Effect of seed soaking in some bioregulators and foliar applications of phosphorus, potassium and zinc on sunflower plants growth and yield in calcareous-saline soil.

Abstract

Field experiments were carried out during 2003 and 2004 seasons to investigate the role of some bioregulators and mineral nutrients in adapting and improving sunflower (Helianthus annuus L.) plants cv. Vidoc under calcareous and salinity stress conditions. Bioregulators; paclobutrazol (PP333) at 10 ppm, salicylic acid (SA) at 10 ppm and thidiazuron (TDZ) at 5 ppm were applied as seed soaking for 4 hours before sowing. Mineral nutrients; phosphorous as H3PO4 0.5%, potassium as KCl 2.0% and Zinc as ZnSO4 0.01% were foliar sprayed (5 and 6 weeks after sowing). Two samples were taken at 50 days after sowing and at harvesting time (90 days after sowing). Application of P showed significant increase in the mean values of plant height. Potassium treatment showed significant increase in shoot fresh and dry weights. In respect to bioregulators, PP333 showed significant increase in shoot fresh and dry weights in both seasons. Salicylic acid and TDZ increased Stem diameter and shoot fresh and dry weights. Application of TDZ reduced Plant height. All mineral nutrients and bioregulators treatments increased number of seeds/ head, seeds weight/ head and seeds yield. Foliar applications of K and Zn decreased Na concentration and increased K, Ca and P concentrations as well as K/Na ratio. Application of P showed an increase in Ca and P concentrations. Trace elements; Zn, Mn and Fe were significantly increased by K and Zn applications. Seed soaking in SA and TDZ significantly decreased Na concentrations and increased K, K /Na, Mg and P concentrations. All mineral nutrients applications significantly increased oil percentage and yield. Regarding mineral nutrients and bioregulators interactions, best results were obtained by K+TDZ and Zn+SA treatments, which recorded the maximum values of shoot fresh and dry weights, yield and its components and unsaturated/saturated fatty acids ratio. Also, the best results of mineral elements concentrations in terms of the lowest values of Na and the highest values of K, K /Na, Mg, Zn, Mn and Fe. The effects of mineral nutrients, bioregulators and their interactions on sunflower growth and productivity under calcareous and salinity stress were discussed.