Effect Analysis of Foliar Spraying with Paclobutrazol on Growth of Young Cunninghamia lanceolata Clones

Abstract

【Objective】Cunninghamia lanceolata is an important timber species in southern China, and the application effect and dose effect of foliar spraying paclobutrazol on different clones of C. lanceolata were explored, aiming to provide reference for early growth regulation of C. lanceolata mother plants.【Method】The young plants from excellent clones of C. lanceolata (T-c04, T-c08 and T-cF1) were used as materials. The effects of paclobutrazol treament with active component concentrations of 0.12, 0.24 and 0.48 g/L on clonal plant height, ground diameter, number of rhizome germination, partial crown, relative chlorophyll content (SPAD) of needles, needle thickness and biomass were determined.【Result】Foliar spraying paclobutrazol had the most significant inhibitory effect on plant height of T-c04 clone (P<0.05), and the increase in plant height was only 24.59%~36.06% of the control (Spraying distilled water as control, CK). However, the increase in plant height of T-c08 and T-cF1 clones was 42.68%~52.68% and 39.97%~46.88% of the control. The application of paclobutrazol had a certain effect on the growth of young clonal plants and the occurrence of rhizome germination. In terms of diameter growth, the application of 0.48 g/L paclobutrazol had the best effect, and the effect on T-cF1 was especially obvious (41.0% higher than the control). In terms of the number of rhizome germination, the application effect of paclobutrazol on T-c04 clones was the most significant (P<0.05), and the treatment with paclobutrazol 0.24 g/L had the best. In addition, paclobutrazol induced partial crown phenomenon of young C. lanceolata. Both paclobutrazol 0.12 and 0.24 g/L treatments caused serious partial crown in young clones T-c04 and T-cF1. The effects of paclobutrazol onrhizome germination (SPAD) and needle thickness of young C. lanceolata clones were different. The aboveground growth and total biomass accumulation of C. lanceolata were inhibited by paclobutrazol, but the seedling strength index of each clonal plant was improved effectively.【Conclusion】Foliar spraying of paclobutrazol had different effects on different clones of C. lanceolata, and there was a certain dose effect. But in general, the application of paclobutrazol inhibited the plant height and aboveground biomass, and promoted the diameter growth, number of rhizome germination, the occurrence of partial crown, and the increase of seedling strength index.

Keywords

• cunninghamia lanceolata
• clone
• paclobutrazol
• growth effect
• partial crown