Effect of Water Stress, Nitrogen and Potassium Fertilizers on Maize Yield Productivity

Two field experiments were carried out at the Farm of Agric. Res. and Exp. Center of Fac. of Agric. Moshtohor, Benha University, Toukh Directorate, Qalyubia Governorate, Egypt, during two successive summer growing seasons of 2015 and 2016 to study the effect of three water stress, i.e. normal irrigation, skipping the second irrigation (skipping one irrigation during vegetative growth stage) and skipping the fifth irrigation (skipping one irrigation during kernels filling stage) and four nitrogen fertilizer rates, i.e. 0, 50, 100 and 150kg N/fed as well as three potassium fertilizer rates, i.e. 0, 24 and 48 kg K₂O/fed on growth, yield and its components as well as some kernels chemical properties of maize (white single cross hybrid 2031 for Misr hytech Seed Int.,). Results of combined analysis of the two seasons showed that kernels filling stage was the most sensitive to water deficit stress and preventing irrigation at this stage (skipping the 5^th irrigation) caused marked decrease in mean values of allmost maize yield and its components, while, full irrigation treatment appeared to be the best irrigation treatment sine it enhanced all maize traits under study. Planting maize under water stress by skipping the 2^nd irrigation and skipping the 5^th irrigation significantly decreased mean values of grain yield/fed (kg) by 25.49 and 41.04 % respectively, compared to mean values of grain yield/fed (kg) of maize under normal irrigation. Planting maize when received 150 kg N/fed caused significant increase in all mean values of maize traits under study such as plant height (cm), ear height (cm), No. of ears/fed, ear diameter (cm), ear length (cm), No. of rows/ear, No. of kernels/row, No. of kernels/ear, ear weight (g), kernels weight/ear (g), kernels shelling (%), 100-kernel weight (g), ear yield/fed (kg), grain yield/fed (kg), stover yield/fed (kg), biological yield/fed (kg), harvest index (%), kernels nitrogen content (%), kernels crude protein (%), nitrogen uptake/fed (kg) and protein yield/fed (kg) Meanwhile, the highest mean values of potassium use efficiency (KUE) which were recorded from growing maize when received 100 kg N/fed. Growing maize under the higher potassium rate (48 kg K₂O/fed) was produced the maximum mean values of plant height (cm), No. of ears/fed, ear length (cm), No. of kernels/row, No. of kernels/ear, ear weight (g), kernels weight/ear (g), 100-kernel weight (g), kernels shelling (%), ear yield/fed (kg), grain yield/fed (kg), stover yield/fed (kg), biological yield/fed (kg), harvest index (%), kernels potassium content (%), nitrogen uptake/fed (kg) and protein yield/fed (kg) while, the highest mean values of KUE which were recorded from growing maize when received 24 kg K₂O/fed. The first order interactions between (normal irrigation X 150 Kg N/fed), (normal irrigation X 48 kg K₂O/fed) and (150 Kg N/fed X 48 kg K₂O/fed) as well as the second order interaction between normal irrigation X 150 Kg N/fed X 48 kg K₂O/fed) were significantly recorded the greatest mean values of maize yield and its components as compared with the others interactions. It could be summarized that grown maize under full irrigation and fertilization by 150 Kg N + 48 kg K₂O/fed in order to maximizing its productivity.