Two field experiments were conducted in 2012/2013 and 2013/2014 winter seasons at Sids Agric. Res. Station, Beni-Suef, Egyptto find out the extent to which onion crop performance was affected by alternate furrow irrigation technique. Two alternate furrow irrigation regimes were assessed i.e. irrigating at 14 or 28 days intervals, comparing with the common furrow irrigation regime. These irrigation regimes were combined with 60, 90 and 120 kgNfed-1 levels and tested in a split plot design with four replicates, where irrigation regimes were represented in the main plots, whereas split ones were assigned for N levels. Onion yield and quality, applied water as well as water, N and consumptive use efficiencies were considered. The most important results could be summarized as follows:
1- The marketable onion bulb and total yields were significantly increased under Alternate Furrow Irrigation at 14 days interval (AFI14), comparable with Alternate Furrow Irrigation at 28 days interval (AFI28) and common furrow irrigation (EFI). The highest values of bulb weight, bulb diameter, bulb total soluble solids (TSS %) and bulb dry matter (DM %) were obtained with AFI14 regime. Increasing N level resulted in gradual increases in marketable, total, culls onion bulb yields, onion bulb weight, bulb diameter, bulb TSS and DM%. The interaction of AFI14 regime and 120 kg Nfed-1 level resulted in the highest figures of the abovementioned parameters.
2- The highest values of seasonal applied water were under every-furrow irrigation (EFI) and reached to 2247 and 2209 m3fed-1, which reduced by (24.86 and 7.29%) and by (24.52 and 7.22%) under AFI28 and AFI14 regimes, respectively, in the consecutive two seasons. The highest seasonal Cu (1712.28 and 1642.37 m3fed-1) were recorded under EFI, which tended to reduction under AFI28 and AFI14 regimes with 17.98 and 5.71% in 1st season, and 19.83 and 6.63% in 2nd season, respectively, lower than that with EFI regime. Increasing N level resulted in gradual increased Cu values, and interaction of EFI regime and 120 kg Nfed-1 level revealed the highest Cu value.
3- TheAFI14 regime exhibited the highest values ofIrrigation Water Productivity, Water and N Use Efficiencies, whereas Consumptive Use Efficiency was improved with AFI28 regime. Irrigation Water Productivity, Water and Consumptive Use Efficiencies, were increased gradually with increasing N level, whereas N use efficiency exhibited a differed trend.
On conclusion, AFI14 regime is capable to mitigate the water stress, during the irrigation cycle, and to increase onion bulb yield. In addition, it is obviously noticed that the alternate furrow irrigation at 14-days interval and120 kgNfed-1 is the best combination to achieve higher marketable onion bulb yield and to improve irrigation and N use efficiencies as well.