Response of white maize hybrids to plant densities and nitrogen fertilizer rates

Two field experiments were conducted on the Farm of Agric. Res. and Exp. Center of Fac. of Agric. Moshtohor, Benha University, Toukh Directorate, Qalyubia Governorate, Egypt, during the two successive summer growing seasons of 2016 and 2017 to study the effect of three plant population densities i.e. 20000, 24000 and 28000 plants/feddan (fed) and three nitrogen fertilizer rates, i.e. 90, 120 and 150 kg N/fed on the growth traits, yield components, yield and some kernels chemical properties of three white single cross hybrids of maize (S.C. 7071, S.C. 30K8 and S.C. 2031). The obvious results of this investigation can be summarized as follows: Increasing plant population density from 20000 to 28000 plants/fed significantly increased mean values of No. of days from planting to 50 % tasseling and silking, leaf area index, plant height (cm), ear height (cm) No. of barren plants/fed, No. of ears/fed, stover yield/fed (kg) and biological yield/fed (kg) in both seasons. On the other hand, mean values of No. of green leaves/plant, leaf area/plant (cm²), No. of plants carried two ears/fed, No. of kernels/ear, ear weight (g), shelling (%), 100-kernel weight (g), ear yield/fed (kg), grain yield/fed (kg), harvest index, nitrogen uptake/fed (kg) and protein yield/fed (kg) were significantly decreased in the two seasons. Allmost traits of maize under study were significantly increased by increasing nitrogen fertilizer rates from 90 and 120 to 150 kg N/fed except, No. of days to 50 % tasseling and silking as well as No. of barren plants/fed were significantly decreased with increasing nitrogen rates in the both seasons, nitrogen fertilizer rate of 150 gave the best mean values for all maize traits under study. White single cross hybrids of maize were significantly differed in all maize traits under study in the both seasons. Maize hybrid of S.C. 30K8 was significantly surpassed S.C. 7071 and S.C. 2031 in mean values of No. of plants carried two ears/fed, No. of ears/fed, No. of kernels/ear, grain yield/fed and harvest index as well as gave the lowest mean values of No. of barren plants/fed and the shortest period from planting to 50 % tasseling or silking in the both seasons. Moreover, S.C. 2031 surpassed the other two maize hybrids in mean values of leaf area/plant, leaf area index, ear weight, 100-kernel weight, ear yield/fed, biological yield/fed, nitrogen uptake/fed and protein yield/fed in the two seasons. Meanwhile, S.C. 7071 recorded the highest mean values of No. of green leaves/plant, plant height, ear height, shelling % and stover yield/fed in the two seasons. The first order interactions between (20000 plants/fed X 150 kg N/fed), (24000 plants/fed X S.C. 30K8), (20000 plants/fed X S.C. 2031) and (150 kg N/fed X S.C. 30K8) as well as the second order interactions between (24000 plants/fed X 150 kg N/fed X S.C. 30K8) and (20000 plants/fed X 150 kg N/fed X S.C. 2031) were significantly recorded the greatest grain yield/fed as compared with the others interactions in the both seasons.