (7.733), respectively, on the 1st planting date. On contrast, the Beauregard cv. developed the fewest store roots plant-1 (4.267) in the 2nd planting date under the control treatments.
2. The highest storage roots length (21.70 cm) were found in Menofia 6 cv. treated with IAA+ kin on the 2nd planting date, whereas the lowest storage roots length (13.53 cm) were observed in Beauregard cv. treated with the same treatments on the 1st planting date.
3. Foliar spraying with IAA resulted in the greatest storage root diameter with Minofia 6 cv. in the 2nd planting date (6.367), while it resulted in the lowest value with Beauregard cv. in the 1st planting date (2.467).
4. The treatments investigated had an effect on the percentage of marketable yield. There were no significant changes between treatments and cultivars in the 2nd planting date, as well as in Menofia 6 cv. and treatments in the 1st planting date. In the 2nd planting date, Beauregard cv. produced the highest percentage of commercial yield (100%) with IAA +kin. In contrast, the same cultivar had the lowest proportion (10%) with IAA treatments in the 1st planting date.
5. In Beauregard cv., the plants treated with IAA as a foliar spray generated the greatest root dry matter (24.13). The same treatment with Menofia 6 cv. yielded the lowest result (13.67) on the second planting date.
Color determination
1. Hunter colour values showed substantial variances in L* a* b*, chroma, and E.
2. Beauregard cv. L* was 88.10 when planted in April under control treatment. Menofia 6 cv had the lowest L* value of 83.23 when it was planted in June and sprayed with Kin.
3. Menofia 6 cv. had the greatest redness (a*) (2.23), planting date (June), and Kin treatments.
4. The yellowness/greenness (b*) rating high for Beauregard cv. with June planting date and IAA+kin treatments. Menofia 6 cv’s minimum b* value was 7.77, however it wasn’t the lowest compared to April planting and kin (b=6.367).
5.Menofia 6 cv. had the greatest ΔE (11.86) when planted in June and treated with kin.