Integrating crop management of rice is the main strategy for maximizing rice productivity in Egypt. Optimizing phosphorous application will ensure high productivity of rice and soil sustainability. Two field experiments were conducted during 2010 and 2011 seasons at the Farm of Sakha Agriculture Research Station, Kafr-El Sheikh Governorate, Egypt. The soil texture was clayey. EC was 1.6 and 1.5 dS/m during 2010 and 2011, respectively. The eleven suggested treatments studied the response of Giza 178 rice variety to various alternates of phosphorous management namely; control(1), basal application the rate of 54 kg P2O5/ha (2), Diammonium phosphate (DAP) spray with the concentration of 2% at mid tillering stage (MT) (3), Potassium triphosphate (KTP) spray at MT 2% (4), DAP spray 2% at panicle initiation (PI) (5), KTP 2% at (PI) (6), DAP spray 2% at booting stage (BT) (7), KTP2% at (BT) (8), basal application of phosphorous+ 2%of DAP at BT(9), basal application of phosphorous + 2% of KTP at BT(10) and DAP spray at the concentration of 2% at the three growth sage (11). The results of this study can be summarized as follows.
Phosphorous application treatments either basal or foliar and their combination at beginning of boot growth stage were significantly increased P leaf content and its uptake. Also, phosphorous application significantly improved growth parameters at heading date viz; LAI, dry matter production, tillers number/hill and plant height. Flag leaf characteristics, i.e. flag leaf area, dry weight of flag leaf and chlorophyll content were significantly improved by phosphorous either basal or foliar spray as combination particularly, at booting stage. Yield components and rice grain yield were significantly improved by phosphorous application involving basal, foliar application and their combinations at booting growth stage were found to the most . Basal application of phosphorous+ 2%of DAP at BT and basal application of phosphorous+ 2%of KTP at BT were found to be the most effective treatments , whereas they were comparable regarding all above mentioned traits and recorded the maximum values of them. Furthermore, DAP spray at three growth stage at mid tillering stage+ panicle initiation + beginning of booting stage and basal application treatments were comparable regarding rice grain yield but the basal application economically surpassed it.
From economic point of view, the treatment of basal application of recommended phosphorous+ 2%of DAP at BT was the best and it could be recommended under similar conditions.