Effects of gibberellin A4/7, 6-benzylaminopurine and chlormequat chloride on the number of male and female strobili and immature cones in Chinese Pine (Pinus tabuliformis) with foliar sprays

摘要

Three kinds of plant growth regulators, gibberellinA<,4/7> (GA<,4/7>),6-benzylaminopurine (BA), and chlormequat chloride (CCC), wereevaluated for their ability to promote strobilus and cone production in aChinese pine (Pinus tabuliformis Carr.) clonal seed orchard. Treatments(0, 250, 500, or 1000 mg-L<'-1>) were applied during three periods (June-July, July-August and August-September) in 2005. Of the three plantgrowth regulators, GA<,4/7> was the best for promoting flower and coneproduction. Trees sprayed with GA<,4/7>(500 mg·L<'-1>) from June to Septem-ber had significantly more female strobili and immature cones than con-trols and other treatments (p≤0.0001). The best time to apply GA<,4/7> was inJune. BA at 500 mg.L<'-1> significantly increased female flower and imma-ture cone production, compared to other treatments and controls(p≤0.0001), while promotion of male strobili was unchanged. Chlorme-quat chloride at 1000 mg.L<'-1> significantly increased the number of malestrobili, compared to the other treatments (P≤0.0001). Spraying CCC at500 mg.L<'-1> significantly increased the number of female strobili, com-pared to controls (p<0.05), but it had no effect on immature cone produc-tion (p>0.05). These results are important for improving seed productionand seed orchard management of Chinese pine.