A 1993 survey of 50 commercial processing tomato fields in California revealed widespread potassium deficiency, as determined by tissue K levels below existing sufficiency standards and the occurrence of vine necrosis consistent with K deficiency. Soils from these fields were analyzed for exchangeable K by ammonium acetate extraction, and for K release rate by a 7 day incubation procedure (1:10 soil:. 01 M CaCl2 at 25°). Soil K release rate was more highly correlated with tissue K at midseason than was exchangeable K. These soils were further examined for K fixation capacity. Three g soil was blended with 3 ml 10 meq K as KNO3, allowed to dry, incubated for 7 days in a 1:10 soil: H2O solution, then extracted in 1 N NH4Cl; added K not recovered was considered fixed. Percent K fixation ranged from 0 to 82%. These data suggest that the inconsistent response of processing tomato to K application in numerous California trials may be related to a) the reliance on extractable K analysis to characterize soil K supply and b) no consideration of soil K fixation capacity in determining K application timing and method.
The effect of potassium (K) nutrition on the shelf life of carrots was studied using a hydroponics system involving rockwool slabs as support. Carrots were grown for 192 days under greenhouse conditions and supplied with 0, 0.1, 1.0, 10, and 15 mm of K. Increase in K concentration in the nutrient medium decreased postharvest weight loss. Carrot weight and tissue K content increased and water potential, osmotic potential, and relative solute leakage decreased with increasing K concentration in the nutrient feed. Differences in postharvest weight loss were mainly associated to root weight and relative solute leakage. Root weight correlated negatively and relative solute leakage correlated positively to water loss. Water and osmotic potential also correlated to water loss, but not as strongly as root weight and relative solute leakage. These results suggest that K nutrition influences postharvest weight loss by influencing carrot size and membrane integrity. Effects on cell water and osmotic potential are also important in this regard but to a lesser extent.
Composted pine bark is one of the most important substrates used in the seedling industry today. Previous work suggested the availability of inherent Potassium (K) in the bark. This research confirmed the availability of K and indicated that little or no K is needed for seedling production when pine bark is used as a substrate. Pre-enrichment rates ranged from 0 to 460 g.K.m-3, with a supplemental solution application of 0 to 200 mg.K.l-1. No evidence of K deficiencies or toxicities were detected. Three K sources, KCl, KNO3, and K2SO4 were used in the pre-enrichment of the bark. No differences were noted for top fresh mass, seedling height, root dry mass, root to shoot ratio and percentage moisture. Seedlings grown in treatments without and supplementary K showed tissue contents of 162.5 mg.K.kg-1. This research suggests the possibility of reducing the levels of-K applied to seedlings grown in a composted pine bark substrate.
Tomato (L.ycopersicon esculentum Mill.) seedlings were nutritionally conditioned with solutions containing factorial combinations of N at 25, 75, and 225 mg·liter -1, P at 5, 15, and 45 mg·liter-1, and K at 25, 75, and 225 mg·liter -1 to determine the effect of nutritional regimes on tomato transplant growth and quality. As N increased from 25 to 225 mg·liter-1, fresh shoot weight, plant height, stem diameter, leaf number, leaf area, shoot and root dry weights, and total chlorophyll increased. Nitrogen accounted for the major source of variation. Phosphorus effects were significant only in 1988; Pat 45 mg·liter-1 increased fresh shoot weight, plant height, stem diameter, leaf number, and leaf area in comparison to 5 and 15 mg·liter -1. Potassium did not significantly influence any of the growth variables measured in the study. For quality transplant production, nutrient solutions should contain at least N at 225 mg·liter-1, P at 45 mg·liter-1, and K at 25 mg·liter-1.
, ammonium phosphate, calcium phosphate, and potassium sulfate and contained 8% NO 3 -N and 10% NH 4 -N. CRF was incorporated on an individual container basis just before planting. Stem cuttings of sweet viburnum [ Viburnum odoratissimum (L.) Ker Gawl
The loss of fertilizer granules collected in turf clippings during routine putting green mowing has not been determined. The objective of this study was to quantify the amounts of greens-grade granular potassium (K) and nitrogen (N) fertilizers collected during the routine mowing of a `Pennlinks' creeping bentgrass (Agrostis palustris Huds.) putting green. In the first study, five K-containing granular fertilizers were applied at K rates of 2.43 and 4.86 g·m-2. A second study was also performed with six granular Ncontaining fertilizers and one liquid N fertilizer applied at an N rate of 4.86 g·m-2. Both studies were performed twice. Irrigation (6.4 mm) was applied immediately after each fertilizer application and again on the following day. These two irrigations, plus additional irrigation and rain, resulted in each study receiving about 2.54 cm of water over each nineday study period. Mowing and clipping collection using a walk-behind greens mower set to cut at 3.96 mm began two days after treatment (2 DAT) and continued until 9 DAT. The clippings were oven-dried and separated from the fertilizer using a small pneumatic seed cleaner. Collected fertilizer was weighed and expressed as a percentage of the fertilizer applied. Liquid N fertilizer loss was estimated to be the difference between clipping N content of treated plots and untreated controls. Total K fertilizer loss was: UHS Signature 15-0-30 (15.3% to 22.9%) > Lebanon Isotek 11-3-22 (8.7% to 10.7%) > Scott's Contec 13-2-26 (4.9% to 7.4%) > Lesco Matrix 12-0-22 (0.1% to 0.4%) = Lesco Matrix 5-0-28 (0.1% to 0.5%). Signature was the only fertilizer significantly affected by rate and a greater percentage of loss occurred at the lower K application rate. Most loss occurred during the first and second mowing events with small amounts of fertilizer found in clippings from later mowings. The two Lesco materials were not found in clippings after the first mowing. Nitrogen fertilizer granule loss was also greatest with the first and second mowings. Total percentage of losses were IBDU 31-0-0 (75.4%) > Polyon 41-0-0 (70.8%)> Milorganite 6-2-0 (55.7%) > Nutralene 40-0-0 (47.0%) > UHS Signature (19.3%) > Isotek 11-3-22 (9.5%) > N-Sure Pro 30-0-0 (1.9%). In both studies, fertilizer loss appeared to be most related to water-solubility of the fertilizer, but size and density might also be factors.
samples for mineral N were collected from 0- to 12-inch depth on the same day as the biomass samples. Field moist soil was added to a 2 M potassium chloride (KCl) solution at a ratio of 1 g soil to 5 mL of KCl. The clear supernatant was extracted and the
A study was undertaken to determine the seasonal dynamics of leaf and fruit K content and the influence of tree K status and fruit growth on leaf and fruit K accumulation rates in French prune (Prunus domestics L. cv. d'Agen). Mature trees in a commercial orchard were treated with various rates of K2 SO4. (O to ≈20 kg/tree) in the fall. Fruit dry weight yield per tree at harvest and fruit K content were higher for high-K trees, but fruit percent K (by dry weight) was ≈1.0% for all trees. Leaf scorch and subsequent abscission severely reduced the canopy of K-deficient trees. Significant positive linear relationships between leaf and fruit K accumulation rates existed for the periods of 28 Apr.-28 May (May) and 28 May-7 July (June). A significant negative linear relationship existed between these two criteria from 7 July-3 Aug. (July). May (0.237 mg K per fruit-day) and July (0.267 mg K per fruit-day) mean fruit K accumulation rates were similar, but both were significantly higher (P = 0.001) than those for June (0.140 mg K per fruit-day). Mean leaf K accumulation rates for May (- 0.007 mg K per leaf-day) and July (-0.010 mg K per leaf-day) were similar, but both were significantly (P = 0.001) less than for June (0.005 mg K per leaf-day). Potassium per fruit accumulation was highest in trees with highest K status. Periods of net leaf K efflux and influx did not precisely correlate with fruit growth stages measured by fruit dry weight. The period of lowest fruit K accumulation (28 May-7 July) coincided with the period of maximum dry matter accumulation by the kernel. After 7 July, all increases in fruit dry weight and K content were due to mesocarp growth.
cavity), and the stage of fruit ripeness is critical for its quantification of lycopene ( Rodriquez-Amaya, 2001 ). Fraser et al. (1994) found an 11-fold increase in fruit lycopene content from the initial breaker stage to 14 d past breaker. Potassium
decreased K concentration ( Table 2 ). Table 2. Leaf potassium (g·kg −1 ) as affected by different orchard floor vegetation management systems, 1998 to 2003. z Leaf Ca, Zn, and Cu concentrations were not consistently affected by treatments (data not shown