Complementary Effect of Biofertilizer with Mineral Nitrogen Fertilizer on Canola Plant Productivity التأثیر المکمل للسماد الحیوى مع التسمید النیتروجینى المعدنى على إنتاجیة نبات الکانولا

Abstract

Biofertilizers are recently used on a large scale to reduce chemical fertilizers and their pollutant effect on soils and water. In this work, a pot experiment was carried out to evaluate the effect of Azotobacter chroococcum, Azospirillum lipoferum and Klebsiella oxytoca with different levels of nitrogenous fertilizer on the growth and yield of canola (Brassica napus L.) and microbial population in the soil during the winter season, 2018. Results reveal that used bacterial species as biofertilizers have a great effect on morphological and yield traits of canola plants, where the plants treated with Azotobacter, Azopirillum and Klebsiella were characterized by increases in plant heights, plant weights as well as numbers of branches and pods. Also, Azotobacter and Azospirillum increased nitrogen, whereas Klebsiella oxytoca increased phosphorus in plants and seeds. The results showed that using triple inoculum (Az. chroococcum, Azosp. lipoferum and K. oxytoca) with 75% of nitrogenous fertilizer (33.75 kg N/feddan) achieved the highest seed yield per plant (24.35 g/plant), while oil percent in seeds was 46.86%, which was not the highest but very close to oil percentage in plants treated with the recommended dose of nitrogen, which was 47.47%. On the other side, using bacterial inoculum stimulate microbial population and increased total bacteria, diazotrophs (Azotobacter and Azospirillum) and phosphate dissolving bacteria counts in the rhizosphere of canola plants.