sandy loams and are typical of pecan orchards throughout the southeastern United States. Growers often experience difficulties maintaining recommended foliar phosphorus (P) levels in their orchard trees due to naturally low P in the soils and the nature
Michael F. Polozola II, Daniel E. Wells, J. Raymond Kessler, Wheeler G. Foshee, Amy N. Wright, and Bryan S. Wilkins
Ricardo González-Ponce, Esther G. López-de-Sá, and César Plaza
Phosphorus is one of the primary nutrients essential for plant growth and crop production ( Mengel and Kirkby, 2004 ). At present, most commercial phosphorus (P) fertilizers on the market such as single superphosphate are derived from phosphate rock
M. Murshidul Hoque, Husein Ajwa, Mona Othman, Richard Smith, and Michael Cahn
more than 150 kg nitrogen (N)/ha/crop ( Jackson et al., 1994 ). Similarly, the excessive accumulation of soil phosphorus (P) has raised water quality concerns ( Sims, 1998 ). Salinas Valley soils often contain more than 30 to 40 mg·kg −1 of bicarbonate
Yang Chen, Xianzhi Zhou, Yongsheng Lin, and Lina Ma
index of soybean in black soil region of Heilongjiang Province Soybean Sci. 32 512 516 Sun, Y. Guo, Y. Yu, S. Jiang, Q. Cheng, L. Cui, Z. Chen, X. Jiang, R. Zhang, F. 2009 Establishing phosphorus and potassium fertilization recommendation index based on
Faridullah K. Wazir, Michael W. Smith, and Stuart W. Akers
Thirty-six-day-old ‘Dodd’ pecan seedlings [Carya illinoensis (Wangenh) C. Koch] were flooded for 31 days or not flooded in factorial combinations with 0, 215, or 430 g P per m3 of media. Flooding decreased leaf number, leaf area, leaf and root dry weight, and induced stomatal closure. Flooding also reduced leaf, trunk, and root K, Ca, Mg, Zn, Fe, and Mn concentrations. Nitrogen was lower in the leaves and trunk of flooded trees, but higher in the roots of flooded trees than unflooded trees. Flooding decreased the leaf P concentration, but did not affect the P concentration in the roots. Phosphorus application increased leaf P concentration in unflooded trees, but not flooded trees.
Rhoda Burrows, F.L. Pfleger, and Luther Waters Jr.
Asparagus offcinalis L. `Mary Washington' seedlings inoculated with Glomus fasciculatum (Thaxter) Gerd. and Trappe emend. Walker and Koske showed increased growth after 9 weeks, compared with noninoculated plants. Phosphorus supplementation (25 g·m-3) increased seedling growth of inoculated and noninoculated plants throughout the 26 weeks of the experiment. However, after 9 weeks, there were no differences in growth of inoculated, non-P-supplemented plants and noninoculated, P-supplemented plants. Fern height, fern and crown weight, and bud numbers correlated positively to the percentage of G. fasciculatum root infection.
Kristian Borch, Kathleen M. Brown, and Jonathan P. Lynch
Bedding plants are frequently exposed to water stress during the postproduction period, resulting in reduced quality. We demonstrated that alumina-buffered P fertilizer (Al-P) provides adequate but much lower P concentrations than conventionally used in soilless mixes. When impatiens (Impatiens wallerana Hook. f. `Impulse Orange') and marigold (Tagetes patula L. `Janie Tangerine') plants were grown with reduced phosphorus using Al-P, P leaching was greatly reduced and plant quality was improved. Diameter of impatiens plants and leaf area of plants of both species were reduced by Al-P. Marigold plants grown with Al-P had more flowers and fewer wilted flowers. Flower wilting was also reduced for impatiens plants grown with Al-P. In marigold plants, roots were confined to a small volume beneath the drip tube in control plants, while roots of Al-P plants were well distributed through the medium. There was no obvious difference in impatiens root distribution. When plants at the marketing stage were exposed to drought, the Al-P plants of both species wilted more slowly than the conventionally fertilized controls. The reduced leaf area in both species and the improved root distribution of marigold may account for the improvement in drought tolerance of the Al-P plants.
Arthur Villordon, Jeffrey C. Gregorie, and Don LaBonte
There is increasing evidence that the availability of Pi, the major form of phosphorus acquired by plants, is a key factor that limits crop productivity on a global scale. Low soil Pi availability has been associated with crop yield losses ranging
161 WORKSHOP 25 (Abstr. 676–680) Phosphorus Management in Horticultural Crops
Gerry H. Neilsen, Denise Neilsen, Peter Toivonen, and Linda Herbert
Phosphorus fertilization of apple orchards has received much less attention than nitrogen (N) and potassium (K) fertilization as a result of limited reports of positive responses to phosphorus (P) fertilization in the historical literature