DIRECT AND RESIDUAL EFFECT OF FOLIAR APPLICATIONS OF COPPER AND MANGANESE ON COTTONSEED YIELD AND QUALITY

In 1986-1987 field experiments at Giza, Egypt, cotton cv. Giza 75 was given foliar application of the micronutrients copper and manganese (C u at 0.0, 12.5, 25.0, and 37.5 ppm and Mn at 0.0, 25.0, and 50.0 ppm) applied at 85 and 105 days after sowing. Individual Cu or Mn applicati ons increased cottonseed yield and seed index above those of the contr ol (0.0 Cu, 0.0 Mn). Cu at 37.5 ppm with Mn at 50 ppm gave the highest seed oil content. Highest oil and protein yields resulted from Cu and Mn at 25 ppm, when applied separately, while oil refractive index, an d iodine value increased from Cu and Mn added separately or in combina tion. Unsaponifiable matter increased as a result of almost all treatm ents. All Cu or Mn treatments, applied either separately or in combina tion, generally decreased saturated fatty acids (myristic, palmitic, a nd stearic) and increased unsaturated fatty acids (palmitoleic, oleic, and linoleic). Cu at 12.5 ppm or Mn at 25 ppm gave the lowest levels of saturated fatty acids.