Cyanobacteria and N-Fertilization Enhance the Efficiency of Rice Plants Grown Under Saline Soil Conditions

Cyanobacteria play an important role in the maintenance and development of soil fertility and can improve nutrient uptake and growth of plants in saline soils. The effect of cyanobacteria applied with or without N fertilizer on enhancing rice growth and yield quality as well as nutrient content and uptake under saline soil conditions was investigated. Cyanobacteria (Nostoc calcicola sp.) were applied in different application methods, i.e., seed soaking, seed coating and foliar spray, and singly or in combination with different N-fertilizer rates during two rice field experiments. The experiments were conducted on a clay loam (saline soil) during 2017 and 2018 in the Sharkia Governorate, Egypt. Applied cyanobacteria as a foliar spray in combination with N fertilizer slightly decreased the soil pH and EC values and increased available N, P, K, Fe, Mn and Zn following rice harvest. Cyanobacterial foliar spray + N at a rate of 75 kg fed.-1 was superior to the other treatments in increasing straw and grain yield as well as N, P, K, Fe, Mn and Zn contents and uptake of rice straw and grains. Foliar cyanobacteria + N at a rate of 100 kg fed.-1 was superior to the other treatments and increased the 1000-grain weight and plant weight as well as the straw and grain weight plant-1. The highest carbohydrate and total chlorophyll contents were obtained with a treatment of 100 kg N fed.-1 + spraying with cyanobacteria. The maximum protein content and yield were observed with 75 kg N fed.-1 + spraying with cyanobacteria. The application of cyanobacterial inoculation combined with an N fertilizer application of 75 kg N fed.-1 improved the soil properties of saline soils. Furthermore, improved availability and uptake of macro-and micro-nutrients were reflected in the rice grain yield and quality.