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1.
The affirmation of acrylamide as a probable carcinogen by the European Food Safety Authority has reinforced the need to lower acrylamide content in fried potato products. Selected for low reducing sugars and acrylamide-forming potential, recently released cultivars ‘Alpine Russet’, ‘Dakota Trailblazer’, and ‘Ivory Crisp’ were evaluated for their processing quality when grown with varying nitrogen (N) fertilizer regimes. The objective of this study was to determine the effects of N fertilizer rate (34, 135, 202, 269 and 336 kg ha?1) on tuber glucose and acrylamide concentration following processing of new cultivars relative to standard cultivars ‘Russet Burbank’ and ‘Snowden’ at harvest, and after 3, 6 and 9 months of storage at 7.2 °C over 2 years. Glucose and acrylamide responses to N rate were similar for chip cultivars, which linearly decreased in 2011, and quadratically increased then decreased in 2012 with increasing N rate. The N rate effect on French fry glucose concentration varied by cultivar and either decreased or did not respond to elevated N rate. Glucose and acrylamide concentrations of chip cultivars generally increased during storage, with a dramatic increase in ‘Snowden’ resulting from senescence sweetening after 9 months of storage. Environmental conditions significantly affected glucose and acrylamide responses of French fry cultivars to storage time. Glucose and acrylamide concentrations of all French fry cultivars generally increased during storage in 2011. In contrast, glucose concentrations of French fry cultivars were stable or increased, while acrylamide concentrations generally decreased during storage in 2012. The relationship between chip color and glucose concentration was significant, but differed by year. Glucose and acrylamide concentrations of French fry and chip cultivars were significantly correlated (R2?=?0.52 and 0.66, in 2011 and 2012, respectively). Generally, acrylamide in fried potato products can be minimized by using low reducing sugar cultivars supplied with a N fertilizer rate that optimizes yield and quality during growing seasons with minimal environmental stress.  相似文献   

2.
Application time of nitrogen (N) fertilizer can significantly influence the yield and quality of potato tubers. The objective of this experiment was to assess the effects of N application time on dry matter accumulation in foliage and tubers, as well as on marketable tuber ratio, dry matter concentration, and specific gravity of the Chinese cultivar KX 13. The four treatments were as follows: all the 150 kg?N?ha?1 applied at planting (T1); 100 kg N ha?1 applied at planting and 50 kg N ha?1 applied 1 week before tuber initiation (20 days after emergence, DAE) (T2); 100 kg N ha?1 applied at planting and 50 kg N ha?1 applied 1 week before tuber bulking stage (35 DAE) (T3); and 100 kg?N?ha?1 applied at emergence and 50 kg N ha?1 applied 1 week before tuber bulking stage (35 DAE) (T4). For all treatments, 90 kg P2O5 ha?1 ((NH4)2HPO4) and 150 kg K2O ha?1 (K2SO4) were applied at planting. Thirty tons per hectare of marketable tuber yield was achieved with T3, while 23 t ha?1 marketable yield was achieved by applying all 150 kg N ha?1 at planting (T1). Relative to treatment T1, T3 also significantly increased harvest index (HI) from 0.76 to 0.86 and marketable tuber ratio from 64.8% to 79.2%. Applying N at planting in conjunction with dressing at 20 DAE (T2) gave a high marketable tuber ratio (74%) and HI (0.86), but the lower total tuber yield led to a lower marketable tuber yield. Without N application at planting (T4), N dressing did not increase the yield and HI. Treatments with N dressing had no significant effect on specific gravity or dry matter concentration of tubers.  相似文献   

3.
Nitrogen and water are important factors influencing potato production, and crop response to these two factors may vary with cultivars. The yield response of two potato cultivars (Russet Burbank and Shepody) to six rates of N fertilization (0-250 kg N ha-1) with and without supplemental irrigation was studied at four onfarm sites in each of three years, 1995 to 1997, in the upper St-John River Valley of New Brunswick, Canada. On average, irrigation increased total yield from 31.9t ha-1 without irrigation to 38.41 ha-1 with irrigation and marketable yield from 25.61 ha-1 without irrigation to 30.71 ha-1 with irrigation. Potato yields were increased by irrigation at nine out of the 12 sites, and the irrigation response was similar for both cultivars. Nitrogen fertilization significantly increased both total and marketable yields at all sites except one. The yield response to N fertilization was greater with irrigation. The N fertilization rate (Nmax) required to reach maximum total and marketable yield, however, was similar with and without irrigation. A large variation in Nmax was observed among sites. With irrigation Nmax varied between 158 and 233 kgN ha-1 for total yield, and between 151 and 250 kg N ha-1 for marketable yield. There was no interaction between N fertilization and potato cultivar for both total and marketable yields. The two cultivars had similar total yields (35 t ha-1). Shepody, however, had a greater marketable yield (28.9 t ha-1) than Russet Burbank (27.4 t ha-1). Our results indicate that the response to two of the most significant factors of potato production, irrigation and N fertilization, varies greatly with sites and climatic conditions, and that field specific recommendations are required for the optimum management of N and irrigation.  相似文献   

4.
Fertilizer nitrogen (N) may be managed to increase crop production and profitability while reducing nitrate contamination of groundwater. A two-year field investigation was conducted to evaluate the effects of applied N on tuber yield and quality, dry matter production and N uptake of potato (Solanum tuberosum L. var. Russet Burbank) grown on irrigated sandy soils in Michigan. Nitrogen was applied as ammonium sulfate [(NH4)2SO4] at rates of 0, 56 and 112, kg N ha?1 in a single application at planting or 112 and 168 kg N ha?1 in split applications during the growing season. Total tuber yield generally increased with N applications up to 112 kg N ha?1. Only one of the three experimental sites showed an increase in marketable tuber yield when 112 kg N ha?1 was split evenly between planting and tuber initiation. Tuber specific gravity was not affected by N rate. Nitrogen rates of 112–168 kg N ha?1 maximized dry matter production and plant tissue N concentration at onset of maturity and harvest. Tuber N concentration at harvest ranged from 13–17 g kg?1 at two of the three locations. Values for the third experiment were 10–13 g N kg?1. Whole crop N uptake at onset of senescence ranged from 45 to 225 kg N ha?1 across all locations and treatments. An average of 67 percent of this N was found in tubers at harvest. Nitrogen fertilization exceeded N removal in harvested tubers by more than 50 kg N ha?1 only for the 168 kg N ha?1 treatment. These results indicate that acceptable tuber yield can be obtained with lower N rates than those currently used by most producers, with the potential for reducing net loss of N from the soil.  相似文献   

5.
Response of russet norkotah clonal selections to nitrogen fertilization   总被引：1，自引：0，他引：1  
The low vine vigor and high N requirement of Russet Norkotah may lead to N loss and groundwater contamination on coarse-textured soils. Recent clonal selections from Texas have produced strains that have larger and stronger vines, which may alter N requirements. This twoyear study examined the N use efficiency (NUE), yield, and quality of Russet Norkotah strain selections fertilized with different N levels on a Hubbard loamy sand in central Minnesota. The selections, Texas Norkotah Strain (TXNS) 112, TXNS 223, and TXNS 278 were grown with standard Russet Norkotah under irrigated conditions and received total N levels of 28, 112, 224, or 336 kg ha-1. Total, marketable, and large (>340 g) tuber yields increased linearly (P>0.05) with rate of N application in 1998 but not in 1997. The genotype main effect was not significant for any of the tuber yield parameters measured based on fresh weight. Vine, tuber, and total dry biomass yields were 116%, 5.8%, and 13.2%, respectively, higher with the selections than Russet Norkotah. Harvest index (HI), or the proportion of total dry matter partitioned to tubers, was 7% greater for Russet Norkotah than the TXNS selections, reflecting the larger vine growth of the selections. The selections accumulated significantly higher N in the vines (0.113 kg kg-1 N) than the standard clone (0.053 kg kg-1 N) as N rate increased from 28 to 336 kg ha-1, and the difference between the selections and the standard clone was larger at higher N rates than at lower N rates. Russet Norkotah partitioned 10% more N to tubers than did the TXNS selections, reflecting the difference in HI between the standard cultivar and its clones. Nitrogen recovered from fertilizer N applied in addition to the 28 kg ha-1 starter N (NUE28) averaged 36% and varied little with genotype, N rate, or cropping year. Biomass accumulation from similar N additions (AUE), however, was significantly higher for the selections than Russet Norkotah at 112 kg N ha-1 in 1997 only. At low N rate (112 kg ha-1), the selections had higher physiological use efficiency (PUE28) (mean 45.9 g g1) than Russet Norkotah (25.9 g g1). Results from this study demonstrate that, although N recovery was similar for the four genotypes, the Texas Norkotah strains produced greater biomass than Russet Norkotah per kg N applied at low rate in 1997 and per kg of fertilizer N absorbed by the plant in both years. However, under the conditions of this study, higher biomass of the selections did not translate into a marketable yield advantage over the standard cultivar.  相似文献   

6.
The effect of chloropicrin fumigation on the soil populations of Spongospora subterranea and the development of powdery scab, formation of root galls and tuber yield was investigated in seven field trials conducted in Minnesota and North Dakota. Sixteen potato cultivars, with different levels of susceptibility to disease on roots and tubers, were planted in plots treated with chloropicrin at rates ranging from zero to 201.8 kg a.i. ha?1. The amount of S. subterranea DNA in soil was determined using qPCR. Bioassays were conducted to further assess the effect of chloropicrin fumigation on root colonization by S. subterranea in two potato cultivars with contrasting disease susceptibility. In the field, chloropicrin applied at rates between 70.1 to 201.8 kg a.i. ha?1 significantly decreased S. subterranea initial inoculum in soil but increased the amount of disease observed on roots and tubers of susceptible cultivars. The effect of increasing disease was confirmed in controlled conditions experiments. Although the amount of S. subterranea DNA in roots of bioassay plants increased with increasing chloropicrin rates, it remained similar among potato cultivars. Chloropicrin fumigation significantly increased tuber yield which in cultivars such as Shepody and Umatilla Russet were associated with the amount root galls (r = 0.30; P < 0.03). Results of these studies contradict earlier reports on the use of chloropicrin fumigation for the control of powdery scab. Factors other than inoculum level, such as environmental conditions that affect inoculum efficiency and host susceptibility, may be significant contributors to the development of powdery scab and root gall formation.  相似文献   

7.
Ivory Crisp was released in 2002 by the experiment stations of Idaho, Oregon, Washington, and North Dakota, and by the USDA/ARS. It resulted from a 1980 cross of ND292-1 and A77268-4. Ivory Crisp is suited for use in both the direct delivery and storage chipping markets. Ivory Crisp is a medium-maturing potato variety with round, white tubers and excellent chipping quality. It has medium to high yield potential, high tuber solids, resistance to most internal and external tuber defects, and the ability to chip from cold storage. In trials in Idaho, Oregon, and Washington, total and U.S. No. 1 tuber yield of Ivory Crisp was similar to Atlantic but lower than Chipeta. Yield of tubers in the size range 113–336 g for Ivory Crisp is higher than for either Atlantic or Chipeta. Ivory Crisp is resistant to growth cracks, secondary growth, hollow heart, and stem-end necrosis, but susceptible to shatter bruise. Tuber sugar content has consistently remained low following cold storage and near-acceptable chip color retained at 4.4 C. Ivory Crisp is susceptible or moderately susceptible to most common field diseases of potato. It is highly susceptible to common scab, powdery scab, and pink rot. Tubers of Ivory Crisp have dry matter content (22.4%) lower than those of Atlantic, but higher than those of Chipeta. Glycoalkaloid content of Ivory Crisp tubers is very low (4.3 mg 100 g-1). An application for Plant Variety Protection has been filed for Ivory Crisp. Seed is available from potato seed growers in Idaho, North Dakota, and Canada. Small amounts of seed, for research purposes, can be obtained by contacting the corresponding author.  相似文献   

8.
Nitrogen and water deficiencies are known to affect potato yield, but much less is known of their effect on tuber growth and biomass partitioning. The objective of this on-farm study conducted at two sites in each of three years, 1995 to 1997, was to determine the effects of supplemental irrigation and N fertilization rates on tuber growth and biomass partitioning of the cultivars Shepody and Russet Burbank. The N fertilization rates were 0,100, and 250 kg N ha-1in 1995, and 0, 50,100, and 250 kg N ha?1 in 1996 and 1997. The highest bulking rate observed in our study (7.3 g fresh tubers m-2 °C-1) can be considered near the potential bulking rate in New Brunswick. The water deficit in the absence of supplemental irrigation reduced this potential bulking rate by as much as 40%, but this reduction was much less at five of six sites and negligible at two of six sites. Nitrogen deficiency reduced the bulking rate at two of six sites. This negative effect of N deficiency on bulking rate was greater with irrigation than without irrigation at two of six sites; the tuber bulking rate with irrigation was reduced by as much as 50% with no N applied at one site. Shepody had a greater bulking rate than Russet Burbank. The tuber bulking of Russet Burbank, however, started earlier and lasted longer than that of Shepody. Water and N deficiencies increased biomass partitioning to tubers and large roots. Shepody partitioned a greater proportion of its biomass to large roots and had a greater root biomass than Russet Burbank. Our results demonstrate the ability of potatoes to modify biomass partitioning when grown under water and/or N stresses. As a result of this compensation, the reduction in tuber yield due to limited N and water stresses is minimized.  相似文献   

9.
Russet Burbank and Shepody potatoes were grown with at-planting N fertilizer rates ranging from 0 to 270 kg ha?1 during 1986 through 1989. Experiments were conducted each year following small grains and red clover. Total yields and tuber size were strongly increased by N on most sites where potatoes followed small grains. Specific gravities declined with increasing N rate. Total yields of Russet Burbank and Shepody were optimized at an average of 196 and 211 kg ha?1 of N, respectively, following small grains. The effect of N fertilizer on yields was much less dramatic following red clover. Total yields averaged 88% of maximum with only 45 kg ha?1 of N applied, compared to 77% of maximum for this N rate following small grains. Total yields for the two varieties were optimized at 126 and 136 kg ha?1, respectively. U.S. #1 yields were generally not increased at N rates above 45 to 90 kg ha?1 following red clover and tuber size was not increased at rates above 90 to 135 kg ha?1. Based on these studies, the N fertilizer credit for red clover grown prior to potatoes can be up to 75 kg ha?1. Maintenance of tuber quality necessitates conservative use of N fertilizer when potatoes are grown following legumes. The highest N rates tested suppressed total yields of Russet Burbank, a late-season, indeterminate variety, by approximately 9% averaged over cropping systems.  相似文献   

10.
Russet Burbank and Shepody potatoes were grown with the following four nitrogen treatments: 1) 90 kg ha?1 at planting; 2) 180 kg ha?1 at planting; 3) 90 kg ha?1 at planting followed by an additional 90 kg ha?1 side-dressed after tuber initiation; or 4) 90 kg ha?1 at planting followed by an additional 45 kg ha?1 sidedressing. When compared to the 90 kg ha?1 at-planting treatment, petiole NO3-N concentrations increased rapidly after sidedressing and were relatively constant through mid-season. Sidedressed N significantly increased total yields relative to the 90 kg N ha?1 at-planting treatment by an average of 5.0 t ha?1 in three of nine experiments. Three of the experiments, where yields did not significantly increase, were on sites which were not expected to respond to supplemental N based on petiole NO3-N testing. A red clover green manure crop was the previous crop for two of these experimental sites. Petiole NO3-N testing criteria were only partially effective in detecting sites where response to sidedressed N occurred. When compared to a single application of 180 kg N ha?1 at planting, split application of 90 kg N ha?1 at planting followed by a 90 kg N ha?1 sidedressing significantly reduced total yields in one of nine experiments and did not affect yields in the remaining eight experiments. Tuber uniformity was improved in three of nine experiments by the split-N treatment. Specific gravity was not significantly affected. Use of 45 kg N ha?1 at side-dressing resulted in similar yield as the 90 kg N ha?1 sidedressing, although yield of large-sized tubers was often decreased with the lower N rate. Use of reduced at-planting N rates followed by sidedressed N does not appear to increase yields of non-irrigated Russet Burbank and Shepody potatoes when compared to the at-planting N rates that are currently recommended. This management approach can maintain yields at levels comparable to at-planting N programs and does provide an opportunity to reduce N application rates on sites where soil N reserves and soil amendments may make a substantial N contribution to the potato crop. Side-dressed N application can frequently improve yields and tuber size when potatoes have been underfertilized at planting; however, some inconsistency in response can be expected in regions that rely on unpredictable natural rainfall.  相似文献   

11.
The release of three new potato (Solarium tuberosum L.) cultivars, Bannock Russet, Gem Russet, and Summit Russet, with unique plant growth characteristics, necessitates the development of appropriate N fertilizer recommendations. These three new cultivars, along with the standard cultivar, Russet Burbank, were treated with four N rates (0, 100, 200, and 300 kg N ha?1) using two different application timing procedures (“early,” with two-thirds N applied preplant, and “late,” with one-third applied preplant). Measurements included total and U.S. No. 1 yields, petiole NO3-N concentrations, and net returns derived from economic analysis using a processing-based contract. Each of the four cultivars showed a unique response to N application treatments. Bannock Russet achieved maximum yield and net returns with relatively small amounts of N fertilizer. It also showed no response to N application timing and had moderate NO3-N sufficiency concentrations early in the season, that decreased markedly late in the season. Gem Russet N requirement for maximum yield was similar to that of Russet Burbank, but required a higher amount of N for maximum net returns. Gem Russet also showed no response to application timing and had NO3-N sufficiency concentrations similar to or slightly higher than those of Russet Burbank. Summit Russet showed a strong trend for improved N use-efficiency when most of the N was applied early. On the other hand, analysis of net returns revealed a trend for greater profitability for Summit Russet when the majority of N was applied during tuber bulking. Petiole NO3-N sufficiency concentrations for Summit Russet were generally higher than those for the other three cultivars. In comparison with some earlier studies with Russet Burbank, this research suggested lower optimal N rates and petiole NO3-N sufficiency concentrations.  相似文献   

12.
A field experiment was conducted during rainy seasons of 2009 and 2010 at New Delhi, India to study the influence of varieties and integrated nitrogen management (INM) on methane (CH4) emission and water productivity under flooded transplanted (FT) and aerobic rice (AR) cultivation. The treatments included two rice (‘PB 1’ and ‘PB 1121’) varieties and eight INM practices including N control, recommended dose of N through urea, different combinations of urea with farmyard manure (FYM), green manure (GM), biofertilizer (BF) and vermicompost (VC). The results showed 91.6–92.5 % lower cumulative CH4 emission in AR compared to FT rice. In aerobic conditions, highest cumulative CH4 emission (6.9–7.0 kg ha?1) was recorded with the application of 100 % N by organic sources (FYM+GM+BF+VC). Global warming potential (GWP) was significantly lower in aerobic rice (105.0–107.5 kg CO2 ha?1) compared to FT rice (1242.5–1447.5 kg CO2 ha?1). Significantly higher amount of water was used in FT rice than aerobic rice by both the rice varieties, and a water saving between 59.5 and 63 % were recorded. Under aerobic conditions, both rice varieties had a water productivity of 8.50–14.69 kg ha?1, whereas in FT rice, it was 3.81–6.00 kg ha?1. In FT rice, a quantity of 1529.2–1725.2 mm water and in aerobic rice 929.2–1225.2 mm water was used to produce one kg rice. Thus, there was a saving of 28.4–39.6 % total water in both the rice varieties under AR cultivation.  相似文献   

13.
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.  相似文献   

14.
Identifying phosphorus (P) requirements and P-use efficiency is crucial to a sustainable potato industry in Eastern Canada. In a three-year study (2013–2015) conducted in Nova Scotia, Canada, we assessed the potato (CV Superior) yield response to P fertilization on two different soils in the Annapolis Valley. Soil organic matter ranged from 3.0% to 4.1% and from 2.0% to 2.5% at the Kentville and Sheffield sites, respectively. Initial soil phosphorus was higher at Kentville site, ranging from 81 to 162 mg kg?1 than at Sheffield site ranging from 75 to 109 mg kg-1. A randomized complete block design was used with five P rates (0, 17.5, 35, 52, and 79 kg P ha?1) applied at planting. Tuber yields were assessed at harvest, and P-uptake efficiency characteristics were measured before vine senescence. Total and marketable yields were not impacted by P rates. Marketable yield was 68% and 57% greater for Kentville than for Sheffield in 2013 and 2015, respectively and were significantly affected by P rates × year interactions at a 5.4% probability level. Quadratic functions were used to describe tuber yield responses to P rates (0.61 > R 2 < 0.85) and P rates corresponding to the maximum yields were 17.5 kg P ha?1 in 2013 and 2015 and 35 kg P ha?1 in 2014 when data from both sites were pooled together. Phosphorus uptake efficiency ranged from 0.47 to 0.54 g DM mg?1 P offtake at Kentville and from 0.45 to 0.49 g DM mg?1 P offtake at Sheffield and was 13% and 7% greater at Kentville than at Sheffield in 2013 and 2015, respectively. While further studies are still needed for recalibration, results from this study provide some of the first information regarding potato response to P fertilization in Nova Scotia. Based on current P recommendations in the region for the same soil P levels, our results suggest that current P rates can be reduced without impacting potato yield.  相似文献   

15.
Weather uncertainty and soil spatial variability impact nitrogen (N) cycling and corn (Zea mays L.) growth, making accurate N predictions a challenge. Field studies were conducted in Lansing, Michigan, to evaluate a computer model (i.e., Adapt-N), a preseason year-based model (i.e., maximum return to N [MRTN]), and a crop sensor model (i.e., active canopy sensor with algorithm) for recommending corn N rates. To determine site-specific economic optimum N rates (EONR), five N rates were also applied (0, 33%, 66%, 133%, and 166% of the suggested MRTN) as starter + sidedress (SD) at V4. In a wet year (i.e., 2015), Adapt-N increased V8 SD N rates 35 kg N ha?1 relative to the MRTN V4 SD N application. Although the greater rate of N may have provided additional yield protection, no statistical yield differences were observed between the two models. The MRTN model increased partial factor productivity (PFP) 20% relative to Adapt-N. Limited expression of V8 corn N deficiency reduced crop sensor total N rates (21–56 kg N ha?1) and yield (0.82–1.05 Mg ha?1) relative to other models. In a drier year (i.e., 2016), N demand was reduced (EONR 64 kg N ha?1 less than 2015), resulting in similar corn response to all three models. Despite differences in actual corn N rate recommendations, all three models resulted in similar economic net returns across study years.

Abbreviations: EONR, economic optimum nitrogen rate; MRTN, Maximum Return to Nitrogen; NUE, nitrogen-use efficiency; PFP, partial factor productivity; SBNRC, sensor-based nitrogen rate calculator; SD, side-dress  相似文献   

16.
The objective of the research was to determine the economic optimum nitrogen (N) fertilization rates and to determine the effects of N fertilization rates on tuber characteristics and fresh mass loss after storage under cold and ambient conditions of four potato cultivars, Ágata, Asterix, Atlantic, and Monalisa. The experiments were, simultaneously, conducted in the same area and similar experimental conditions during the fall/winter period in Viçosa, Minas Gerais State, Brazil. In each experiment, five N fertilization rates (0, 50, 100, 200, 300 kg ha?1) were evaluated in a randomized complete block design. For all cultivars, increasing N fertilization rate increased total and marketable yields and tuber dry matter yield up to a maximum following a quadratic model. Increasing N fertilization rate linearly increased the tuber protein concentration of Atlantic and Monalisa and had no effect on tuber pH. N fertilization rate effects on tuber mass, tuber titratable acidity, and fresh mass loss during storage were cultivar-dependent. N use efficiency (tuber yield divided by N fertilization rate) decreased with increase in N fertilization rate. The economic optimum N fertilization rates ranged from 147 to 201 kg ha?1 depending upon cultivar and relative prices of N and potato tubers. Depending on the cultivar, under favorable price conditions (low N price and high tuber price), the economic optimum N fertilization rates to be applied by potato growers were 92–95% of the estimated N fertilization rate for obtaining the maximum potato yield, whereas under unfavorable conditions (high N price and low potato tuber price) the economic optimum N fertilization rates to be applied should be decreased to 86–92% of the rates for maximum yield.  相似文献   

17.
Nitrogen fertilization, irrigation, and cultivars affect tuber characteristics such as tuber size, specific gravity, and N concentration. Few studies, however, have investigated the interaction of irrigation and N fertilization on the tuber characteristics of potato cultivars, particularly in Atlantic Canada. The objective of this on-farm study, conducted at four sites in each of three years, 1995 to 1997, was to determine the effects of supplemental irrigation and six rates of N fertilization (0-250 kg N ha-1) on the number of tubers per plant, the average fresh tuber weight, tuber N concentration, nitrate (NO3-N) concentration, and specific gravity of the cultivars Shepody and Russet Burbank. Nitrogen fertilization increased the average fresh tuber weight, tuber N and N03-N concentrations, and decreased specific gravity. Effects of increasing N fertilization on tuber characteristics were often more pronounced for Shepody than for Russet Burbank, and for irrigated than for non-irrigated conditions. Shepody had greater average fresh tuber weight and tuber N concentration, lower specific gravity, and fewer tubers per plant than Russet Burbank. Supplemental irrigation increased the average fresh tuber weight and the number of tubers per plant, but it had a limited effect on specific gravity and tuber N and NO3-N concentrations. Tuber NO3-N con centration and specific gravity were strongly related to tuber N concentration, which in turn depended primarily on N fertilization. Incidents of lowest specific gravity and highest NO3-N concentration occurred with a relative yield close to or equal to 1.0. We conclude that the risks of low specific gravity and high tuber NO3-N concentration are greater when fertilization exceeds the N requirements to reach maximum tuber yield.  相似文献   

18.
New hybrid grass cultivars may enhance animal performance in forage-livestock systems if they possess traits that address edaphoclimatic challenges and pest susceptibility. The objective was to assess herbage accumulation, plant-part composition, nutritive value, and animal performance of ‘Ipyporã’ [Brachiaria ruziziensis Germ. & Evrard × B. brizantha (Hochst. ex A. Rich.) Stapf] and ‘Mulato II’ (B. ruziziensis × B. brizantha × B. decumbens Stapf) hybrids in the Brazilian Amazon biome. From May 2016 to May 2018, pastures were maintained under continuous stocking with variable stocking rates to maintain canopy height at 30-cm. Herbage accumulation (HA) was greater in Mulato II (17,370 kg dry matter [DM] ha−1 year−1) than Ipyporã pastures (14,930 kg DM ha−1 year−1) across the years. In Year 1, Mulato II had greater stocking rate (1685 vs. 1215 kg body weight [BW] ha−1) and greater gain ha−1 (1130 vs. 850 kg) than Ipyporã. However, in Year 2, both cultivars had similar plant and animal responses. The Year 1 ADG was similar among cultivars or seasons but in Year 2, rainy seasons had 21 and 77% greater ADG than dry seasons for Mulato II and Ipyporã, respectively. Both cultivars can contribute to the diversification of pasture-based livestock systems in humid tropical regions. Mulato II presented superior performance when soil moisture and fertility were not limiting (i.e., Year 1). However, both cultivars provide similar plant and animal responses in Year 2, offering viable alternatives for the diversification of pasture-based livestock systems in the Amazon Biome.  相似文献   

19.
The area grown with processing potato crops in the Argentinian Pampas has been increasing steadily since 1995. The aim of this work was to assess the effects of N, P and S upon yield and tuber quality and their impact on CO2 emissions assessed with the Cool Farm Tool-Potato. During the spring-summer growing seasons 2008/2009 and 2009/2010, ten fertilization experiments to individually assess N, P and S effects were carried out in the southeast region of the Argentinian Pampas. Nitrogen (four N rates), phosphorus (four P rates) and sulfur (three S rates) were applied at planting and tuber initiation; at combined rates of 0, 50, 100 and 150 kg N ha?1, and at rates of 0, 25, 50 and 100 kg P ha?1 and 0, 10 and 20 kg S ha?1. N and P had a positive effect on total tuber yield, but tuber dry matter concentration (DMC) decreased at higher N rates. The fraction of marketable tubers suitable for processing into French fries increased with the addition of N, showed no variations with P fertilization, and decreased when S was applied. French fry colour, length/width (L:W) ratio and tuber defects were not affected by N, P and S fertilization. With regard to CO2 emissions assessed with the Cool Farm Tool-Potato, results showed that the higher the N rates the higher the CO2 emissions, but they decreased at higher yields. P and S rates did not have an impact on the CO2 emissions, which also decreased at higher yields. Under the production system of the Pampas, N should be split between planting and tuber initiation, and intermediate P rates should be applied all at planting, in order to improve crop yield and quality and to reduce CO2 emissions.  相似文献   

20.
Early potatoes are typically produced using less nitrogen than a full season potato crop as high rates of nitrogen may delay tuber set and lead to excessive vine growth that is difficult to terminate prior to harvest. Bintje and Ciklamen potato cultivars were grown with preplant soil nitrogen levels of 34 to 38, 67, and 101 kg N ha-1 in 2013 and 2014 near Paterson, Washington. Nitrogen rate had little impact on the number of tubers and stems per plant of both cultivars, but increasing nitrogen rate tended to increase leaf area of both cultivars. Vine desiccation of Bintje with diquat was less complete as nitrogen rate increased, while Ciklamen vine kill was reduced by higher nitrogen in 1 of 2 years. Tuber skinning injury, tuber weight loss, and tuber size distribution were not affected by nitrogen rate. Tuber skinning injury and tuber weight loss were reduced in both cultivars by harvesting at 4 weeks after initial vine kill compared to harvesting at 2 weeks after vine kill. Total tuber yield was lower for both Bintje and Ciklamen in 1 of 2 years at the 34 to 38 kg N ha-1 rate. Tuber nitrogen and zinc levels tended to increase with increasing nitrogen rates, while most other nutrients, vitamin C, total phenolics, and antioxidant capacity showed little response. It appears that 67 kg N ha-1 provides adequate nitrogen to produce a good tuber set and yield of small tubers while not producing excessive vine growth that may be more difficult to kill.  相似文献   

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