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.     

Effects of nitrogen fertilization and in-row seedpiece spacing on yield of three potato cultivars in Prince Edward Island

AC Novachip and NorWis were recently introduced as new potato (Solanum tuberosum L.) chip cultivars on Prince Edward Island (P.E.I.), Canada. Variability of nitrogen application and in-row seedpiece spacing, required for maximum yield, exist among cultivars presently grown in P.E.I. This study was conducted to determine the N rate and in-row seedpiece spacing required for optimum production of AC Novachip and NorWis compared to the standard cultivar Norchip, and also, to determine the effects of treatments and harvest dates on AC Novachip. Treatments included N applied at 90, 134, and 179 kg/ha with in-row seedpiece spacings at 20.3, 25.4 and 30.5 cm. In addition to the 120 day harvest for all three cultivars, treatments for AC Novachip were also harvested at 80 and 100 days after planting. For the 120 day harvest, yield of Canada No. 1 size tubers was higher for NorWis compared to Norchip while yields for AC Novachip and Norchip were similar. Nitrogen application had no effect on yields of AC Novachip. Similar to Norchip, increasing the rate of applied N more than 134 kg/ha resulted in little or no increase in yields of NorWis. Yields of Canada No. 1 size tubers decreased as in-row spacing increased for AC Novachip and were greater at 25.4 compared to 30.5 cm spacing for Norchip. In-row seed-piece spacing had no affect on Canada No. 1 size tuber yields of NorWis. Increasing the days to harvest increased the yields of AC Novachip. Nitrogen rate or in-row spacing had no effect on Canada No. 1 yields of AC Novachip at the 80 and 100 day harvests. The results of this study suggest that little gain in yield of Canada No. 1 size tubers for NorWis, similar to the standard cultivar Norchip, can be obtained with N application more than 134 kg/ha or for AC Novachip by increasing the rate of N from 90 to 179 kg/ha. Unlike NorWis yields of AC Novachip and NorWis are reduced when in-row seedpiece spacing is increased from 25.4 to 30.5 cm.     

The effect of in-row spacing and seedtype on the yield and quality of a potato cultivar

The effect of irregular in-row spacing on tuber production and yield of Russet Burbank potatoes was tested at 2 locations in 1979 and 1980. At a similar mean spacing, no yield reductions were observed when irregular seedpiece spacings (CV levels 25, 50 and 75%) were compared with evenly spaced seedpieces (CV level of 0%). No significant interaction was found between irregular spacing and seedtypes with mass ranging from 59.0 to 67.9 g. No significant interaction was found between three accurate spacings (30.4, 45.7 and 60.9 cm) and the same range of seedpiece mass; however, the crop grown from large seedpieces had a higher marketable yield at the widest spacing tested. Mainstem numbers per plant were influenced by seedpiece mass while axillary branches increased with decreases in intra-plant and inter-plant competition. The incidence of hollow heart was generally unaffected by irregular inrow spacing. Incidence of this disorder was highest in 1979 and appeared to increase with increased plant stresses.     

Effects of nitrogen application and seedpiece spacing on yield and tuber size distribution in eight potato cultivars

The responses of eight cultivars to nitrogen fertilizer and spacing treatments were examined from 1992 to 1996. Experiments were carried out at the Agriculture and Agri-Food Canada Research Farm in Harrington, Prince Edward Island. Four nitrogen rates and three seedpiece spacings were compared. Total and Canada #1 yields were investigated for patterns of responses of the individual cultivars to both treatments, and possible interactions between the treatments. Response surfaces were presented for all cultivars. Nitrogen application increased both total and Canada #1 yields for all cultivars. Increasing rates of nitrogen showed linear and/or quadratic trends for both total and Canada #1 yields in all cultivars, whereas responses to spacing treatments showed linear patterns for total yield, but little change for Canada #1 yields in seven of the eight cultivars. No interactions were detected between fertilizer and spacing treatments for total or Canada #1 yields. Generalized regression equations representing the responses of the cultivars to fertilizer and spacing treatments for both total and Canada #1 yields were also derived. These equations should be useful as a guideline for determining appropriate nitrogen rates and seedpiece spacing for the eight cultivars tested. Ratios of Canada #1 to total yield were higher after initial application of nitrogen (0 to low rate) in all but one cultivar. However, only two cultivars showed higher ratios as nitrogen rate was further increased. Wider seedpiece spacing yielded higher ratios of Canada #1 in five of the eight cultivars tested.     

Effect of cultivar, row spacing, and weed management on weed biomass, potato yield, and net crop value

Research was conducted to quantify the effects of potato cultivar, row spacing, and weed control treatments on weed biomass, crop yield, and net crop value. Cultivars evaluated included Russet Burbank, Russet Norkotah, Goldrush, Dark Red Norland, Snowden, and Atlantic. Inter-row spacings of 76 and 91 cm with an intra-row spacing of 30 cm were evaluated in 1996 and 1997. Weed control treatments included a herbicide tank-mix of metribuzin and metolachlor, cultivation, and a hilling-only control. Common lambsquarters and total weed biomass were greater in the 76-cm row spacing than in the 91-cm row spacing across all cultivars in 1996 and 1997. In 1997, chemical control resulted in less weed biomass than both the hilling-only and cultivation treatments. Total marketable yield was greater in the 91-cm row spacing than in the 76-cm row spacing across cultivars in 1996, but was similar across row spacings in 1997. Net crop value was greater across cultivars in the 91-cm row spacing than in the 76-cm row spacing in 1996. Reduced weed biomass in 1996 and 1997, coupled with greater total marketable yield and net return in 1996, indicated that the 91-cm row spacing was the optimal row spacing for Russet Burbank, Goldrush, Russet Norkotah, Snowden, and Atlantic cultivars in 1996 and 1997. Similar yields and net crop value among weed control treatments in 1996 and 1997 indicated that cultivation and possibly even hilling-only areas within fields can be viable alternatives to herbicide use.     

Population density and row spacing effects on dry matter yield and bark content of kenaf (Hibiscus cannabinus L.)

Efforts to bring kenaf from experimental crop status to an accepted alternative in established cropping systems have been ongoing for years. To compete with existing crops and maximize monetary returns, the effects of agronomic practices on yield and crop quality must be better understood. Row spacing and population density are implicated in dry matter yield, and therefore, bast fiber production. Four row spacings, four population densities, and two cultivars were examined to determine these effects on dry matter accumulation and bark content. Of all factors evaluated, only row spacing significantly affected dry matter yield. Yield was greatest at the 35.5-cm row spacing, and lowest at the 71- and 101.6-cm row spacings. With regard to bast yield, calculated as a percentage of total sample dry weight, a significant cultivar × row spacing interaction occurred. However, data indicate that manipulating row spacing to maximize total stalk yield per hectare resulted in the highest bast fiber yield for the two cultivars tested. The narrowest row spacing of 35.5 cm, gave the greatest biomass yield as well as the highest bark yield per hectare.     

Influence of plant spacing on potato (Solanum tuberosum L.) morphology,growth and yield under two contrasting environments

Summary In experiments at a temperate (43^oN) and a tropical (14^oN) location, closer plant spacing decreased stem branching, root growth, and mean tuber size but increased tuber yields per ha. Closer spacing increased plant height at the temperate site but decreased it at the tropical site where canopy cover did not reach 100%. The increased branching at the wider spacing did not compensate for fewer plants/m². Total and tuber weight per plant increased with wider spacing and was much greater under temperate than tropical conditions. Tuber yield/stem also increased with lower stem densities. Although these results provide initial data for modelling, the contrast between the two environments and interactions between spacing and cultivar suggest that further experiments need to be done with a range of cultivars at intermediate locations.     

Effect of Nitrogen Rate on Growth,Yield, Economics and Crisps Quality of Indian Potato Processing Cultivars

A field study was conducted during 2000–2001 and 2001–2002 at the Central Potato Research Institute Campus, Modipuram, India, in order to increasing the processing-grade tuber yield of India’s first ever developed processing potato cultivars, Kufri Chipsona-1 and Kufri Chipsona-2. Tuber yield and post-harvest quality characteristics were evaluated in response to five N levels (0, 90, 180, 270 and 360 kg N ha^-1). The crop growth traits (stem number, plant height and compound leaf number) responded positively to N application, whereas the effect of N fertilization on processing-grade tuber number, total tuber number per ha and tuber number per plant was quadratic. There was a steady increase in tuber weight per plant, processing-grade tuber yield, total tuber yield and biomass yield in response to N application. Kufri Chipsona-1 produced a 23.6% higher tuber yield per plant than Kufri Chipsona-2. Agronomic N use efficiency decreased linearly with increased N doses. Specific gravity and tuber dry matter percentage responded positively to N application, while crisps colour (at harvest and after storage) and reducing sugars remained unaffected. Cultivar was the major factor that influenced the tuber quality parameters (specific gravity, crisps colour). Higher values of these quality traits were observed in Kufri Chipsona-2 as compared to Kufri Chipsona-1. Net income and benefit cost ratio (B:C) indicated that Chipsona cultivars should be fertilized with 270 kg N ha^-1 for realizing higher processing-grade yields and desirable quality tubers.     

Influence of seedpiece spacing and population on yield, internal quality, and economic performance of Atlantic, Superior, and Snowden potato varieties in eastern North Carolina

In recent stand assessment surveys on North Carolina farms, potato plant stands averaged only 67% of target populations. In response to these findings, this study was designed to determine the effects of seed-piece spacing and varying seedpiece populations on yield, internal quality, and economics of three potato varieties commonly grown in North Carolina: Atlantic; Snowden; and Superior. The three varieties responded differently to changes in spacing and population. Atlantic was sensitive to differences in spacing and populations, with reduced yields of grade A tubers as spacing increased above 23 cm. Atlantic was not able to compensate for wide (46 cm) spacing, even when seed-piece populations were high (doubles planted every 46 cm). Yield of B tubers was greater for 15 cm spacing and decreased significantly as spacing was increased. Yield of Superior was affected less by increases in spacing than decreases in population. Superior was able to compensate for wide gaps in spacing if seedpiece populations were high. Superior produced more B tubers at the 15 cm spacing, and less at the 46 cm spacing. Yield of grade A Snowden tubers did not differ with spacing or population; however, there were more B tubers in the 15 cm, 23 cm, and 46 cm (doubles) treatments than the wider spacing treatments. Incidence of hollow heart and heat necrosis increased in Atlantic in treatments that tended to have larger tubers. Economic analyses of data suggest that growers can significantly increase profit/hectare by optimizing spacing and populations with Atlantic and seedpiece populations in Superior.     

The response of cassava (Manihot esculenta) to spatial arrangement and to soybean intercrop

Response of cassava to row spacing and plant population density (0.62 plants m⁻² in 180-cm rows; 1.23 plants m⁻² in 90-, 180-, 270-, and 270- plus 90-cm (i.e. paired rows); and 2.46 plants m⁻² in 90- and 180-cm rows), and to soybean intercrop at two row spacings of cassava (90 and 270 cm) was studied at a high latitude (27°S) in south-east Queensland, Australia, where low temperature limits a growing season to 9 months. Detailed observations were made in sole crops on leaf canopy structure and light penetration in the three row spacings at the medium density to allow an estimation of light availability for an intercrop between cassava rows.The low plant density or the 270-cm row plants produced the lowest total dry matter and tuber yield at harvest, while the two higher densities or the two narrower rows produced similar total and tuber dry weight. Intercropped cassava produced a similar tuber yield to the sole crop at the corresponding spatial arrangement, but total dry matter was lower in the former.Leaf area index was similar among the 90-, 180- and 270-cm row spacings in sole crops throughout the growth period. However, leaf area was unevenly distributed horizontally for a longer time as row spacing increased. This resulted in light penetrating the inter-row space for a longer period in wider rows in sole crops, more than 50% full sunlight reaching soil level for 90, 120 and 130 days after planting in the 90-, 180- and 270-cm rows, respectively. This light environment would be available for an intercrop if cassava growth is not affected by the intercrop. The results for cassava intercropped with soybean show that in fact cassava growth was reduced by the associated soybean, and hence light available for the soybean growth would have been more than that estimated above.     

Varietal differences in the response of potatoes to repeated short periods of water stress in hot climates. 2. Tuber yield and dry matter accumulation and other tuber properties

Summary The effect of repeated short periods of water stress during the hot season on six potato cultivars was investigated. The number of tubers per plant tended to decrease in response to water stress in cultivars which had more than 9.8 tubers per control plant (Désirée, Alpha, Elvira). In the other cultivars, no consistent effect of water stress on tuber number per plant was observed. Except for Spunta, the percentage of large tubers (>60 g/tuber) was reduced in the water-stressed plants. Consequently, the average weight of these tubers was greater than that of tubers harvested from the unstressed plants, indicating that the sink force of the individual tuber was not impaired by drought. However, tuber yield per plant was reduced due to drought in all cultivars tested. The smallest decrease in dry matter accumulation as well as the greatest lowering of the osmotic potential in the tuber tissue was found in Alpha. No consistent effect of water stress on the percentage of misshapen and sprouting tubers was observed, indicating the marked effect of the high temperature on these traits. Contribution from the Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel, No 310-E, 1981 series. This investigation was sponsored by a grant from the Ministry for Development Cooperation of the Netherlands.     

Effect of planting depth and hilling practices on total, U.S. No. 1, and field greening tuber yields

Previous research suggests that field greening of potato tubers can be minimized by planting seedpieces at an appropriate depth along with sufficient hilling to minimize exposure to sunlight. The appropriate planting depth and hilling practices to minimize field tuber greening have not been determined for newer cultivars. Two separate studies, each conducted for three years, are reported here. The first measured the effect of seedpiece planting depth on the yield, quality, and field greening tuber yield of ‘Russet Burbank’, ‘Frontier Russet’, and ‘Shepody’ potatoes. Seedpieces were handplanted in pre-formed hills at 8, 15, or 23 cm measured from the top of the seedpiece to the top of the hill. Planting at 23 cm resulted in significantly lower total yield compared with the 8- and 15-cm depths for Russet Burbank and Frontier Russet, but planting depth did not affect total yield of Shepody. U.S. No. 1 yield of Russet Burbank was not affected by planting depth, but U.S. No. 1 yield of Frontier Russet was significantly less at the 23-cm depth. For Shepody, the 8-cm depth caused a significant reduction in U.S. No. 1 yield compared with the 15-cm depth. Field greening tuber yield of Russet Burbank was significantly less at the 23-cm planting depth compared to 8 cm. For Frontier Russet and Shepody, planting at 15 or 23 cm resulted in significantly less field tuber greening compared to the 8-cm depth. The second experiment examined the effects of planting depth and hilling practices on yield, quality, and field tuber greening of Russet Burbank and Gem Russet potatoes. Six planting depth and hilling treatment combinations were used. Seedpieces were planted at a depth of either 8 or 15 cm, then hilled to either 15 or 23 cm at emergence or after plants had formed a rosette of leaves approximately 10 cm in diameter (post-emergence hilling). At-emergence hilling treatments had no effect on total or U.S. No. 1 yields of Russet Burbank compared with the 15-cm planting depth, non-hilled control. However, all post-emergence hilling treatments significantly reduced Russet Burbank total and U.S. No. 1 yields. Planting Russet Burbank at 8 cm and hilling to 23 cm at emergence, or planting at 8 or 15 cm and hilling to 23 cm post-emergence reduced field tuber greening of Russet Burbank. The effects of planting depth and hilling on Gem Russet total and U.S. No. 1 yields were less definitive than for Russet Burbank, and no treatments significantly reduced field tuber greening yield compared with the control.     

Effects of several microbial seedpiece treatments on emergence,yield, tuber defects,tuber size distribution,and specific gravity of Katahdin and Russet Burbank potatoes in Maine

Several microbial seedpiece treatments were applied to Katahdin and Russet Burbank to determine their effects on emergence rates, yield, tuber defects, tuber size distribution, and specific gravity under Maine conditions. None of the seedpiece treatments affected total yield, final plant stand, or specific gravity, although several treatments caused slight delays in rate of plant emergence. Several of the seedpiece treatments increased yield of small tubers of Russet Burbank and shifted the yield of Katahdin slightly toward the larger grade size classes. None of the microbial seedpiece treatments was substantially different in performance from the other treatments; and none can be recommended as beneficial for potatoes in Maine.     

Growth and yield studies of potato development in a semi-arid region. 3. Effect of water stress and amounts of nitrogen top dressing on physiological indices and on tuber yield and quality of several cultivars

Summary The response of five potato cultivars (Alpha, Cardinal, Désirée, Spunta and Up-to-Date) to a range of amounts of irrigation nitrogen top dressing (N.t.) in a rainless region was studied by means of the line-source sprinkler method. The irrigation-to-evaporation ratio,K _p, ranged from 0.14 to 1.27 and N.t. from 12 kg/ha to 201 kg/ha, respectively. In all cultivars, the yield increased linearly up toK _p=1.0; at higher ratios there was a yield decline in all cultivars except for Cardinal, in which the yield function flattened off. Spunta was the highest yielding cultivar (16t/ha) in the dry range (K _p=0.14; N.t.=12 kg/ha). Désirée was the highest yielding cultivar (64 t/ha) in the wet range (K _p=1.0; N.t.=201 kg/ha), and Alpha was the lowest yielding cultivar in both the dry and wet range (9 and 46 t/ha, respectively). Leaf permeability, leaf water potential and photosynthesis rate decreased, and tuber dry matter percentage increased with decreasingK _p: these indices also varied with plant age, and among cultivars. Yields were adversely affected when soil water potential at the 30-cm depth dropped below −0.4 bar. Contributon from the Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel. No E-811, 1983 Series.     

Effects of plant population on the performance of seven varieties in the Klamath Basin of Oregon

The effects of seed spacing on the performance of seven potato cultivars grown at the Klamath Experiment Station in Southern Oregon were evaluated from 1987 through 1991. Seed spacings in 81 cm rows included 17, 22, and 30 cm, representing the range of local commercial practice. Most varieties evaluated experienced highly significant increases in tuber size as plant populations were decreased. Atlantic was the only variety that demonstrated reduced total yield or total yield of U.S. No.1’s at low populations. Plant population had limited effects on the incidence of hollow heart and no effect on specific gravity in most varieties. Optimum seed spacing for fresh market or processing crops ranged from 17 cm for Century Russet and Atlantic to 30 cm for Russet Norkotah. Century Russet, Gemchip, and Atlantic produced the highest marketable yields. Russet Norkotah experienced the largest yield variability between years. Atlantic and Gemchip were the most consistent in yield of U.S. No.1’s over years     

Economic Optimum Nitrogen Fertilization Rates and Nitrogen Fertilization Rate Effects on Tuber Characteristics of Potato Cultivars

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.     

水氮限量供给下两个高产小麦品种物质积累与水分利用特征

为给小麦节水高产高效栽培提供科学依据,以主栽小麦品种济麦22和石麦15为材料,在大田条件下,设置2个灌水水平[春灌一水(W1)和春灌二水(W2)],在每个灌水水平下设置2个施氮量处理[192kg.hm-2(N1)和270kg.hm-2(N2)],探讨了有限水氮供给条件下两品种的干物质生产与水分利用特征。结果表明:(1)在W1水平下,济麦22的N1与N2处理籽粒产量和水分利用效率无显著差异,石麦15的N1处理籽粒产量和水分利用效率显著高于N2处理;在W2水平下,两品种籽粒产量和水分利用效率均以N1处理较高;在相同施氮水平下,两品种籽粒产量和水分利用效率均以W2处理较高;在不同水氮处理下,济麦22籽粒产量和水分利用效率高于石麦15。(2)在相同灌溉水平下,两品种花后物质积累量和分配比例均以N1处理高于N2处理;在相同施氮水平下,两品种花后物质积累量和分配比例均以W2处理高于W1处理;2个品种比较,石麦15花后物质积累量和分配比例高于济麦22,而济麦22花前物质积累量及其对产量的贡献率高于石麦15。(3)在不同水氮处理下,济麦22总耗水量、土壤贮水消耗量及花后耗水比例均大于石麦15。综合上述结果认为,两小麦品种在W2N1水氮组合下可实现高产与水分高效利用的协调统一。     

A survey of stand establishment and in-row spacing uniformity in Washington potato fields

Missing plants and non-uniform in-row plant spacing can result in economic loss for potato growers. In-row seedpiece and plant spacing uniformity of 70 Washington potato fields was measured, and factors contributing to missing plants investigated from 2000 through 2002. Ninety-one percent of the fields were planted with cut seedpieces, and the remaining 9% were planted with cut seedpieces, and the remaining 9% were planted with whole, uncut seed tubers. Russet-type cultivars were planted in 79% of the fields, and the remaining 21% were planted with red-skinned and yellow- and white-fleshed cultivars. Seedpiece or plant spacing deviated an average of 25% from the intended spacing mean, with a range of 7% to 43%. Coefficients of variation (CV) for grower in-row plant and seedpiece spacing ranged from 18% to 69% compared with a hand-planted check average of 13%. Based on the growers’ intentions, the average plant population of the 70 fields should have been 44,000 plants ha^?1, but averaged only 40,600 plants ha^?1. On average, 6% of the grower-intended stand was missing because of planter skips, while less than 1% was missing due to seedpiece failure or decay. There were 1,980 clumped seedpieces ha^?1 and each clump typically contained two seedpieces. Twenty-one percent of the fields had at least 700 planter-skips ha^?1 where three or more consecutive plants were missing. Despite management efforts, planters were typically unable to place seed uniformly at the intended spacing. Improved planter and seed-cutting-operation management along with new planter technology would likely improve Washington potato stands.     

Fertilizer injury to potatoes as affected by fertilizer source,rate and placement

To investigate fertilizer injury to potatoes under field conditions, a three year study from 1979 to 1981 was undertaken in Central New York. The study was carried out on a well drained Howard gravelly silt loam; pH 6.6–6.8 with high organic matter (6.1–6.4%) and cation exchange capacity (CEC) of 13.4–14.9. When applied at a normal rate equivalent to 1,685 kg/ha of 10-15–15-1.2 the blended fertilizer containing urea N did not significantly reduce the tuber yield compared to ammoniated fertilizer and blended fertilizer containing ammonium nitrate (AN). However, when it was placed in contact with the seedpiece, the urea delayed emergence and early growth of the plant. Fertilizers containing urea-diammonium phosphate (DAP) and ureatriple superphosphate (TSP), applied at higher than normal rates and placed in contact with the seedpiece, significantly delayed emergence and reduced tuber yield.     

Cultivar and seedpiece spacing effects on potato competitiveness with weeds

Field studies were conducted in 1991 and 1992 to evaluate the effects of cultivar, row spacing, and within-row spacing on potato yield and quality under weedy and weed-free conditions. Cultivars tested were Russet Burbank, an indeterminate, large-vined cultivar, and Frontier Russet, a determinate, small-vined cultivar. The two cultivars were grown under weedy and weedfree conditions with either 76 or 91 cm row spacings in factorial combination with either 15, 25, or 35 cm within-row spacings. The major competitive weeds were redroot pigweed, common lambsquarter and hairy nightshade. The weedy plots consistently produced less vine and tuber biomass and less total and U.S. No. 1 tuber yield than the weed-free plots. The time of weed emergence strongly affected potato competitiveness with weeds. In 1991, weeds emerged after potatoes, giving the crop some competitive advantage. In 1992, weeds emerged before the potatoes, resulting in heavy competition and large decreases in vine and tuber production for both cultivars. Reductions in U.S. No. 1 tuber yield were proportionally greater than the reductions in total yield. Weedy plots in 1991 and 1992 produced 25% and 68% less total yield and 43% and 92% less U.S. No. 1 yield, respectively, than weed-free plots. Russet Burbank was more competitive with weeds than Frontier Russet. Frontier Russet suffered substantial losses in productivity due to the presence of weeds, even under moderate weed pressure in 1991. Decreasing the row width from 91 to 76 cm did not provide a competitive advantage for potatoes as measured by vine or tuber biomass, or tuber yield. Decreasing within-row spacing under weedy conditions provided some competitive advantage and resulted in higher vine and tuber biomass and greater total tuber yield. The closer within-row spacing resulted in a substantial decrease in U.S. No. 1 yield with Russet Burbank but a slight increase with Frontier Russet. There were several significant interactions involving cultivar, weed level, and within-row spacing. These were due, in part, to each cultivar’s unique response to inter-and intraspecies competition. Cultivar had a greater influence on competitiveness than any plant spatial arrangement.