Growth, yield components and micronutrient nutrition of field-grown maize (Zea mays L.) as affected by nitrogen fertilization and plant density
Growth and yield components in field-grown maize (Zea mays L.) were enhanced by nitrogen fertilization ranging from 50 to 200 kg N ha−1. Ear diameter, kernel depth, grain: stover ratio, number of ears plant−1, plant height and dry matter production increased as N fertilization rate was increased up to 100 or 150 kg N ha−1. Tasselling in maize was hastened by N fertilization. Increasing plant density from 25000 to 75000 plants ha−1 increased plant height, dry matter production and delayed tasseling but reduced ear diameter, kernel depth, grain: stover ratio and number of ears plant−1. Increased N supply and plant density had no influence on the concentrations of Mn, Zn, Cu, and Fe in ear leaf; except that Mn concentration increased as N fertilization rate was increased up to 150 kg N ha−1. Nitrogen × plant density interactions on the concentrations of the micronutrients in maize ear leaf were not significant.
MAIZE RESPONSE TO TIME AND RATE OF NITROGEN APPLICATION
To find out effective use of nitrogen (N) in autumn planted maize (Zea mays L.) hybrid, a field experiment was conducted during 2009 at Agronomic Research Area, University of Agriculture, Faisalabad. Three N split application timings depending upon various development stages were kept in main plots and five rates of N; N1 (100 kg ha -1 ), N2 (150 kg ha -1 ), N3 (200 kg ha -1 ), N4 (250 kg ha -1 ) and N5 (300 kg ha -1 ) were randomized in sub plots. Results revealed that maximum plant growth, number of kernels per cob (419) and grain yield (8.27 t ha -1 ) were recorded in N4 treatment. Contrary maximum days to maturity (103.3 days) and biological yield (16.56 t ha -1 ) were recorded in N5 treatment. Based on the results, it was concluded that application of N in three split (at V2, V16 and R1 stage) @ 250 kg ha -1 can be recommended for achieving optimum grain yield under semi arid environment of Pakistan.
Variability in the Concentration of Twelve Elements in Corn Grain
Corn grain (Zea mays L.) samples were collected from nine Univ. of Illinois Agronomy Research Fields situated throughout Illinois and from six soil associations in Fulton County, Ill. The 243 samples were obtained from sites receiving only inorganic fertilizers. The objective was to determine levels of selected elements in corn grain as it is commonly grown in Illinois. Chemical analysis of the corn grain for Ca, Fe, K, Mg, Mn, Na, Cd, Cr, Cu, Ni, Pb, and Zn showed that the concentrations of K and Mg were the highest, while levels of Cd, Cr, and Pb were <0.2 ..mu..g/g. Variability of Na, Cd, and Cr in the grain samples was high, while that of Mg, Zn, and Mn was low. Element concentrations in grain were within ranges given in the literature. Concentrations of Ca, Mg, Mn, K, Na, Cd, Cu, Cr, Ni, Pb, and Zn from the nine research fields varied significantly with location. Soil type at the six Fulton County soil associations significantly affected the concentrations of Mg, Mn, K, Cd, and Cr in the grain. There was a highly significant positive correlation for applied fertilizer N and the grain Mn content for samples from the research fields. Highlymore » significant negative correlations were observed for applied fertilizer N and the K, Na, Cd, and Pb levels in corn grain. An evaluation of possible health effects for selected corn grain metals indicated that the background levels of Cd, Cr, Cu, Pb, and Zn observed would not present any human or animal health problems.« less