الفهرس 
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Abstract
A field experiment was carried out during the growth seasons of 2017 and 2018 at the Experimental Farms of Mallawy Agriculture Research Station, Hort. Res. Institute, Giza, Egypt to evaluate the effect of vine cuttings age and potassium fertilizer sources on the growth, yield and its yield components of the sweet potato cv. ”Mabrouka”. The treatments comprised three vine cuttings age (3-days, 5-days and 7-days old) as well as fresh cuttings (control treatment) from the apical vines and four sources of potassium fertilizer (K-sulphate, K-silicate, K-citrate and K-humate). As wallas the control treatment (zero-k).
The site of the farm is located at an altitude of 52.0 m above sea level, latitude 27°04’ N and longitude 80°12’ E. the texture grade of the soil was Silt/Clay.
Planting was immediately carried out after irrigation where apical vine cuttings of 25-30 cm in length with at least 4 nodes were used as planting material. The apical cutting with intact leaves was obtained from the apical portion of the selected vine. The apical cuttings were stored under shade for 3, 5, 7 days before planting as well as the control treatment (Fresh cutting) .The cuttings treatments were planted upright in a vertical position and inserted in the soil to about two thirds (2∕3) of their length at the distances of 25-30 cm apart on May 7th and 10th for the two growing seasons, respectively. All other agricultural practices; fertilization, irrigation, weeding and pests control were followed according to the recommendations of the Ministry of Agriculture, Egypt.
Conclusion:
1- The best treatments for survival rate of vine cuttings age was achieved with the treatments of 3-days old of vine cuttings and immediate planting (fresh cutting).
2- The greatest sweet potato growth and yield components (vine fresh weight ton.fed-1, storage root yield (ton.fed-1), Biomass yield (ton.fed-1) storage roots length, total sugar content, starch content, K % and color parameters (L* and whiteness*) were produced with the treatment of immediate planting and 3-days old of vine cuttings.
3- Storage root diameter, storage root dry matter% and marketable yield% does not affected by storage duration of vine cuttings in both seasons.
4- The all K- sources used as foliar application affect the growth and yield characters of sweet potato. The treatments of K- Si and K-H showed the best treatments for no. storage roots, root diameter, vine fresh weight as ton.fed. and K-sulphate for root yield and biomass yield (ton. fed.) and K-H for improvement total sugar content, color parameters (L*,a* and whiteness) of sweet potato flour, K-Si for starch content
5- The combined treatments of immediate planting × K-silicate showed the greatest values for number of storage roots, root yield, root diameter, starch content and biomass yield (ton.fed-1). Also, the combined treatment of 3-days old × K-H for vine fresh weight (ton.fed-1) and total sugar content and 3-days old × K-Si for enhancement the lightness (L*) and whiteness of sweet potato flour cv. Mabrouka”.