nitrogen and soil water were studied in loblolly pine (Pinus taeda L.) seedlings grown in monoculture and in competition with sweetgum (Liquidambar styraciflua L.) or crab grass (Digitaria spp.). Rhizotron cells were maintained at high soil water availability (approximately −0.1 MPa) or subjected to three dry-down cycles to low soil water availability (approximately −1.0 MPa), over two growing ...

An embryo classification system has been developed based on observations of Pseudotsuga menziesii (Mirb.) Franco (Douglas-fir) and Pinus taeda L. (loblolly pine) zygotic embryos and on the literature concerning embryology within the pine family. This system is suitable for classification of both zygotic and somatic embryos of loblolly pine, Picea abies L. (Norway spruce), and Douglas-fir. This ...

To probe variation in Al sensitivity of two co-occurring pine species, seedlings from six full-sib families of loblolly pine (Pinus taeda L.) and slash pine (Pinus elliottii Engelm.) were grown in solution culture containing 4.4 mM (high-Al) or 0.01 mM (low-Al) AlCl(3) at pH 4 for 58 days. On average, both pine species had 41% less total dry weight in the high-Al treatment than in the low-Al tr...

-Since the 1950s the existence of natural hybrids between shortleaf pine and loblolly pine has been recognized and reported in the literature. In a range-wide study of isoenzyme diversity in shortleaf pine. we found 16 percent of the trees from western populations were hybrids. based on the isocitrate dehydrogenase (IDH) locus. In stands thought to be pure shortleaf pine in west central Arkansa...

A synthetic version of the CRY1Ac gene of Bacillus thuringiensis has been used for the transformation of loblolly pine (Pinus taeda L.) using particle bombardment. Mature zygotic embryos were used to be bombarded and to generate organogenic callus and transgenic regenerated plants. Expression vector pB48.215 DNA contained a synthetic Bacillus thuringiensis (B.t.) CRY1Ac coding sequence ̄anked b...

Prediction equations based on 130 sample trees from thinned and unthinned loblolly pine (Pinus taeda L.) plantations in central Louisiana re presented for the green and dry weights of aboveground tree components. Sample trees ranged from 2 to 21 in. dbh, 18 to 94 ft in height and from 9 to 55 yr in age. Significant differences in partial stem weight between trees from thinned and unthinned stan...

Loblolly and slash pine seed were inoculated at sowing with 1 of 12 different strains of plant growth-promoting rhizobacteria (PGPR) in the greenhouse. Time to germination and seedling densities were determined at 21 days, and seedling biomass was measured at 12 wk after sowing. All bacterial strains significantly increased the speed of seedling emergence over nontreated pine seed. By 12 wk, ho...

Loblolly pine (Pinus taeda L.) and shortleaf pine (Pinus echinata Mill.) have widely overlapping geographic ranges. Hybridization between the two species has interested tree breeders for a long time. Morphologically, the two pine species are different. The needles of loblolly pine are 6 to 9 inches long, usually with three yellow-green needles per fascicle; but shortleaf pine needles are 3 to 5...

Over the past few decades, reports of forest health problems have concerned scientists and forest managers in loblolly pine forests of the southeastern United States. Several interacting factors likely contribute to observed reductions in loblolly pine health, including low resource availability on many upland sites that were once dominated by longleaf pine. Currently, land managers are interes...

Loblolly pine (Pinus tueda L) has become the most important source of wood fiber in the southern United States. This tree is an excellent competitor and recovers well from a variety of adverse conditions. ‘a2 The value of loblolly pine as a plantation tree has encouraged many researchers to devote their careers to the study of this species. It is surprising then that the root system of loblolly...