1.3. Effect of nitrogen feeding on the vegetative and generative features of field pepper grown with drip irrigation

An investigation on the influence of the rates and frequency of nitrogen fertilization over the vegetative and generative features of field pepper was conducted. The experiment was carried out on the field of the Department of Horticulture at the Agricultural University in Plovdiv. The experiment was made with the Kurtovska kapiya pepper cultivar as a mid-early field production, planted at the end of Nay and the beginning of June. The soil profile was a raised flat bed and the applied planting scheme was 110+50/20cm with one drip tape. Eight variants were initiated at two rates of NPK fertilization: I – N₁₂P₁₂K₁₂ – (A) in the following schemes:
A₁ – twofold nitrogen incorporation at 50% prior to planting and at the beginning of flowering (the control);
A₂ – twofold incorporation at 50% at the beginning of flowering and at the beginning of fruit-bearing;
A₃ – threefold incorporation – 30% prior to planting, 35% at the beginning of flowering and 35% at the beginning of fruit-bearing;
A₄ – threefold incorporation – 20% prior to planting, 20% after rooting, 30% at the beginning of flowering and 30% at the beginning of fruit-bearing.
II – N₂₄P₂₄K₂₄ – (B) in the following schemes:
B₁ – twofold incorporation (the control);
B₂ – twofold incorporation;
B₃ – threefold incorporation;
B₄ – fourfold incorporation.
A positive relation was found between the nitrogen feeding frequency through fertigation during vegetation and the height and mass of the stems. The variants with threefold and fourfold nitrogen incorporation surpassed the control by 5% – 62% depending on the phase and the rate of fertilization. A similar trend was observed in the number and mass of the leaves. The fruits of the same variants were more in number and had a bigger average mass. The variants with the greatest economically-significant early ripening were those with threefold and fourfold feeding, surpassing the control by 2% to 20%. The standard yield of red pepper was also higher in those variants and varied in absolute figures between l.370kg to 1.390 kg/dka. The overall market yield of the same variants surpassed the control by 6% to 16.4% and the fertigation at the lower fertilization rate (I) resulted in a similar yield to the one received at higher rates (II).