Influence of calcium on internal heat necrosis of Atlantic potato

While Atlantic is the cultivar of choice of potato chip processors for the mid-Atlantic region, susceptibility to internal heat necrosis (IHN) greatly increases grower risk of economic loss from unsalable tubers. Yield, tuber calcium levels, and percentage of tubers with IHN of several cultivars from a common seed source were examined at two locations. The percentage of tubers with IHN were significantly higher for Atlantic while the tuber Ca concentration was lower than those of Superior. Both the percentage of tubers with IHN and tuber Ca concentration was higher in New Jersey than Virginia. Lower Ca levels were found in tubers with necrotic medullary tissue than in those without. Studies were completed in Virginia and New Jersey to evaluate the influence of Ca source, Ca rate and location within the hill as well as nitrogen rate on the onset and progression of IHN of Atlantic potato. Tuber yield was not significantly influenced by either Ca source (calcium carbonate (CaCO₃) or calcium sulfate (CaSO₄)) or Ca rate (0-1800 kg Ca/ha). Calcium rate had no influence on size distribution. As expected, a significantly greater percentage of large tubers were noted with delayed harvest. In a short growing season (<110 days) yield was not influenced by nitrogen rates ranging from 84 to 252 kg/ha. However, with delayed harvest, yield was increased and IHN slightly reduced with 168 or 252 kg N/ha when compared to 84 kg/ha. The influence of applied Ca on IHN varied between years, but the addition of Ca or N did not reduce IHN sufficiently to avoid out-of-grade because of internal defects. Location of applied Ca within the hill had no effect on yield, specific gravity, IHN, or tissue Ca concentrations. Slightly higher leaf Ca was found when using CaCO₃ than CaSo₄. The influence of Ca rate in 1987 and 1988 on leaf, periderm, or medullary Ca concentrations was not consistent. Nitrogen had no significant influence on tissue Ca levels.     

Increased calcium availability improves potato micropropagation and microtuberization

Summary Liquid scintillation counting (LSC) was used to screen six potato cultivars (Alpha, Bintje, Green Mountain, Kennebec, Russet Burbank, and Shepody) and two wild species(S. microdontum andS. kurtzianum) for ability to take up the tracer⁴⁵Ca²⁺ from treatment solutions containing high (15 mM) or low (5 mM) Ca²⁺ levels. In vitro potato micropropagation, microtuberization, and tissue calcium content, determined by flame atomic absorption spectrophotometry (FAAS), were compared for the six cultivars when Murashige-Skoog basal medium Ca²⁺ level was increased from 3, to 5 or 15 mM. All aspects of growth were improved when medium Ca²⁺ level was 15 mM. Microtuber induction occurred earlier, leading to improved yield (19–31%), and microtuber tissue Ca²⁺ concentration was greater (38–226%). Cv. Bintje was the most efficient genotype at accumulating Ca²⁺ from treatment solutions or growth media containing high or low Ca²⁺ levels. It could be identified as a calcium-packer using either LSC or FAAS screening.     

Methods for assessing bacterial density on potato tubers

Summary Formulae which determined tuber surface area from tuber dimensions and weight were tested by using samples from three potato cultivars. Surviving populations of a labelled isolate ofErwinia carotovora ssp.atroseptica following planting, and populations of a fluorescent pseudomonad following dusting with a bacterial powder formulation were used to demonstrate the application of these formulae to the calculation of bacterial density on the tuber surface. Results obtained by washing whole tubers using the formulae to calculate the surface area were shown to be comparable in sensitivity with those obtained by dilution-plating of periderm discs of 1cm².     

Accumulation of mineral elements in tuber periderm of potato cultivars differing in susceptibility to common scab

Summary Concentrations of Ca, P, K, Mg, Al, Fe, Mn, Cu and Zn were determined in healthy tuber peelings of cultivars less (Karin, Santé and Symfonia) and more (Agria, Désirée and Tomensa) susceptible to common scab when grown at two sites that differed in the level of scab incidence. The accumulation of some elements was significantly influenced by site, year, cultivar, maturity and the age of tuber periderm. At both sites, Ca and P in periderm tissue declined but Mg increased during the growing season. The Ca/P ratios in tuber periderm of all cultivars greatly decreased 83 days after planting. Concentrations of mineral elements measured at harvest may not reflect conditions present during the infection period, and consequently may not be related to scab incidence or severity.     

Response of potatoes (cv russet burbank) to supplemental calcium applications under field conditions: Tuber calcium, yield, and incidence of internal brown spot

Potato tuber tissue is low in calcium as compared to leaves and stems. Several recent studies have provided evidence linking tuber quality with tuber tissue Ca concentration. The purpose of the present study was to determine the influence of supplemental Ca and N fertilization on tuber Ca concentration and internal brown spot of potato. Three soluble products (calcium nitrate, calcium chloride, and N-Plus; 9N:0K:0P:11Ca) were used as Ca sources with and without gypsum. In addition, a combination of calcium chloride, urea, and calcium nitrate (CUC) was also used without gypsum. Each treatment consisted of five replications, which received the same total amount of N (252 kg ha^?1) supplied either alone or in various combinations of ammonium nitrate, urea, calcium nitrate, calcium chloride, and N-Plus. The soluble sources of Ca were added at 68.8 to 168.0 kg ha^?1 while gypsum supplied Ca at 49 kg ha^?1. The application of all N by hilling (non-split) was compared to split application of N and Ca at hilling and 2, 4, and 6 wk after hilling. Tubers were mechanically harvested and graded according to industry standards. About 100 U.S. No. 1 tubers from each replication were cut in half along the longitudinal axis and visually inspected for internal defects. From each replication, non-periderm tissue from 15 tubers was combined for Ca analysis. There was no treatment effect on tuber yield in both years. Application of gypsum, either alone or in combination with the soluble sources, was not effective in reducing incidence of internal brown spot (IBS). Furthermore, with one exception, application of gypsum either alone or in combination with soluble sources of Ca was not effective at increasing tuber tissue Ca concentration. Combined analyses of data from 2 years showed that the application of soluble sources of Ca without gypsum increased tuber Ca concentration and decreased the incidence of IBS. Furthermore, split application of N had similar beneficial effects as compared to non-split N. Data from 1997 (a year with high IBS) gave a significant inverse relationship between tuber Ca and IBS, suggesting that an increase in tuber Ca can reduce IBS incidence.     

Irrigation,nitrogen and gypsum effects on specific gravity and internal defects of Atlantic potatoes

Irrigation, nitrogen and gypsum were investigated in a 3-year study to determine their influence on specific gravity and internal physiological defects. Excess irrigation during August and September reduced specific gravity, increased the incidence of hollow heart, and in some years, internal brown spot. Tuber yields were not significantly affected by excess irrigation. Exclusion of late season irrigation, however, significantly reduced tuber yields. No consistent yield response to nitrogen was evident, but a response up to 168 kg/ha was observed in 1987. Nitrogen rate did not effect hollow heart, internal brown spot or chip color. The incidence of internal brown spot in the tubers of check treatments was quite variable from year to year, and ranged from 8 to 21%. The lowest incidence of internal brown spot observed in 1989 coincided with the highest calcium levels in the tuber peel. Although gypsum treated potatoes had reduced incidence of internal brown spot, the effects were partial and inconsistent. Significant increases in peel and petiole calcium concentrations in the gypsum treated plots only occurred in one year. The peel calcium levels appeared to be influenced more by the season and to a lesser extent by gypsum. Gypsum applications produced no effects on total or US#1 tuber yield, specific gravity, hollow heart, or chip color. Preliminary data also suggested that gypsum did not markedly influence the incidence of blackspot. Based on this study, a routine gypsum application to improve the tuber quality of the variety Atlantic is not recommended.     

Effects of Calcium Concentration in Potato Tuber Cells on the Formation of Cross-Links between Pectin Molecules by Ca<Superscript>2+</Superscript>

The formation of cross-links between pectin molecules via Ca²⁺ in the potato tuber cell wall is a determinant factor on processing properties of potato and the quality of its products such as French fries. Thus, in this study, potato tubers varying significantly in their calcium concentrations were analyzed to investigate whether an increased absorption of calcium by a potato tuber led to an increase in the calcium concentration in the cell wall and how the calcium concentration in the cell wall influenced on the formation of cross-links between pectin molecules via Ca²⁺. Correlation analysis revealed that calcium absorbed by a potato tuber was bound to the cell wall as a water insoluble form 99 days after planting or later. Furthermore, with an increase in the calcium concentration in the cell wall, the content of chelator soluble pectin increased throughout tuber bulking and maturation stages. However, the degree of methylation was not a limiting factor in the formation of cross-links between pectin chains via Ca²⁺. Atomic force microscopy images of parenchyma cell walls prepared from mature potato tubers indicated an increase in the amount of calcium cross-linked pectin molecules with an increase in the calcium concentration in the cell wall. The present study demonstrated that the calcium concentration of the cell wall of potato tubers significantly affected the formation of cross-linkages between pectin molecules and, consequently, contributed to an enhanced formation of pectin-calcium networks in the cell wall.     

Effects of gypsum,sulfur, terraclor and terraclor super-x for potato scab control

An investigation was made to determine possible effects of gypsum and sulfur for control of common scab of potato [Streptomyces scabies (Thaxt.) Waksman and Henrici] in a highly buffered calcareous soil. This investigation included a comparison of the effectiveness of gypsum and sulfur with Terraclor and Terraclor Super-X. Both gypsum and sulfur reduced potato scab and measurements indicate that change of soil pH was slight (0.1–0.4 pH reduction). Band applications of sulfur in the sulfate (gypsum) or elemental form were effective at 600 lbs/A (672.5 Kg/ha) but not at lower rates. The weight of tubers thrown out of grade with scab was reduced by 53% with the effective sulfur rate. Treatment effects of gypsum (600 lb S/A-672.5 Kg/ha) were not significantly different from sulfur dust (600 lb/A-672.5 Kg/ha), Terraclor or Terraclor Super-X (both at 25.0 lb PCNB/A-28.0 Kg/ha). Tissue analyses of tuber peelings showed a significant reduction in calcium from treatments involving sulfur and gypsum, indicating that calcium levels in tuber peelings were positively correlated with scab susceptibility.     

The effect of irrigation and nitrogen on powdery scab and yield of potatoes

Summary Powdery scab, caused by the fungusSpongospora subterranea, has developed in the Cappodocia region of Turkey because of changes in agronomic practices, such as excessive irrigation and nitrogen fertilizer use and growth of highly susceptible cultivars. The most suitable irrigation and nitrogen application levels were established to maintain powdery scab at minimum levels without affecting potato yield. Three irrigation levels were used in 1998 (673, 897, 1121 mm) and five in 1999 (329, 494, 658, 823, 987 mm). Nitrogen levels were applied 150, 300, 450, 600 kg N ha⁻¹. In 1998, least powdery scab occurred with 673 mm irrigation, which yielded 41 t ha⁻¹ potatoes. The lowest disease severity occurred in 1999 with 494 mm irrigation and 150 kg N ha⁻¹. At these levels, tuber yield was 34 t ha⁻¹ which was not significantly different from the highest yield measured. In 1999 and at two of the three irrigation levels inl998, nitrogen increased disease severity.     

Soybean inoculation: Dose, N fertilizer supplementation and rhizobia persistence in soil

The effect of rate of application of Sinorhizobium (Ensifer) fredii SMH12 or Bradyrhizobium japonicum USDA110 inoculants on grain yields of soybean [Glycine max (L.) Merrill] cv. Osumi was studied in a field experiment laid out in Southern Spain. All inoculant doses tested (10⁴, 10⁵, 10⁶ and 10⁷ rhizobia/seed) produced higher seed yields than those obtained in un-inoculated plots. Increments in nodule dry weight, seed yield and seed N content were observed when the number of rhizobia applied to seed increased from 10⁴ up to 10⁷. The addition of N fertilizer to inoculated soybean plants (50 kg N/ha applied at R1 or R4 stage) did not increase seed yields in comparison with treatments that were only inoculated. Survival of strains SMH12 and USDA110 was monitorized for three years in two different soils of Southern Spain after soybean inoculation. Rhizobia survival was varied dependent on the soil and the rhizobia strain used.     

Evaluation of <Emphasis Type="Italic">sawah</Emphasis> rice management system in an inland valley in southeastern Nigeria. I: Soil chemical properties and rice yield

Failures in agricultural development in parts of West Africa may have been caused by the inability of the farmers to develop the abundant inland valleys for cultivation of such crops like rice, using appropriate water management systems. An inland valley in southeastern Nigeria was used to evaluate the influence of sawah and non-sawah water management using inorganic and organic soil amendments on the soil chemical properties and rice grain yield. Soil chemical properties tested were soil organic carbon, total nitrogen, pH, exchangeable K⁺, Ca²⁺ and Mg²⁺. Others were CEC, percent base saturation and exchangeable acidity while the grain yield of rice was also measured. The soils are loose, low in pH and poor in plant nutrient elements. In spite of that, the sawah-managed system was able to improve the pH of the soil by raising it slightly both in the first and second year of planting. Generally, essential plant nutrients such as exchangeable K⁺, Ca²⁺ and Mg²⁺, including fertility index like the CEC, were improved within sawah management within the period. Also, rice grain yield increased significantly (5.62 and 6.25 tons/ha in the first year and 5.32 and 6.53 tons/ha in the second year for non-sawah and sawah, respectively) with sawah system such that about 11 and 23% yield increases were obtained in sawah over the non-sawah in the two years, respectively. Although organic carbon can be used to explain the variation in total grain yield in the first year, it was the CEC that explained the total grain yield in the second year. The study revealed the superiority of sawah over non-sawah in the production of lowland rice in an inland valley in southeastern Nigeria.     

The resistance of potato plants toErwinia carotovora subsp.atroseptica in relation to their calcium and magnesium content

Summary The effect of adding gypsum (CaSO₄) to growing media on the resistance toErwinia carotovora subsp.atroseptica (van Hall) Dye of potato (Solanum tuberosum L.) stems and mother and daughter tubers was examined in field and glasshouse experiments. The decayin situ of inoculated mother tubers from field plots treated before planting with gypsum was significantly delayed compared with tubers sampled from non-amended plots. Blackleg development was also significantly delayed in the gypsum-amended plots; however, for both mother tubers and stems the increased resistance associated with the application of gypsum later disappeared. Stem resistance tended to be related to tissue calcium and magnesium concentrations which were higher in plots treated with gypsum than in untreated plots. Daughter tubers produced in plots amended with gypsum generally contained a higher concentration of calcium in their cortex and were more resistant to decay byE. carotovora subsp.atroseptica but the effect was not consistent.     

Effect and interaction of crop management factors on the glycoalkaloid concentration of potato tubers

Summary Potato tuber glycoalkaloid content was measured in response to nitrogen fertilizer rate, storage temperature, length of storage period and cultivar. Cvs Gemchip, Norchip and Russet Burbank were grown with applied nitrogen fertilizer rates of 0, 168 or 336 kg/ha and then stored at either 4.4 or 10°C. Total glycoalkaloid content was determined one month before harvest, at harvest, after three months of storage and after nine months of storage. Higher rates of nitrogen, higher storage temperature and a period of storage all resulted in significantly (P<0.05) higher concentration of glycoalkaloids. The cv Norchip had higher glycoalkaloids than cvs Gemchip or Russet Burbank. Only the storage period had more influence than the environment (difference between years). Significant (P<0.05) two-way interactions were detected for year x cultivar, year x nitrogen, storage period x cultivar and nitrogen x cultivar. Most interactions were due to the unique responses of cultivars.     

Calcium and potassium fertilization of potatoes grown in North Florida I. Effects on potato yield and tissue Ca and K concentrations

Potatoes (Solanum tuberosum L.) were grown during 3 seasons on an Ellzey fine sandy soil to evaluate the effects of Ca and K rate, Ca placement, and cultivar on tuber yield and Ca and K concentration. Mehlich I soil extractable Ca concentration ranged from 436 to 860 mg·kg^t-1. Application of Ca at 0, 450 and 900 kg·ha^t-1 from gypsum increased soil Ca in each season, petiole Ca in 2 of 3 seasons, and tuber medulla and periderm Ca concentrations in one of three seasons. Tuber yields were increased from 29.8 to 31.6 t·ha^t-1 with an increase from 0 to 450 kg Ca·ha^t-1 in one of three seasons. Tuber specific gravity was not affected by Ca rate. With an increase in application of K from 225 to 450 kg·ha^t-1, Ca concentrations were decreased in the petiole and medulla in 2 of 3 seasons and in the periderm in 1 of 3 seasons. Petiole, medulla, and periderm K concentrations were increased in 2 of 3 seasons with an increase in K rate. Yields were not affected by K rate, but specific gravities of tubers were lower in 2 of 3 seasons with an increase in K rate. Broadcast placement of Ca resulted in higher petiole, medulla, and periderm Ca and higher tuber yields in 1 of 2 seasons than with band placement (the placement effect on yield occurred in the season that placement had no effect on tissue Ca). Periderm tissue of Superior was higher in Ca than that of La Chipper, and petiole tissues of Atlantic were higher than that of Superior, but medulla tissue in 1 of 2 seasons was higher in Ca with Superior than Atlantic. Tuber yields and specific gravities were higher with La Chipper and Atlantic than with Superior.     

Performance of Dimethomorph + Mancozeb Applied to Seed Potatoes in Early Management of Late Blight (<Emphasis Type="Italic">Phytophthora infestans</Emphasis>)

Treating seed potatoes with contact fungicides prevents infection of Phytophthora infestans from tuber to tuber during handling but does not prevent field infections in the young plant. Dimethomorph (DMM) 9% + mancozeb 60% (Acrobat MZ, BASF) can cover both aspects due to the contact and systemic action of mancozeb and DMM, respectively. Experiments were performed under greenhouse and field conditions (three seasons and two locations) with cvs Kennebec, Shepody, Spunta, Russet Burbank, and Ranger Russet. Immediately after cutting, seed pieces were treated with Acrobat MZ at doses equivalent to 2, 3, and 4 kg ha⁻¹. At any dose, Acrobat MZ protected healthy seed tubers against P. infestans infections. Acrobat MZ (4 kg ha⁻¹) also protected the foliage of all cultivars against artificial inoculation of P. infestans, assessed by the detached-leaf method. These effects were observed up to 30 days after emergence in greenhouse experiments and up to 28 days after crop emergence under field conditions in two growing seasons. In cv Spunta, significant foliage protection was observed up to 35 days after field emergence whereas in seed tubers of cv Kennebec planted in sandy soils, significant foliage protection persisted longer. Additional evidence for acropetal translocation of Acrobat MZ in field crops was also found. With this strategy, there is no need to apply contact or systemic fungicides early in the season, and spraying costs and environmental risks are also reduced.     

Effect of different levels of nitrogen and farmyard manure on yield and quality of spinach (Spinacea oleracea L.)

The effect of different levels of nitrogen N₀(0kg/ha), N₁(30 kg/ha), N₂ (60 kg/ha), and N₃ (90 kg/ha) and farmyard manure F₀ (0 tonnes/ha), F₁ (10 tonnes/ha), and F₂ (20 tonnes/ha) on the yield and nutrient composition of spinach and its uptake was investigated on a sandy loam soil. Yield; phosphorus, iron, manganese, zinc, and copper uptakes; and ascorbic acid content increased with the application of both the inorganic nitrogen fertilizer and the farmyard manure, with a maximum at the N₃F₂ level, i.e. at 90 kg N/ha with 20 tonnes FYM/ha. However, the contents of protein, -carotene, and reducing sugars were maximum at the highest dose of nitrogen without the application of farmyard manure.     

Influence of storage temperature on rate of potato tuber tissue infection caused byPhytophthora infestans (mont.) de bary estimated by digital image analysis

Summary Potato tubers were inoculated with two biotypes ofPhytophthora infestans then stored at 3,7, 10 and 15°C. Image analysis quantified average reflective intensity (ARI) of diseased tissue from cut surfaces of sample tubers. Tuber tissue infection and infection rate were measured by calculating Mean ARI of samples. Average tuber tissue infection and infection rate was minimal at 3°C (P.i.-US8 orP.i.-US1). Tuber tissue infection increased at temperatures >3°C, from 220 Mean ARI seven days after inoculation (dai) to 190–150 Mean ARI 50 dai (depending on cultivar and biotype ofP. infestans). Rate of tuber tissue infection caused byP.i.-US1 at 7°C was about zero in cv. Snowden but greater than −0.2 ARI day⁻¹ (cvs Russet Burbank and Superior). Rate of late blight infection in tuber tissue generally increased with temperature from −0.2 ARI day⁻¹ (at 7°C) in all cultivars to a maximum of −0.8 ARI day⁻¹ (10°C).     

Calcium translocation and accumulation into potato tubers

Summary Calcium uptake into potato plants was examined using test solutions containing 5% safranin dye (C₂₀H₁₉N₄C1 mw 350.85) and the radiotracer⁴⁵CaCl₂. When minitubers were suspended in test solutions for up to 5 days, safranin moved into the outer pith tissues while⁴⁵Ca²⁺ was located throughout the pith. Ca²⁺ is apparently taken up directly from the tubersphere by a slow diffusion process. Plantlets with one microtuber were used to investigate calcium uptake via basal roots.⁴⁵Ca²⁺ was well ahead of the safranin dye front in all plantlet stems.⁴⁵Ca²⁺ in shoot tips was significantly greater than in microtubers and no safranin entered the microtubers. Greenhouse-grown ex vitro plantlets with minitubers attached were used to determine the relative uptake by basal and stolon roots. Basal root feeding contributed significantly more⁴⁵Ca²⁺ to shoot tips and tubers than stolon root feeding while combined feeding gave the greatest shoot tip and tuber⁴⁵Ca²⁺ levels.     

Potato responses to calcium application on several soil types

On low cation exchange capacity, sandy soils where soil test Ca is low, potato tuber (Solanum tuberosum L.) Ca levels may not be optimal for maximum yield or quality; therefore, this study evaluated the effect of several levels of applied Ca on potato yield and quality on four soil types in Wisconsin. Calcium was applied to a Plainfield loamy sand, a Keiner loamy sand, a Pence sandy loam, and an Antigo silt loam at five rates in 1984 (0, 84, 252, 420, and 588 kg Ca ha^?1) and at six rates in 1985 (0, 56, 112, 168, 224, and 336 kg Ca ha^?1) as a band of CaSO₄ in the hill. In 1984, on the Plainfield soil, three rates of sidedress Ca(NO₃)₂ (0, 84, and 168 kg Ca ha_?1) were factorially combined with the five CaSO₄ treatments to evaluate the efficacy of Ca(NO₃)₂ as a concomitant Ca and N source. In general, total yield was not affected by CaSO₄ additions; however, the addition of approximately 100 kg Ca ha^?1 as Ca(NO₃)₂ increased total yield 3.6 Mg ha^?1. On the low-CEC, low-Ca soils (Plainfield and Kelner), improved tuber grade and/ or US1A size grade were detected with the addition of up to approximately 300 kg Ca ha^?1 as CaSO₄. The percent of US1A tubers increased 5 to 10% and the yield of US1A prime size (170–370 g) tubers increased 3.4 to 8.4 Mg ha^?1 above control values. These improvements were accompanied by increased periderm Ca concentrations, even though leaflet Ca concentrations were not affected by Ca applications. The use of 100 kg Ca ha^?1 asCa(NO₃)₂ in combination with CaSO₄ was more effective than CaSO₄ alone. On higher soil test Ca soils (Pence and Antigo), responses were inconsistent and periderm Ca was generally not increased.     

Effect of haulm treatment and harvest time on incidence of tuber rots of potato (Solanum tuberosum L.) after standard wounding and on frequency of stem lesions caused byPhoma foveata Foister

Summary Various haulm treatments and harvest times differentially influenced the incidence of storage rots in potato tubers (Solanum tuberosum L.) in field experiments in Sweden performed over 4 years. The incidence of gangrene caused byPhoma foveata Foister (Phoma exigua var.foveata (Foister) Boerema) increased in cv. Bellona after spraying haulms with diquat as did the amount of infection caused byFusarium avenaceum (Corda ex. Fr.) Sacc. in all three cultivars (Bintje, Bellona, and Magnum Bonum). The lowestP. foveata infection levels occurred after pulling haulms. Late harvesting increased the frequency ofP. foveata in cvs Bintje and Bellona both at 2 and 4 wks interval between haulm treatment and harvest. Tuber and visible stem infection caused byP. foveata were correlated for cvs Bintje and Bellona, but not for cv. Magnum Bonum. The possible relation between tuber and stem infection is discussed.