INFLUENCE OF PINCHING, SOME FERTILIZATION TREATMENTS AND SPRAYING WITH ALAR ON SOLIDAGO PLANTS. A. VEGETATIVE GROWTH CHARACTERISTICS

An open field study was carried out at Dept. of Ornamental Hort. Fac. Agric., Cairo Univ., and the applied part was carried out at the Experimental Farm of Hort. Res. Inst., ARC., Giza, Egypt during 2015 and 2016 seasons to investigate the effect of pinching, bio- and chemical fertilization (as soil drench), foliar spraying with alar (a growth retardant) and their interactions on vegetative growth of goldenrod (Solidago hybrida, "Tara") with the aim of producing high quality plants appropriate to be used as pot plants. Non-pinching was more effective than pinching procedure in increasing plant height, stem diameter and leaf area while pinching produced the highest values in terms of herb fresh and dry weights. Chemical fertilization with NPK at either 1.5 or 3 g/pot with or without bio-fertilization resulted in the highest values when compared with the other fertilization treatments.  Alar at 1500 ppm produced the highest values in of plant height, stem diameter and leaf area (first season only), while alar at zero ppm produced the heaviest fresh and dry herb weights and the widest leaves (in the second season only). Non-pinching treatments increased plant height, stem diameter and leaf area to the highest values when combined with NPK at only 1.5 g/pot, while pinching treatments combined with all fertilization treatments (except for bio-fertilizer only and control) presented the highest herb fresh and dry weights. Non-pinching in addition to alar at 1000 ppm presented the highest values of plant height and stem diameter, while  non-pinching in addition to alar at 500 ppm produced the highest leaf area. Pinching goldenrod plants in addition to spraying with alar at zero or 500 ppm increased herb fresh and dry weights. NPK at only 1.5 g/pot in addition to alar at 1000 or 1500 ppm produced the highest values of plant height and stem diameter. In this concern the highest fresh and dry weights were obtained by treating with bio-fertilization plus NPK at 3 g/pot in addition to alar at 500 or 1500 ppm. NPK at 1.5 g/pot + alar at 1500 ppm produced the highest leaf area in the first season, while in the second one bio-fertilizer + NPK at 1.5 g/pot + alar at zero ppm was more effective. Triple combined treatments showed a great variation in effects on vegetative growth characteristics, in general non-pinching treatments in addition to all fertilization treatments (except for bio-fertilizer only) and alar at all concentrations led to increase plant height, stem diameter and leaf area. However, pinching treatments in addition to bio-fertilization + NPK at 3 g/pot + alar at either 500 or 1500 ppm presented the highest fresh and dry weights, respectively. According to the previous findings and from an aesthetic point of view, it is recommended to treat goldenrod transplants grown in 14 cm pots with pinching in addition to bio-fertilization plus NPK at 3 g/pot + spraying with alar at 1500 ppm to produce high quality goldenrod plants appropriate to be used as pot plants.