Effects of β-cedrene and α-humulene, sesquiterpenes (SQTs) emitted by Suillus bovinus (Sb), on the growth of Pinus massoniana. Effects of different concentrations of β-cedrene on a root branching and b root length. Effects of different concentrations of α-humulene on c root branching and d root length. e Images of P. massoniana seedlings after 35 days of 1000 ppb β-cedrene or 100 ppb α-humulene treatment, CK, control seedlings; Scale bars: 2 cm. Effects of adding of β-cedrene or α-humulene to culture medium containing lovastatin (Lov) inhibits (which inhibits the synthesis of S. bovinus SQTs) on f root branching and g root length. n = 15. Error bars indicate ± the SE. Different letters between treatment after the same number of days of VOC exposure in (a, c), and different letters above the columns in (b, d, f, g) indicate significant differences between treatments (P < 0.05).