Understanding the fertilization and irrigation response of seed orchard loblolly pine

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A study of loblolly pine (Pinus taeda L.) reproduction began in January 2015 at the International Forest Company seed orchard near Evans, LA. Three levels of fertilization and two levels of irrigation were planned to favor reproduction. Fertilization levels were August broadcast application of (1) 112 kg ha-1 nitrogen plus boron (1N), (2) 1N plus August application of 28 kg ha-1 phosphorus (1N1P), or (3) 1N1P plus September application of 112 kg ha-1 nitrogen (2N1P). Irrigation treatments were no irrigation or drip irrigation of 1090 l ramet-1 day-1 between mid-July and late September. Foliar nutrition and vegetative and reproductive growth were not affected by fertilization or irrigation in summer of 2015. This may be attributed to ramet adaptation to edaphic conditions since establishment. Correlation between reproductive carbohydrate demand and photosynthate supply validates the importance of available carbohydrate to new vegetative and reproductive organs. Ramet environment and shoot order are likely to affect these relationships.

  • Citation:

    Sayer, Mary Anne S.; Sung, Shi-Jean S.; Leduc, Daniel J.; Tule, James; Muir, Nicholas G.; Dougherty, Phil. 2018. Understanding the fertilization and irrigation response of seed orchard loblolly pine. In: Kirschman, Julia E., comp. Proceedings of the 19th biennial southern silvicultural research conference; 2017 March 14-16; Blacksburg, VA. e-Gen. Tech. Rep. SRS-234. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station: 136-145.

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