Effects of moisture stress and nitrogen fertilization on tuber nitrate-nitrogen content

Moisture stress in potato plants results in a significant increase in tuber NO_3?N levels. Research plots with three irrigation treatments and four nitrogen fertilizer rates (0, 100, 200, and 500 lb N/A) (0, 112, 224, and 560 kg N/ha) were established to test the influence of soil moisture and nitrogen rate on tuber NO_3?N content. Data from these plots showed that regardless of nitrogen rate, potato tubers from plants subjected to moisture stress had NO_3?N levels approximately twice as high as tubers from plants under optimum or excessive irrigation. With low nitrogen fertilizer rates, tuber NO_3?N levels were 78 to 80 ppm under optimum and excessive irrigation treatments as compared to 144 ppm under the deficient irrigation treatment. With excessive nitrogen fertilizer rates, tuber NO_3?N levels were 151 to 154 ppm under optimum and excessive irrigation treatments compared to 370 ppm under deficient irrigation. Correlation between tuber NO_3?N and petiole NO_3?N levels suggest that moisture stressed plants have a different relationship between tuber and petiole than plants under proper to high soil moisture conditions.     

Effect of daily irrigation rate and soil texture on yield and quality of Russet Burbank potatoes

Adequate soil water is needed for satisfactory yield and quality of potato tubers. With sprinkler irrigation systems it is common practice to apply more water than the crop uses in order to maintain high soil water levels. A study was initiated to evaluate the response of Russet Burbank potatoes to a wide range of daily sprinkler irrigation rates when grown on two soilsa loam and a sand—differing in water holding capacity. The results from the two soils were very different. On the loam soil, yields generally increased with increased applications of water, up to the equivalent of 40 to 50% estimated Et. Irrigation treatment effect on percent No. 1 tubers was inconclusive. In 1978, percent No. 1 tubers increased with water applied up to about 70% estimated Et. In 1980, irrigation rates between the equivalent of about 20 and 80% estimated Et had little effect on tuber grade. Yields and percent No. 1 tubers were depressed at irrigation rates greater than about 80% estimated Et. On the sand, yields and percent No. 1 tubers increased with increased irrigation rates up to about 100% and 80% estimated Et, respectively. Tuber specific gravity was not affected to an important degree by irrigation treatment on either soil. These results indicate that a good crop of potatoes can be grown on a loam soil at daily irrigation rates considerably less than estimated Et rates, while such reductions will decrease yields and grade on a sandy soil.     

Changes in endogenous abscisic acid,soluble sugars and proline levels during tuber dormancy inSolanum tuberosum L.

Abscisic acid (ABA), sucrose, reducing sugars and proline contents were monitored over an eleven-month period in tubers of three potato cultivars that varied in tuber dormancy. ABA and proline levels increased after top pulling the haulms and were not affected by harvest date. Proline did not change in either a storage temperature or cultivar-specific manner. The highest concentrations of ABA were found in tubers stored at 2°C while the lowest concentrations occurred in tubers stored at 20°C. At 10°C, the end of tuber dormancy in the cultivars Kennebec and Nooksack (but not Sebago) coincided with the decline in ABA content. There was no evidence of a threshold concentration of ABA below which sprouting would occur. Tuber samples of 10 different cultivars were removed from 10°C and placed in 20°C storage (in darkness). Initial ABA concentrations (i.e., at the time of removal from 10°C storage) were positively correlated with duration of dormancy and negatively correlated with subsequent rates of sprout elongation at 20°C. Sucrose content was negatively correlated with duration of dormancy. Reducing sugars responded primarily to storage temperature and did not appear to be related to dormancy or sprouting.     

Irrigation,nitrogen and gypsum effects on specific gravity and internal defects of Atlantic potatoes

Irrigation, nitrogen and gypsum were investigated in a 3-year study to determine their influence on specific gravity and internal physiological defects. Excess irrigation during August and September reduced specific gravity, increased the incidence of hollow heart, and in some years, internal brown spot. Tuber yields were not significantly affected by excess irrigation. Exclusion of late season irrigation, however, significantly reduced tuber yields. No consistent yield response to nitrogen was evident, but a response up to 168 kg/ha was observed in 1987. Nitrogen rate did not effect hollow heart, internal brown spot or chip color. The incidence of internal brown spot in the tubers of check treatments was quite variable from year to year, and ranged from 8 to 21%. The lowest incidence of internal brown spot observed in 1989 coincided with the highest calcium levels in the tuber peel. Although gypsum treated potatoes had reduced incidence of internal brown spot, the effects were partial and inconsistent. Significant increases in peel and petiole calcium concentrations in the gypsum treated plots only occurred in one year. The peel calcium levels appeared to be influenced more by the season and to a lesser extent by gypsum. Gypsum applications produced no effects on total or US#1 tuber yield, specific gravity, hollow heart, or chip color. Preliminary data also suggested that gypsum did not markedly influence the incidence of blackspot. Based on this study, a routine gypsum application to improve the tuber quality of the variety Atlantic is not recommended.     

Response of Nooksack potatoes to nitrogen fertilizer

The Nooksack cultivar because of differing characteristics may have different responses to grower management practices developed principally for Russet Burbank. This study was conducted to determine the effects of nitrogen on yield, grade, and specific gravity of the Nooksack cultivar. In irrigated field experiments, N fertilizer was sprinkler-applied daily on Quincy sand soil. In other experiments, on a Warden silt loam soil all N was broadcast and incorporated before planting. Fertilization rate did not significantly affect tuber grade or specific gravity. Short term shifts in N supply did not cause tuber deformities and poor grades as they commonly do with Russet Burbank. Nooksack, while responsive, did not have a strong positive response to N fertilization. Tuber yields were depressed at fertilizer plus residual N levels above 200 kg/ha on Warden silt loam and above 300 kg/ha on Quincy sand. This difference was because of variation in NO₃ leaching and soil N mineralization and was reflected in calculation of optimum N rates. Nooksack may require less N fertilization than Russet Burbank partially because of the strong dormancy of Nooksack tubers that retards emergence and shortens growing season. Management to promote more rapid dormancy break and lower N nutrition during tuber initiation could result in earlier establishment, earlier tuber bulking, and greater yields of Nooksacks.     

不同氮水平对马铃薯产量构成和土壤NO_3~--N含量的影响

在滴灌条件下对比研究了不同氮水平下马铃薯(Solanum tuberosum L).的产量构成和土壤NO3--N含量的动态变化。结果表明,随着氮素水平的升高,产量和商品率都先上升后下降,氮水平在180 kg N.hm-2时最高;大部分块茎大小分布都集中在4.5～7 cm范围内,还有一定的增产空间;氮素量对薯块的大小影响很大,而对畸形薯所占比例的大小没有规律性影响;随着施氮量的增加,氮淋失程度加深,土壤中的NO3--N含量逐渐增加,各施氮水平下随着土层的加深又有不同程度的递减。     

Changes in chlorpropham residues in stored potatoes

Chlorpropham (CIPC)³ concentrations were measured in peel samples of tubers taken from large commercial potato storages and from test bins after aerosol application. Tuber samples were taken at different levels within the pile and at numerous sites near the surface. The minimum concentration of CIPC in the peel layer for complete inhibition of sprouting was estimated to be 20 ppm. Immediately after commercial application of CIPC, 99% of the sample sites had concentrations high enough to completely inhibit sprouting, and residues in the peel were generally highest in samples obtained from the surface and from the bottom of the pile. CIPC concentrations decreased during the storage season in nearly all sites tested. Storages differed in the rate at which CIPC was lost. Mean peel residues fell below the level necessary for sprout inhibition in some storages but not in others. The rate of CIPC loss increased at the same time that air movement to maintain the desired temperature increased. With the 20 ppm threshold level as a guide, it is possible to monitor commercial storages for sprout-inhibition status. Retreatment before peel residues drop below 20 ppm can extend sprout inhibition in storage.     

灌溉施肥对冬小麦土壤氮素盈亏的影响

通过田间小区试验,研究了灌溉和施肥对冬小麦生育期间0～400cm土壤硝态氮累积、移动特征及小麦产量的影响,并对0～200cm土壤氮素的盈亏、氮肥利用率、残留率及损失率进行了表观估算,旨在为小麦的氮素利用与推荐施肥提供理论依据。结果表明,0-400cm硝态氮累积量随着施氮量的增加而显著增加。施氮量对0～100cm土体硝态氮累积量有显著影响,施氮与灌水对200cm以下土壤中的硝态氮累积都有影响,同时水氮交互作用不容忽视。施氮并结合灌水可以显著提高冬小麦籽粒产量,施氮而不灌水也有一定的增产作用。0～200cm土壤氮素的表现盈余主要出现在小麦拔节～灌策期间,表观亏缺主要在播种～拔节期及灌策～收获期。相同灌水量下,氮肥利用率随施氮量的增加显著降低,而损失率增加。施氮130kg／hm^2、灌水60mm处理的氮肥利用率最大,为25．7％。从硝态氮累积量、产量及氮肥利用率等方面考虑,本试验比较合理的肥水配比应为施氮130kg／hm^2,灌水60mm。     

水氮互作对百农207种子发芽特性及贮藏物质转运的影响

为了研究不同水氮处理下收获的百农207种子发芽特性和贮藏物质转运的差异,以百农207为材料,结合当地冬小麦灌溉施肥制度设置水氮两因素裂区试验,水分为主区,氮素为副区,设置W0(返青后不灌水)、W1(返青后灌拔节水)、W2(返青后灌拔节水和开花水)、W3(返青后灌拔节水、开花水和灌浆水)4个灌溉水平以及N0(不施氮)、N1(120kg·hm-2)、N2(180kg·hm-2)、N3(240kg·hm-2)4个施氮水平。在百农207收获后进行标准发芽实验,测定种子的发芽指数、活力指数、生长特性和贮藏物质转运等相关指标。结果表明,灌水和施氮对收获后的百农207种子活力指数、幼苗根冠比、贮藏物质转运率和转化效率的影响呈正向耦合效应。水分是决定收获后小麦种子活力指数、种子贮藏物质转运率和转化效率的主要因子;氮素是决定收获后种子发芽阶段根冠比的主要因子。高水肥处理(N3W3)的种子发芽指数和活力指数最高,水分和养分胁迫(N0W0和N1W0)下发芽阶段的根芽长比值较高。在一定施氮量范围内,增加灌水并不能促进收获种子在发芽阶段幼苗根冠比的增加。在W2和W3水平下,不同施氮处理的百农207种子贮藏物质转运率和贮藏物质转化效率均高于60%。种子发芽阶段幼苗生长相对最优的水氮处理为N2W2。这说明一定水分和氮素营养供应范围内降低氮肥用量,不会降低收获后百农207种子的贮藏物质转运率和转运效率,符合当前的减肥增效原则。     

Production and chemical composition of potatoes related to placement and rate of nitrogen

Experiments with 11 N rates were conducted 3 years with Kennebec potatoes on Bodenburg silt loam in the Matanuska Valley of Alaska. Fertilizer placed in the row was compared with that mixed with the soil in the row for 2 years. Foliage and tuber samples were analyzed for chemical content. Stand reduction and decreased vigor occurred when row placed N exceeded 120–160 1b per acre. Foliage dry matter decreased 2 years as rate of N increased. Tuber dry matter was decreased one year by N rates exceed ing 100 1b per acre. U. S. No. 1 yield and dry matter with row placement of fertilizers at 40–80 1b N were highest in 2 years. When fertilizer was mixed with soil, both US No. 1 and dry matter yields increased each year with each N increment through 160 1b per acre. Increasing amounts of N tended to increase the N in foliage and tubers, the Mn in foliage but to decrease the Ca, Mg, Al, Ba, and Sr in foliage. Mixing the fertilizer with the soil as compared to placement in the row increased the Ca, Mg, Al, Ba, Fe, and Sr in foliage, and the tuber uptake of N, K, Mg, and Sr and decreased foliage N. Alaskan potato growers have doubled or tripled their rate of application of fertilizer over the past 15 years. At digging time potato plants are usually green and some growers have felt these higher fertilizer rates were supplying an excess of N which was delaying tuber maturity and decreasing tuber quality.     

Small tuber studies of sugar accumulation in potatoes

Small potato tubers, less than 1 cm in diameter, responded in a manner typical of larger tubers and accumulated sucrose and reducing sugars during storage at 1°C. Prolonged soaking (50% submerged) was used as a method for introducing metabolic inhibitors into intact, small tubers. Judging from the effects on respiration, cycloheximide was absorbed within 25 h. Cycloheximide treatment inhibited the sucrose and reducing sugar accumulation associated with storage at 1°C     

Photoinduction of glycoalkaloids in cured potatoes

Curing of Sebago potatoes for 10 days at 25°C prior to common storage at 5°C, reduced the responsiveness of tubers to photoinduced glycoalkaloid synthesis. Continuous illumination with 15 and 25-Watt incandescent light for 10 days increased glycoalkaloid content of peelings (12–14% of tuber weight) in uncured potatoes by a factor of 3.2 and 2.8, respectively, while the corresponding factor for cured tubers was only 1.8 for both lights. The peeled tuber portion (86–88% of tuber weight) had negligible amounts of glycoalkaloids, averaging about 1 mg per 100 g of fresh weight. The rise of glycoalkaloid levels in peels of uncured tubers was nearly linear to 164.7 mg/100g (15W light) with no indication of levelling off. In peels of cured tubers, the rise began only after the 4th day of light exposure with an apparent maximum and levelling off at 94.7 mg or approximately 43% lower than the final TGA levels in uncured tubers.     

Influence of calcium on internal heat necrosis of Atlantic potato

While Atlantic is the cultivar of choice of potato chip processors for the mid-Atlantic region, susceptibility to internal heat necrosis (IHN) greatly increases grower risk of economic loss from unsalable tubers. Yield, tuber calcium levels, and percentage of tubers with IHN of several cultivars from a common seed source were examined at two locations. The percentage of tubers with IHN were significantly higher for Atlantic while the tuber Ca concentration was lower than those of Superior. Both the percentage of tubers with IHN and tuber Ca concentration was higher in New Jersey than Virginia. Lower Ca levels were found in tubers with necrotic medullary tissue than in those without. Studies were completed in Virginia and New Jersey to evaluate the influence of Ca source, Ca rate and location within the hill as well as nitrogen rate on the onset and progression of IHN of Atlantic potato. Tuber yield was not significantly influenced by either Ca source (calcium carbonate (CaCO₃) or calcium sulfate (CaSO₄)) or Ca rate (0-1800 kg Ca/ha). Calcium rate had no influence on size distribution. As expected, a significantly greater percentage of large tubers were noted with delayed harvest. In a short growing season (<110 days) yield was not influenced by nitrogen rates ranging from 84 to 252 kg/ha. However, with delayed harvest, yield was increased and IHN slightly reduced with 168 or 252 kg N/ha when compared to 84 kg/ha. The influence of applied Ca on IHN varied between years, but the addition of Ca or N did not reduce IHN sufficiently to avoid out-of-grade because of internal defects. Location of applied Ca within the hill had no effect on yield, specific gravity, IHN, or tissue Ca concentrations. Slightly higher leaf Ca was found when using CaCO₃ than CaSo₄. The influence of Ca rate in 1987 and 1988 on leaf, periderm, or medullary Ca concentrations was not consistent. Nitrogen had no significant influence on tissue Ca levels.     

Effect of applied fertilizer on Kennebec potato top desiccation and yield with diquat

Experiments conducted at Charlottetown, Prince Edward Island (P.E.I.) during 1979–1982 on potato (Solanum tuberosum L. cv. ‘Kennebec’) demonstrated that excessive levels of applied nitrogen made leaf and stem desiccation with diquat (6,7-dihydrodipyrido [1,2- :2′ ,1′-C] pyrazinediium ion) more difficult. A split application of diquat (0.42 kg ai/ha 5 days apart) improved leaf and stem desiccation by as much as 21 and 27% respectively compared to a single application at 0.84 kg ai/ha. Diquat treatments had no effect on vascular discoloration. The high levels of applied nitrogen increased the yield of tubers greater than 60 mm in diameter but reduced the yield of seed size tubers in the 40 to 60 mm size range.     

Reaction of potato tuber slices toPhytophthora infestans in relation to physiological age

Tuber resistance toPhytophthora infestans was studied in relation to physiological age in tubers of the cultivars Atzimba, Katahdin, Kennebec, and Sebago. Resistance to race1,2,3,4 was evaluated in freshly harvested tubers, and tubers stored at 5 C for up to 215 days. Atzimba tubers were highly resistant when freshly harvested but became increasingly susceptible as they aged physiologically. Tubers of the other three cultivars were susceptible when freshly harvested and also when aged. Further, 57 tuber selections from among 11 crosses initially gave resistant reactions. However, after storage for six months at 5 C, 26.3% of the selections remained resistant, 22.8% were moderately resistant, 31.6% moderately susceptible, and 19.3% fully susceptible.     

The effect of some vine desiccants on periderm development on cut potato tuber pieces

Russet Burbank, Red Pontiac, and Superior potato plants were treated with vine desiccants at the rate of 0.50 kg/ha and 1.12 kg/ha paraquat + X77, diquat + X77 and 2.24 kg/ha of Dow General, alone and with Crop Oil, 2 to 4 weeks before harvest. Untreated and treated tubers were selected for anatomical examination directly after harvest and after 22 weeks of storage. The tubers were cut in half longitudinally and exposed to optimum environmental conditions for 25 days when they were examined for periderm formation. Wound periderm in untreated tubers consisted of uniformly shaped and continuous layers of cambial cells. Tubers treated with 0.56 kg/ ha paraquat had a less developed periderm than untreated ones, but it would serve as a barrier against the invasion of pathogens. Diquat at the same concentration had fewer cambial cells and they were not continuous so that pathogen entrance was possible. With 1.12 kg/ha paraquat the periderm was less and with diquat more differentiated than the 0.56 kg/ha treatment indicating that concentration had some effect. Treatment with Dow General resulted in the formation of a periderm adequate for prevention of pathogen entrance. The effectiveness of the 3 chemicals to form periderm in Superior and Red Pontiac was similar to that of Russet Burbank. Periderm was most highly differentiated in untreated tubers followed by paraquat, Dow General, and diquat treated tubers.     

Influence of temperature and length of storage on resistance of potato to tuber rot induced byErwinia chrysanthemi

Tubers of 11 clones ofSolanum tuberosum subsp.andigena (andigena) and 12 cultivars ofS. tuberosum subsp.tuberosum (tuberosum) were inoculated with water suspensions (5.5 × 10⁴ 5.5 × 10⁵, 5.5 × 10⁶ CFU/ml) ofErwinia chrysanthemi. Tubers were inoculated immediately after harvest and after 6 and 16 wk of storage at 4 and 23°C. Tuber rot incidence in andigena and tuberosum increased as inoculum concentration increased. Based on tuber rot severity, clones of andigena were classified as resistant, intermediate, or susceptible and cultivars of tuberosum were classified as intermediate or susceptible. Rot severity increased in all tubers stored at 4°C and in tubers of tuberosum stored at 23°C; rot did not increase in tubers of andigena stored at 23°C. Electrolyte leakage (EL), total sugars (TS), reducing sugars (RS), non-reducing sugars (NRS) and dry matter (DM) were determined in non-inoculated tubers. There was a significant positive correlation between the rate of EL, concentration of RS and tuber rot in andigena and tuberosum. Tuber rot and DM were negatively correlated in tubers of andigena; but they were not correlated in tuberosum. Clones of andigena with low EL, TS, RS, and high DM were resistant to tuber rot, and the incidence of tuber rot in these clones was much less influenced by temperature and length of storage. The influence of temperature and length of storage on susceptibility toE. chrysanthemi may be explained by increased cell membrane permeability; increased leakage of accumulated sugars in potatoes stored at 4°C could favor bacterial proliferation resulting in more disease.     

Tuber yield, storability, and quality of Michigan cultivars in response to nitrogen management and seedpiece spacing

Information is required on nitrogen (N) fertility and seedpiece management for new cultivars and advanced breeding lines. Interactions amongst N fertilizer rate, genotype, and seedpiece spacing are complex, and can affect tuber yield, quality, and storability as well as N fertilizer efficiency. A field study was carried out in 2001 and 2002 at MSU Montcalm Research Farm in central Michigan. Tuber yields and post-harvest quality characteristics were evaluated for five potato genotypes (MSG227-2, MSE192-8Rus, Jacqueline Lee, Liberator, and Snowden) in response to a factorial combination of three N levels (200 kg N ha^-1, 300 kg N ha^-1-, and 400 kg N ha^-1) and two seedpiece spacings, narrow (0.20 m or 0.25 m) and wide (0.33 m or 0.38 m). Narrow seedpiece spacing consistently produced the highest U.S. No. 1 yields in all genotypes tested (37 and 34 t ha^-1, narrow vs wide spacing, respectively). There was a tradeoff between seedpiece spacing and N level in 2001 as tuber yields were enhanced by higher N levels at wide seedpiece spacing, but not at narrow spacing. In 2002, tuber yield was not enhanced, but petiole nitrate-N and tuber-N increased as N fertilization increased. Genotype was the major factor that influenced tuber quality characteristics at harvest and for stored tubers (e.g., specific gravity, internal defects, bruising, chip color rating, sucrose, and glucose). Spacing had minimal effects, whereas higher levels of N slightly reduced specific gravity both years, reduced internal defects in 2001 and enhanced sucrose at harvest in 2002. The cultivars tested demonstrated excellent storage characteristics for different N fertility levels and seedpiece spacing combinations. Overall, the recommended N fertilizer level for moderately long-duration potato cultivars in Michigan (200 kg N ha^-1) and a narrow seedpiece spacing optimized yield and tuber quality performance while conserving N fertilizer.     

Efficiency of nitrogen uptake by potatoes

White Rose potatoes were fertilized with isotopically labeled ammonium sulfate at rates of 67, 134, 202 and 270 kg N/ha to evaluate N uptake efficiency. All N application increased yields above the control, however the 3 higher N rates produced the same yields statistically. All N rates which maximized yields maintained petiole levels of total N above 600 ppm. Rapid changes in petiole inorganic N occurred during the growing season. Fertilizer derived inorganic N decreased at rates ranging from 67 to 518 ppm/day during the third month after planting. Total inorganic N in petioles during the same period dropped at rates ranging from 500 to 880 ppm/ day. Tubers grown in N-fertilized plots assimilated total N in a nearly linear pattern during the period 82 to 125 days after planting. Uptake of total N ranged from 142 to 233 kg/ha. In assessing N utilization by 3 methods, good agreement was achieved between the isotope and difference method in the first and third (last) samplings, however, agreement was poor between the two in the second sampling. With N rates to 202 kg/ha the uptake efficiency was about 57% but dropped to 39% with application of 270 kg N/ha. When uptake efficiency was measured by dry matter production in relation to units of N fertilizer, the 67 kg N rate was superior to other rates. Inorganic N levels in the surface meter of soil were higher before planting and fertilizer application than after harvest. Following harvest the control plots had more N below 1.5 m than did the N fertilized plots. In control plots, the total inorganic N between 1.5 and 2.5 m depths was equivalent to 170 kg N/ha. Virtually none of the accumulated N below 1 m was due to labeled N applied in the experiment. Using 134 kg N/ha as the optimum rate, tubers removed 178 kg N/ha of which 78 kg was derived from the applied fertilizer. With total N input of 191 kg/ha (57 kg N/ha from irrigation water) the N rate required for maximum yield would pose no risk of nitrate pollution since it represents only 13 kg more than crop removal (191 vs 178 kg N/ha).