Tuber Size Distribution Research Articles

Hilling of Transplanted Seedlings from Novel Hybrid True Potato Seeds Does Not Enhance Tuber Yield but Can Affect Tuber Size Distribution

A novel cropping system for potato was tested for two consecutive years under normal Dutch agronomic conditions. Seedlings from two experimental genotypes of hybrid true potato seeds were produced in a greenhouse nursery and transplanted into the field 5 weeks after sowing to assess tuber yield levels and to study effects of hilling on tuber yield and number, tuber size distribution and tuber greening. Field experiments had a split-plot design with hilling treatments as the main plots and genotypes as the sub-plots. Final harvest was at 122 and 132 days after transplanting in 2017 and 2018, respectively. Hybrid seedlings were transplanted into small initial ridges and irrigated straight after planting. Three hilling treatments were applied between transplanting and 100% canopy cover. Treatment ‘zero hilling’ did not receive any additional hilling after transplanting. Treatments ‘double hilling’ and ‘triple hilling’ received two and three additional hilling treatments, respectively. Total tuber yields at final harvest in both years were not affected by the hilling treatments. Yields for the respective genotypes were 26 and 30 Mg/ha in 2017 and 25 and 32 Mg/ha in 2018. Total tuber numbers were only affected by hilling treatments in 2017, where under hilled conditions, plants produced more tubers compared with plants under zero hilling. Plants under zero hilling yielded more tubers in size class > 40 mm compared with triple hilling in 2017. In 2018, no significant effects of hilling on tuber numbers were found, but the trend was similar to that in 2017.

Comparison of Aeroponics and Conventional Potato Mini Tuber Production Systems at Different Plant Densities

Mini tubers are the starting materials of a disease-free seed potato production scheme. Low multiplication rates as well as non-homogenous tuber size distribution are considered the main constraints of a conventional mini tuber production system. In recent years, an aeroponics production system has been developed to overcome the aforementioned problems. It has previously been observed that this system allows multiple harvests with an average yield of 20–50 mini tubers per plant. Several factors, such as cultivar, planting density, nutrient composition of the mist solution, spraying interval and duration and lighting also affect both tuber number and tuber size. However, less attention has been paid to the association of these factors with the aeroponics system. This paper highlights the importance of planting density effect on conventional and aeroponics system. The mini tuber production performances of three potato cultivars (Hermes, Marabel and Sante) were compared at four different planting densities (25, 50, 100 and 200 plants/m2) under both conventional and aeroponics systems in two production cycles. The number of tubers per plant increased with decreasing planting density, being highest at 25 plants/m2 and lowest at 200 plants/m2 for both cycles. Mean tuber number in the aeroponic system was 19.85 tubers per plant at 25 plants/m2 and 13.20 tubers per plant at 200 plants/m2. As the number of tubers per plant decreased, so did their size. As planting density increased, tuber yield per plant both in aeroponics and conventional system decreased, but in general, tuber yield per plant was higher in aeroponics than in the conventional system. In the 1st cycle, the number of tubers per m2 for Hermes, Sante and Marabel was 290, 364 and 334, respectively, in the conventional system and 787, 1021 and 1168, respectively, in the aeroponics system. Similar numbers were recorded in the 2nd cycle. The average tuber weight was higher in the conventional than in the aeroponics system. Tuber yield/m2 in this study varied from 5.9 to 9.3 kg/m2 in the aeroponics system, about twice as high as in the conventional system.

Genetic mapping of tuber size distribution and marketable tuber yield under drought stress in potatoes

Drought sensitivity of potato leads to a reduction in total tuber yield and marketable yield. An investigation of drought effects on tuber yield attributes will facilitate our understanding of how to reduce such huge yield losses. We have evaluated tuber yield, tuber size distribution and marketable yield of a set of 103 European commercial potato cultivars under irrigated and non-irrigated conditions in the field. The multi-year results from two locations, Connantre, France (2013–2015) and Nieuw-Namen in Zeeland, The Netherlands (2013–2014), were analysed. We used Normal and Gamma Distribution models to describe the tuber size distribution of tuber fresh weight and tuber number, respectively. The interactions among parameters of tuber size distribution and total/marketable tuber yield traits were analysed using correlation matrices and biplots. Finally, we used a 14K Infinium SNP marker array to find associations between the parameters or traits and genetic loci on the potato genome. Late foliage maturity facilitated a wider spread of tuber size distribution in favour of larger-sized tubers. Drought effects on total yield were representative of their impact on marketable yield, however, absolute values of total tuber number may not be indicative of marketable number of tubers. We found significant marker-trait associations between a region on chromosome 3 and the spread of tuber number distribution, size class with maximum tuber number and marketable fractions of tuber number and tuber weight. These findings will contribute to improvement and selection for drought tolerance in potato.

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.

Investigations into the opportunity for spatial management of the quality and quantity of production in UK potato systems

Effectively adopting site-specific crop management is dependent on there being production variation within the system. There has been very little published material on yield variation in potatoes and almost none on tuber quality. A review of literature and a systematic survey of 13 potato fields in the UK was performed to better understand within-field variability in potato quantity and quality attributes, including stem density, total yield, marketable yield and tuber size distribution. Non-spatial and spatial statistical analysis of manual and sensor observations was performed on the survey data. Ware production fields exhibited more structured spatial variation in quality attributes (tuber size distribution and % marketable yield) rather than yield attributes. Seed production systems were inversed, with more structured spatial variability in yield attributes than quality attributes. Manual and sensor yield data exhibited a similar level of spatial variation, however the spatially denser sensor data indicated a nested effect with a large amount of short-range variation that may be management related. Both quality and quantity parameters showed sufficient magnitude and range in variation for site-specific management to be considered. The results presented here provide a baseline for spatial variation in both potato quantity and quality to inform future work, particularly for work considering spatial management or spatial modelling in potatoes.

English

Potato (Solanum tuberosum L.) is an important food and cash crop in Ethiopia; serving, as a food security crop due to its nutrition content, wider adaptability and early maturing behavior. However, the yield of the crop is constrained by a number of factors. Among which unspecified seed tuber size and limited availability and distribution of improved varieties are among the important limiting factors. A field experiment was conducted to study the effects of seed tuber size on growth and yield performance of potato varieties at Agarfa, Agricultural Technical and Vocational Education and Training College experimental field during 2017. The treatments consisted of three potato varieties (Gudenie, Jalene and Kellacho) and three seed tuber sizes (25-34, 35-45 and 46-55 mm). The experiment was laid out in a randomized complete block design with a factorial arrangement and replicated three times. The results showed that, seed tuber size and varieties significantly affected phenological parameters, stem number, leaf area index, stem density, marketable, unmarketable and total tuber yield, shoot fresh and dry weight, underground fresh weight, and medium weight of tuber size. Leaf number, and underground dry weight and tuber size were significantly affected only by seed tuber size. Varieties and seed tuber size interact to influence plant height, leaf area, number of tuber per plant, dry matter concentration and harvest index. Gudenie and Jalene produced the highest total tuber and marketable yields. Large seed tuber size (46-55 mm) produced higher marketable tuber yields than medium and small tuber sizes. In conclusion, Gudenie variety and large seed tuber size showed superior performance both for tuber yield and tuber dry matter concentration compared with the remaining varieties and small tuber size. Therefore, farmers are encouraged to produce Gudenie or Jalene variety with the use of medium to large seed tuber size for potato production. Key words: Agarfa, Gudenie, Jalene, potato, seed tuber size and tuber yield.

TerraRossa: A Mid-Season Specialty Potato with Red Flesh and Skin and Resistance to Common Scab and Golden Cyst Nematode

TerraRossa (POR01PG20–12) is a mid-season specialty potato, released by Oregon State University, and is a product of the Northwest Potato Variety (Tri-State) Development Program. This cultivar is unique among commercially available potato cultivars in that plants produce small- to medium-sized smooth, oblong- to long-shaped tubers with red skin and red flesh. Total tuber yields of TerraRossa are similar to Dark Red Norland and less than Red La Soda. Average tuber size (136 g) is less than both of the comparison cultivars, reflecting inherent differences in tuber size distribution. TerraRossa tubers have total antioxidant levels higher than traditional white fresh varieties and comparable to the All Blue purple potato, known for its high antioxidant levels. Sensory evaluations of TerraRossa tubers indicated that it has good culinary attributes following boiling, baking, and microwaving. Potato chips made from TerraRossa tubers retained their unique red color, which represents a novelty in the chipping industry. TerraRossa could be a good candidate for the organic sector due to its tolerance to common scab (Streptomyces scabies) and tuber late blight (Phytophthora infestans) and its resistance to golden cyst nematode (Globodera rostochiensis). Due to its high yields, high chipping quality, good culinary properties, high antioxidant content and disease resistance, TerraRossa is a good candidate for opening new specialty type markets, adding diversity to the marketplace.

Efficacy of Seed Aging and Gibberellin Treatments for Manipulating Apical Dominance, Tuber Set and Size Distribution of cv. Shepody

The cultivar Shepody has excellent early processing qualities and produces above average tuber yields but sets relatively few tubers that often become excessively large relative to market demand. Optimizing tuber set and size of Shepody for seed and frozen processing markets currently entails adjusting in-row spacing and vine kill date. However, arresting tuber growth by vine killing for size control sacrifices yield potential. Aging seed by storing at 12, 22, and 32°C for 80-, 450-, and 900-degree days, or gibberellin (GA) treatments, were evaluated as more direct approaches for modulating stem number (apical dominance), tuber set, and size distribution relationships. Shepody proved to be inherently resistant to high temperature-induced age-priming treatments. In contrast to other cultivars studied previously, age-priming Shepody seed during storage had no effect on plant emergence and the resulting increases in stem number, tuber set, and associated decreases in average tuber weight were marginal. By contrast, GA applied as seed dip or spray effectively hastened plant emergence, reduced apical dominance, increased tuber set, and decreased average tuber size. The magnitude of these GA-induced effects depended on concentration and application technique (seed dip versus spray). For frozen processing, GA applied as a seed dip at 1 mg L-1 added an additional tuber per plant and decreased average tuber size by 15% without affecting U.S. No. 1 tuber yields and gross returns; however, 2 and 3 mg L-1 GA decreased U.S. No. 1 tuber yields and crop value by an average of 16 and 14%, respectively. Spray applications of 2–6 mg L-1 GA also reduced U.S. No. 1 tuber yield and frozen processing value. Conversely, the increase in tuber set (1.5 tubers plant-1) and associated 25% reduction in average tuber weight induced by 2 mg L-1 GA applied as either dip or spray increased gross crop values on a seed contract by 25 and 38%, respectively. The differential efficacies of dip versus spray applications of GA on tuber set and size distribution were likely attributable to differences in GA deposition on the seed. Applying low concentrations of GA to cut seed of Shepody as either a dip (1–2 mg L-1) or spray (2 mg L-1) effectively modulated tuber set and size to significantly increase gross returns for seed, and to better satisfy the needs of processors for more moderate size tubers.

The Effect of Nitrogen Rate on Vine Kill, Tuber Skinning Injury, Tuber Yield and Size Distribution, and Tuber Nutrients and Phytonutrients in Two Potato Cultivars Grown for Early Potato Production

Sixteen vine kill programs were tested on Bintje and Ciklamen potato cultivars grown for early potato production over a three year period near Paterson, Washington. Mechanical (flail chopping, flail chopping and undercutting), chemical (glufosinate, diquat, sulfuric acid, carfentrazone, pyraflufen-ethyl), and physical (flaming) vine kill methods, and sequential combinations of the three were effective in killing rapidly growing potato vines of Bintje and Ciklamen. Rolling and crimping did not kill vines as completely and more vine regrowth occurred than with most other methods tested. Tuber skinning injury was greatly reduced when harvesting at 4 weeks after initial vine kill than at 2 weeks. None of the vine kill programs were able to hasten skin set enough to allow tubers to be harvested at 2 weeks after initial vine kill without significant tuber skinning injury. Glufosinate treatments that were applied several days earlier than other initial vine kill treatments tended to average less skinning injury at the early harvest possibly due to more time elapsing between initial vine kill and harvest. Total tuber yield and size distribution were similar among most vine kill treatments, with the exception of the earlier applied glufosinate treatments, which tended to reduce total yield, but still yielded a similar mass of desired 25 to 35 mm diameter tubers. Tubers from vine-killed plots tended to average greater N, P, K, Fe, and Ca content than tubers from non-killed control plots of both cultivars. Tuber ascorbate levels were also greater in non-killed controls, whereas total phenolic content tended to be greatest in earlier-applied glufosinate treatments. Nonchemical vine kill methods, chemical vine kill methods, and combinations of the two were identified that killed vines well, had low skinning injury at the 4 week harvest, and yielded similar amounts of 25 to 35 mm diameter early potato tubers.

Tuber yield parameters in organic potato production with green manures as preceding crop, catch crop and with farmyard manure

The effect of different preceding crops, catch crops and manure application on the agronomic performance of potato was studied in two consequential years in an organic farming system. Within the study the effect of three different preceding crops: viz. lucerne, field pea and spring barley; incorporated catch crops as green manure: non-legume or mixture; and farmyard manure (30 tones ha-1) are tested on subsequent potato yield and tuber size distribution. The catch crop treatments were studied in comparison to control bare fallow. The subsequent crop response to preceding crops was negligible since there was no indication of a greater tuber yields (fresh tuber, marketable and dry matter) after legume pre-crops compared to barley. Catch crops and manure effects both slightly increased tuber dry matter yield from 4.9 tones ha-1 to 5.2 tones ha-1 in 2010 only, on the contrary dry matter yield was not affected by catch crop and manure in 2011. The significant interaction effect was found between year and catch crop for fresh and dry matter tuber yield and non-standard small sized tubers. Catch crops had a positive effect on potato yield only in 2010 when mineral nitrogen availability was low. The catch crops significantly (P &lt; 0.01) increased the percentage of large sized tubers (&gt; 65 mm in diameter); however catch crops even negatively affected potato medium sized tuber yield and quality. Significant (P &lt; 0.01) interaction effect was found between year and catch crop for small sized tubers, also.

Phosphorus Uptake by Potato from Fertilizers Recovered from Anaerobic Digestion

The rising costs of fertilizers have encouraged the development of technologies to recover nutrients from dairy, cattle, swine, and poultry operations. Field experiments were conducted in the Columbia Basin of Washington to assess the yield of potato (Solanum tuberosum L.) to application of P‐enriched materials recovered from anaerobic digestion of manure. Four rates of P from five sources, three recovered from anaerobic digesters (AD), AD‐dairy P‐enriched fine solids (ADD), AD centrifuged poultry solids (ADP), and AD dairy struvite‐P (ADS) compared to a commercial poultry fertilizer (PBP) were compared to mono‐ammonium phosphate (MAP) and non‐amended control (No‐P). Fertilized treatments had higher yields than the No‐P treatment. Phosphorus source and application rate had significant effects on petiole P concentrations. Increases in petiole P concentrations averaged 300 to 500 mg kg−1 tissue with each rate increase for MAP and ADS. Tuber yields among P fertilizers and rates of P application were not significant but were different between years, averaging 2 and 10 Mg ha−1 fresh weight higher than the No‐P treatment. Tuber size distribution showed a significant shift from smaller tubers &lt;170 g to the 285+ g tuber classes. The P recovery efficiency averaged 42% among treatments receiving 56 kg P2O5 ha−1 and declined to 22% for higher rates of ADS, ADD, and MAP. Recoveries were lowest for poultry derived materials, ranging 20 to 30%. The P fertilizer sources evaluated performed similarly when equal rates of P were applied and method of application was comparable. Phosphorus recovered from anaerobic digesters can effectively substitute for commercial mined P fertilizers. Potato yields among recovered P fertilizers and rates of P application were not significantly different. Recovered P fertilizer performed similarly when equal rates were applied and method of application was comparable.

Differential Sensitivity of Genetically Related Potato Cultivars to Treatments Designed to Alter Apical Dominance, Tuber Set and Size Distribution

The cultivar, Bondi, was selected from a cross between Ranger Russet (maternal parent) and Karaka and is currently being evaluated as a frozen processing cultivar. Relative to Ranger, Bondi produces vigorous foliar growth, low tuber set and high yields of large tubers that frequently exceed optimum size for seed and processing markets. We evaluated the relative efficacies of gibberellin (GA), cytokinin (benzyladenine (BA)) and seed aging for altering apical dominance, tuber set and size distribution of these genetically related cultivars. GA applied to cut seed prior to planting hastened emergence, reduced apical dominance, increased tuber set and decreased average tuber size; however, the optimal concentration to maximally shift tuber size distribution without decreasing marketable yield was 4–5-fold greater for Bondi than Ranger. BA marginally hastened plant emergence (Bondi) and decreased apical dominance (both cultivars) only when combined with GA, but had no further effects on tuber set, yields or tuber size distributions in either cultivar. Age-priming Ranger seed for 700 degree days (DD) at 32 °C during storage shifted the tuber size distribution to a much greater extent than 2 mg L−1 GA (optimal concentration) without reducing marketable yield. The combined age and GA treatment resulted in no further shift in size distribution for Ranger beyond that induced by the 700-DD treatment alone, but reduced the marketable yield by 9.6 MT ha−1. In contrast to GA, the mechanism by which age-priming altered tuber size distribution in Ranger could not be explained by effects on stem number/tuber set relationships alone. Bondi, however, exhibited an even greater shift toward smaller tubers with no reduction in yield with the combined 700-DD/GA (2 mg L−1) treatment, reflecting its decreased sensitivity to GA. Moreover, the shift in tuber size distribution induced by aging Bondi seed for 700 DD was approximately equal to that observed by treating seed with 8 mg L−1 GA (optimal concentration). The reduced sensitivity of Bondi to GA was likely inherited from its paternal parent Karaka, which displays similar morphological traits, including high yield of large tubers.

Optimizing crop geometry for processing-grade tuber yield, quality and economics of potato in Grey Terrace Soil

ABSTRACTCrop geometry has great influence on economically important characteristics such as total yield, processing-grade yield, tuber size distribution and tuber quality in Grey Terrace Soil. An experiment was conducted to develop a suitable crop geometry for the production of higher processing-grade yield and quality of potato tubers. The treatment consisted of three levels of inter-row spacing (60, 67.5 and 75 cm) and four levels of intra-row spacing (20, 25, 30 and 35 cm). Crop geometry significantly influenced growth, yield contributing characters, tuber size distribution and yield of potato. The highest chips, French fry grade tubers and total potato tuber yield were found in 67.5 cm × 25 cm crop geometry without affecting processing quality but all were in the highly acceptable range. Intra-row spacing of 25 cm produced the maximum processing quality tubers, closely followed by 30 cm. The highest gross and net returns with a benefit–cost ratio of 1.75 were recorded in 67.5 cm × 25 cm crop geometry. Therefore, the 67.5 cm × 25 cm crop geometry can be recommended for higher potato tuber yield and processing-grade tubers as well as higher economic return.

Effect of integration of nutrient sources on yield and quality of potato under rainfed conditions

The effect of integration of nutrient sources on potato tuber yield and quality was investigated during three consecutive years (2011–2013) at Central Potato Research Station, Shillong, Meghalaya. The trial was laid out in randomized block design, replicated thrice, with 8 treatments, viz., control (no nutrients application); 100% recommended dose of mineral fertilizers (RDF); 75% RDF + 25% Nitrogen (N) through farm yard manure (N-FYM); 50% RDF + 50% N-FYM; 75% RDF and tuber inoculation with biofertilizers [Azotobacter (Azot) + phosphate solubilizing bacteria (PSB)]; 75% RDF and 25% N-FYM + inoculation with biofertilizers (Azot + PSB); 50% RDF + 50% N-FYM + inoculation with biofertilizers (Azot + PSB) and 100% N-FYM. The integration of 75% recommended dose of fertilizers through synthetic sources and 25% recommended dose of nitrogen through farm yard manure (FYM) alongwith inoculation of biofertilizers (Azotobacter and phosphate solubilizing bacteria) brought about the significant improvement in plant population, yield attributes, total yield, desirable grade wise tuber size distribution and quality parameters in potato especially nitrogen concentration and discarded tuber proportion. Marketable and total tuber yields were significantly reduced due to production of higher proportion of total weight of discarded tubers with the application of 100% recommended dose of fertilizers through FYM on nitrogen basis. Both biofertilizers played significant role in supplementing the nutrient needs of potato through augmenting the availability nitrogen and phosphorus. The incidence of late blight was higher with application of synthetic fertilizers, whereas scabbed and discarded tubers were more with sole application of FYM.

Optimizing Tuber Set and Size Distribution for Potato Seed (Solanum tuberosum L.) Expressing Varying Degrees of Apical Dominance

Plant emergence, apical dominance, tuber set, and size are affected by the physiological age of seed tubers, which can substantially impact overall crop value. This study investigated the efficacy of seed spacing (15, 25, and 35 cm) and 1-naphthaleneacetic acid (NAA) seed treatments in altering these variables in cv. Ranger Russet to improve yield and tuber size distribution of seed expressing low (2.8 stems/seed piece) and high (4.8–5.4 stems/seed piece) apical dominance. Age primed, high-stem seed produced more tubers per plant and per ha than non-aged seed; however, tuber number per ha from both seed lots fell to the same extent with decreasing plant density. Importantly, tuber set per plant increased substantially more for the physiologically older, high-stem seed as plant spacing increased. Average tuber weight also increased with decreasing plant density but the response was greatest for the physiologically younger, low-stem seed. Regardless of seed age, marketable yields were comparable at 25- and 35-cm spacing. Tuber size distributions from the 2.8-stem seed shifted from oversize (>340-g) tubers to higher percentage 113–284-g tubers as spacing decreased from 35 to 15 cm. The 5.4-stem seed produced less undersize ( 284-g tubers when planted at 35-cm spacing. Adjusting in-row spacing relative to seed age and expected stem numbers improved tuber size distribution and value. However, because plants from older seed set more tubers in response to decreasing plant density than younger seed, average tuber weight and size distribution never matched the younger seed at any spacing. Restoration of apical dominance by treatment of seed with NAA was more effective in this regard. Depending on seed age, NAA delayed plant emergence (22–74 %) and decreased stem (24–38 %) and tuber numbers per plant (8–13 %). Stem numbers from age-primed seed fell from 4.8 to 3.0 as NAA concentration increased. Marketable yields were not affected by seed age but decreased slightly (7.3 %, P 284-g) tubers, resulting in a yield profile approaching that of the non-treated younger seed. Although seed spacing and NAA treatments are effective techniques for altering tuber size distribution to maximize crop value in relation to seed age and expected stem numbers, tuber age had a small but residual effect on productivity beyond that attributable to apical dominance.

A Robust Potato Model: LINTUL-POTATO-DSS

In 1994, LINTUL-POTATO was published, a comprehensive model of potato development and growth. The mechanistic model simulated early crop processes (emergence and leaf expansion) and light interception until extinction, through leaf layers. Photosynthesis and respiration in a previous crop growth model—SUCROS—were substituted by a temperature-dependent light use efficiency. Leaf senescence at initial crop stages was simulated by allowing a longevity per daily leaf class formed, and crop senescence started when all daily dry matter production was allocated to the tubers, leaving none for the foliage. The model performed well in, e.g., ideotyping studies. For other studies such as benchmarking production environments, agro-ecological zoning, climatic hazards, climate change, and yield gap analysis, the need was felt to develop from the original LINTUL-POTATO, a derivative LINTUL-POTATO-DSS with fewer equations—reducing the potential sources of error in calculations—and fewer parameters. This reduces the number of input parameters as well as the amount of data required that for many reasons are not available or not reliable. In LINTUL-POTATO-DSS calculating potential yields, initial crop development depends on a fixed temperature sum for ground cover development from 0% at emergence to 100%. Light use efficiency is temperature dependent. Dry matter distribution to the tubers starts at tuber initiation and linearly increases up to a fixed harvest index which is reached at crop end. Crop end is input of the model: it is assumed that the crop cycle determined by maturity matches the length of the available frost-free and or heat-free cropping season. LINTUL-POTATO-DSS includes novel calculations to explore tuber quality characteristics such as tuber size distribution and dry matter concentration depending on crop environment and management.

Reply of mulch systems on weeds and yield components in potatoes

Surface mulch is an important factor of soil protection technology in the cultivation of potatoes. Presented herein are the results of three years (2009–2011) of field trials at two sites (Leskovice and Uhřiněves), where two cultivars (Finka and Katka) were grown. Three mulching treatments (grass mulch after planting, grass mulch before germination and black polypropylene mulch textile) were used in the study. The weight of marketable tubers (tuber over 40 mm) and tuber size distribution were influenced significantly by mulching. The application of grass mulch on surface of the row ensured a 20.5–24.8% increase of weight of marketable tubers and higher occurrence of tubers over 56 mm (resp. tubers 56–60 mm and over 60 mm). There was no consistent effect of grass mulch on the aboveground biomass of weeds. Higher occurrences of larvae of Colorado potato beetle was found on the plots with black polypropylene textile in warmer site Uhřiněves.

Relationship between Visual Injury from Synthetic Auxin and Glyphosate Herbicides and Snap Bean and Potato Yield

Agronomic crops with resistance to the herbicides dicamba and 2,4-D are currently in the regulatory approval process. The potential increased use of these herbicides has raised concern among vegetable producers about potential off-target movement and implications to crop yield. The overall goal of this research was to describe the relationship between visually estimated crop injury and snap bean and potato yield and quality. In snap bean in 2011, injury from dicamba 7 d after treatment (DAT) ranged from 19% at the 1.2 g ae ha−1application rate to 45% at the 7.0 g ae ha−1application rate. By 28 DAT in 2011, injury from 2,4-D was similar to the nontreated control. However, early-season injury in 2011 delayed snap bean flowering and reduced crop yield compared to the nontreated control for all treatments except where the 1.4 g ae ha−1rate of 2,4-D and glyphosate at 7.0 g ae ha−1were applied. Snap bean injury from dicamba was greater than that from 2,4-D at all rating timings in 2011 and two of three rating timings in 2012, and crop yield was reduced compared to where 2,4-D was applied and the nontreated control in both years. Potato tuber size distribution was variable and total yield did not differ among treatments and the nontreated control in 2011. In 2012, tuber size distribution was again variable, but more nonmarketable cull potatoes were harvested when dicamba was applied to 25-cm potato plants at the 7.0 g ae ha−1rate compared to any other treatment. Snap bean injury observations about 3 wk prior to harvest were strongly correlated with crop yield (r= −0.84 and −0.88 in 2011 and 2012, respectively), allowing time to make informed harvest decisions relative to crop quality. In contrast, the relationship between potato injury and tuber yield was poor and highly variable in both years.

The Influence of Ethephon Application Timing and Rate on Plant Growth, Yield, Tuber Size Distribution and Skin Color of Red LaSoda Potatoes

Optimizing the response of growth regulators depends in part on finding the most appropriate application rate and timing. Preliminary trials indicate that ethephon (2-chloroethylphosphonic acid) may be useful for improving potato (Solanum tuberosum L.) tuber appearance and skin color of red-skinned cultivars, but relatively little is known about optimum application practices. Two separate trials were conducted at the University of Idaho Parma Research and Extension Center to evaluate the effect of ethephon foliar application timing and rate on plant growth, tuber yield, size distribution, and skin color of the cultivar Red LaSoda. Skin color was rated visually and by colorimeter at harvest and periodically throughout storage at 4 °C. In 2011, ethephon application timing did not influence plant height, total yield, tuber size or skin color but did affect some tuber size classes. In contrast, all of these parameters were significantly influenced by application timing in 2012. The optimum application timing to influence skin color was a relatively narrow window during initial flower development, to 10 days after initial flowering (coinciding with tuber initiation). Increasing rates of ethephon significantly reduced plant height, increased foliar injury symptoms, and reduced average tuber size, but did not influence total yield in Red LaSoda. Higher ethephon rates resulted in significantly darker tuber skin (lower L* values) and increased red color (increased chroma and reduce hue angle values) when compared to the non-treated control. Evaluation of samples held in storage showed that differences in skin color ratings at harvest were maintained throughout the storage period. It is concluded that two foliar applications of ethephon at a rate between 292 and 438 ml ha−1applied ten days apart, initiated at pre-bloom, will provide the optimum change in skin color and reduce average tuber size without reducing total yield.

Diversity of crop development traits and nitrogen use efficiency among potato cultivars grown under contrasting nitrogen regimes

Potato (Solanum tuberosum L.) requires abundant nitrogen (N) to perform well and has low nitrogen use efficiency (NUE). We assessed phenotypic variation among 189 potato cultivars for NUE and the association between NUE and ecophysiological variables describing canopy development (CDv), under high and low N input. In 2009 and 2010, 189 cultivars were grown with N supply (soil N + fertiliser N) of 75 or 180 kg N/ha at Bant, the Netherlands. CDv was assessed weekly as the percentage of soil covered by green potato leaves (%SC). Data were analysed using a model that described CDv as a function of thermal time, based on the Beta function and estimates of cardinal temperatures. Nitrogen significantly affected model-derived, biologically relevant, curve-fit parameters for each cultivar. The t 1 (i.e., thermal time required to reach maximum soil cover (Vx)) was higher at low than at high N. Other parameters were higher at high than at low N, especially Vx and the period over which it was maintained. Nitrogen also affected tuber dry matter yield, tuber size and weight distributions, N content and N uptake but not tuber dry matter percentage. The total area under the %SC curve was highly correlated with yield in both years. Cultivars performing well under high N also performed well under low N. There was large variation in NUE component traits among cultivars; maturity type partially explained this variation. Variables of the CDv model captured this variation, N effects on light interception and its correlation with yield.