[Nitrification inhibitors as a way to improve cucumber fruits quality and to decrease nitrate content in them]

The problem of high nitrates content is usual at a cultivation of vegetables in a greenhouse. The main factors of nitrate accumulation in cucumbers are light deficiency and high doses of nitric fertilizers applied. The experiments were carried out within 3 years on cucumber F1 hybrids of Estafeta variety. The nitrification inhibitors, namely N-hydroxymethyl-3(5)-methylpyrazole (HMMP) and dicyandiamide (DCDA), were brought in soil. There was a problem to choose such doses of preparations so that the productivity of cucumbers does not decrease essentially, but their quality rises. It is established that the optimum dose for HMMP is 1.5% and for DCDA 2.0% from nitrogen level containing in fertilizers. It is possible to add these preparations during base or additional fertilizing terms. The biochemical composition of fruits was defined in March (every decade) and in the 1st decade of April. It is shown that at fertilizing by ammonium nitrate or urea without nitrification inhibitors the vitamin C content in cucumbers does not exceed 6.81 mg-%. In the similar conditions but in the presence of HMMP it makes up 8.11 mg-% and 8.29 mg-% in the presence of DCDA. The similar dynamics is observed concerning the sum of sugars which was higher in the presence of HMMP or DCDA and lower in their absence. There were no essential differences in the dry matter content between the control and experimental variants. At the beginning of harvest period the nitrates content of control variants was 674 mg/kg (at urea fertilizing) and 759 mg/kg (at ammonium nitrate fertilizing). In the presence of HMMP or DCDA this index varied within 296-394 mg/kg. In the end of harvest period (1st decade of April) the content of nitrates in the control variants was 387 and 394 mg/kg respectively and 232-274 mg/kg in experimental variants. It is concluded that the using of HMMP or DCDA at a cultivation of cucumbers in a covered ground is rational, because it makes possible to produce cucumbers with the low content of nitrates.