The Effect of N Fertilizer Placement and Timing on the Aboveground Biometric Characteristics of Spring Wheat ( Triticum aestivum L. cv. Spectrum) on Leached Chernozem

摘要

The maintenance of optimum levels of nitrogen (N) in the soil has a fundamental influence on biometric characteristics of spring wheat. A study was carried out to determine the effect of N fertilizer placement and timing on biometric characteristics of spring wheat at Krasnodar Agricultural Research Institute in Krasnodar County (45°5`N, 38°50`E, >400 m elev.) in Eastern Europe. The experiment was designed as Randomized Complete Block with four replicates, which were subjected to six N fertilizer treatments (T1-T6). Spring wheat was grown under rainfed conditions with treatments varying on N fertilizer placement and timing. Single split N fertilizer applied at tillering stage by broadcasting method (T3 plots) had comparatively taller stems than other treatments for the first (85.4 cm) and second (84.9 cm) seasons of the study. Wheat plant stems in T3 plots were 2.4-3.3 cm and 2.4-3.2 cm taller than in other N fertilizer treated plots for first and second seasons respectively. Single split and triple split applications of N45 at tillering (T3) and N15 at tillering, N15 at stem elongation and N15 at heading (T4) phenological stages both by broadcast method consistently amplified (F<0.001) the number of developed spikes per sample collected from 0.25 m2. For both years of the study, T3 and T4 had 1.32-16.56% and 1.33-16.67% of developed spikes above those in other N fertilizer treated plots. For both seasons of the study, results show a distinct corrolation between the numbers of stems, spikes and spikeless stems per 0.25 m2 sampled from each plot (r2 = 0.7605). Generally, N fertilization diminished the prevalence of unproductive tillers per wheat plant station across almost all treatments subjected to N fertilizer treatments. Compared with the control plots, N fertilization increased the number of developed spikelets per plant station by 50%. The numbers of productive spikelets recorded in plots treated with triple split applications of N fertilizer at tillering, stem elongation and heading stages banded as a solution in the root system zone of both sides of plant rows were consistently higher than those in other N fertilizer treated plots.