SUMMARYA study of insect pollinators and their impact on canola yield was conducted during the 2013/2014 and 2014/2015 growing seasons. The study was carried out at an experimental farm, Faculty of Agriculture, Suez Canal University, Ismailia. The results revealed that 21 species of insect pollinators belonging to 14 families under four orders visited canola flowers. The abundance of Hymenoptera insects reached the maximum of 67.90%, followed by Diptera 14.97%, Coleoptera 13.61%, then Lepidoptera 2.26% as average of both seasons. In open pollination, Colletes lacunatus had the maximum percent abundance in the two seasons (30.45 and 29.34%, respectively) followed by Apis mellifera (12.34 and 17.73%, respectively), compared to other bees and different pollinators. Peaks of foraging activity of both C. lacunatus and A. mellifera were mainly observed from 1:00 to 3:00 pm and they corresponded to the number of flowering plants. Open pollination increased the number of pods per plant, seeds per pod, weight of 1000 seeds, yield per plant, yield per feddan (1 fed = 0.42 ha) and seed germination, compared to non-open pollination.

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Laboratory studies showed that the Gezira soils contain appreciable amounts of fixed ammonium.Values for the surface soils varied from 0.25-0.30 me/lOOg. The soils have the capacity to fix a large quantity of applied ammonium.In the two soil profiles studied the amounts of fixed ammonium and the ammonium-fixing capacity increased with depth reaching a maximum in the grey layer at a depth of about 70 to 140 cm below which it decreased again. The fixed ammonium values varied from 0.28 to 0.40 me/lOOg and comprised from 5.0 to 5.9 per cent of the total ammonium-fixing capacity (oven-dry condition).When expressed as percentage of Kjeldahl nitrogen the fixed ammonium increased with depth, varying from 12.5 to 20.2 per cent. As expected the amount of fixed ammonium was found to depend on the type and amount of the clay minerals present.The current cropping and fertilization practices were found to have very little effect on the fixed ammonium content of the soil, but it is expected from the high-fixing capacity of these soils that the amount of fixed ammonium will increase with the increase in frequency and dose of NH4-N fertilizers application.

Field experiments were made under irrigated semi-arid conditions to determine the effects of sowing date and nitrogen application on the growth and yield of wheat and nitrogen-uptake by wheat plants. Early sowing was found to be favourable to high grain production because the post-anthesis period coincided with relatively lower temperatures. Late sowing was unfavourable to grain yields since the period between anthesis and leaf senescence was curtailed by the onset of relatively higher temperature. The benefits from nitrogen were greater with early sowing because of higher nitrogen-uptake during early vegetative growth as a consequence of which, nitrogen was readily available to the plants. This resulted in better leaf expansion, and higher leaf-area indices and leaf-area duration. With late sowing nitrogen-uptake was much lower during early vegetative growth and this resulted in decreased leaf expansion, reduced leaf-area indices and leaf-area duration and therefore diminished response in grain yield to nitrogen application.