This work was carried out during the two successive summer seasons of 2013 and 2014 at a Private Vegetable Farm in El-Khattara distract, Sharkia, Governorate, to investigate the effect of different application methods and concentrations of chitosan ( 0, 0.025, 0.075 and 0.125 %) on growth , yield , tuber roots quality and storability of sweet potato cv. Buregard grown under sandy soil conditions using drip irrigation system.
Dipping the base of the stem cuttings in chitosan solution before planting + foliar spraying of the plants with chitosan was the best method for increasing dry weight of shoots, N,P and K uptake by shoots, marketable yield and total yield and also, for decreasing weight loss (%) and decay (%) in tuber roots during storage period.
Chitosan solution 0.075 % increased growth, average tuber weight , total yield, starch and total sugar in tuber roots, whereas chitosan 0.125 % increased chlorophyll a, total (a+b) in leaf tissues, N,P and K uptake by shoots and marketable yield and also recorded minimum values of weight loss and decay (%) in tuber roots during storage period.
Dipping the base of the stem cuttings in 0.075 % chitosan solution before planting + spraying plants with 0.075 % chitosan solution gave the highest values of vine length , dry weight of shoots/ plant, chlorophyll a and total chlorophyll ( a+b) concentration in leaf tissues, average weight of tuber root, total yield , whereas the same treatment gave the lowest values of weight loss percentage and decay (%) in tuber roots during storage period. On the other hand, the base of stem cuttings in 0.125 % chitosan solution before planting + spraying plants with 0.125 % chitosan gave the highest values of N,P and K uptake, marketable yield, starch and total sugar contents in tuber roots.
Conclusively, from the foregoing results of this study, it could be concluded that, under the same conditions, dipping the base of the stem cutting in 0.075 % chitosan solution before planting + spraying plants with 0.075 % chitosan solution three times at 15 days intervals beginning 25 days after transplanting gave the best interaction treatment for increasing plant growth, yield and its components, tuber roots quality and storability of sweet potato plants.