Production function determination of onion as affected by water amounts, evapotranspiration and nitrogen fertilization rates in the Central Jordan Valley [Jordan]
1987
Al-Rajabi, M.F.
Results showed that at all water levels, application of nitrogen at 0, 100 and 200 kg N/ha rates produced significantly higher yield than the 400 kg N/ha rate. Yield for all nitrogen rates has increased gradually with increasing water amounts except at 0 and 200 kg N/ha rates at 73.4 cm water amount. The max onion bulb yield (39.92 t/ha) was obtained from treatment W3N1 which represented 40% available soil moisture depletion (ASMD) or 63.5 cm applied water or 55.8 cm total evap2048otranspiration (ET) and zero nitrogen rate. There were linear relationships between onion bulb and total water applied and seasonal ET. Yield was highly correlated with nitrogen (N) and water (W), and with N and ET. Consumptive use of water increased with increasing water application rates. Daily consumptive use reached its max value after 12-15 weeks from transplanting. Diameter, length, dry-weight percentage of onion bulb, and total soluble solids (TSS%) were not significantly affected by N rates. Significant differences in nitrogen contents of onion bulb were detected between N4, N3, and N1 rates. Significant differences in nitrogen contents of leaves were also detected between N4 and both N2 and N1 and between N3 and N2. The data were used to develop function for onion bulb yield, as affected by nitrogen fertilization rates, and irrigation water amounts and also as affected by nitrogen fertilization rates and evapotranspira
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