الفهرس 
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Abstract
The present work was carried out at the experimental farm of Arid land Agricultural graduate studies and Research Institute (ALARI), Faculty of Agriculture, Ain Shams University, Shubra al-Khaimah, Qalyubiah Governorate. Latitude and longitude for this farm are 30.1155436, 31.2446941 in the two successive cultivation seasons of 2014/2015 and 2015/2016. It included three planting dates (18th of Dec, 7th of Jan and 27th of Jan.) and three irrigation levels (60, 80, and 100% of irrigation requirement). Split plot experiment was designed in order to study the effect of climate changes on the growth and yield of potato crop under Egyptian climatic conditions. The results obtained could be summarized as follows:
5.1 Vegetative characters.
The highest plant growth characters, i.e. leaf number and plant height, were recorded at the first planting date, while the lowest values were noticed at the third planting date.
The best growth characters were obtained for plants irrigated with the high water level, but the lowest values were shown in those subjected to the low irrigation level.
The highest plant chlorophyll readings were recorded in the treatment of the first planting date and the low irrigation level 60%, in the two seasons. The lowest plant chlorophyll readings were shown at the third planting date and the high irrigation level (100%) in the two seasons.
The interaction reveled that the highest values of plant growth characters were obtained in plants grown during the first planting date and irrigated with the high level.
5.2 Tuber characteristics and tuber yield.
The highest tuber dry matter, specific gravity and yield were produced from plants grown at the first planting date whereas the lowest values were obtained from those of the third planting date in the two seasons.
The highest tuber dry matter, specific gravity and yield were found with the high irrigation level and the lowest tuber record with the low irrigation level in the two seasons.
The highest values of these parameters were observed in treatments of the first planting date combined with the high irrigation level in the two seasons. The lowest values were shown in those of the third planting date combined with the low irrigation level in the two seasons.
5.3 Tuber nutrient contents.
The highest tuber nutrient percent, i.e. nitrogen, phosphorus, potassium percentage and calcium, were recorded at the third planting date with the high irrigation level in the two seasons. The lowest values were noticed at the first planting date with the low irrigation level in the two seasons.
5.4 Water use efficiency.
The present study experiment revealed that the best potato productivity was obtained at the first planting date at the high irrigation level. While in case of water use efficiency calculation, the result showed that the medium irrigation level was the best at the first planting date.
5.5 Climate change scenarios.
The amount of irrigation water increased under all climate change scenarios in different proportions compared to the current conditions. The lowest amount of irrigation water required per cubic meter to irrigate one feddan of potatoes is projected in the RCP3 scenario in 2050; Irrigation water requirements under climate change under RCP4.5, RCP6.0, and RCP 8.5 compared to the RCP3 scenario have increased the highest seasonal irrigation water requirements as projected under RCP8.5 in 2050 and 2100. The data obtained showed that the amount of seasonal irrigation water for potatoes will increase under climate change with different values; The lowest current and future seasonal irrigation water amounts were estimated at the first planting date; While the highest amount of seasonal irrigation water was estimated at the third cultivation date. Present study experiment revealed that the best potato productivity was obtained at the first planting date at the high irrigation level. While in case of water use efficiency calculation, the result showed that the medium irrigation level was the best at the first planting date.