Abdou, S. M. M, K.M. Abd El- Latif, Farrag, R. M. F. and Yousef, K. M. R.
Two field experiments were conducted during the 2009 planting seasons 2010 at the Tameia Agricultural Research Station, Fayoum, Egypt to study the combination effects of three sowing dates (D1: 1st of June, D2: 15th of June and D3: 1st of July) and three irrigation scheduling treatments technique on yield, yield components and water relations such as seasonal crop water consumptive use (ETC) and crop coefficient (Kc) of sunflower (Sakha 53 cv.). This was in accordance to the cumulative pan evaporation (C.P.E.), (I1 0.8; I2 1.0 and I31.2). A split- plot design with four replications was used. The results indicated that the sowing dates and irrigation scheduling treatments significantly affected seed yield and yield components in two seasons. The highest averages of plant height, head diameter, head weight, seed weight/head and 100 seed weight in two seasons were obtained from June 1st sowing and irrigation at 1.2 C.P.E. treatment. The highest seed yield 1050.1 and 1130.4 kg seeds/feddan however, July 1st sowing and irrigation at 0.8 C.P.E. gave the lowest values in the two seasons. The third sowing date (D3) and irrigation at 0.8 C.P.E. gave the lowest seed yield/fed 560.7 and 596.2 kg seeds/feddan in two seasons, respectively were detected from (D1I3) in the two successive seasons. ETC averaged 47.76 and 49.86 cm in two seasons, respectively. The highest ETC values, 53.19 and 52.73 cm were recorded from (D1I3) in two seasons, respectively, whereas the lowest values, 42.18 and 44.19 cm in the two successive seasons were resulted from (D3I1). The daily ETC rates were low during June, and increased during July to reach its peak during August then declined during September in both seasons. The KC values, for high grain yield were 0.46, 0.65, 0.91, and 0.64 for June, July, August and September, respectively (as average in two seasons). The highest water use efficiency, i.e. 0.470 and 0.486 kg seeds/m3 water consumed were obtained from (D1I3) treatment in two seasons, respectively.
