Large Tubers Research Articles

English

In Ethiopia, potato sub-sector is expanding, with more value added products, such as potato chips, mainly due to increasing demands associated with growth of population and urbanization. Processing industry is very dependent on the quality parameters of tuber to satisfy the increasing demand of customers. Thus, this experiment was conducted with the objective to evaluate the quality of some improved potato varieties at Shebench district of Bench-Maji Zone. The study comprised of nine improved potato varieties laid out in randomized complete block design (RCBD) with three replications. The tuber size distribution and proximate quality data were collected and analyzed by using SAS Version 9.2 statistical software. The results of the study revealed that all of the variables considered were significantly (P<0.01) affected by varieties except pH. Accordingly, considering tuber size distribution, the highest percentage of medium tuber was observed for Gudanie (77.4) followed by Belete (72.18). Whereas the highest percentage of large tuber was observed for variety Belete (17.35) followed by Shenkola (14.03). On the other hand, the least percentage of small tuber size was observed for variety Belete (10.47) followed by Gudanie (13.59). With regard to physicochemical qualities, the highest value of dry mater content (21.67%), specific gravity (1.08) and starch content (14.69%) were observed for Gudanie variety whereas Degemegn (3.28%) and Gudanie (3.27%) varieties showed the highest protein contents. Therefore, considering majority of the tested marketable and processing quality attributes, variety Gudanie can be considered as superior and recommended for the study area. In addition to this, growers in the study area can also use variety Belete for its good marketable tubers and varieties Gera, Gorebela and Chala for their acceptable processing quality. Key words: Potato, variety, quality, gudanie.

English

Population density and seed tuber is an important agronomic management practices in the production of potato (Solanum tuberosum L.). However, potato farmers in Ethiopia often use random population density and tuber sizes, which contribute to the low yield of the crop. Thus the objective of this study is to review effect of population density and tuber size on yield components and yield of potato. The result of this review shows that the highest plant height and main stems number was found in wider spacing and in medium to large tuber size. In the same way, the number of tuber per plant, average tuber weight and marketable yield increased when potatoes are planted in medium intra row spacing (60 x 30) and using medium (35 to 45 cm) to large (45 to 55 cm) tuber size. However, total tuber number/ha and unmarketable yield increased in closer spacing and medium (35 to 45 cm) tuber size. Thus according to the review to increase total yield and marketable yield, it is better to use medium plant spacing (60 x 30 cm) and medium-sized tubers (35 to 45 mm). Key words: Population density, potato growth, potato yield, tuber size.

QTL analysis of domestication syndrome in zombi pea (Vigna vexillata), an underutilized legume crop.

Zombi pea (Vigna vexillata (L.) A. Rich) is an underutilized crop belonging to the genus Vigna. Two domesticated forms of zombi pea are cultivated as crop plants; seed and tuber forms. The cultivated seed form is present in Africa, while the cultivated tuber form is present in a very limited part of Asia. Genetics of domestication have been investigated in most of cultivated Vigna crops by means of quantitative trait locus (QTL) mapping. In this study, we investigated genetics of domestication in zombi pea by QTL analysis using an F2 population of 139 plants derived from a cross between cultivated tuber form of V. vexillata (JP235863) and wild V. vexillata (AusTRCF66514). A linkage map with 11 linkage groups (LGs) was constructed from this F2 population using 145 SSR, 117 RAD-seq and 2 morphological markers. Many highly segregation distorted markers were found on LGs 5, 6, 7, 8, 10 and 11. Most of the distorted markers were clustered together and all the markers on LG8 were highly distorted markers. Comparing this V. vexillata linkage map with linkage maps of other four Vigna species demonstrated several genome rearrangements in V. vexillata. QTL analysis for 22 domestication-related traits was investigated by inclusive composite interval mapping in which 37 QTLs were identified for 18 traits; no QTL was detected for 4 traits. Number of QTLs detected in each trait ranged from 1 to 5 with an average of only 2.3. Five QTLs for tuber width and three QTLs for tuber weight. Interestingly, 2 QTLs each for tuber width and tuber weight detected on LG2 and LG4 were located at similar position and wild allele increased tuber width and weight. This indicated wild germplasm having small tuber have potential to increase yield of large tuber cultivated type. Large-effect QTLs (PVE > 20%) were on LG4 (pod length), LG5 (leaf size and seed thickness), and LG7 (for seed-related traits). Comparison of domestication-related QTLs of the zombi pea with those of cowpea (Vigna unguiculata), azuki bean (Vigna angularis), mungbean (Vigna radiata) and rice bean (Vigna umbellata) revealed that there was conservation of some QTLs for seed size, pod size and leaf size between zombi pea and cowpea and that QTLs associated with seed size (weight, length, width and thickness) in each species were clustered on same linkage.

Cranial anatomy of the basal neoceratopsian Auroraceratops rugosus (Ornithischia: Ceratopsia) from the Yujingzi Basin, Gansu Province, China

ABSTRACTThe basal neoceratopsian dinosaur Auroraceratops rugosus was described based on a single skull from the Gongpoquan Basin in northwestern Gansu Province, China. The genus is now known from over 80 specimens, including many from the neighboring Yujingzi Basin. Auroraceratops is one of the best-known basal neoceratopsians. Auroraceratops can be diagnosed by the following autapomorphies: inflated premaxillary teeth; a fungiform expansion of the lacrimal; large tuber caudodorsally on the dentary near the contact with the surangular; and tubercle on the lateral face of the dentary at about the middle of the mandible. Auroraceratops also has a combination of plesiomorphic and derived characters. It possesses characters plesiomorphic to Neoceratopsia, such as broad nasals (seen in basal ceratopsians, such as Yinlong), the absence of a lateral ridge on the surangular, a relatively high number of premaxillary teeth (three), and rugosity on the dentary, jugal, surangular, and sometimes the postorbital, which is in detail similar to that seen in chaoyangsaurids. At the same time, Auroraceratops possesses derived characters not seen in Liaoceratops, the earliest diverging member of Neoceratopsia. These features include an epijugal and a surangular wall lateral to the mandibular glenoid fossa. The cranial anatomy of the early horned dinosaur Auroraceratops rugosus is described.Citation for this article: Morschhauser, E. M., D. Li, H. You, and P. Dodson. 2019. Cranial anatomy of the basal neoceratopsian Auroraceratops rugosus (Ornithischia: Ceratopsia) from the Yujingzi Basin, Gansu Province, China; pp. 36–68 in Hailu You, Peter Dodson, and Eric Morschhauser (eds.), Auroraceratops rugosus (Ornithischia, Ceratopsia) from the Early Cretaceous of northwestern Gansu Province, China. Society of Vertebrate Paleontology Memoir 18. Journal of Vertebrate Paleontology 38(Supplement). DOI: 10.1080/02724634.2017.1399136.

Flooding tolerance of Sagittaria latifolia and Sagittaria rigida under controlled laboratory conditions

AbstractPool‐scale growing‐season water‐level reductions (drawdowns) have been implemented on the Upper Mississippi River in an effort to improve fish and wildlife habitat. Aquatic vegetation is a key habitat component, with perennial emergent species, such as Sagittaria latifolia and Sagittaria rigida, especially important. River managers have assumed the need for continuous drawdown during the growing season with limited reflooding and used this guidance in assessing the potential for an ecologically successful drawdown. However, information on the effects of growing‐season flooding episodes on survival and growth of Sagittaria is limited. To assess the flooding tolerance of S. latifolia and S. rigida, we evaluated multiple levels of timing, duration, and depth on survival and productivity of plants. Plants were produced from S. latifolia and S. rigida seeds and S. latifolia tubers; all were reared under moist‐soil or shallow‐flooded rearing conditions. Mortality of plants was low (2%) among plants from large tubers, low (7%) among seedlings (and largely associated with early flooding treatments), and modest (11%) among plants from small tubers (with no clear effects of inundation). Flooding treatments generally had a positive effect on biomass production from seedlings, particularly when treatments occurred early, were relatively shallow, and were short in duration. There were no clear effects of depth, duration, or timing components of flooding treatments on plant biomass arising from tubers. This experiment indicates that S. latifolia and S. rigida are relatively tolerant of flooding events during the growing season and may actually benefit from some level of inundation.

Effect of anaerobic soil disinfestation amendment type and C:N ratio on Cyperus esculentus tuber sprouting, growth and reproduction

SummaryAnaerobic soil disinfestation (ASD) is a cultural technique primarily targeted for control of soilborne plant pathogens, but can also impact weed propagules. A repeated pot study was conducted to evaluate ASD treatment impact on sprouting and growth of introduced Cyperus esculentus (yellow nutsedge) tubers using dry molasses‐based and wheat bran‐based amendment mixtures at four carbon‐to‐nitrogen (C:N) ratios (from 10:1 to 40:1) and compared with a non‐amended control. The mean percentage of sprouted tubers recovered after ASD treatment was lower for wheat bran‐based (42%) than dry molasses‐based (65%) amendments, and tuber production was 1.6‐fold higher in dry molasses‐based than wheat bran‐based treatments. The highest percentage of sprouted tubers (79%) and the highest mean production of large tubers (threefold higher than wheat bran‐based and 1.7‐fold higher than molasses‐based amendments) were observed for the non‐amended control. Tuber sprouting was significantly lower from all ASD treatments (regardless of amendment C:N ratio) compared with the non‐amended control at a 15 cm burial depth. New tuber production was lowest at C:N ratios of 10:1 and 20:1 and more than twofold higher in the non‐amended control. Wheat bran‐based amendments reduced above‐ground C. esculentus biomass compared with the non‐amended control and ASD treatments with molasses‐based amendments, and reduced below‐ground biomass compared with molasses‐based amendments. Above‐ground biomass was highest at amendment C:N ratio of 10:1, and below‐ground biomass was highest at amendment C:N ratio of 40:1 and the non‐amended control. ASD treatment with wheat bran‐based amendments at lower C:N ratios reduced tuber sprouting and reproduction compared with the non‐amended control, but not at rates high enough to use as a primary weed management tactic.

An Economic Analysis of the Effects of Harvest Timing on Yield, Quality, and Processing Contract Price for three Potato Varieties

Harvesting potatoes at or near physiological maturity increases the likelihood of producing high quality tubers which contributes to producing high quality processed end-product. Some growers harvest earlier than recommended in order to meet contract requirements and supply processors with early potatoes. Early harvest impacts the incentive-adjusted price (IAP) and revenue even after an early harvest incentive is applied. This study utilized a typical frozen processor contract and compared the economic impact of harvest timing (early, normal, and late) on the IAP of three potato varieties: Russet Burbank, Clearwater Russet, and Alpine Russet, grown in field trials at Parma, Idaho during 2014 and 2015. Contract quality incentives included percent of tubers greater than 170 g, percent sugar ends, percent of U.S. No. 1’s, and specific gravity. When compared to normal or late harvest, early harvest resulted in a decrease in the IAP and overall profit due to a significant reduction in specific gravity. Early harvest incentive did not offset the loss of revenue with Russet Burbank, but did offset revenue loss with Clearwater Russet and Alpine Russet. Clearwater Russet and Alpine Russet had significantly lower sugar end scores than Russet Burbank. Clearwater Russet consistently produced higher specific gravities and Alpine Russet produced larger tubers compared to Russet Burbank. Clearwater Russet and Alpine Russet have agronomic characteristics that can provide an increase in IAP over Russet Burbank.

Yield and Quality Response of Two Potato Cultivars to Nitrogen Fertilization

Potatoes require high nitrogen (N) fertilizer rates because of their poor N efficiency. Better understanding of N dynamic in potato crops could improve N efficiency and thus enhance crop profitability and reduce N losses. A similar field experiment was conducted in Switzerland in 3 years, from 2009 to 2011, to investigate the yield and quality response to N fertilization of two commercial potato cultivars with different tuber qualities, Bintje and Laura. Five doses of ammonium nitrate were tested: 0, 80, 120, 160 and 200 kg N ha−1. Aboveground and belowground biomass evolution, total yield, starch concentration and tuber sizes were measured annually. In 2011, the total N uptake and the soil mineral N content were also measured during the growing season and at harvest. The study showed that N fertilization had a positive effect on yield and the percentage of large tubers (> 70 mm) and a negative effect on starch concentration. Both cultivars presented the same potential yield, although cv. Laura’s yield was more affected by N fertilization deficiency and more responsive to the late N fertilizer application. At harvest, both cultivars had a similar N uptake efficiency and N utilization efficiency. However, they differed with respect to N uptake dynamics. Nitrogen uptake was slower for cv. Laura than for cv. Bintje due to a longer period required for the development of the belowground biomass. The results provide useful recommendations for improvement of N fertilization practices (e.g. rate and time of application) of these two cultivars in Swiss conditions.

The Effect of Wireworm Agriotes spp. in Many Types of Potatoes

The present study demonstrate the infection (injury and damage) of wireworm on potato crop in spring and autumn season. This study was conducted in Abu- Greeb fields in Baghdad– Iraq during 2009 – 2010 In order to assessment the damage caused by wireworm Agriotes spp. on four type of growing Solanum tuberosum crop (Rodeo, Lotona, Bleni, Deseri) in spring and autumn season. The results of this study showed that Agriotes spp. was more damage in spring season more than autumn season. Percentage of the numbers of damage potato tuber to the four types was 1.81, 4.87, 6.66, 8.33 % respectively. While it was 6.55, 3.63, 10.52, 9.09 % total weight of Rodeo, Lotona, Bleni, Deseri , respectively. The Rodeo type was more injury in spring season with ratio of 11 tuber number. The result showed that the potato was damage in spring season more than autumn season and this may be due to the presence of the larvae near soil surface that liege with temperature during season. Also may be due to size of potato tuber which cultured large tuber with wide surface area be more damaged and injury.

Evolutionof Fertilizer Potential of Sea Weed (Kappaphycus and Gracilaria) Saps inPotato Crop inNorth Eastern Hill Region of India

A field experiment was conducted during the summer season of 2013 at Central Potato Research Station, Shillong, Meghalayato study the effect of sea weed saps on growth and productivity of potato in the North Eastern hill region of India.The trial was laid out in randomized block design, replicated thrice, with 10 treatments. The number of shoot per plant was found to be non-significant and vary from 2.8 to 3.0. The maximum plant at harvest was recorded under application 7.5 Kappaphycus Spray + 100% RDF while lowest under 6.25% + 50% RDF.Maximum small size tuber was found with an application of 10 % Gracilaria spray + RDF which was at par with 2.5 % Kappaphycus spray + RDF and 7.5 % Gracilariaspray + RDF but significantly superior to other treatment. However, the highest medium size tube of potato was noticed under 6.25% Kappaphycus spray along with 50% recommended dose of fertilizer. Highest large size tuber was recorded with an application of 5% Kappaphycusspray + RDF followed by 2.5% Kappaphycus spray along with RDF as well as 7.5 % Gracilaria spray + RDF which was at par, but significantly superior to rest of treatment. Application of 2.5% Kappaphycus spray + 100% RDF recorded the highest productivity of potato (27.1 t/ha) followedby 100% RDF + Kappaphycus spray @ 5.0% (26.6 t/ha) which were at par with each other but significantly superior to the rest of treatments.Based on the economic yield of potato, it may be concluded that the application of 2.5 % Kappaphycus spray + 100% RDF was found to be more profitable under rainfed condition of Meghalaya

Nitrogen Response of French Fry and Chip Cultivars Selected for Low Tuber Reducing Sugars

New cultivars ‘Alpine Russet’, ‘Dakota Trailblazer’ and ‘Ivory Crisp’ have lower tuber reducing sugars and acrylamide-forming potential. Adoption of new cultivars by growers requires information about their responses to agronomic factors such as nitrogen (N) fertilizer. The objective of this study was to determine the effect of N rate on yield and quality of new cultivars relative to conventional cultivars ‘Russet Burbank’ and ‘Snowden’. The experiment was conducted over two years as a randomized complete block design replicated four times with five N rates and five cultivars. The new cultivars had comparable or higher marketable yields, and a higher percentage of large tubers (greater than170 g) than the standard cultivars. Total and marketable yields responded quadratically to N and optimized at 231 kg ha−1 in 2011 and 319 kg ha−1 in 2012 for all cultivars. ‘Dakota Trailblazer’ had high hollow heart incidence (greater than 10% at N rates above 125 kg ha−1), and excessively high specific gravity, making it undesirable for processing but with potential to be a parent in a breeding program. ‘Alpine Russet’ and ‘Ivory Crisp’ had specific gravity suitable for commercial processing, and low hollow heart incidence at all N rates. Critical petiole nitrate-N concentrations 50 and 70 days after planting for all cultivars were greater in 2012 than in 2011, suggesting that interpretation of critical values can be affected by growing conditions.

Size and temperature characteristics of potatoes help predict injury following impact collisions

ABSTRACTPotato (Solanum tuberosum L.) production in Victoria, Australia is an important horticultural industry. Tuber quality is maintained by avoiding injuries during harvest and subsequent handling. This study examined characteristics of both tubers and handling techniques that effect surface injury response to impact. Laboratory drop tests subjected cultivar ‘Atlantic’ to impacts ranging between 1.47 and 3.92 km/s2 and examined effects of small (120 ± 5 g) and large (262 ± 15 g) tuber mass, and core temperatures of 7°C, 12°C and 20°C, on the development of surface injury. Larger tuber mass, colder temperature and impacts over 1.96 km/s2 generally contributed to surface injuries of larger diameter. Tuber surface injury regression models were successfully used to estimate conditional probability of tuber injury on the worst impact sites on grading lines. Two assessed lines had the potential to damage over 5% of the crop if potato tubers were cold (7°C) and large.

Effects of plastic mulch on the radiative and thermal conditions and potato growth under drip irrigation in arid Northwest China

Drip irrigation and plastic-film mulch are useful water-saving tools for potato (Solanum tuberosum L.) production in arid Northwest China. Effects of the radiative and thermal conditions produced by the plastic-film mulch on potato growth can be positive or negative. The objective of this study is to know how radiative and thermal conditions and potato growth are affected by the two most commonly used plastic-film mulches (transparent and black) to efficiently use the positive effects of the plastic-film mulch. Field experiments were conducted at the experimental station located in Wuwei, Gansu Province to explore the effects of transparent mulch (TM), a non-mulched check (NM), and black mulch (BM) on the net radiation (Rn), soil heat flux (G), soil temperature, and potato growth under surface drip irrigation during different plant development stages in 2014 and 2015. Results indicated that the daily integral Rn in the BM treatment was greater than in the TM treatment, while the amplitude of G in the BM treatment was lower than in the TM treatment. The BM treatment had 3.0 and 3.9°C greater maximum mulch surface temperature than the TM treatment and had greater longwave radiation on the canopy emitted from the mulch surface. The differences in Rn, G, and soil temperature among the treatments diminished with plant canopy enlargement. The potato plant height rankings were BM>TM>NM. The BM treatment had 26% higher jumbo plus large tuber yield than the TM treatment in 2014. Compared with the BM treatment, the TM treatment had the similar potato yield but 9% and 8% less evapotranspiration in 2014 and 2015. The results suggested that the black plastic-film mulch was more suitable for large potato tuber production, while the transparent plastic-film mulch was favorable for water-saving.

The influence of compost and zeolite co‐addition on the nutrients status and plant growth in intensively cultivated Mediterranean soils

AbstractThe main objective of the study was to test the benefits of compost and zeolite co‐addition on the fertility of organic‐rich Mediterranean soils. Previous pot study in greenhouse found that zeolites mixed with compost significantly improved potassium availability as well as exchangeable potassium capacity in the soils. To further test this finding, a field experiment was conducted using potato – Solanum tuberosum L., desiree cultivar in peat soils of the Hula Valley, Israel. Adhering to the protocol of the greenhouse experiments, the treatments included 5% compost addition with no zeolites, 2% zeolite addition without compost, co‐addition of 5% compost mixed with 2% zeolites and control. We found that compost addition increased significantly the potatoes yield and the number of large tubers; however, the zeolite addition had no impact on yield. Co‐addition of compost and zeolites did not improve total crop yield or number of large tubers compared with compost addition only. The results are consistent with nutrients availability (N, P, K) across the treatments. In a commercialized field using the experiment conditions, the 2% zeolite addition would amount to 18 ton of zeolites per hectare. Hence, we conclude that soil amendment with the tested zeolite might be beneficial to improve soil retention for cationic nutrients (e.g. K+) under high leaching systems such as plant culture in pots, but in the field with high loads of compost, its effect is minor.

Wplyw Tytanitu� na plon i elementy skladowe plonu bardzo wczesnych odmian ziemniaka

The growing period for early potatoes is extremely short, only 50-80 days from planting to harvest. To obtain a high marketable tuber yield in such a short period good conditions for plant growth must be ensured. In modern agriculture, plant growth stimulants have been gaining increasing importance. Although titanium (Ti) is neither a major nor minor nutrient for plants, it is classified as a beneficial element for plant growth. This paper analyses the effect of dose (0.2 dm3*ha-1 or 0.4 dm3*ha-1) and date (leaf development stage – BBCH 14-16, tuber formation stage – BBCH 41-43, leaf development stage and tuber formation stage) of the application of Tytanit® (8.5 g Ti in 1 dm3) on the yield and yield components of very early-maturing potato cultivars (‘Lord’ and ‘Milek’). Potatoes were harvested 75 days after planting (the end of June). Tytanit® caused an increase in the tuber number and tuber weight per plant, particularly under stress conditions, although the effect of cultivars was not consistent. The growth stimulant did not have any effect on the average tuber weight. Following the application of Tytanit®, the total tuber yield was higher, on average, by 2.26 t*ha-1 (7.5%), and the marketable tuber yield (diameter above 30 mm) by 1.88 t*ha-1 (6.4%). The tuber number per plant was higher when Tytanit® was applied at the dose of 0.2 dm3*ha-1. Potato plants produced greatest tubers when Tytanit® was only applied in the leaf development stage (BBCH 1416). With double Tytanit® applications, i.e. in the leaf development stage and with repeated treatment in the tuber formation stage, both the tuber number and tuber weight per plant were lower. The Tytanit® application contributed to improved marketable value of the early potato yield due to a decreased share of small tubers (diameter below 40 mm) and an increased share of large tubers (diameter above 51 mm) especially in a year with a periodical water shortage in the tuber growth period. The examined very early-maturing potato cultivars showed a differential response to Tytanit®. The growth stimulant had a greater effect on the tuber number and tuber weight per plant for the ‘Lord’ cultivar. Following the Tytanit® application, the total tuber yield of ‘Lord’ cultivar was higher, on average by 3.71 t*ha-1 (12.7%) and marketable tuber yield by 3.22 t*ha-1 (11.4%). Tytanit® caused an increase in tuber yield of ‘Milek’ cultivar only in year with the highest air temperature and water shortage in June – the total tuber yield was higher, on average by 2.16 t*ha-1 (8.5%) and marketable tuber yield by 2.02 t*ha-1 (8.2%).

Effect of environmental variables on performance of Jerusalem artichoke (Helianthus tuberosus L.) cultivars in a long term trial: a statistical approach

Tuber yield, together with tuber number and size are the basic agronomic and breeding traits in Jerusalem artichoke and can be significantly affected by environmental factors. We report the results of a long term trial on the performance of 20 Jerusalem artichoke cultivars. The random model for means with restricted maximum likelihood (REML) procedure was used to estimate the overall effects of the genotype, environment and genotype by environment interaction on traits. The partial least square regression (PLSR) model was used for modeling genotype by environment interaction variance components with a set of available correlated environmental variables. The REML variance component estimates model revealed that tuber number and yield are more dependent on GE interaction which allowed identification of best genotypes for specific environments. The PLSR model revealed that the most important climatic variables for optimal emergence, canopy development, high tuber number and yield are adequate soil and air temperatures in April. For larger tuber mass, precipitation variables and even distribution of rainfall were the most important factor, together with soil and air temperature in June when tuber growth is initiated. The knowledge obtained in this study is valuable for the identification and understanding of key environmental factors that contribute to the performance of Jerusalem artichoke.

Yield and weight distribution of two potato cultivars grown from seed potatoes of different physiological ages

ABSTRACTAfter seed potatoes (Solanum tuberosum L.) are harvested, they may be stored in sheds, in low temperature coolers or left un-lifted in the ground. This research describes the response of tuber yield and distribution (formed by the weight grade of each potato) of ‘Bondi’ and ‘Fraser’ crops planted from seed potatoes at different physiological ages generated from different combinations of these storage regimes applied in the Early and Late phases of storage. De-sprouting half of the potatoes prior to planting was used to accelerate the rate of physiological ageing, synchronise the planting material and increase the range of treatments. Total yield and number of potatoes produced were unaffected by any of the storage treatments and reflected a constant pattern of canopy development, radiation use efficiency and harvest index. The largest tubers were attained by higher rates of tuber growth which was inversely related to the number of stems per plant.

Yield and weight distribution of two potato cultivars grown from seed potatoes of different physiological ages

ABSTRACTAfter seed potatoes (Solanum tuberosum L.) are harvested, they may be stored in sheds, in low temperature coolers or left un-lifted in the ground. This research describes the response of tuber yield and distribution (formed by the weight grade of each potato) of ‘Bondi’ and ‘Fraser’ crops planted from seed potatoes at different physiological ages generated from different combinations of these storage regimes applied in the Early and Late phases of storage. De-sprouting half of the potatoes prior to planting was used to accelerate the rate of physiological ageing, synchronise the planting material and increase the range of treatments. Total yield and number of potatoes produced were unaffected by any of the storage treatments and reflected a constant pattern of canopy development, radiation use efficiency and harvest index. The largest tubers were attained by higher rates of tuber growth which was inversely related to the number of stems per plant.

FACTORS INFLUENCING THE AGRONOMIC PERFORMANCE OF THE ADAPTED YAM MINISETT TECHNIQUE IN NIGERIA – PLANTING DATE AND GENDER OF THE FARMER

SUMMARYThis paper describes the results of 3 year's data from farmers using the Adaptive Yam Minisett Technique (AYMT) to produce seed yams in Nigeria. A total of 30 sites were established each year between 2013 and 2015 in the Idah area (Kogi State) of Nigeria and 58 plots in the Amoke area (Benue State) in 2015. Each site had yam setts (80 to 100 g) untreated and treated with a pesticide ‘dip’ prior to planting and farmers (male and female) were free to select the variety and manage the sites as they wished. In line with previous research, the results suggest that treatment does increase the weight of tubers produced by a sett but not necessarily the number of tubers. Varietal differences were also observed. For the first time, the results suggest that the time of planting does have a significant impact on seed tuber weight, with later planting leading to small tubers. Also, the gender of the farmer had an impact on some of the agronomic variables, with male owners of the site generally producing more and larger tubers per sett planted and sprouted than female owners. Various mechanisms for the latter are discussed in the paper.

Maximization of Seed Size Tubers in Potato through Manipulation of Intra Row Spacing, Nitrogen Levels and Crop Duration under Irrigated Condition in Indo –Gangetic Plains of Bihar

A field experiment was conducted during winter season (Oct-Feb) of 2013-14 and 2014-15 with four replications and eight treatments to produce maximum yield of seed size tubers of potato cultivar, “Kufri Pukhraj” by interaction of two nitrogen levels (120 and 150 kg N/ha), two intra row spacing (15 and 20cm), and two crop duration(haulm cutting at 70 and 80 days after planting). The narrow intra row spacing i.e. 15 cm, produced significantly higher yield of seed size grade tubers while wide spacing i.e. 20 cm produced higher yield of large grade tubers. The total tuber yield and tuber number was significantly more in closer spacing. Percent production of seed size tubers to total tubers (both on weight as well as number basis) was higher at narrow spacing. Haulm cutting at 80 days after planting produced significantly higher yield of large grade tuber, while haulm cutting at 70 days after planting, produced significantly higher yield of seed size grades tubers. The total tuber number and tuber yield was significantly higher in haulm cutting at 80 days after planting. Lowest total tuber yield and number was observed in wider spacing with lower nitrogen level and shorter duration. Per cent production (both on weight as well as number basis) of seed size tubers to the total tuber was significantly higher at 60 x 15 cm with 120 kg N /ha and longer crop duration. Plant spacing of 60 x 15 cm with higher fertility levels and shorter crop duration (70 day) was found to be second best treatment in terms of production of seed size tuber.