Comparative growth responses of field- and pot-grown open-pollinated maize varieties to N fertilizer application

Field and screen house experiments were conducted during the 1997 cropping season at the University of Ilorin, Nigeria. The experiments designed as 2 x 5 factorial and laid out in split-plot were to compare responses of field- and pot-grown maize varieties to N fertilizer application. Two open-pollinated maize varieties (DMRSR-Y and TZBP-W) were evaluated at five N levels (0, 30, 60, 90 and 120 kg N ha-1) in both the field and the controlled environment. Data collected included leaf growth measurements, morphological growth characters such as plant height, tassel and silk appearance dates, and physiological growth indices at both vegetative and reproductive stages. Yield components and grain yield were also measured at harvest. Responses of the evaluated varieties to N fertilizer application were similar for both the pot- and field-grown plants. However, the effects of low N levels were greater in the potted plants than in the field-grown ones, due to the adaptation of the field –grown plants to low N application, resulting from large volume of soil available to field-grown plants. Conversely, at the higher N levels, the values of most measured parameters were generally higher in the pot-grown plants than in the field. This was however, attributable to adequate soil moisture resulting from daily watering of potted plants as against the field plants which were rain fed and suffered water stress due to inadequate rainfall for sometime during the growing period, thereby unable to utilize the applied N fertilizer. Conclusively, this study showed that the results of the potted plants did not differ significantly in trends, but rather in magnitude, thereby suggesting that care should be taken in using controlled environment data in modeling for field evaluation of grain yield under rain fed conditions.