Dry matter accumulation in potato clones under seasonal high temperature conditions in Pakistan

The effects of seasonal high temperatures on potatoes were investigated under field conditions near Peshawar, Pakistan. Five potato clones (A79196-1, Desiree, DTO-28, LT-1, Russet Burbank) were grown during the spring season at two locations. Canopy development, vine dry weight and tuber dry weight were determined at 13-day intervals, starting 68 days after planting (DAP). Tuber yield was higher in heat tolerant clones compared to heat susceptible clones. Location significantly affected tuber dry weights. Tuber dry weights of Russet Burbank were consistently lower than those of DTO-28. Ground canopy cover of DTO-28 occurred earlier and reached maximum at 75 DAP, compared to 90 DAP for Desiree. DTO-28, because of its high tuber yield under cool as well as hot temperatures, and its relatively early bulking, should be a promising clone for a short duration crop in hotter regions.     

Alturas: A multi-purpose, Russet potato cultivar with high yield and tuber specific gravity

‘Alturas’, a late-maturing, high-yielding, russet potato cultivar with high tuber specific gravity, was released in 2002 by the USDA-ARS and the Agricultural Experiment Stations of Idaho, Oregon, and Washington. Originally selected for dehydration processing, its cold-sweetening resistance also makes it suitable for processing out of storage into french fries and other frozen potato products. Culinary quality is high, with larger tubers suitable for fresh market if heavily russeted skin is not essential. Alturas consistently produced greater total and U.S. No. 1 yields than ‘Russet Burbank’ and ‘Ranger Russet’ in southern Idaho trials. Across other western trial sites, total yields of Alturas have on average been 29% and 14% greater than Russet Burbank and Ranger Russet, respectively. Alturas is resistant to Verticillium wilt (Verticillium dahliae) and early blight (Alternaria solani). Compared with Russet Burbank and Ranger Russet, Alturas is less susceptible to corky ringspot and foliar and tuber infection by late blight (Phytophthora infestans). It also is less susceptible to tuber net necrosis and Fusarium dry rot than Russet Burbank, and is more resistant to common scab (Streptomyces scabies) than Ranger Russet. However, Alturas is more susceptible to infection by PVY and PVX than Ranger Russet. Total nitrogen application recommendations for Alturas are approximately 40% less than those for Russet Burbank. Alturas requires 15% to 20% more water during the growing season than does Russet Bur-bank.     

Bannock russet: A dual-purpose, russet potato cultivar with high U. S. No. 1 yield and multiple disease resistances

Bannock Russet, a late-maturing, long russet potato cultivar, was released in 1999 by the USDA-ARS and the experiment stations of Idaho, Oregon, and Washington. It is suitable for processing into french fries and other frozen products. Its attractive russeted skin and excellent culinary qualities also make it suitable for fresh market. Bannock Russet, in comparisons with Russet Burbank, has consistently produced greater U.S. No. 1 yields in trials conducted throughout southern Idaho. In other western trial sites, total yields of Bannock Russet have been comparable to or smaller than that of Russet Burbank, but its percentage of undersize and cull potatoes is consistently less. Bannock Russet is resistant to potato virus Y (PVY), Verticillium wilt, common scab, and leafroll net necrosis. It also has moderate resistance to early blight (foliar and tuber) andErwinia soft rot. With respect to other potato diseases/disorders, Bannock Russet’s level of susceptibility is similar to that of Russet Burbank; the exception being shatter bruise, with Bannock Russet displaying a greater susceptibility. Cultural management guidelines have been developed to minimize shatter bruise in Bannock Russet. Bannock Russet’s multiple disease resistances coupled with its low nitrogen requirement, make it a low-input cultivar that could significantly reduce growers’ production costs.     

Histopathological and parasitological study of the gastrointestinal tract of dogs naturally infected with Leishmania infantum

Background

The aim of this study was to provide a systematic pathological and parasitological overview of the gastrointestinal tract (GIT), including the stomach, duodenum, jejunum, ileum, caecum and colon, of dogs naturally infected with Leishmania.

Methods

Twenty mongrel dogs naturally infected with Leishmania (Leishmania) infantum and obtained from the Control Zoonosis Center of the Municipality of Ribeirão das Neves, Belo Horizonte Metropolitan area, Minas Gerais (MG) state, Brazil, were analyzed. The dogs were divided into two groups: Group 1 comprised nine clinically normal dogs and group 2 comprised 11 clinically affected dogs. After necropsy, one sample was collected from each GIT segment, namely the stomach, duodenum, jejunum, ileum, caecum and colon. Furthermore, paraffin-embedded samples were used for histological and parasitological (immunohistochemistry) evaluation and a morphometrical study were carried out to determine the parasite load (immunolabeled amastigote forms of Leishmania). The Friedman and the Mann Whitney tests were used for statistical analysis. The Friedman test was used to analyze each segment of the GIT within each group of dogs and the Mann Whitney test was used to compare the GIT segments between clinically unaffected and affected dogs.

Results

The infected dogs had an increased number of macrophages, plasma cells and lymphocytes, but lesions were generally mild. Parasite distribution in the GIT was evident in all intestinal segments and layers of the intestinal wall (mucosal, muscular and submucosal) irrespective of the clinical status of the dogs. However, the parasite load was statistically higher in the caecum and colon than in other segments of the GIT.

Conclusion

The high parasite burden evident throughout the GIT mucosa with only mild pathological alterations led us to consider whether Leishmania gains an advantage from the intestinal immunoregulatory response (immunological tolerance).     

Agronomic and economic impact of missing and irregularly spaced potato plants

Missing and irregularly spaced potato plants compromise grower revenue. A recent survey of 70 commercial fields in Washington State, USA, indicated that in-row seedpiece and plant spacing was irregular due to multiple planter skips and clumped seedpieces. Seven percent (2950 missing plants ha^?1) of the intended stand was missing: 6% from planter skips and 1% from nonviable seedpieces. To estimate economic loss to Washington potato growers, two potato (Solanum tuberosum) cultivars, Russet Burbank and Russet Norkotah, were grown in small-plot experiments designed to mimic spacing errors commonly found in Washington fields. Yield and economic values of uniform (optimum) spacing were compared to values coming from treatments that simulated planter skips/missing plants and seed clumps (doubles) in 2001 and 2002. The planter-skip treatments produced the lowest total, market, and U.S. No. 1 yields for both cultivars. In-row plants on both sides of a skip collectively compensated for 56% to 67% of the missing plant’s economic value. Plants in adjacent rows failed to compensate for their missing neighbor. Doubles reduced average tuber size for both cultivars compared with optimum spacing. Using processing market values, 2950 missing Russet Burbank plants ha^?1 reduced seed-cost-adjusted gross income 2.9% or $205 ha^?1. Doubles did not affect Russet Burbank processing value. Using fresh market values, 2950 missing and 1980 doubles ha^?1 reduced Russet Norkotah adjusted gross income 4.4% or $250 ha^?1. Improved planter technology and management efforts would likely improve plant spacing in commercial fields and in turn, grower revenue. Planter manufacturers and growers should consider this information when making management decisions.     

Relationship between leaf gas exchange characteristics and productivity of potato clones grown at different temperatures

The rate of dark respiration (Rd) and net photosynthesis (Pn) at various leaf temperatures was examined in three potato clones (Solatium tuberosum L.) differing in heat tolerance. Plants were grown at low (25/12 C, day/night) and high (35/25 C) greenhouse air temperatures for five weeks, beginning two weeks after tuberization. Gas exchange characteristics were measured by manometric and infrared gas analyzer techniques. Respiration:photosynthesis ratios were calculated as indicators of leaf carbon balance. High greenhouse temperature reduced whole plant and tuber growth rate of all clones, however, the reduction was highest in the cultivar Russet Burbank (heat sensitive). Gas exchange characteristics did not explain differences in heat tolerance. The heat tolerant cultivar Desiree had Rd similar to Russet Burbank, while the clone DTO-28, also heat tolerant, had lower Rd of mature leaves than Russet Burbank or Desiree. However, all clones had similar Rd of immature leaves. There was no apparent relationship between heat tolerance and Pn for the three clones. DTO-28 had lower respirationrphotosynthesis ratios of immature and mature leaves than Russet Burbank 4 weeks after the start of the high temperature treatment. Desiree had respiration:photosynthesis ratios as high as Russet Burbank. At different sampling times, Rd increased in a linear and curvilinear manner with increasing leaf temperature up to 40 C. Heat tolerant and sensitive clones had similar rates of increase in Rd with increasing leaf temperature. Simultaneous measurement of Rd and Pn did not help explain differences in heat tolerance among clones. However, determination of respirationrphotosynthesis ratios may help explain the physiological basis for heat tolerance of some clones.     

Harvesting potatoes with minimum damage

Temperature, tuber condition and harvester operation must be considered if potatoes are to be harvested with minimum damage. In general, total damage increased as temperature decreased; however, the type of damage resulting from impact was influenced by temperature and tuber condition. The data indicate that a tuber turgidity level occurs wherein total damage susceptibility level is minimal for a given tuber temperature and that the proper tuber turgidity level changes as temperature changes. A tuber hydration level which produces little damage when bruised at a flesh temperature of 65–70 F results in severe damage (shatter bruise) when subjected to the same force at 45–50 F. Conversely, a hydration level which results in severe blackspot at 65–70 F may result in slight to moderate total damage when subjected to the same impact at 50–55 F. Data from several commercial harvester studies indicate that damage may increase rather than decrease with a reduction of harvester speed. The ratio of chain speeds to forward speed was found to be more important than forward speed alone. The optimum ratios varied and were dependent on potato yield. Theoretical ratios based on the volume of tubers at different yield levels and harvester chain capacities were calculated and compared with actual ratios of commercial harvest operation. Harvesters operated with chain speed to forward speed ratios near the theoretical ratios resulted in low tuber damage (25%) with forward speed ranges of 1.60 to 3.25 mph. Harvesters operating with ratios differing considerably from theoretical ratios resulted in a high level of damage (66%). The catechol test identified shatter bruise damage which ruptured the skin, but did not detect internal blackspot. Therefore, the catechol test should be used with discretion when attempting to determine the total damage level. Lye peeling and abrasive peeling identified both blackspot and severe shatter bruise damage and should be used when determining harvester operation speeds when both types of damage occur.     

Incorporation of urea-derived 13C into microbial communities in four different agriculture soils

The objective of this study was to investigate changes in the composition of the soil microbial community brought about by urea application and differences in the incorporation of urea-derived C into the soil phospholipid fatty acid (PLFA) pool at differing soil pH. We selected four soils which ranged in pH from 3.9 to 7.8. ¹³C-labeled urea was applied at two concentrations 100 and 200 mg N kg^?1 which represents commonly used and high levels of application. Significant hydrolysis of applied urea occurred within 2 h; less than 2 % of urea-C was retained in the soil with one exception, the fluvo-aquic soil at pH 7.8 amended with 200 mg kg^?1 urea-N 3 days after urea application. According to principal component analysis (PCA), the effect of urea and incubation time on microbial community composition was far weaker than differences between the four soils due to their large differences in basic properties; the scores of PC2 were significantly correlated with pH values. The incorporation of ¹³C-urea to PLFAs increased with soil pH; this may be related to increases in the speciation of inorganic C into bicarbonate.¹³C label was primarily incorporated into 16:1ω5c, 16:0, and cy19:0 in red soil, pH 3.9; and into 16:1ω7c, 16:0, and 16:1ω5c in fluvo-aquic soil, pH 7.8. A wider range of PLFAs became labeled in the two paddy soils at pH 5.2 and 6.7. This suggests that the profile of PLFAs labeled from the application of ¹³C-urea may be affected by redox potential.