Effects of indole-3-butyric acid (IBA), bacteria and, radicle tip-cutting on lateral root induction in Pistacia vera

Experiments were conducted to determine the effects of 50 mg 1(-1) and 100 mg 1(-1) indole-3-butyric acid (IBA), each of three strains of non-pathogenic Agrobacterium rubi (A1, A16 and A18), a non-pathogenic strain of Bacillus subtilis (OSU-142), and radicle tip-cutting (RC) alone, or a combination of bacteria and RC on the number of lateral roots, plant height, stem diameter, root length, and fresh and dry root weights of Pistacia vera seedlings. Treatment of germinated seeds of P vera with IBA, bacteria, RC, or bacteria plus RC, caused significant increases in lateral root formation in seedlings. Treatments with 50 mg 1(-1) and 100 mg 1(-1) IBA, RC, A. rubi A1, A16, A18, B. subtilis OSU 142, RC+A1, RC+A16, RC+A18 or RC+OSU-142 increased average lateral root numbers from 2.1 in untreated controls, to 8.4, 10.3, 5.3, 7.8, 6.9, 6.2, 5.4, 8.1, 7.8, 5.9 and 5.4, respectively. IBA (100 mg 1(-1)) gave the highest number of lateral roots. Agrobacterium rubi strain Al was found to be more effective than the other bacterial strains, RC or control treatments in increasing the numbers of lateral roots.