A filed experiment was carried out during the two successive seasons of 2016/2017 and 2017/2018 at the experimental farm of El- Gemmeiza, Agric Res. Station, ARC, Gharbiya Governorate (Middle Nile Delta, Egypt) to study the effect of planting date (20th September (Sep) and 10th October (Oct), irrigation water level at 50, 75 and 100 % of filed capacity (FC) and two foliar spray with Ca (1%) as calcium chloride and/or boron (60 ppm) as boric acid besides unsprayed treatment (control), and their interactions on yield and its components, tuber cracking and tuber quality under clayey soil conditions using flood irrigation system. The adopted treatments were arranged in a split - split plot design with three replicates. The planting dates were arranged in the main plots, irrigation water quantities were arranged in the sub plots, while Ca and/or B foliar sprays were randomly distributed in sub - sub plots.
The obtained results indicate that, the tertiary interaction of planting on 10th Oct. , irrigation at 100% FC and sprayed plants with Ca + B resulted in higher values of total tuber yield, average tuber weight , number of tuber № plant-1 , tuber yieldplant-1 ,N, K, Ca and B contents and DM percentages in 1st and 2nd seasons. Total carbohydrates were the highest with the interaction of planting on 10th Oct. and irrigating at 100 %FC and sprayed plants with B. The increases in total tuber yield were about 253.75 and 177.82 % for tertiary interaction of planting on 10th Oct , irrigation at 100% FC and sprayed with Ca + B over the interaction of planting on 20th Sep , irrigation with 50%FC and unsprayed plants, in the 1st and 2nd seasons, respectively. As for tuber cracking %, the lowest values were obtained with the tertiary interaction of planting on 10th Oct, irrigation with 75 %FC and sprayed with Ca + B (11.37 and 10.41 %) in the 1st and 2nd seasons, respectively, while the highest values were obtained with the tertiary interaction of planting on 20th Sep, irrigation at 100 %FC and without Ca and B (25.38 and 26.57 % in the 1st and 2nd seasons, respectively).
Conclusively, under similar conditions it could be concluded that , the tertiary interaction of planting on 10th Oct , irrigation at 100 % FC and sprayed plants with Ca + B was superior for enhancing both total tuber yield and quality. Furthermore, on reducing tuber cracking, combination of planting on 10th Oct, irrigation at 75% FC and spraying the plants with Ca + B is recommended.