Field experiments were conducted to investigate the interactive effects between different irrigation treatments and N application rates on grain and straw yields of wheat plants grown on a clay soil and to describe the relationships between irrigation treatments and yield of wheat plants at different N treatments. The factors were nitrogen fertilizer(N): 0(N0), 75(N1), 150(N2), and 225(N3) kg.ha-1 as urea and four treatments of irrigation(I): fully-irrigation with canal water(I1), 2 times well water + canal water (I2), 4 times well water + canal water(I3), and 6 times well water + canal water(I4). The obtained results indicated that grain and straw yields were significantly increased with increasing application rate of N fertilizer at all treatments of irrigation. On the other hand, grain and straw yields of wheat plants were decreased significantly with increasing number of well water irrigation times. The maximum nitrogen use efficiency (NUE) for grain yield (63.73 kg kg-1 N) was found with a 75 kg N ha-1 and I1(fully-irrigation with canal water). In contrast, the minimum NUE for grain yield (19.56 kg kg-1 N) was found with a 225kg Nha-1 and I4 (6 times well water,4500 m 3 ha-1 + canal water, 1500 m 3 ha-1)for first season. Similarly, irrigation with well water decreased the agronomic efficiency (AE) for grain yield noticeably at all N application rates. The reduction in AE for grain yield of wheat was much higher at I4 treatment than of that at I2 treatment. The mean agronomic efficiency (AE) for grain yield for the second season confirmed the results of first season and was very close to each other. Future research works should be made by further developing more efficient wheat varieties that could use N more efficiently at lower rates (<225 kg N ha −1). It can be concluded that the limited amount of available fresh water should be applied during the initial growth stage and supplemented with well water at later growth stages of wheat plants.

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Field experiments were conducted to study the influence of three irrigation methods and nitrogen fertilization rates on yield and yield components of onion (Allium Cepa L., cv. Creole Red) grown under Russian environmental conditions during the growing seasons of 2012 and 2013. The three applied irrigation methods were the rain fed (RF), surface drip irrigation (SDI) and subsurface drip irrigation (SSDI) in which placement depths of drip laterals were 10 cm. Nitrogen fertilizer , as ammonium sulfate, was applied at three rates of 0 , 90 and 180 kg N.ha -1 . The experiment was implemented in a randomized complete block design with three replicates. Plant height, number of leaves/plant, Bulb dry matter, bulb diameter and bulb weight of onion (yield components) were measured and consequently crop yield and water use efficiency (WUE) were determined for all treatments. The obtained results indicated that surface drip irrigation or subsurface drip irrigation with 90 kg N/ha resulted in higher yield and yield components. The highest values of plant height, number of leaves/plant, and neck diameter were obtained by SDI + 90 kg N/ha treatment while the lowest values belonged to RF treatment with zero (0.0) rate of Nitrogen. The fresh crop yield was the highest (38.0 t ha -1 ) with SDI + 90 kg N/ha treatment, while RF treatment with 0.0 nitrogen produced the lowest value of crop yields (20.5 t. ha -1 ). The highest WUE (0.89 t. ha -1 cm -1 ) was obtained by the SDI + 90 kg N.ha -1 treatment while the lowest value of WUE was obtained through RF treatment with 0.0 nitrogen. It can be concluded that SDI + 90 kg N.ha -1 treatment was found to be the most effective irrigation method and nitrogen application rate in improving WUE and increasing the yield and yield components of onion grown under Russian environmental conditions.

The present experiment was conducted during 2011/2012 and 2012/2103 winter seasons to study the effect of irrigation regimes e.g. 60, 80 and 100% ETo and foliar application of Potassium Silicate (PS) and Salicylic Acid(SA) in 250 and 400 mgL -1 for both and interactions. The adopted treatments were assessed a splitplot design with 3 replicates. The irrigation regimes were represented inthe main plots, whereas foliar application of PS and SA treatments were allocated to the split plots. The obtained results could be summarized as follows: 1-Water saving reached to 20 and 40% under irrigation onion crop at 80 and 60% ETo regimes, comparable with 100% ETo regime. Total onion yield and both Bulb diameter and Single bulb weight were significantly affected due to the adopted treatments in 1 st and 2 nd seasons. Under100% ETo regime, higher values of total onion yield, Bulb diameter and Single bulb weight were recorded, comparable with those under 80 and 60% ETo regimes in 1 st and 2 nd seasons. Higher values of total onion yield, Bulb diameter and Single bulb weight were observed with PS 500 foliar application, comparing with those under PS 250, SA 250 andSA 500 . Interaction of100% ETo regime and PS 500 foliar application resulted in higher figures of total onion yield, Bulb diameter and Single bulb weight 2-Total Soluble Solids (TSS), marketable bulb yield% and dry matter % were significantly increased under 60% ETo, whereas the assessed foliar application e.g. PS or SA treatments did not significantly increase such parameters. nteraction of 60% ETo regime and SA 250 exhibited higher TSS %, Dry matter content% and marketable bulb yield%% 3-Values of IWUE tended to increase with reducing irrigation rate and vice versa. Additionally, foliar application of Potassium Silicate at 500 mgL -1 concentration (PS 500 ) exhibited higher IWUE figures, comparing with PS 250, SA 250 and SA 500 . The 60% ETo irrigation regime as interacted with foliar application of Potassium Silicate at 500 mgL -1 (PS 500 ) exhibited higher IWUE figures. 4-Under the present experiments circumstances, it is advisable to irrigate the onion crop at100% ETo regime combined with foliar application of potassium silicate at 500mgL -1 concentration. However, in water constraint situation irrigating at 80 or 60% ETo regimes and foliar application of potassium silicate at 500 mgL -1 concentration is recommended due to irrigation water saving(20 to 40%) and acceptable onion bulb yield with higher quality and efficient water use as well.