Microtuberization of Potato (Solanum tuberosum L.) as Influenced by Supplementary Nutrients, Plant Growth Regulators, and In Vitro Culture Conditions

Five experiments with in vitro-grown plantlets of potato cvs ‘Superior,’ ‘Early Valley,’ ‘Golden Valley,’ and ‘Winter Valley’ were carried out to investigate in a stepwise approach the potential for enhancing microtuber production of (1) adding supplementary nutrients (SN) including KNO₃, NH₄H₂PO₄, Ca(NO₃)₂.4H₂O, and MgSO₄ in full- or half-strength Murashige and Skoog (MS) medium, (2) adding a pretested combination of plant growth regulators (PGRs), i.e., 10 mg l⁻¹ 6-benzyl aminopurine plus 200 mg l⁻¹ succinic acid 2,2-dimethylhydrazide, (3) varying the timing of the supplemental applications, and (4) varying the replenishment of the medium. Plantlets of ‘Superior’ for microtuberization were grown from two-node explants for 75 days under environmental conditions consisting of 22 ± 2 °C and a 16-h photoperiod on a solid basal medium consisting of half-strength MS (1/2 MS) medium containing 6 % sucrose and a moderate concentration of supplementary nutrients, SN-2 (KNO₃, 1.22 g l⁻¹; NH₄H₂PO₄, 1.41 g l⁻¹; Ca(NO₃)₂4H₂O, 0.23 g l⁻¹; and MgSO₄, 0.74 g l⁻¹). Thereafter, plantlets were grown for 60 days under dark conditions. Liquid media containing different combinations of MS, SN, and PGR levels plus 8 % sucrose were added as a supplement and were evaluated for their ability to increase tuberization compared to the control composition of the supplement (MS with 8 % sucrose). In the first experiment, addition of 1/2 MS liquid medium containing 8 % sucrose and SN-2 before dark incubation induced the highest total number of microtubers (on average 1.4 per plantlet), a significantly higher weight and size than the control, and the highest percentage (50 %) of large-sized (>500 mg) microtubers. In the second experiment, addition of 1/2 MS liquid medium containing 8 % sucrose, SN-2, and PGRs produced the highest number (on average 1.5 per plantlet) and total yield (on average 971 mg per plantlet) of microtubers, and significantly the highest percentage (66 %) of large-sized (>500 mg) microtubers. The size of the microtubers was higher than for the treatment without growth regulators. The optimum time for addition of supplemental medium containing 8 % sucrose, SN-2, and PGRs was shown in experiment 3 to be latest 1 week before dark incubation. This timing resulted in both the highest microtuber number (on average 1.6 per plantlet) and yield (on average 1208 mg per plantlet), and the highest percentage (64 %) of large-sized microtubers. Finally, it was found that a second supplemental treatment consisting of 50 % replacement of the liquid medium (by volume) 2 weeks after transfer to dark conditions gave rise to the highest number (on average 1.9 per plantlet), yield (on average 1346 mg per plant), and also significantly the highest percentage (25 %) of large-sized microtubers (>1000 mg) as compared to replacement of a greater or smaller proportion of the medium. Four potato cultivars, ‘Superior,’ ‘Early Valley,’ ‘Golden Valley,’ and ‘Winter Valley’ produced acceptable numbers and yield of microtubers of relatively large-sized tubers using a process that included supplemental liquid medium with 1/2 MS, 8 % sucrose, moderate concentration (SN-2) of SNs and PGRs, followed by a 50 % replacement of the same medium.     

Potato cuttings as models to study maturation and senescence

Summary Single leaf cuttings with their subtended axillary buds proved to be useful models to study maturation and senescence in potato (Solanum tuberosum L.). Senescence was more rapid if the cultivar was early maturing or if plants were exposed to short days before cuttings were taken. Rooting was decreased by short days before cutting; excision of the buried bud only partially overcame the effects on senescence and rooting. High rates of N to mother plants in the field delayed senescence of cuttings in a way analogous to the delayed senescence of field plants. The tuberization of cuttings from late maturing cultivars was decreased by high rates of N. The color of crisps made from bud tubers was positively correlated with the color of crisps made from ordinary tubers of the same cultivars. Sugar concentrations in bud tubers decreased as cuttings became more senescent and increased after cold storage. Bud tubers harvested while ‘immature’ had greater concentrations of reducing sugars after 90 d at 10°C than did ‘mature’ bud tubers. Paper No. 878, Department of Vegetable Crops, Cornell University. This research was supported through HATCH project NYS161414, a contributing project to Regional Project NC150, and through HATCH project NYS161407.     

Specific Gravity,Dry Matter and Starch Concentration of Different Potato Cultivars as Affected by Arsenic Contamination

Arsenic (As) contamination of the soil may affect the quality of potato tubers. When assessing the processing quality of potato cultivars, specific gravity (SG) is the measurement of choice for estimating dry matter (DM) and starch concentrations in the potato tubers. In this study, effects of the As concentration in the soil on quality parameters (SG, DM, starch concentration and total soluble solids (TSS)) of 11 potato cultivars in Bangladesh were investigated in an outdoor pot experiment with a randomized complete block design (RCBD) and three blocks, at Sher-e-Bangla Agricultural University, Dhaka, Bangladesh, from November, 2012 to March, 2013. The results showed highly significant differences between cultivars in quality parameters, except SG. Both As levels (25 and 50 mg As kg^?1 soil) reduced the DM and starch concentration in the tubers of the potato cultivars compared to the control (0 mg As kg^?1 soil), but had no significant effects on SG and TSS. ‘Lady Rosetta’ showed the highest SG (1.093 g cm^?3), DM (23.02%) and starch concentration (16.60%). The lowest SG (1.065 g cm^?3), DM (17.04%), and starch concentration (10.96%) was found in ‘Granola’. Highest TSS (5.91) was found in ‘Jam Alu’ while ‘Meridian’ had the lowest °Brix value (3.76). Bangladeshi potato farmers will benefit from the information generated regarding potato cultivation under As affected areas.     

Effect of CIPC on Sprout Inhibition and Processing Quality of Potatoes Stored Under Traditional Storage Systems in India

Indigenous non-refrigerated methods like heaps and pits are used in India for short-term storage of potatoes (Solanum tuberosum L.) to avoid distress sale. Storing untreated potatoes generally results in high losses from sprouting, moisture loss and rotting. To reduce storage losses by inhibition of sprouting and to determine the suitability of stored potatoes for processing into crisps, a single spray application of a commercial formulation of 3-chlorophenyl carbamate (CIPC or chlorpropham) 50% a.i., (Oorja, United Phosphorus Limited, Mumbai, India) of CIPC (or chlorpropham) was tested on potatoes during storage from March to June under two traditional storage methods [heap (17–33 °C, 58–92% relative humidity (RH)) and pit (17–27 °C, 72–95% RH)] in 2 years [2005 up to 90 days of storage (DOS) and 2006 up to 105 DOS], using four cultivars and two rates of CIPC application (20 and 30 mg a.i. kg⁻¹ tubers). The two rates of application were comparably effective in reducing weight losses, sprouting and sprout growth in stored tubers, and the effect was more pronounced in pit storage than in heap storage. By contrast to untreated tubers, CIPC-treated potatoes remained turgid under the two storage methods and fetched market prices comparable to those for cold-stored (2–4 °C) potatoes after 105 days of storage. Reducing sugar concentrations in treated potatoes decreased during storage especially in 2006 when the initial reducing sugar concentration was higher than in 2005. Crisp colour improved only in 2005 after 90 DOS, but it deteriorated in 2006 during storage up to 105 DOS. Sucrose concentration increased tremendously during storage in 2 years. Only one cultivar (Kufri Chipsona-1) with low initial reducing sugar concentration and less sucrose accumulation during storage could produce acceptable colour crisps after storage in both years. The remaining three cultivars—with high initial reducing sugar concentration—were suitable for processing after storage in heap and pit in 2005, but not in 2006. Stored potatoes were safe for human consumption as the CIPC residue concentrations were far below the permissible level of 10 mg kg⁻¹ as prescribed by the European Union. Single spray application of CIPC (20 mg kg⁻¹ treatment) can effectively reduce storage losses in potatoes stored in traditional non-refrigerated methods of heap and pit and extend the storage life by 90 to 105 days.     

Chemical and Morphological Characteristics of New Clones and Commercial Varieties of Globe Artichoke (<Emphasis Type="Italic">Cynara cardunculus</Emphasis> var. <Emphasis Type="Italic">scolymus</Emphasis>)

The globe artichoke is a widely consumed vegetable in the Mediterranean Basin, with Italy being the leading producer. In southern Italy, its cultivation contributes to local economic stability and social development. The producers are increasingly choosing to replace autochthonous varieties, such as ‘Violetto di Sicilia’, with cultivars bred or selected outside of the region, putting pressure on the maintenance of traditional varieties. Here, we have undertaken a detailed morphological and chemical analysis of a group of clones selected from a population of ‘Violetto di Sicilia’. All the traits measured displayed genetic variation, particularly the total content of phenolics and minerals. The capitula of the ‘Violetto di Sicilia’ clones contained, on average, 6.3 g kg⁻¹ of fresh weight total phenolics, compared with 4.5 g kg⁻¹ in the two commercial varieties. The clones also had more inulin than commercial varieties (254 vs. 225 g kg⁻¹ of dry matter), as well as a good mineral content. The set of clones is of interest in the context of the proposed improvement of the crop through breeding and selection of genotypes with high nutritional quality and a specific end-use (industrial processing or fresh consumption).     

Slow Growth In Vitro Conservation of Potato Germplasm at Low Temperature

The efficacy of mannitol versus sorbitol for in vitro conservation of potato microplants at low (7 ± 1 °C) temperature was studied. Two concentrations of sucrose (20 and 40 g l⁻¹) in combination with two concentrations (20 and 40 g l⁻¹) of either mannitol or sorbitol in Murashige and Skoog (MS) medium were tested. Microplant survival, microplant condition, and root growth in three potato genotypes belonging to different maturity groups were studied up to 18 months of in vitro storage without sub-culturing. Best results were achieved with MS medium having 20 g l⁻¹ sucrose plus 40 g l⁻¹ sorbitol. After 18 months without sub-culturing, maximum survival (58.0%) coupled with a microplant condition good enough to provide suitable nodes for sub-culturing was observed with the use of this medium. The results showed that the in vitro storage period could be prolonged by reducing the root growth. The success of conservation was unaffected by the maturity group of the genotypes.     

Effect of Cooking and Processing on CIPC Residue Concentrations in Potatoes and Processed Potato Products

Residue concentrations of the sprout suppressant chlorpropham (or CIPC) were determined in raw and cooked potatoes and processed potato products, 48 h after CIPC aerosol treatment and after 30 days of subsequent storage at 4 or 12 °C. In the raw (uncooked) tuber, 48 h after CIPC treatment, the CIPC residue in the peel was 4.7 mg kg^-1, while in the peeled tuber it was 0.1 mg kg^-1. Boiling resulted in a decrease in residue concentration in the peel, but no significant differences in the residue concentration of the peeled tuber were observed. Pressure cooking resulted in a significantly increased residue concentration in the peel, but no significant change in the peeled tuber, whereas microwave cooking also did not increase the residue concentration in the peel significantly compared with that in raw tubers. Also the trend towards increases in residue concentration in microwave-cooked peeled tubers was not significant. The CIPC residue concentration detected in peeled tubers was 0.4–0.7 mg kg^-1 after boiling, 0.4–1.5 mg kg^-1 after pressure cooking and 0.4–3.8 mg kg^-1 after microwave cooking. The highest values were always found for tubers stored for 30 days at 4 °C. Processed products such as crisps, French fries, dehydrated sliced potatoes and starch contained different concentrations of CIPC residue, which was also detected in the cooking water and frying oil. The highest residue concentrations detected were 0.7, 4.7, 1.3 and 0.2 mg kg^-1 in crisps, French fries, dehydrated sliced potatoes and starch, respectively. The highest CIPC residue concentration observed in raw potatoes was much lower than the maximum residue level of 10 mg kg^-1 prescribed by the European Union.     

Improving production and health of seed potato stocks in Italy

Summary When nodal explants from sprouts grown from virus-free tubers of ten cultivars were propagated on half-strength Murashige and Skoog medium, cvs Arsy, Nicola, Kennebec and Spunta grew best. Rooted plantlets, 5–8 cm tall, were transplanted from culture vessels into pots containing soil, vermiculite and sand. They were weaned by growing in a glasshouse for about three weeks. Over 90% of the plantlets survived and these were then planted in the field and protected against aphids by a double screen (a large tunnel covering four adjacent small tunnels) and chemical treatments. Prebasic seed tubers thus obtained were virus-free and production ranged from 49.9 t.ha⁻¹ (‘Monalisa’) to 27.1 t.ha⁻¹ (‘Majestic’). A survey showed that ‘elite’ (near virus-free) seed could be produced from prebasic seed by early planting and early haulm killing regardless of location, but late planting on the plains and normal planting dates on the mountains resulted in 1 to 5% virus infection levels acceptable only for certified seed.     

Accumulation of arsenic and its distribution in rice plant (Oryza sativa L.) in Gangetic West Bengal, India

The presence of arsenic in irrigation water and in paddy field soil were investigated to assess the accumulation of arsenic and its distribution in the various parts (root, straw, husk, and grain) of rice plant from an arsenic effected area of West Bengal. Results showed that the level of arsenic in irrigation water (0.05–0.70 mg l⁻¹) was much above the WHO recommended arsenic limit of 0.01 mg l⁻¹ for drinking water. The paddy soil gets contaminated from the irrigation water and thus enhancing the bioaccumulation of arsenic in rice plants. The total soil arsenic concentrations ranged from 1.34 to 14.09 mg kg⁻¹. Soil organic carbon showed positive correlation with arsenic accumulation in rice plant, while soil pH showed strong negative correlation. Higher accumulation of arsenic was noticed in the root (6.92 ± 0.241–28.63 ± 0.225 mg kg⁻¹) as compared to the straw (1.18 ± 0.002–2.13 ± 0.009 mg kg⁻¹), husk (0.40 ± 0.004–1.05 ± 0.006 mg kg⁻¹), and grain (0.16 ± 0.001–0.58 ± 0.003 mg kg⁻¹) parts of the rice plant. However, the accumulation of arsenic in the rice grain of all the studied samples was found to be between 0.16 ± 0.001 and 0.58 ± 0.003 mg kg⁻¹ dry weights of arsenic, which did not exceed the permissible limit in rice (1.0 mg kg⁻¹ according to WHO recommendation). Two rice plant varieties, one high yielding (Red Minikit) and another local (Megi) had been chosen for the study of arsenic translocation. Higher translocation of arsenic was seen in the high yielding variety (0.194–0.393) compared to that by the local rice variety (0.099–0.161). An appreciable high efficiency in translocation of arsenic from shoot to grain (0.099–0.393) was observed in both the rice varieties compared to the translocation from root to shoot (0.040–0.108).     

Determination of the glycoalkaloids α-solanine and α-chaconine levels in 18 varieties of potato (Solarium tuberosum L.) grown in Oman

Summary The glycoalkaloid content in 18 potato varieties grown in Oman was measured by HPLC using peel and flesh tissues. The total glycoalkaloid content of the tubers was found to be variety dependent and varied greatly between the 18 varieties. The total glycoalkaloid in the tubers of seven varieties was within the safe limit of ≤200 mg kg^{− 1} FW recommended for food safety, whereas the remaining 11 varieties exceeded this upper limit. The principal glycoalkaloids α-chaconine and σ-solanine were present in higher concentration in the peel than in the flesh of all varieties with the former being the principal alkaloid in the peel. The flesh of all of the 18 potato varieties contained total glycoalkaloid levels lower than the upper safety limit. The leaves of the 18 potato varieties were also analyzed for glycoalkaloids. The levels of glycoalkaloids in expanding leaves were higher than that of expanded leaves with the exception of six varieties. The principal glycoalkaloid in expanding and expanded leaves was α-chaconine. No correlation was observed between the glycoalkaloids levels of in the leaves and tubers.     

Glycoalkaloid content, cooking quality and sensory evaluation of early introductions of potatoes into New Zealand

Summary The indigenous Maori people quickly adopted early introductions of potatoes into New Zealand. These early cultivars known as Maori Potatoes are smaller in size and differently coloured when compared to modern potato cultivars and are thought to have remained unselected. The glycoalkaloid content of tubers ranged from 38.7 to 142.6 mg kg⁻¹ (mean 76.5). A taste test conducted on 10 different cultivars showed that they were generally well accepted; however all panellists noted a slightly bitter after taste in some of the cultivars. The texture and flavour were within acceptable limits for all the cultivars tested.     

Beziehungen zwischen Stengel- und Knollenzahl bei der Kartoffel in Abhängigkeit von wichtigen Einflußfaktoren. I. Der Einfluß der Pflanzgutvorbehandlung und der Sorte

Zusammenfassung Die Pflanzgutvorbehandlung beeinflu?te die Stengelzahl signifikant. Abgekeimtes Pflanzgut der Sorten ‘Adretta’ und ‘Mariella’ entwickelte weniger Stengel und Knollen pro Pflanze jedoch mehr Knollen pro Stengel als vorgekeimtes und keimgestimmtes Pflanzgut. Die st?rker negativen Korrelationen zwischen Stengelzahl pro Pflanze und Knollenzahl pro Stengel sowie die h?here Reduktionsrate der angelegten Knollen bei der Sorte ‘Adretta’ weisen auf Sortenunterschiede in der Sch?rfe der Konkurrenz zwischen den Stengeln und innerhalb der Knollenanlagen eines Stengels hin. Die Ernteknollenzahl wurde bei ‘Mariella’ wesentlich durch die Zahl der Knollenanlagen, bei ‘Adretta’ hingegen st?rker durch die Reduktionsrate bestimmt.

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Summary Three different seed treatments and two cultivars were studied over seven years of field experiments (Table 1). Differences were detected between the cultivars in all characteristics studied: numbers of stems, maximum number of tubers (tuber initials), the number of harvestable tubers (>3 cm) at maturity per plant and per stem, and tuber reduction (percentage of initiated tubers that did not develop). Apart from the number of harvestable tubers, there were also differences between seed treatments (Tables 2, 3 and 4). Chitted seed of ‘Mariella’ and sprouted seed of ‘Adretta’ gave the greatest number of tubers per plant (Tables 3 and 4). In both cases desprouting reduced the numbers of stems and tubers per plant but increased the number of harvestable tubers per stem. Chitted seed set the most tubers per plant and per stem but had the highest levels of tuber reduction (Table 4). Due to intra- and inter-stem competition in both cultivars the percentage tuber reduction is significantly correlated with the number of tuber initials (maximum tuber number, Table 5). Smaller numbers of tubers per stem (Table 3) and significantly negative correlations between the number of stems and the maximum and harvestable number of tubers per stem (Table 5) highlight the effect of strong inter-stem competition in ‘Adretta’. Moreover, in this cultivar intra-stem competition seems to play an important role too. The rate of tuber reduction was significantly higher than in ‘Mariella’ (Table 3), and the final number of tubers significantly depended on the percentage of tuber reduction during the period of tuber growth (r=0,57^*, Table 5). In contrast, the number of harvestable tubers per plant in ‘Mariella’ was significantly correlated with the maximum tuber number during the period of tuber set (r=0,61^*, Table 5).

     

The Effects of Different Nitrogen and Phosphorus Rates on Some Quality Traits of Potato

This study was conducted to determine the effects of nitrogen (0, 120, and 240 kg N ha⁻¹) and phosphorus (0, 90, and 180 kg P₂O₅ ha⁻¹) doses on some tuber quality traits of the potato cultivar Agria under the ecological conditions of Erzurum in the years 2005 and 2006. The effects of N levels were significant only on the protein content of tubers while the P levels only significantly affected the oil content of the crisps. No significant N × P interaction effects were found on any of the traits evaluated. Based on these results, it could be concluded that the potato crop should be fertilized with 120 kg ha⁻¹ N and that phosphorus fertilizers should be added when soils are P deficient in the Erzurum region.     

Using Ethylene Gas and Chlorpropham Potato Sprout Inhibitors Together

Marketplace preference for lower pesticide residues in foods has led to research to reduce the residue of chlorpropham (isopropyl N-3-chlorophenyl carbamate; CIPC), a postharvest-applied sprout inhibitor which is widely used around the globe to prevent sprouting of stored potatoes (Solanum tuberosum L.). Ethylene gas, an effective, safe and non-toxic sprout inhibitor used in several countries, sometimes has negative effects on the colour of processed potato products when used alone. Trials were conducted over 3 years using cv. Shepody (French fry) and cv. NorValley (potato chips/crisps) to determine whether a combination of these two sprout inhibitors, at reduced dosages, could inhibit sprouting while maintaining good processing colour. CIPC applied at 0, 0.1, 0.25 and 1.0 times the recommended dosage was combined with 4 μll⁻¹ of ethylene gas applied or no ethylene at all (0 ethylene), for 1 day in 4 days, for 1 day in 2 days or continuously, in a factorial design. Sprout inhibition in both cultivars was excellent at all levels of CIPC application except the 0 rate. In both cultivars, sprouting was inhibited by the continuous ethylene treatment. However, all levels of ethylene exposure except the 0 rate negatively affected processing colour in both cultivars. The darkening was dose dependent, whereby the colour was darkest in continuous ethylene and was less affected by the intermittent exposures. In continuous ethylene, the colour was progressively lighter during storage after initial darkening. Shepody tubers appeared to be more sensitive to ethylene than the NorValley tubers. In Shepody only, colour in the ethylene of 1 day in 4 days treatments was progressively darker with increasing time in storage.     

Demand for Processed Potato Products and Processing Quality Potato Tubers in India

Potato processing in India has shown a tremendous growth in the recent past, creating a proportionate increase in demand for processing quality potatoes. Reliable annual demand estimates of processing quality potato tubers in India were not available; hence, the current study was undertaken to provide such estimates. The study was based on a survey of 442 households in the state Maharashtra in India, which was regarded to be representative for India in the consumption of processed potato products. The annual expenditure on potato products during 2006–2007 in Maharashtra was estimated to be INR 5,254 million (€ 93.82 million), which was equivalent to 28,148 Mg of physical processed potato products and 83,333 Mg of processing quality potato tubers (0.38% of national potato production during 2006–2007, i.e. 22.09 million Mg). When the estimates were generalised to a national level, the requirement of processing-quality potato tubers in 2006–2007 was equal to 4.04% of national potato production. The forecasted annual demand of potato products in Maharashtra during 2011–2012 was 75,375 Mg and the corresponding demand of processing quality potato tubers was 230,760 Mg (0.75% of the estimated national potato production during 2011–2012, i.e. 30.89 million Mg). When generalised at national level, the demand of processing quality potato tubers during 2011–2012 was found to be 8% of the estimated national potato production.     

Potato tuber sugars, starch and organic acids in relation to ozone exposure

Summary Data from two Swedish and one Finnish open-top chamber experiments were combined to investigate effects of ozone exposure on potato (Solanum tuberosum L.) tuber content of starch, sucrose, fructose, glucose, malic, citric and ascorbic acids. The glucose, fructose and malic acid concentrations showed strong negative correlations with ozone exposure, while citric acid, consistently increased with ozone exposure. No ozone effects could be demonstrated on starch, sucrose or ascorbic acid concentrations. It is discussed to what extent the changes found in potato tuber composition can be explained in terms of ozone effects on tuber maturity. Ozone exposure was expressed as the accumulated exposure over a cut-off concentration of 40 nmol mol⁻¹ (AOT40) and as the accumulated uptake of ozone over an ozone uptake rate threshold of 7 nmol m⁻² s⁻¹ (CUO 7). The difference in ability of the exposure indices to explain observed effects was small.     

Effect of Nitrogen Rate on Growth,Yield, Economics and Crisps Quality of Indian Potato Processing Cultivars

A field study was conducted during 2000–2001 and 2001–2002 at the Central Potato Research Institute Campus, Modipuram, India, in order to increasing the processing-grade tuber yield of India’s first ever developed processing potato cultivars, Kufri Chipsona-1 and Kufri Chipsona-2. Tuber yield and post-harvest quality characteristics were evaluated in response to five N levels (0, 90, 180, 270 and 360 kg N ha^-1). The crop growth traits (stem number, plant height and compound leaf number) responded positively to N application, whereas the effect of N fertilization on processing-grade tuber number, total tuber number per ha and tuber number per plant was quadratic. There was a steady increase in tuber weight per plant, processing-grade tuber yield, total tuber yield and biomass yield in response to N application. Kufri Chipsona-1 produced a 23.6% higher tuber yield per plant than Kufri Chipsona-2. Agronomic N use efficiency decreased linearly with increased N doses. Specific gravity and tuber dry matter percentage responded positively to N application, while crisps colour (at harvest and after storage) and reducing sugars remained unaffected. Cultivar was the major factor that influenced the tuber quality parameters (specific gravity, crisps colour). Higher values of these quality traits were observed in Kufri Chipsona-2 as compared to Kufri Chipsona-1. Net income and benefit cost ratio (B:C) indicated that Chipsona cultivars should be fertilized with 270 kg N ha^-1 for realizing higher processing-grade yields and desirable quality tubers.     

The Use of True Potato Seed as Pro-poor Technology: The Efforts of an International Agricultural Research Institute to Innovating Potato Production

The International Potato Center (CIP) and collaborating institutions implemented an intensive research programme over a period of 25–30 years on the use of botanical seed of potato as an alternative way of growing a potato crop. The use of botanical or ‘true’ potato seed (TPS) had many advantages over the use of seed tubers. Potentially, the use of TPS was especially attractive for small-scale farmers in developing countries. The difference of using TPS as compared to using seed tubers meant in many respects the development of a new crop–commodity chain, requiring research on breeding, seed production, agronomy and marketing aspects. This research made it possible to produce potatoes from TPS at commercial scale: it removed a number of important constraints in the uniformity and earliness of the TPS varieties and in seed physiology. Experimentation and adoption by farmers in a wide range of countries showed that the technological advantages of using TPS were only translating in economical benefits as compared to tuber seed when the last one was costly or not available. Since the economic performance of seed tubers is likely to continue to fluctuate, TPS remains an interesting alternative. Study of the use of TPS in various countries could contribute to better understanding of factors that promote or inhibit crop technology innovation. The article gives an overview of the various areas of TPS research in CIP and presents information on the application of TPS technology in several developing countries.     

Potato and Human Exploration of Space: Some Observations from NASA-Sponsored Controlled Environment Studies

Future space exploration by humans will require reliable supplies of food, oxygen and clean water to sustain the expeditions. Potato is one of several crops being studied for such a “life support” role. Tests sponsored by the US National Aeronautics and Space Administration (NASA) confirmed the well-known short day tendencies for tuberisation, but also revealed that some cvs. (e.g., Norland, Denali and Russet Burbank) could tuberise well under continuous high light. Horticultural tests showed that plants grew well and tuberised readily using a nutrient film technique (NFT). CO₂ enrichment studies with potato showed typical C₃ responses in photosynthesis and yield, with maximum rates occurring near 1000 μmol mol⁻¹. The highest tuber yields from these controlled environment studies reached 19.7 kg FM m⁻² or equivalent to nearly 200 t ha⁻¹. This equated to a productivity of 38 g m⁻² DM m⁻² day⁻¹. Stand evapotranspiration (ET) rates ranged from 3.4 to 5.2 l m⁻² day⁻¹ throughout growth, while maximum ET rates for canopies could approach 10 l m⁻² day⁻¹. Harvest indices (tuber DM/total DM) typically ranged from 0.7 to 0.8, indicating that waste (inedible) biomass from potato would be less than that from many other crops. An experiment was conducted in 1995 on NASA’s Space Shuttle using excised potato leaves to study tuber formation at axillary buds during spaceflight. The results showed that tubers formed equally well in space as in the ground controls, indicating that reduced gravity should not be an impediment to tuberisation.     

Potato production and utilization in world perspective with special reference to the tropics and sub-tropics

Summary Potato production is increasing rapidly in the tropics and sub-tropics and is declining gradually in the temperate zone. It is not expected that in the near future potato production for ethanol production will become important or that the production for starch or stock feed will increase. Consumption per capita is more or less stable in Western Europe and North America but is increasing in Africa and Asia. On average, energy and protein from potatoes cost the developing-country consumer at least three times as much as from wheat or rice. Better application by farmers of existing and newly developed technologies — including better adapted cultivars, healthy seed tubers, botanical seed and low-cost storage and processing — can reduce costs per unit of output substantially, mainly by increasing yield. Doubling the yield without considerable increases in production costs per hectare would allow the potato to become a cheap vegetable in many tropical or sub-tropical areas and to become a staple food in others with favourable growing conditions. Derived from a paper prepared for the International Symposium ‘Research for the potato in the year 2000’ (CIP, Lima, 1982).