[en] These greenhouse studies conducted on a Mediterranean Terra Rose soil in an plastic greenhouse, were designed to investigate the response of drip-irrigated tomatoes (Lycopersicon esculentum Mill.)grown as a spring production and peppers (Capsicum annuum) heated for anti frost to four nitrogen levels continually applied with the irrigation stream. Water containing 0,50,100 or 150 mgN/l for tomatoes, 0,70,140 or 210 mgN/l for peppers as NH₄S₂O₄, and uniformly supplied with 60 and 180 mg/l of P and K respectively were applied two times a week. Three adjacent plants in each plot were fertigated with N labeled NH₄S₂O₄ (2% a.e. enrichment). These treatments were compared with banded application of NH₄S₂O₄ at the rate of 320 kgN/ha for tomatoe sand 350 kgN/ha for peppers that were equivalent to the 100 mgN/l and 140 mgN/l treatments. The total amount of water applied was 345 mm for tomatoes and 260 mm for peppers. The results obtained showed that the highest yield was achieved in 100 mgN/l for tomatoes and in 140 mgN/l for peppers. The percentage fertilizer N utilization and yield increase by tomatoes and peppers were significantly increased with applying the N fertilizer by the irrigation water, fertigation, relative to the soil application of N at the same level fertilization. Evidently, the nutrient uptake efficiency as indicated by the highest yield is higher with fertigation which is extend means more environmental friendly approach. These experiments demonstrated that the amount of N fertilizer by applying in the irrigation water is to be recommended 100 mgN/l for tomatoes and 140 mgN/l for peppers to obtain high yield

[en] This greenhouse study conducted on a Mediterranean Terra Rose soil, as a single crop production, heated only for anti frost, was designed to investigate the response of drip-irrigated tomatoes (Lycopersicon esculentum Mill.) to four nitrogen levels continually applied with the irrigation stream. Water containing 0, 50, 100 or 150 mgN/l and uniformly supplied with 60 and 180 mg/l of P and K, respectively, were applied two times a week. Three adjacent plants in each plot were fertigated with N¹⁵ labeled NH₄S₂O₄ (2% a.e. enrichment). For each plant the amount of water, P,K and the N¹⁵ applied through the bottles was equivalent to that amount applied through a single dripper. These treatments were compared with banded application of NH₄S₂O₄ at the rate of 400 kgN/ha that was equivalent to 100 mgN/l treatment. The resulting N application totals ranged from 200 to 600 kgN/ha.The total amount of water applied was 427mm. The results obtainedshowed that the percentage fertilizer utilization by the tomatoes was the highest in 50 mgN/l (200 kgN/ha) treatment, 100 mgN/l (400 kgN/ha) treatment, was on the second row, the percentage fertilizer utilization in 150 mgN/l (600 kgN/ha) and soil applications (400 kgN/ha) were the same and were significantly lower than the other treatments. The highest yield was achieved in the 100 and 150 mgN/l (400 and 600 kgN/ha) treatments. This experiment demonstrated that the amount of N fertilizer by applying in the irrigation water is to be recommended 100 mgN/l for tomatoes to obtain high yield in production under greenhouse conditions

[en] This greenhouse study conducted on a Mediterranean Terra Rose soil in an unheated plastic greenhouse was designed to investigate the response of drip-irrigated tomatoes (Lycopersicon esculentum Mill.) and peppers (Capsicum annum) to four nitrogen levels continually applied with irrigation stream. Water containing 0,67,134 or 201 mgN/l and uniformly supplied with 80 and 240 mg/l of P and K, respectively, were applied two times a week. Three adjacent plants in each plot were fertigated with N¹⁵ labeled NH₄S₂O₄ (2% a.e. enrichment). For each plant the amount of water, P, K and the N¹⁵ applied through the bottles was to that amount applied through a single dripper. In addition to the fertigation soil application of 400 kgN/ha was included with three adjacent plants in each plot were fertilized receiving N¹⁵ labeled (3.3 % a.e. enrichment) The total amount of water applied was 392 mm and the resulting N application totals ranged from 200 to 600 kgN/ha. According to the results obtained, the maximum yield of tomatoes and peppers were achieved with 67 mgN/l (200 kgN/ha) treatment. The percentage fertilizer utilization by tomatoes was highest with 67 mgN/l (200 kgN/ha), which was followed by 134 mgN/l (400 kgN/ha) .The percentage fertilizer utilization was the lowest with 201 mgN/l (600 kgN/ha) or soil application (400 kgN/ha). The results indicated that the percentage fertilizer utilization of tomatoes was significantly greater by the fertigation than the soil application of N at the same level fertilization (400 kgN/ha). The fertilizer N uptake by peppers was significantly greater with 134 mgN/l (400 kgN/ha) than the other applications. The results indicated that although the percentage fertilizer utilization was the same, the fertilizer N uptake by peppers was significantly greater with the fertigation than the soil application of N at the same level fertilization (400 kgN/ha)

[en] A number of experiments were conducted to investigate the influence of different N rates applied through drip irrigation on the growth and N uptake by tomato, pepper, cucumber, melon and eggplant under greenhouse conditions. It was found that, for tomato, the % NUE was significantly increased by applying the N fertilizer through fertigation (53.9%) as compared to the soil application (34.0%) at 100 mg N/L. In general, any further increase of N fertilizer did not have an improving effect on the tomato yield. With pepper, the % NUE was significantly increased by applying the N fertilizer in the irrigation water (49.2%) as compared to the soil application (33.9%) at the same N level (140 mg N/L), being the optimum N rate under our greenhouse conditions. At a fertilization level of 100 mg N/L with fertigation, the % NUE was significantly increased as compared to the soil application. With respectively cucumber, melon and eggplant; the % NUE with fertigation was 63.4, 21.4 and 50.8%, while with soil application it was 34,0 11.0 and 18.8%. (author)