Field studies were conducted at Toshka region , South Valley of Egypt , during the summer of 2014 and 2015 seasons to evaluate the some yellow maize single crosses, i.e. SC-162, SC-168 and SC-176 under three plant population densities of (21000 , 27300 and 33600 plants/fed.) and three nitrogen fertilizer levels (90,120 and 150 Kg N/fed.) .
The main results can be summarized as follows:
- The results showed that N- rates were significant in all characters under study, whether growth characters' , grain yield and protein content and the nitrogen use efficiency (NUS) except leaf area of the top most ear/plant. Nitrogen use efficiency has resulted in an average of 150 kg N / fed to the significant increase in grain yield and recorded value of 4340 and 4235 kg / fed.in 2014 and 2015 respectively , while the decreased NUS when using 150 kg N / fed in both seasons .
- As well as that the greater the plant densities there was a significant effect in the studied characters except leaf area of the top most ear/plant , ear length , ear diameter , number of grains/row , protein content . The increase in plant density from 21,000 to 33,600 plant/fed. to an increase in grain yield of 13.44 and 17.27 % in seasons 2014 and 2015 season .
- All characters under study were not significant between single crosses except ear length , NUE and grain yield during the 2014 season , where he gave the hybrid Sc 176 higher values 4246.6 kg / fed of grain yield in the first season.
- The effect of interactions between-rates and plant densities significantly in plant height and NUE in both seasons, grain yield in the 2015 season . The highest grain yield (4510.8 Kg/fed.) when using 150 kg N and cultivation of 33,600 plant / fed . The interaction between plant density and maize hybrids were significantly as ear length, grain yield and nitrogen use efficiency in the 2014 season and the 500-grain weight during the 2015 season. The results also showed that there was a significant between the three factors in the grain yield and nitrogen use efficiency through the 2014 season and ear length 2015 season where he recorded the highest value of the nitrogen use efficiency using 90 kg N /fed +33.600 plant/fed + SC 176.
- Economic study showed that the highest net return obtained from the addition of 150 kg N / fed with the use of plant density rate of 33 600 plant/fed. and cultivation of hybrid SC 176 . Through the results obtained can be recommended using 150 kg N , plant density of 33,600 plant/fed. and the cultivation of hybrid SC 176 to get the highest grain yield /fed .