Differential Response of Cotton Growth, Yield and Fiber Quality to Foliar Application of Cyanobacteria Extract and Urea Fertilizer

Two-seasons field experiment were carried out at the experimental farm of the Sakha Agriculture Research Station, Kafr Elsheikh, Egypt (31°18′30″N & 30°48′14″E) during the two successive seasons 2016 and 2017 to study the response of yield attributes of cotton (cultivar Giza 94) to foliar application of ascending amounts of culture extract of the cyanobacterium of Spirulina platensis (476, 952 or 1428 ml. /he., and urea fertilizer (46%) at 96, 144 or 192 kg N/ hectare. Application of the cyanobacterial extract significantly affected the plant height at harvest, number of fruiting branches and open bolls/plant, leaf area, contents of photosynthetic pigments, gibberellins, seed yield while improved fiber length, fineness and strength comparing with the corresponding control plants. Nitrogen fertilization with 192 kg N/he.  positively scored the highest figures of the parameters. In addition, application of the cyanobacterial extracts at 1428 ml. /he. scored the highest values. Application of 192 kg N/he. along with 476 ml Spirulina extract /he. exhibited the superior enhancement effects comparing to the other treatment combinations.