Two field experiments were conducted at El-Bustan region (EL-Behaira Governorate) in 1998/1999 and 1999/2000 seasons to evaluate three new wheat genotypes of bread wheat (Triticum aestivum, L.) namely; Gemmeiza 5,Sakha 93 and Giza 168 compared to the two commercial cultivars Sakha 69 and Sids 1 in the sandy soils at three different nitrogen rates (72, 144 and 216 kg N/ha) with four sprinkler irrigation treatments viz., irrigation at 7-day intervals throughout the growing season + increasing the intervals from 7 to 14 days only at either of the three stages of crop growth i.e., from planting to booting, from booting to milk stage and from milk stage to maturity.
Obtained results indicated that irrigation every seven days through the season resulted in the highest grain yield from all tested genotypes. Elongating the interval of irrigation from 7 to 14 days at any of the three growth stages resulted in significant reductions estimated by 19.6, 13.4 and 9.8%, respectively, indicating that the first stage from planting to booting was the most sensitive period for water stress. Yield components; number of spikes/m², number of kernels/spike and 1000-kernel weight were also depressed by elongating the irrigation intervals with reductions being more at the first stage.
Grain yield and yield components of the different genotypes were significantly increased with each successive level of nitrogen application. In addition, differences in grain yield among the tested genotypes were significant. Gemmeiza 5 gave the highest grain yield (5.81 t/ha) but was not significantly different from that produced by Sakha 93. Giza 168 and Sids1 were next to follow whereas, Sakha 69 gave the lowest grain yield (4.61 t/ha).The interactions between the different treatments were significant and the highest yields were produced from cultivars Gemmeiza 5 and Sids 1 irrigated every 7 days throughout the season and fertilized with 216 kgN/ha.
In addition, substantial difference among the genotypes in their response to increasing N fertilizer level was observed. Grain yield response index (GYRI) was highest for cultivar Gemmeiza 5 and lowest for Sakha69. Furthermore, GYRI and water-use efficiency(WUE) were highest when the shortest irrigation interval of 7 days was followed at both the first and the second growth stages and were declined with elongating the intervals at either one of them, particularly in the first stage. Likewise, WUE significantly increased with increasing N application.
Moreover, significant genotypic variation for WUE was obtained and the highest values were achieved from the high-yielding genotypes.
In conclusion, the new cultivars; Gemmeiza 5 followed by Sakha 93 and Giza168 along with the commercial cultivar Sids 1 are highly recommended to be grown in the sandy soil of new reclaimed area of El-Bustan region (El-Behaira Governorate) and for maximum yield, irrigation should be practiced every 7 days and N fertilizer should be applied at a rate of 216 kgN/ha.