Percentage Of Tubers Research Articles

YIELD EVALUATION OF DIFFERENT VARIETIES OF POTATO IN BAJHANG DISTRICT OF NEPAL

A field experiment was carried out in Bithadchir rural municipality of Bajhang district, Nepal in 2021 in the title “Yield evaluation of different varieties of potato in Bajhang district”. The experiment was carried out to find out the best varieties for the hills and high-hills of Nepal based on their availability, suitability and previous record of performance and to assist the farmers to increase the potato production and ensure their food security. One factorial RCBD experimental design was used to evaluate the yield of different varieties. The varieties used as a treatments are Cardinal, Desire, Axona, Blue Danube and Bajhang Local. The results from our experiment shows that cardinal had maximum tuber weight per plant (515.75 gm), highest large grade tuber percentage (37.95%) and also the highest productivity (29.47 t/ha). Moreover, highest number of tubers (14.55) with maximum medium grade tuber percentage (34.71%) was found in Bajhang local. Similarly, being a native variety of the region, the growth parameters (number of main stems per hill, leaves and leaflet numbers, and canopy diameter) and also some yield parameters (number of tubers per plant, tuber size grade) of Bajhang local were also impressive. Therefore, the findings of our research conclude that Cardinal is the best variety under study in terms of yield and variety Bajhang local cultivation should also be promoted due to its wide adaptability in the existing local microclimate.

Effect of low gamma irradiation doses on growth, productivity and chemical constituents of Jerusalem artichoke (Helianthus tuberosus) tubers

BackgroundThis field experiment was carried out during the two successive seasons of 2019 and 2020 at the experimental farm of the National Center for Radiation Research and Technology, Nasr City, Cairo, Egypt, to evaluate the effect of low gamma irradiation doses (0, 2.5, 5 and10 Gray) on growth, yield and chemical constituents of Jerusalem artichoke tubers as one of the non-traditional vegetable crops which had a high nutritional and medicinal value.ResultsThe obtained results show that gamma irradiation at dose rate 5 Gy gave the best results of plant height, number of branches, shoot fresh and dry weight compared with treatments exposed to gamma irradiation at dose rate 2.5 and 10 Gy and also higher photosynthetic pigments such as chlorophyll a, b, a + b and carotenoids than un-irradiated tubers. Same stimulative dose (5 Gy) yielded the highest total yield per feddan, plant yield, tuber fresh weight and dry matter percentage of tubers. Regarding chemical constituents of tubers, it was observed that gamma irradiation at dose 5 Gy scored higher percentage of nitrogen, phosphorus, potassium, total carbohydrates and inulin than other doses. From another point, the highest concentration of total soluble phenols and flavonoids was correlated with 5 and 10 Gy of gamma irradiation.ConclusionsThe moderate dose of gamma irradiation 5 Gy has a stimulative effect on growth of Jerusalem artichoke which reflects on tubers yield and their chemical constituents.

Potato Response to Drought Stress: Physiological and Growth Basis.

Drought poses a major challenge to the production of potatoes worldwide. Climate change is predicted to further aggravate this challenge by intensifying potato crop exposure to increased drought severity and frequency. There is an ongoing effort to adapt our production systems of potatoes through the development of drought-tolerant cultivars that are appropriately engineered for the changing environment. The breeding of drought-tolerant cultivars can be approached through the identification of drought-related physiological and biochemical traits and their deployment in new potato cultivars. Thus, the main objective of this study was to develop a method to identify and characterize the drought-tolerant potato genotypes and the related key traits. To achieve this objective, first we studied 56 potato genotypes including 54 cultivars and 2 advanced breeding lines to assess drought tolerance in terms of tuber yield in the greenhouse experiment. Drought differentially reduced tuber yield in all genotypes. Based on their capacity to maintain percent tuber yield under drought relative to their well-watered controls, potato genotypes differed in their ability to tolerate drought. We then selected six genotypes, Bannock Russet, Nipigon, Onaway, Denali, Fundy, and Russet Norkotah, with distinct yield responses to drought to further examine the physiological and biochemical traits governing drought tolerance. The drought-induced reduction in tuber yield was only 15–20% for Bannock Russet and Nipigon, 44–47% for Onaway and Denali, and 83–91% for Fundy and Russet Norkotah. The tolerant genotypes, Bannock Russet and Nipigon, exhibited about a 2–3-fold increase in instantaneous water-use efficiency (WUE) under drought as compared with their well-watered controls. This stimulation was about 1.8–2-fold for moderately tolerant genotypes, Onaway and Denali, and only 1.5-fold for sensitive genotypes, Fundy, and Russet Norkotah. The differential stimulation of instantaneous WUE of tolerant and moderately tolerant genotypes vs. sensitive genotypes was accounted for by the differential suppression of the rates of photosynthesis, stomatal conductance, and transpiration rates across genotypes. Potato genotypes varied in their response to leaf protein content under drought. We suggest that the rates of photosynthesis, instantaneous WUE, and leaf protein content can be used as the selection criteria for the drought-tolerant potato genotypes.

Studies on impact of storage materials and methods on potato tuber moth, Phthorimaea operculella Zeller (Lepidoptera: Gelechiidae) on potato

Potato tuber moth (PTM), Phthorimaea operculella Zeller originated in Latin America and co-evolved with its host plant potato (Solanum tuberosum L.). It has become one of the most serious insect pests around the world, including in India. Laboratory studies were conducted against PTM for the pest build-up; % tuber dried and rot and extent of tuber tunneling. The mean% infestation of PTM using different storage materials after 90 days of storage was witnessed highest (56.92%) in wooden bins and it was least in cartoon box stored tubers (48.59%), while among different storage methods, it was recorded highest with 61.88% in plastic bin stored tubers and was lowest in low temperature stored tubers (5.45%).% tubers dried after 90 days of storage period was maximum in tubers inserted with agave leaf bits (40%) and it was minimum in nylon mesh bags (5%) among different storage materials. The same was resulted with no tubers dried in both low temperature and pit stored tubers among different storage methods and it was highest in heap method with paddy straw cover (10%). A maximum of 85.00% tuber rot was recorded in tubers inserted with agave leaf bits and a minimum of 10.00% in tubers stored in wooden bins among the storage materials. Among different storage methods, percent tuber rot ranged from 10.00 to 75.00% in tubers storage in low temperature and heap method, respectively. Extent of tuber tunneling among storage materials ranged from 22.22% (40 mesh nylon bags stored tubers) to cent percent (tubers stored in wooden bins and bamboo bins). The same was witnessed with a minimum of 0.33% in low temperature storage method in polythene bags and a maximum of 73.33% in plastic bin stored tubers. Therefore, the development of control technologies and intensive monitoring is necessary in future days to come, for stable potato production as well as potato post-harvest.

STIMULATE THE ABILITY OF POTATO PLANT TO TOLERANCE LOW TEMPERATURE IN WINTER PLANTATION

This research was conducted during two baffling agricultural seasons of 2016/2017 and 2017/2018 at Kaha Vegetables Research Farm, Hort. Research Institute., Agriculture Research Center, Egypt to study the stimulation of the potato plant's cv. Picasso ability to tolerance low temperature and improving tubers yield and qualities through appropriate agricultural practices in parallel with the addition of adequate fertilizers of NPK plus micro-nutrients spraying and some anti-stress substances. The experiment included eight treatments consisting of two fertilization treatments in main plots and four anti-stress as sub plots. The results indicate that treating plants with a suggested nutrients program, along with foliar spraying with some minor elements and some anti-stress, such as selenium plus vitamin C or vitamin E in addition to a commercial anti-stress compound led to stimulating the plant's ability to tolerance low temperature and improved plant growth. Anti-stress commercial compound at 100 ppm concentration exhibited the significant superiority in most of vegetative growth traits (stem length - average number of both stems and leaves as well as fresh weight of stems and leaves and reflected so positively on the total yield of tubers, quality characteristics and the percentage of tubers starch. Also, results indicate that the remainder of the treatments recorded significant differences and gave values that reached the level of significance in most of the characteristics of vegetative growth and yield and its components, compared to the control treatment, which recorded the lowest values of all studied traits. Conclusively, the recommended program for planting in the off-season growing cycles will give the highest yield due to the balanced fertilization and anti-stress /anti-oxidants, as well as, in the same time will take care of the tubers quality. So that, the tubers yield will gain the highest values of economic competition in locally and international markets and to contribute as a good source of hard currency for Egypt.

EFFECT OF ORGANIC AND CHEMICAL FERTILIZERS ON GROWTH AND YIELD OF THREE LOCAL POTATO VARIETIES

The study was carried out in the field of vegetables/ Department of Horticulture and Landscape Design / Faculty of Agriculture and Forestry / University of Mosul / Iraq during the spring growth season 2018 to study growth and yield of three potato varieties which local produced tubers from last spring season, with addition organic fertilizer: Rice residue and poultry manufactured manure (Italian origin), and chemical fertilizer NP, and control treatment. The experiment involved 12 treatments (3×4) carried out in the field using a split plot system within Randomized Complete Block Design (RCBD) with three replicates. The cultivars were placed in the main plots and fertilizers treatments placed in the sub plots. The results could be summarized as follows: The Volar variety gave the least days for tuber emergence and higher tuber emergence percentage. The sylvana variety significantly increased chlorophyll content in leaves. The Arizona variety increased significantly tuber weight, tuber number per plant, plant yield and tubers total yield 71.05 gm, 9.90 tuber. Plant-1 , 707.66 gm. plant-1 and 37.741 t. ha-1 respectively. No significant differences observed between varieties in the yield quality. The addition of chemical fertilizer significantly increased plant higher, tuber weight, tuber number per plant, plant yield and tubers total yield 61.63 cm, 81.54 gm, 10.54 tuber. Plant-1 , 859.43 gm. plant-1 and 45.835 t. ha-1 respectively. Poultry manure increased significantly quality yield such as tubers dry matter percentage, starch percentage and specific gravity of tubers. The interaction between volar variety with chemical fertilizer gave least days for tuber emergence. Arizona variety with chemical fertilizer significantly increased plant higher 62.86 cm, tuber weight 83.77 gm, and tuber number 11.76 tuber. Plant-1 , plant yield 985.13 gm. plant-1 and total yield of tubers 52.540 t. ha-1 . Sylvana variety with control increased chlorophyll content in leaves, but Arizona variety with rice residue increased significantly dry matter percentage, starch percentage of tubers and specific gravity of tubers.

Comparative Evaluation of the Effects of Gibberellic Acid Concentrations on Dormancy Break in Tubers of Solanum chacoense

Solanum chacoense is a wild relative of potato (Solanum tuberosum) that is of interest because of its many desirable traits, but it exhibits variations in tuber dormancy across accessions. The objective of this study was to determine an appropriate gibberellic acid (GA3) concentration and soak time treatment to encourage sprout development across four accessions of S. chacoense (A, B, C, and D) from the 174 accessions of the U.S. Department of Agriculture Potato Genebank. Twelve treatments were created by using four concentrations of GA3 (0, 50, 100, and 150 μg·mL−1) across three soak periods (5, 45, and 90 minutes). Small (average weight, 1.4 g), medium (2.6 g), and large (5.6 g) tubers were distributed among all treatments. Percentage of tubers sprouted, time to sprouting, sprout length, and sprout number per tuber were analyzed to determine the effectiveness of GA3 treatments on dormancy breaking. GA3 concentrations of 50, 100, and 150 μg·mL−1 partially broke dormancy within accessions B and C. None of the tested treatments were effective for breaking dormancy in accession D within 46 days after treatment. Accession A showed weaker dormancy, thus producing a similar percentage of sprouted tubers across all GA3 treatments. Soak time had no significant effect on all parameters measured. Larger tubers produced greater sprout number per tuber and percentages of sprouted tubers. Soaking tubers in 50 μg·mL−1 of GA3 may be an effective treatment for S. chacoense accessions with mild dormancy, but alternative methods to break dormancy may be required for S. chacoense accessions with stronger dormancy.

Calcium-sorbitol Chelating Technology and Application in Potatoes

Researches on low-molecular organic compounds are concentrated in amino acid and Humic acid chelating fertilizer, but few in sorbitol chelated calcium. In this study, selecting sorbitol as chelating agent, the technological conditions of chelating sorbitol with calcium and the effect of sorbitol chelated calcium on potato were studied. The impact factors on the stability of the fertilizer were investigated, including sorbitol dosage, pH value, chelating time and temperature. Then a field experiment was conducted on potato. Three treatments included water sprayed as a control, calcium nitrate and sorbitol chelated calcium sprayed. Each treatment had three replicates. The results showed that by orthogonal experiments, the sorbitol dosage has the greatest influence on the stability of the chelating system. The optimum conditions for the synthesis were determined as follows: The sorbitol dosage of 12 g, the chelating temperature of 50°C, the pH of 4 and the chelating time of 45 min. Compared with those of potatoes fertilized with inorganic calcium nitrate, the yield of potatoes sprayed with sorbitol chelated calcium increased by 14.23% and their marketable tuber percentage increased by 3.58%; the nitrate nitrogen content in potatoes decreased by 11.89%; the accumulation of phosphorus and potassium in potato tubers increased. Generally, the application effect of our prepared sorbitol chelated calcium on potato was remarkable.

Tuber Depth and Yield Response of Tiger Nut (Cyperus esculentus) to Soil Texture and Rates of Poultry and Pig Manure

A pot experiment was conducted to evaluate tuber depth and weight of tiger nut produced in loamy fine sand and sandy clay soil using 0, 200, 300 or 400 g per pot of poultry or pig manure in a 2 × 2 × 4 factorial experiment arranged in completely randomized design and replicated three times. Total tuber weight and weight of tubers at 10 cm were significantly increased by application of manure compared with the control. Significant interaction of soil texture X manure types X manure rates was recorded on weight of tubers at 20 cm. Percentage of tubers at 0-10 cm was 90.6-92.1% (91.5-93.6% tuber weight); while 6.68-8.96% of the tubers (5.49-8.47% tuber weight) were harvested between 10-20 cm soil depth; only 0-0.94% of the tuber weight was harvested beyond 20 cm depth. Pig manure had positive effect on tiger nut productivity on loamy fine sand and sandy clay soil, while with poultry manure tiger nut productivity was enhanced on sandy clay soil; 300 g of pig or poultry manure produced similar weight of tiger nut tubers and is considered optimum for tiger nut productivity. Sandy clay and loamy fine sand had similar effect on depth and yield of tiger nut. More than 99% of the tubers were confined to 0-20 cm soil depth. Information on how deep the tubers of tiger nut can grow in soil of different texture and fertility status will enhance precise harvesting.

Protection of stored potatoes from infestation with the potato tuber moth, Phthorimaea operculella (Zeller)(Lepidoptera: Gelechiidae) using plant powders

BackgroundThe potato tuber moth (PTM), Phthorimaea operculella (Zeller) (Lepidoptera: Gelechiidae), is an important storage pest of potato (Solanum tuberosum L.) in Saudi Arabia and Egypt. Infestation in the store starts mostly through freshly harvested infested tubers or through moths entering the storage facilities. Larvae mine in tubers making them unsuitable for sale and consumption. Damage increases rapidly when several generations develop during the storage period. Larvae are capable of causing damage to the crop either in the field or in the store. Biopesticides are certain types of pesticides derived from animals, plants, bacteria, and certain minerals. During the course of evolution, plants have developed, as part of their defensive mechanism, various chemical molecules, which proved a protection against insect pests, since the overall pressure of insect on plant is much more than any other herbivore. Biopesticides prepared from plants are reported to have the ability to kill or keep away the pests. They are eco-friendly. The plant products have additional advantage over synthetic insecticides, as they are biodegradable, safe to non-target organisms, leave no residues, and decrease the buildup of resistance strains of insects. Present research is conducted to evaluate the capacity of certain natural local alternative plant powders against PTM under storage conditions as attempts to providing alternative and novel strategies that can be used by both the commercial and/or small-scale potato farmers to control the pest in the store.MethodsTwelve different plants (Zygophyllum, Solanum, Coriander, Arnoglosse, Jasmine, Senna, Colocynth, Camomile, Harmel, Geranium, Basil, and Mint) locally available in the fields of the Eastern Province of the Saudi Arabian kingdom were air-dried under a shad at ambient tropical condition. The air dried materials were grinded into fine powders and kept in tight containers until using. Potato tubers were shacked with the plant powders for a good mixing, until tubers were uniformly covered and the powders stick well to the tuber surfaces. Different dried leaves or fruits of the 12 tested plants were powdered to be used at rate of 25 g plant powder per 1 Kg tubers. The experiments were distributed in a randomized complete block design. Different biological aspects of the treatments were calculated; damage index to tubers and persistence of protection to the tubers during different intervals of storage were recorded.ResultsAll plant powders had a reduction effect on the deposited eggs laid on the treated tubers with different degrees. The dried powders of Coriander, Clocynth, and Zygophyllum reduced egg deposition on the treated tubers than the control, followed by Jassmin, Senna, Cammomil, and Harmel. The powders of Basil and Solanum also recorded a moderate reduction in egg deposition. Zygophyllum and Coriander could protect the tubers for more than 8 weeks. All other treatments greatly minimized the number of emerged moths from the treated tubers (F1), as follows: Coriander = Zygophyllum (0) > Basil (17.39) > Geranium (17.85) > Cammomil (18.75) > Arnoglosse (19.32) > Jasmine (21.62) > Mint (21.69) > Harmel (52.77) > Senna and Colocynth (72.72) > Solanum (100) compared with untreated tubers (95.17). All treatments had no effects on the tuber germination.ConclusionThe study showed that all the tested plant powders, at the rate of 25 g plant powder per 1 Kg potato tubers, could protect the tubers for more than 8 weeks from PTM infestation during storage. The most potent powders were Coriander and Zygophyllum. All other powders decreased the number of the emerged adults from the treated tubers, with variable degrees, and decreased the percentage of tubers’ damage index recorded. Besides, all the tested plant powders had no effects on the tubers’ germination.

Response of Potato Productivity and Storability to some Potassium Levels and Foliar Spray with some Macro and Microelements

Two field trials were conducted on potato plants cv. Spunta, in vegetable private farm at Al-Enaniya village, Sinbelawin district, Dakahlia Governoraten, during 2014/2015 and 2015/2016 seasons to study the effect of soil application of potassium levels (96, 72 and 48 kg K2O/fed), either single and/or in combination with foliar spray of macro and micronutrients compound (N=25%, P=16%, K=12%, Zn=0.5%, Fe=0.5%, Mn=0.5%, Cu=0.3%) at different levels i.e., 6, 4 and 2 g/L on plant growth, yield and its components, as well as chemical constituents and storability of tubers. In general, results showed that potato plants fertilized with potassium sulfate at the level of 96 kg K2O/fed significantly increased plant stem length, number of leaves, leaf area and foliage plant fresh and dry weights as well as total yield, number of tubers/plant and tuber weight/plant, Moreover, this level of potassium significantly increased TSS, dry matter, specific gravity, Ascorbic acid (mg/g FW) and concentrations of macro and micronutrients (N, P, K, Fe, Zn, Mn, Cu). Also, potassium fertilization at of 96 kg K2O/fed had the most interesting observation which enhancing storability during storage period. Foliar spray with macro and micro nutrients at a rate of 6 g/L resulted in an increases in the most vegetative growth parameters, yield and tubers quality traits. However, weight loss percentage of tubers was significantly reduced during storage period.The combined treatments of potassium levels and foliar spray with some macro and micronutrients were generally more effective on the most studied parameters than single ones. The best results were obtained by application 96 kg K2O/fed with foliar spray of macro and micronutrients at the rate of 6 g/L. This treatment achieved increases in vegetative growth characters, total tubers yield (ton/fed), ascorbic acid (mg/g FW), TSS% of tuber, concentrations of N, P, K, micronutrients (Fe, Zn, Mn and Cu) in tubers and enhanced the tubers storability comparing with the other ones. Therefore, this treatment could be recommended for raising potato yield and improving tuber quality during storage period under similar conditions to this work.

Effects of deficit irrigation on the potato tuber development and quality

This study was conducted to determine the effects of deficit irrigation on tuber growth and quality of potato (Solanum tuberosum L.). Certified seeds of potato variety “Agria” were used as study material. Irrigation treatments was consisted of one irrigation interval (5 days) and five different levels (I100, I85, I70, I55, I40) of soil water deficit measured before irrigations. First irrigation was applied by drip irrigation up to field capacity the soil water content in 0-60 cm depth in all treatments. Subsequent irrigations were applied according to the treatments. The irrigation water and evapotranspiration (ET) values of treatments ranged from 243.0 to 311.9.4 mm and from 337.1 to 385.9 mm in the first year, respectively, and from 166.7 to 223.2 mm and from 204.0 to 255.7 mm in the second year, respectively. Yields varied from 30.85 to 47.13 t/ha in the first year and from 28.77 to 44.45 t/ha in the second year. The yields were decreased based on water deficit levels. The highest yields were obtained from I100 treatment. The results have indicated that water restriction had a significant effect on yield, single tuber weight, percentage of marketable tuber, plant length, mean tuber length, mean tuber diameter and percentage of tuber peeling. The results were showing that the I100 treatment in especially was of the most importance for the highest percentage marketable tuber and tuber yield obtained per unit water applied. Therefore, the I100 treatment can be recommended for potato cultivation under similar climatic and soil conditions.

First Report of Streptomyces scabies Causing Potato Common Scab in Punjab, Pakistan

Common scab (CS) is caused by gram positive, soilborne, filamentous Actinobacteria in the genus Streptomyces. Potato common scab is very prevalent in the potato growing region of Pakistan (Anwar et al. 2013). In this study, 14 CS-infected potato samples were collected from three different potato growing fields of Punjab, Pakistan, during 2015. The samples were heavily infected with a superficial corky layer to pitted scars of CS. The procedure for isolating Streptomyces spp. from the scabby portion of potatoes was adopted as mentioned by Song et al. (2004). One isolate was identified as Streptomyces scabies after morphological and physiological characterization (Wanner 2006). The Streptomyces isolate was grown in yeast maltose broth for 3 days at 28°C. The pellet was used for genomic DNA extraction by using Gene Jet genomic DNA purification kit (Thermo Scientific, USA) and DNA quantity was checked by NanoDrop system (Thermo Scientific). High quality DNA was used for PCR amplification of 16S rRNA gene using primer pair pA/pH (Edwards et al. 1989). The amplicon was sequenced and submitted to NCBI to obtain an accession number. Species and strains specific 16s rRNA gene amplification was performed with PCR. This Streptomyces strain, designated AC-46, gave positive PCR band amplification with primer pairs of S. scabies scab1m/scab2m and S. europaeiscabiei scab1/scab2m (Wanner 2006). To definitely determine whether AC-46 was S. scabies or S. europaeiscabiei, internal transcribed spacer (ITS) region was amplified using primer pair ITSL/ITSR (Song et al. 2004). The amplification was subjected to digestion with restriction enzyme Hpy99I (New England Biolabs). After restriction fragment length polymorphism (RFLP) analysis, Streptomyces strain AC-46 was confirmed as S. scabies with accession no. KU560917. Although Anwar et al. (2013) previously reported the occurrence of S. scabies from CS-infected potato tubers in Pakistan, the methodologies used did not enable definitive identification as S. scabies. Genes responsible for pathogenesis including txtAB, nec1, and tomA were also analyzed. PCR amplification confirmed the presence of txtAB gene with primer pairs txtAB1/txtAB2 (Wanner 2006), nec1 gene with primer pair nf/nr (Bukhalid et al. 1998), and tomA gene with primer pair tom3/tom4 (Wanner 2006), respectively. Pathogenicity of S. scabies strain AC-46 was evaluated in a pot assay. Medium sized (8 liter) pots were filled with substrate (Autoclaved Compo-Sana Universal, Germany). Potatoes (cv. Astrax) were grown at 25 to 28°C in pots for 3 weeks until they germinated. S. scabies strain AC-46, S. scabies (kindly provided by Dr. J. Leiminger, Germany, DSMZ41658) as positive control, and nonpathogenic Streptomyces spp. (KU560918, txtAB negative) as negative control were grown in yeast malt broth in five separate pots in duplicate. Pellets of bacterial suspension were dissolved in 100 ml of sterile normal saline to obtain 106 CFU/ml concentration. One hundred milliliters of vermiculite (bacterial suspension) was drenched into germinated potato plants, separately. After 12 weeks, plants were harvested and disease symptoms were recorded based on percentage of tubers affected by S. scabies. The disease symptoms varied from mild to severe deep pitted scabs (Wanner 2006) without netted scab while no visible CS symptoms were observed for negative controls. Disease severity calculated for S. scabies, AC-46, and negative control was 34.6, 57, and 0%. Pathogenic Streptomyces strain was reisolated from infected tubers to confirm Koch’s postulates.

Mulch and planting depth influence potato canopy development, underground morphology, and tuber yield

The response of potato (Solanum tuberosum cv Haryeong) to mulching and different planting depths was evaluated during 2010–2013. Two different plastic mulches, black and clear polyethylene (PE) were compared with the unmulched control and seed tubers were planted at 5-, 10-, 15-, and 20-cm depths in each treatment. The objectives were to determine how mulching and planting depth affected the canopy development, underground morphology, and tuber yield. Early emergence, canopy development and tuber growth rate were improved in the mulched treatment; while delayed or decreased as the depth of planting increased. The number of stems per plant increased as seed pieces were planted closer to the soil surface in two of the four seasons, but was not affected by mulches except for 2012. Stolon length was longest in black mulches, especially on upper part of underground stem, but it was long on lower part of the stem in unmulched potatoes. Percent tuber bearing stolons were increased in the mulches and deep (10–20cm) planted potatoes. Particularly, on the lower part of underground stem, a higher percentage of tubers were formed irrespective of mulches and planting depth. Harvest index was significantly higher in clear PE mulches in two of the four seasons while it was not affected by planting depth. Mulching potatoes produced higher total and >80g yields, while varying the depth of planting affected the total yield which was lower in the deepest (20cm) planted potato.

Growth and yield response of potato genotypes to deficit irrigation

In Ardabil region potato crop needs several irrigation, however ground water supplies arebeing exhausted due to reduced precipitation and intensive irrigation. In this research droughttolerance of 10 commercial potato cultivars was studied at three irrigation treatments (100%,80% and 60% of required irrigation water) in Ardabil in a two years field study, 2013-2014.At harvest, marketable tuber yield, tuber weight per plant, mean tuber weight, tuber number perplant, percent tuber dry matter, plant height and the main stem diameter were measured. Alsothe stress indices such as water stress susceptibility (SSI), tolerance (TOL), mean productivity(MP), geometric mean productivity (GMP) and stress tolerance (STI) were determined and usedto select the tolerant cultivars to water deficit. There were significant differences amongirrigation treatments, cultivars and cultivars × irrigation treatments for all studied traits; betweenyears and interaction of years × cultivars for marketable tuber yield, tuber weight per plant,mean tuber weight and tuber numbers per plant. The cultivar Satina produced the highestmarketable tuber yield, tuber weight per plant, mean tuber weight and plant height and also hadhigher MP, GMP and STI indices in all three irrigation treatments, therefore, it can berecommended for cultivation under water deficit condition. Cultivar Caesar showed the lowestSSI and TOL indices under both mild and severe water deficit conditions, therefore it can beused in breeding programs for developing drought–tolerant potato cultivars. Under both mildand severe stress conditions a high correlation was found between marketable tuber yield andplant height, but a negative correlation existed between mean tuber weight and tuber number perplant. Cultivar Savalan showed the highest tuber dry matter content.

The effects of using seed treatments on sprouting, health condition and yield of potato

Summary The impact of applying Prestige 290 FS, as well as biological treatments: FZB 24 WG and Proradix WP on the infection of potato tubers by Rhizoctonia solani and Streptomyces scabiei, the sprout development rate and the yield of potato tubers of three cultivars (Cyprian, Finezja and Flaming) was studied in the years 2011–2013. The experiment was conducted in a randomized split-block method in 4 repetitions. The applied chemical treatment significantly increased the potato sprouting rate and decreased the percentage of tubers infected by R. solani when compared to the application of biological treatments, as well as not treated tubers. The treatment did not affect the infection rate of tubers caused by S. scabiei. The infection of tubers caused by R. solani did not depend on the cultivar, while in case of S. scabiei the highest infection rate was observable in case of the Cyprian cultivar. Applying both chemical and biological treatments did not affect the yield of tubers.

Response of yams exposed to different sources and doses of nitrogen fertilizers in the State of Maranhão, Brazil

This study was carried out at the State University of Maranhão, São Luís, Brazil from January to November 2012. We assessed the behavior of the yam Dioscorea cayenensis ‘Da Costa’, fertilized with different rates and sources of nitrogen (N). The experimental design was randomized, with treatments in a 6 × 2 factorial design. The factors were represented by six rates of N fertilization (0, 50, 100, 150, 200, and 250 kg·ha-1) and two sources (ammonium sulfate and urea) by using four replicates. We evaluated the mean mass, commercial root yield, leaf N content, starch content in the tubers, and percentage of tubers with symptoms of nematode infection (dry and thick skins). The maximum values for the mean masses of commercial tubers were 2.5 and 1.9 kg with doses of 130 and 160 kg of N ha-1 from ammonium sulfate and urea, respectively. Doses of 130 and 154.3 kg of N ha-1 produced the maximum yields of commercial tubers of 19.7 and 14.9 t·ha-1 with ammonium sulfate and urea fertilization, respectively. The maximum levels of foliar N by using urea and ammonium sulfate were 36.5 and 29.3 g·kg-1, respectively, at a dosage of 250 kg·ha-1. The maximum starch contents of 25.7 and 28.3 % were obtained at doses of 114 and 116 kg of N ha-1 of ammonium sulfate and urea, respectively. The percentage of tubers infected with nematodes was 10% when the N source was urea and 15.6% when the source was ammonium sulfate, both at a dosage of 250 kg·ha-1.

Genetic variability and association between agronomic characters in some potato (Solanum tuberosum L.) genotypes in SNNPRS, Ethiopia

Thirteen (13) potato genotypes were evaluated for genetic variability and association of agronomic characters among themselves and tuber yield. The study aimed to find out the genetic variability, and interrelationships among different characters in potato. The plot design used for the experiment was a randomized complete block design with three replications. The analysis of variance showed that the mean square due to genotype were highly significant (p<0.01) for all characters studied, which indicates the existence of sufficient genetic variability and there was less coefficient of variation in all of the characters indicating good precision of the experiment. Genotypic correlation coefficient was found to be higher in magnitude than that of phenotypic correlation coefficients, which clearly indicated the presence of inherent association among various characters. Tuber yield was positively correlated with plant height, biological yield, harvest index and big tuber percentage at both the phenotypic and genotypic levels. In contrast, it was negatively correlated with small and medium tuber percentage at both levels. Path coefficient analysis at the phenotypic level revealed that days to flowering, plant height, tuber diameter, biological yield, harvest index and medium tuber percentage showed positive direct effects on tuber yield. The genotypic path analysis also indicated that biological yield and harvest index showed positive and significant correlation. Therefore, these characters are more important than other traits for the genetic improvement of potato. Key words: Genetic variability, potato, heritability, correlation, path coefficient analysis.

Analysis of Polyphenols, Anthocyanins and Carotenoids in Tubers from Solanum tuberosum Group Phureja, Stenotomum and Andigena

Sixty-five Solanum tuberosum group Andigena, Phureja and Stenotomum genotypes from an initial population of 1,500 were analyzed for phenylpropanoids, carotenoids, and antioxidant capacity. Total phenolic content ranged from 3 to 49 mg g−1 DW, total carotenoids from 4.1 to 154 μg/g DW, anthocyanins from 0.27 to 34 mg g−1 DW and antioxidant capacity from 60 to 1,767 μmol TE/g DW. HPLC analysis of phenolic extracts revealed that 5-O-chlorogenic acid (5CGA) was the most abundant polyphenol in all genotypes. Ten genotypes were independently grown out for more in-depth phytonutrient analysis. The Phureja genotypes RN 27.01 had the highest polyphenol, anthocyanin and antioxidant content, while RN 39.05 had the highest carotenoid content. The tuber percentage dry matter varied markedly among the ten genotypes, influencing the phytonutrient values when expressed on a dry weight basis. Chlorogenic acid concentrations ranged from 1.7 to 29.4 mg g−1 DW and kaempferol-3-rutinose was present up to 3 mg g−1 DW. Petunidin-3-O-coum-rutinoside-5-O-glu or pelargonidin-3-O-coum-rutinoside-5-O-glu were the most abundant anthocyanins. The principal carotenoids were lutein, zeaxanthin, violaxanthin, and antheraxanthin, but no one carotenoid was predominant in all genotypes. These findings further support utilization of Phureja group germplasm for phytonutrient enhancement efforts.

Establishing suppressive conditions against soilborne potato diseases with low rates of fish emulsion applied serially as a pre-plant soil amendment

Soil amendment with fish emulsion (FE) can suppress potato scab and verticillium wilt, but the effective broadcast rates (20 000 L ha−1) may not be feasible for commercial use. The aim of this 4-year study was to establish suppressive conditions against soilborne potato diseases and increase tuber yield with economically feasible rates of FE. Diluted FE (1000 and 2000 L ha−1 or 0.05 and 0.1%) was applied to field plots or micro-plots twice a year before planting and after harvesting potatoes starting in autumn of 2007 and ending in spring of 2010. In the micro-plots, FE (0.1%) added to an infested potato soil (site BL) consistently reduced scab severity by 44.9% (2008), 44.8% (2009) and 30.9% (2010) compared with the control. Scab severity on tubers harvested from these plots was also low in 2011 when no further FE was applied, but the effect was not significant. In the field, FE (2000 L ha−1) consistently reduced scab severity by 45% (2008), 53% (2009), 44% (2010) and 38% (2011); reduced the percentage of tubers with deep-pitted scab by 48% (2008), 51% (2009), 66% (2010) and 77% (2011); and increased the percentage of marketable tubers by 37% (2008), 83% (2009), 20% (2010) and 8% (2011). These field plots also showed a low percentage of Verticillium dahliae-infected potato plants during the first 3 years of the field trial. Fish emulsion treatments increased total tuber yield by 7–20% in the first 3 years, but there was no effect in the fourth year when no FE was applied. Marketable tubers were consistently higher in the plots amended with FE (2000 L ha−1). Fish emulsion soil treatments increased soil bacteria but the numbers dropped to the control level in the fourth year when no FE application was made. There was no change in total fungal numbers. The results suggest that economically feasible rates of FE can provide disease suppression and enhance tuber yield and the effect may last a year or more after the last FE application.