Impact of Irrigation Water Quality, Nitrogen Fertilization Rates and Foliar Application of Ascorbic Acid on Wheat Yield and Some Soil Properties in the North Middle Nile Delta Region

Lysimeter experiment was performed during winter season of 2015/2016 in Sakha Agricultural Research Station farm, Kafr El-Sheikh Governorate, to study the effect of irrigation water salinity, nitrogen fertilizer rates and foliar application of ascorbic acid on yield and its components of wheat crop and some soil properties. The experiments were designed as split-split plot with three replicates. The main plots were occupied by irrigation water salinity as: S1(0.56 dS m-1), S2(2 dS m-1), S3(4 dS m-1), and S4(6 dS m-1), sub plots were devoted to N-fertilization rates N1(75%N), N2(100%N), and 125%N recommended dose and sub-sub-plots ascorbic acid concentration A1(100 ppm) and A2(200 ppm).

The results can be summarized as follows

• Irrigation water salinity, N-fertilizer rates and foliar application of ascorbic acid have a high significant on grain and straw, biological yield and 1000-grain weight.
• The highest value for grain and straw yield (2290.30 and 3190.22 kg fed-1) was obtained with applying irrigation water (0.56 dS m-1), as compared to irrigation water salinity levels (2, 4 and 6 dS m-1), (2.4 Fed.= hectare).
• The highest value for grain and straw yield (29830.50 and 3172.20 kg fed-1) were obtained by applying 125% N from recommended dose and (2785.38 and 2991.63 kg fed-1) as foliar spraying of ascorbic acid (200 ppm).
Grain yield was decreased by 4.04, 6.46 and 10.06%, under water salinity levels 2, 4 and 6 dS m-1, respectively with irrigation water compared to fresh water (0.5 dS m-1).
• The straw yield of wheat was reduced by 8.56, 10.95 and 19.86% under irrigation water salinity levels 2, 4 and 6 dS m-1 compared to fresh water (0.5 dS m-1).
• The highest mean values for both water productivity (WP) and productivity of irrigation water (PIW) were recorded under irrigation water salinity S1 and S2 comparing with S3 and S4 treatments. Also both nitrogen rates and ascorbic acid as foliar application have had positive effect on both (WP) and (PIW) for grains and biological yield where the highest mean values were recorded with N3 and A2 treatments.
• The highest salt accumulation in soil profile under ECiw 2, 4 and 6 dS m-1were increased by 14.23, 22.79 and 46.94%, respectively as compared to ECiw 0.56 dS m-1 while SAR values were increased by (6.97, 10.92 and 25.38%).
• The above mentioned results indicated that the applied leaching fraction 20 to 30% was not efficient to remove salts in the soil profile and further work needs to be done in order to maintain the acceptable salinity level in the root zone.
• The highest values of grain and straw, biological yield and weight of 1000-grain were achieved with ascorbic acid at 200 ppm as compared to 100 ppm.