Effect of N supply on growth and development of Zea mays L.

The objective of this study was to quantitatively determine and to separate the effects of nitrogen deficiency on growth and development of Zea mays L. Maize varieties V1 (Sadaf) and V2 (Sultan) were grown in a sand culture. When the coleoptiles leaf was fully expanded, three level of N supply i.e. (optimum nitrogen supply) = 12 mM; (medium nitrogen supply) = 6 mM and (zero nitrogen supply) = 0 mM were established by varying N concentration in the Long Ashton nutrient solution. The supply of respective nutrient media was maintained from coleoptiles leaf stage through silking. A thermal time in growing degree days (GDD) was calculated to characterize the thermal environment of the corn plants. The leaf area was estimated daily non- destructively as a measure of growth of a maize plant. Number of leaves per plant, irrespective of leaf size and the number of leaves per plant in Haun scale were used as a measure of development of a plant and were also recorded on daily basis. There was linear relationship between the number of leaves of V1 and V2 and the thermal time since sowing for each level of N supply. The development rate of both V1 and V2 in (zero nitrogen supply) was about 30% slower than that in (optimum nitrogen supply) and (medium nitrogen supply). The development rate of V1 in (medium nitrogen supply) was not affected but development rate of V2 in (Medium nitrogen supply) was 11% slower than that in (optimum nitrogen supply). At leaf stage 11, the leaf area in (zero nitrogen supply) and (medium nitrogen supply) was 66 and 20% smaller than the leaf area in (optimum nitrogen supply), respectively. At the stage of tussling, the leaf area in (zero nitrogen supply) treatment was 69 and 75% less relative to leaf area in (medium nitrogen supply) and (optimum nitrogen supply), respectively. The leaf area in (medium nitrogen supply) was 20% less than the leaf area in (optimum nitrogen supply). The differences established in the size of leaf area by the differential supply of N at the tussling stage were maintained at the silking stage.