Effect of Nitrogen Fertilization Lvels on Potassium Absorption by Some Wheat Varieties in Northern Delta Region

Abstract

A field experiment was conducted at Sakha Agricultural Research Station farm, Kafr El-Sheikh Governorate, Egypt during 2008/2009 winter season to assess the effect of nitrogen fertilization levels on potassium. absorption by some wheat (Triticum aestivum L.) varieties. Split plot design with four replicates was applied, the main plots were assigned by four wheat varieties , Gimiza 9, Sakha 61, Sakha 93 and Giza 168. The subplots were assigned by four nitrogen levels of 0, 30, 60 and 90 kg N fed.-1 (ha = 2.4 fed.). Eight plant samples were collected during the growth periods to determine the daily increase of dry plant weight, N%, and K% in the dry matter, K uptake during the growing periods and K/N ratio during the physiological stages. The obtained results can be summarized as follow:  Potassium percentage high significantly decreased during the growth periods up to 111 days from sowing.  Wheat plant absorbed potassium rapid at tillering stage followed by moderately absorption at stem extension stage followed by relatively slow absorption at heading stage and finally followed by slow absorption at flowering stage.  There were highly significant differences in potassium percentage between the used varieties after 40 days from sowing.  Potassium percentage high significantly increased by increasing nitrogen levels up to 90 kg N/ fed.  The mean values of potassium percentage of the used varieties can be arranged according to the following order : Giza 168 > Sakha 61 > Sakha 93 > Gimiza 9.  The mean values of K uptake showed that the used varieties arranged in the following order, Giza 168 > Sakha 61 > Gimiza 9 > Sakha 93.  The highest three mean values of growing stages of 3.697, 4.042 and 3.087 (mg K/plant/day) obtained at the (50-83 days) middle of plant age.  Potassium uptake increased as nitrogen levels increased from N0, to N30, N60 and N90, respectively.  The highest values of potassium uptake were obtained at the periods of (50-61), (61-69), and (69-83) days from sowing, at the heading stage..  The highest K/N ratio values of wheat varieties of 2.93, 2.32, 2.95 and 2.74 were obtained through the period of (69-83) days  Increasing nitrogen fertilizer levels from N0 to N30, N60 and N90 led to decrease K/N ratio from 2.04 to 1.91, 1.97 and 1.86, respectively.  The K/N ratio values reached its highest value at head development stage in all varieties  Increasing the wheat yield of different varieties was associated with decreasing K/N ratio .