The effect of varying nitrogen doses at different periods to the nitroen use efficiency, grain yield and quality of the corn genotypes at Çukurova conditions

ABSTRACTPhD THESISTHE EFFECT OF VARYING NITROGEN DOSES AT DIFFERENTPERIODS TO THE NITROEN USE EFFICIENCY, GRAIN YIELD ANDQUALITY OF THE CORN GENOTYPES AT CUKUROVA CONDITIONSGökhan BÜYÜKINSTITUTE OF NATURAL AND APPLIED SCIENCESUNIVERSITY OF ÇUKUROVADEPARTMENT OF SOIL SCIENCESupervisor : Prof. Dr. Hayriye IBRIKCIYears : 2006, Pages: 143Jury : Prof. Dr. Hayriye IBRIKCIProf. Dr. Zulkuf KAYAProf. Dr. A.Can ULGERProf. Dr. Yusuf KIRTOKAssoc. Prof. Dr. Abdullah OKTEMThis study, for solving the issues of effective uptake of nitrogen, optimumapplication dose and time within the Çukurova region, aimed to determine a) effectof N fertilisation to plants development, dry matter production and grain yield atthree different times with four varying doses; b) plants N fertiliser use efficiency atregion conditions; and c) reaction of experiemental corn genotypes (P31G98 veRX9292) to N fertilisation.Experimental and regression analyses revealed that, the use of 20-28 kg/da Nat III. application period (1/2 was applied following 2 weeks of germination, and 1/2was when the plant is 60 cm high) yielded highest grain production, and N useefficiency with decreasing values following said application amount. Also, it is foundthat at conditions when soil Nmin is sufficeint, N fertilisation could be postponed tofurther periods, but the determined amount in soil should be taken into account at thetime of fertilisation.Key words: Nitrogen rates, Nitrogen use efficiency, Nitrogen timing, Yield.II