Potassium Requirements for Maximum Yield and Fruit Quality of Processing Tomato

Abstract

<jats:p>A survey of 140 processing tomato (<jats:italic>Lycopersicon esculentum</jats:italic> Mill.) fields in central California was conducted in 1996-97 to examine the relationship between K nutrition and fruit quality for processing. Quality parameters evaluated were soluble solids (SS), pH, color of a blended juice sample, and the percent of fruit affected by the color disorders yellow shoulder (YS) or internal white tissue (IWT). Juice color and pH were not correlated with soil K availability or plant K status. SS was correlated with both soil exchangeable K and midseason leaf K concentration (<jats:italic>r</jats:italic> = 0.25 and 0.28, <jats:italic>p</jats:italic> &lt; 0.01) but the regression relationships suggested that the impact of soil or plant K status on fruit SS was minor. YS and IWT incidence, which varied among fields from 0% to 68% of fruit affected, was negatively correlated with K status of both soil and plant. Soil exchangeable K/√Mg ratio was the measure of soil K availability most closely correlated with percent total color disorders (YS + IWT, <jats:italic>r</jats:italic> = -0.45, <jats:italic>p</jats:italic> &lt; 0.01). In field trials conducted to document the relationship between soil K availability and the fruit color disorders, soil application of either K or gypsum (CaSO<jats:sub>4</jats:sub>, to increase K/√Mg ratio) reduced YS and total color disorders. Multiple foliar K applications were effective in reducing fruit color disorders at only one of two sites. In no field trial did K application improve yield, SS, or juice color.</jats:p>

Efficiency of fertilizer formulation, stock solution volume and media on chili (Capsicum annumkulai F1)

“…The highest and lowest P content was obtained in 750 (7400 ppm) and 400 L volume (4100 ppm), respectively. The CD+EFB and CD media showed the maximum P content with 6400 and 5100 ppm, respectively as reported by Hartz (1999), as higher P contents improved fruit quality and yield. The calcium (K) content was significantly different between the volumes and types of media (α=0.005).…”

Changes of Tomato Yield and Fruit Elemental Composition in Conventional, Low Input, and Organic Systems

“…Because the SAFS soil had adequate bicarbonate extractable P (> 12 µg g Ϫ1 ) and ammonium-acetate-extractable K (> 0.3 cmol kg Ϫ1 ) for high-yield tomato production (Hartz, 1997;Hartz et al, 1999), no P or K fertilizers were applied as sidedressing in the conventional and low input systems in either years. Fertilizer N applications as urea (46% N) to conventional and low input systems were sidedress applied 6-8 weeks after planting.…”

Estimating soil potassium availability for processing tomato production

“…A survey of 140 processing tomato fields in central California was conducted in 1996 -97 to examine the relationship between K nutrition and fruit quality for processing (6). During this survey, soil (0 -30 cm depth) and whole leaf tissue samples (full bloom growth stage) were collected in each field.…”

“…At harvest fruit samples were collected and evaluated for the following parameters: juice color, soluble solids content (SS, o brix), and YS incidence (% of fruit affected); details of the evaluation procedures can be found in Hartz et al (6). Fruits were oven-dried, ground and analyzed for K concentration as previously described for leaf tissue.…”

“…YS was present at problematic levels (. Hartz et al (6) also found K ex to be useful in classifying fields as to the relative danger of encountering severe YS expression, with only 5 of 45 fields with K ex . Neither K ex nor K sol was predictive of YS incidence.…”