Abd-Allah Bardisi

A field experiment was carried out during the two successive winter seasons of 2020/2021 and 2021/2022 to study the effect of mineral nitrogen levels and plant density on dry weight, yield and its components, as well as bulb quality of onions (cv. ‘Ahmar Tanawy’). This experiment included 12 treatments, which were combinations between four levels of mineral nitrogen (0, 192, 240 and 288 kg N/ha) and three plant densities (4, 5 and 6 rows/ridge equal 33.33, 41.67 and 50 plants/m², respectively). These treatments were arranged in a split-plot design with three replications. Nitrogen levels were randomly arranged in the main plots, and plant densities were randomly distributed in the subplots. Nitrogen application at 192,244 and 288 kg N/ha led to increase dry weight/plant compared to control (zero N) and 288 kg N/ha gave the highest values of dry weight of leaves, dry weight of bulbs, and total dry weight per plant at 100 days in both seasons. The increases in total dry weight per plant were about 4.84 and 4.80 g per plant for 192 kg N/ha, 4.76 and 3.87 g per plant for 244 kg N/ha, and 6.86 and 5.74 g per plant for 288 kg N/ha over the control at 100 days in the 1^st and 2^nd seasons, respectively. The interaction between N at 288 kg/ha and low plant density (4 rows/ridge) gave the highest values of dry weight of leaves, bulb, and total dry weight/plant and increased yield of grade 1, exportable yield, average bulb weight, as well as nitrate and sulphur contents in bulbs, whereas the interaction between N at 244 kg/ha and high plant density (6 rows/ridge) increased grades 2, 3, and 4, marketable yield, and total yield/ha.

One field experiment was carried out during the two successive winter seasons of2015/2016 and 2016/2017 at a Private Farm in El-Sowa Village, Abo Hammad District, SharkiaGovernorate, Egypt, to study the effect of cultivars, mineral phosphorus, and mycorrhizae fungiinoculation on plant dry weight and chemical composition of onion plants under clay soil conditionsand flood irrigation system. The experiment included 18 treatments which were the combinationsamong two onion cultivars (Giza 20 and Beheri improved), three levels of mineral phospours fertilizer(0, 30 and 45 kg P2O5/fad.) and three levels of mycorrhizae (0, 2 and 4 kg/fad.). These treatments werearranged in a split split plot design system with three replicates. Cultivars were randomly arranged inthe main plots, levels of P2O5 were randomly distributed in the sub plots, while mycorrhizae levelswere randomly arranged in the sub sub plots. The triple interaction treatments among onion Giza 20cultivar, P2O5 at 45 kg/fad., and inoculation with mycorrhizae at 4 kg/fad., significantly increased dryweight of roots, bulbs, leaves and total dry weight/plant at 75 days after transplanting, as well as, N, Pand K uptake by roots, bulb and leaves at 105 days after transplanting.