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Growth Promotion of Yunnan Pine Early Seedlings in Response to Foliar Application of IAA and IBA
College of Biological Science, Technology of Beijing Forestry University, Beijing 100083, China
Key laboratory for Forest Resources Conservation and Use in the Southwest Mountains of China, College of Forestry, Southwest Forestry University, Kunming 650224, China
These authors contributed equally to this work.
* Author to whom correspondence should be addressed.
Received: 21 February 2012; in revised form: 18 May 2012 / Accepted: 21 May 2012 / Published: 24 May 2012
Abstract: A field experiment was conducted using a 3 × 3 orthogonal regression design to explore the growth promotion of one-year-old Yunnan pine seedlings (Pinus yunnanensis Franch.) in response to foliar application of IAA (indole-3-acetic acid) at rates of 0, 200 and 400 mg·L−1 and IBA (indole-3-butyric acid) at rates of 0, 200 and 400 mg·L−1 in order to promote the growth during the seedlings’ early stage. The experiment was conducted at the Lufeng Village Forest Farm of Yiliang County in Kunming, Yunnan, China. The results showed that IAA and IBA were effective in growth promotion of Yunnan pine seedlings. The response of both growth increment and biomass accumulation to the concentration of IAA and IBA can be modeled using a bivariate surface response, and each growth index had a peak value. Growth indexes increased with the increase of the dosage of photohormones before reaching a peak value, and then decreased. The different growth indexes had various responses to the concentrations and ratio of IAA and IBA. The foliar application of IAA in combination with IBA showed the largest improvement on the biomass of the needles, followed by stems and roots. The higher ratio of IAA promoted stem diameter growth, root system development and biomass accumulation in the needles, while a higher ratio of IBA contributed to height growth and biomass accumulation in the stem. Based on the auxin effect equations on the different growth indexes and surface response, the optimum concentrations and the (IAA:IBA) ratios can be obtained. The optimum concentrations of IAA and IBA were 167 and 186, 310 and 217, 193 and 159, 191 and 221, and 206 and 186 mg·L−1, with corresponding ratios of 1:1.11, 1:0.70, 1:0.82, 1:1.15 and 1:0.90, respectively, at the maximum seedling height and collar diameter growth as well as biomass accumulation at the root, stem and needle. The above growth indexes were 22.00%, 79.80%, 48.65%, 82.20% and 107.00% higher than the control treatment.
Keywords: exogenous IAA and IBA; foliar application; seedling growth promotion; Yunnan pine (Pinus yunnanensis Franch.)
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MDPI and ACS Style
Xu, Y.; Zhang, Y.; Li, Y.; Li, G.; Liu, D.; Zhao, M.; Cai, N. Growth Promotion of Yunnan Pine Early Seedlings in Response to Foliar Application of IAA and IBA. Int. J. Mol. Sci. 2012, 13, 6507-6520.
Xu Y, Zhang Y, Li Y, Li G, Liu D, Zhao M, Cai N. Growth Promotion of Yunnan Pine Early Seedlings in Response to Foliar Application of IAA and IBA. International Journal of Molecular Sciences. 2012; 13(5):6507-6520.
Xu, Yulan; Zhang, Yuemin; Li, Yunfei; Li, Genqian; Liu, Daiyi; Zhao, Minchong; Cai, Nianhui. 2012. "Growth Promotion of Yunnan Pine Early Seedlings in Response to Foliar Application of IAA and IBA." Int. J. Mol. Sci. 13, no. 5: 6507-6520.