highly significantP < 0.001
Highly significant main effects of PGR type (df = 2, Wald χ2 = 20538.041, P < 0.001; df = 2, Wald χ2 = 75.219, P < 0.001; df = 2, Wald χ2 = 1961.779, P < 0.001) and PGR concentration (df = 3, Wald χ2 = 7854.678, P < 0.001; df = 3, Wald χ2 = 186.271, P < 0.001; df = 3, Wald χ2 = 1570.579, P < 0.001) were detected for callus induction rates.