This study investigates the effects of growth substances on the growth of macadamia-nut rootstocks and the possibility of shortening the period of time plant formation on nursery. Four-month-old rootstocks were sprayed with gibberellic acid 50, 100, 250 and 500 ppm, naphtalenacetic acid 50, 100, 250 and 500 ppm, gibberellic acid 100 ppm plus naphtalenacetic acid 100 ppm, and check treatment. Gibberellic acid 500 ppm applied 12 0 days after sowing (D.A.S.) promoted increases in plant height, gibberellic acid 50 ppm applied 120 and 181 D.A.S. showed effectiviness too. Spraying with gibberellic acid 500 ppm or gibberellic acid 100 plus naphtalenacetic acid 100 ppm 120 D.A.S. promoted increases in stem diameter, gibberellic acid 50 and 150 ppm applied 120 and 181 D.A.S. showed effectiviness too.
Macadamia integrifolia; early growth; growth regulators