Inter-stem and inter-tuber competition in potatoes

Summary Seed pieces of varying size and bearing different numbers of uniform growing sprouts were planted in specific combinations. Sequential harvests were made and the growth of the plants followed. There appeared to be competition between emerging sprouts for nutrients and water from the soil. This competition influenced the number of stems produced per sprout and the size attained by these stems. There was no effect of size of the seed piece on the apparent time to tuber initiation. A constant number of tubers were formed per stem despite large variations in stem size, but the final weight of tubers per stem was lower the greater the number of stems per hill. The number of tubers larger than 2| inches (5.7 cm) remained constant over the whole range of stem numbers per hill and the mean weights of tubers in the two size categories larger than 1| inches (3.2 cm) remained constant after the second harvest. These results suggest that only a few of the tubers in each hill were growing rapidly at any one time. There was no effect of cutting the seed tubers on any aspect of the growth of potatoes that was measured which could not be attributed to an effect on either the size of the seed piece or on the number of sprouts per seed piece.     

Comparative performance of three small seed tuber sizes and standard size seed tubers planted at similar stem densities

Summary Small seed tubers of 1–5 g, 5–10 g and 10–20 g were planted at the same sprout densities as standard size seed tubers of 40–60 g in order to give similar stem densities. Early ground cover by foliage, total yield, and yield of tubers >45 mm were consistently greater in plots planted with larger seed tubers. The effect of seed tuber size on yield and tuber number per stem varied between years but 1–5 g seed tubers always gave lower yields per stem than larger seed tubers. Reducing the spacing between rows from 90 cm to 60 cm and maintaining the same sprout density was more effective in increasing yields from small seed tubers than increasing sprout density from 20 to 40 sprouts per m² by reducing plant spacing within the row.     

Influencing seed tuber yield of Ranger Russet and Shepody potatoes with gibberellic acid

Freshly-cut seed pieces of the potato cultivars Ranger Russet and Shepody were dipped in 0, 0.5, 1 or 2 mg/1 Gibberellic Acid (GA₃) prior to planting. GA₃ treatments increased stem and tuber numbers per hill of both cultivars and shifted tuber size profile toward the production of more seed-sized (up to 226 g) tubers and fewer large (greater than 340 g) tubers. The effect of GA₃ on reducing average tuber size was similar for the two cultivars. Total tuber yields were not affected. A 2 mg GA₃/1 seed piece dip decreased the yield of US#1 tubers in Ranger Russet primarily due to a significant increase in yield of tubers less than 226 g. Also, yields of culls were greater after a 1 mg GA₃/1 seed piece treatment, suggesting Ranger Russet is sensitive to this concentration of GA₃. One and 2 mg GA₃/1 seed piece dips to Shepody increased yields of tubers less than 113 g by 93% and reduced the yield of tubers greater than 340 g by 25% to 50%. GA₃ at 1 to 2 mg/1 may be useful in the production of seed potatoes with the cultivar Shepody which tends to produce many large tubers.     

Spacing uniformity — Yield effects and in-field measurement

Trials were done to investigate the effects of spacing uniformity on crop yield, and to assess a method of measuring spacing uniformity without the need to calculate the coefficient of variation. Spacing uniformities ranged from perfect to the worst observed in a previous field survey. Improved spacing uniformity gave increased marketable yields, with an improvement of 10% in gross return over the worst uniformity treatment. Such improvements are possible in commercial situations with proper attention to equipment maintenance and calibration and uniformity of seed piece size. Spacing uniformity is often measured by the coefficient of variation, which is derived from the mean and standard deviation of measured seed piece or plant spacings. This is not the best method to use, since the measure of uniformity is referenced to the actual spacing, not the desired or target spacing. The alternative method of assessing spacing uniformity involved counting the number of spaces that lie in a pre-determined “acceptable range” and calculating the percentage of “acceptable spaces”. The necessary calculations are easy if a suitable number (e.g. 40 or 50) of seed piece spaces are used.     

Potato planter performance and effects of non-uniform spacing

A survey of potato (Solanum tuberosum L.) plant stands in upstate New York over a three-year period showed that the average distance between plants was 4 cm wider than intended. Plant stands averaged 83%. The failure to plant seed pieces was the major reason for missing hills. Seed rot was not generally a problem, although one field in the survey was severely affected. Speed of planting up to 6.7 km/h had no consistent effect on average spacing or uniformity of seed piece distribution. Seed type (whole or cut) and mechanical condition of planter influenced spacing. Experiments conducted over four years indicated that the non-uniform seed piece distribution delivered by commercial picker-arm planters does not adversely affect crop yield or tuber size. Non-uniform seed distribution with extremely high coefficients of variation (greater than 100%), however, affected yield, tuber size and tuber number. Tuber numbers and yields were decreased by reducing the number of seed pieces planted per unit area whether or not the pieces were uniformly spaced.     

Relationships between stem number,tuber set and yield of Russet Burbank potatoes

Five storage temperatures and three planting dates were used to obtain differences in seed performance. As seed storage temperature increased, average stem number per seed piece significantly increased. Stem number also increased with later planting dates. Germination tests, conducted under controlled temperatures, resulted in a curvilinear response with the least stems per seed piece at 10°C. a maximum stem number at 16°C and a slight decline in number at 21°C. The major effect of planting date was manifested through differences in germinating temperatures which resulted in increased stem number with later plantings. Yield of U.S. No. 1 tubers (5cm or 112 gm minimum) declined significantly as stem number increased. In the first planting, the correlation coefficient between stem number per seed piece and yield was r = ?0.95. Increased stem number and declining yield were attributed to advanced physiological age resulting from exposure to higher temperatures in storage and in the field. As stem number increased with planting date, tuber number also increased. The correlation coefficient between stem and tuber number for the first planting date was r = 0.92. The relationship declined significantly on the third planting date to r = 0.46. From these results it was concluded that economic yields are influenced by stem and tuber number which in turn can be manipulated by control of seed storage temperatures and planting dates.     

Influence of seed placement on Russet Burbank potato yield and grade

Potato seed pieces were hand planted with different spacings in the row and percentages of doubles to determine the effects on total yield and tuber size distribution. The objective was to determine acceptable performance levels for commercial potato planters. Average tuber size increased as the percentage of double seed pieces decreased or as the in-row spacing between single seed pieces increased. Yield of tubers smaller than 113 g was the most sensitive parameter and they increased as in-row spacing decreased and as the percentage of double seed pieces increased. Yield of tubers larger than 283 g increased as in-row spacing increased but only for the first year. Total yield was not affected by the change of in-row spacing or the percentage of doubles.     

Effect of seed tuber and seed piece size on growth and incidence of hollow heart in Norgold Russet potatoes

Small seed pieces decreased yield and number of tubers. Both seed tuber and seed piece size affected the percentage of tubers with hollow heart. Hollow heart increased from 14 to 22% as the seed tuber size increased from 57 to 228 g and decreased from 27 to 19% as the seed piece size increased from 28 to 57 g. The least hollow heart (11%) occurred in tubers of plants grown from 57 g whole seed pieces and the most (26%) in tubers of plants grown from 228 g seed tubers cut into 28 g seed pieces. Hollow heart was positively correlated with the mean tuber size and negatively correlated with the number of mainstems per hill, total yield, and total number of tubers.     

The influence of physiological age,stem numbers and fertility on yield and grade of Russet Burbank potatoes

The present study was initiated to determine if increased stem numbers produced by physiologically older seed can be compensated for by increased fertilizer rate. Seed tubers held for 2 months at 16 C (physiological older seed) which averaged 3.7 main stems were compared in yield parameters to physiologically younger seed kept at 4 C (average 2.4 stems). The comparison was made at three levels of fertilizer 0, 140, and 280 kg/ha of nitrogen applied in a 16:16:16 (N-P²O⁵-K²O) formulation. Seed size and spacing were equal. Total and U.S. No. 1 yield were significantly higher for the younger seed. The greatest difference was that the younger seed at 140 kg/ha fertilizer yielded significantly more large size (over 280 g size) tubers than the older seed at equal to or double (280 kg/ha) the fertilizer rate indicating that additional fertilizer was not sufficient to overcome the effects of higher stem numbers from older seed. On the other hand, the older seed produced significantly higher yield of the undesirable small sizes.     

Effect of plant population and harvest timing on yield and chipping quality of Atlantic and Norchip potatoes at two Iowa locations

The effect of plant population and harvest timing on potato yield and chipping quality was studied at two Iowa locations during 1986, 1987, and 1988. Evaluations were conducted in eastern Iowa near Muscatine and in western Iowa at Whiting. The cultivars Atlantic and Norchip were planted at in-row spacings of 15, 31, and 46 cm and were harvested approximately 12, 14, and 16 weeks after planting. Delaying harvest until 14 or 16 weeks after planting resulted in greater yields and better specific gravities for both cultivars. At Muscatine, chip color was not significantly affected by harvest date, but at Whiting, each successive harvest produced lighter-colored chips. Greater seed piece populations increased both Atlantic arid Norchip yields. Greater planting populations also caused a small increase in specific gravity. Seed spacing did not significantly affect chip color. In comparison with Norchip, Atlantic produced tubers with higher specific gravities throughout the season and greater total yields on the final harvest date. Atlantic did, however, show susceptibility to hollow heart. The incidence of hollow heart was reduced by close seed spacing.     

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.     

THE EFFECT OF DRILL WIDTH ON THE SEED PRODUCTIVITY OF LEAFY VARIFTIES OF THREE GRASS SPECIES

Three leafy grass varieties, S215 meadow fescue, S37 cocksfoot and S51 timothy. were subjected to four dril spacings of 6, 15, 24 and 36 in. under two levels of nitrogen application. Over three harvest years, meadow fescue gave better seed yields with 6- and 15-in, drill spacings. Cocksfoot gave very similar yields from 1.5, 24- and 36-in, drills but a signincantly reduced yield from 6-in, spaced drills. Timothy produced significantly higher yields at the 24 in spacing.
The three varieties showed a significant response to nitrogen application.
Aphids seriously affected the vegetative growth of meadow fescue and timothy at the wider spacings, but the 6-in. drills m boths species remained relatively free of aphid attack, as also did the cocksfoot block.     

Field performance of peat-lite mix encapsulated small minitubers

Small minitubers (1.3 to 1.9 cm diameter), produced in the greenhouse from tissue culture plantlets are usually discarded because they are undersized for field planting. They have potential as a means of expanding the production of basic nuclear potato seedstocks. Field trials were conducted to evaluate the performance of greenhouse-produced minitubers at 15 and 30 cm spacings, with one or two minitubers/hill, and with or without encapsulation in a moist ball of artificial greenhouse peat-lite mix. All minitubers were green-sprouted for about two weeks under 16 hr/day fluorescent lighting before planting. Encapsulation in moist peat-lite mix significantly increased total yield by an average of 44% over minitubers without the soil mix. Independent of encapsulation, closer seed spacing and two minitubers/hill increased yields by an average of 35% and 20%, respectively, compared to wider spacing and one minituber/hill. Yields of encapsulated minitubers compared favorably with cut (50 gm) and whole (80 gm) seed, averaging 103% of the cut and 87% of the whole seed yields, respectively. These results indicate that small minitubers can be used effectively to expand production of basic nuclear seedstocks.     

Effect of seed piece size on performance of three potato varieties in the Klamath Basin of Oregon

A survey of cut seed lots from Klamath Basin commercial potato operations showed poor uniformity of seed piece size and numerous undersize seed pieces in most of the 18 seed lots examined over two years. Experiments were conducted in 1995, 1996, and 1997 to evaluate effects of seed piece size on the performance of Russet Burbank, Russet Norkotah, and Century Russet cultivars. Weighed seed tubers were cut into four pieces to obtain seed piece sizes of 21, 35, 50, 64, and 78 g (+/-2 g). Seed pieces less than 50 g resulted in delayed emergence and reduced stem numbers in all varieties. Effects of seed piece size on yield and tuber size distribution were greatest for Century Russet and least for Russet Norkotah, but were significant for all varieties over the three-year study. Increasing seed piece size increased yield of U.S. No.1 and total yield, while reducing tuber size. An economic analysis, based on crop values for fresh market use and seed costs, found optimum seed piece sizes of 64 g for Russet Burbank and Century Russet and 50 g for Russet Norkotah.     

Effect of seed piece population on the yield and processing quality of Russet Burbank potatoes

The effect of seed piece population on tuber yield, size distribution and processing quality of Russet Burbank potatoes grown under nonirrigated conditions in southern Manitoba from 1983 to 1987 was determined. Seed pieces were planted at 21.7, 26.3, 33.3 and 45.5 thousand seed pieces per hectare, and plant emergence generally exceeded 90% of the seed piece population. Marketable tuber (greater than 5 cm in diameter) yields were not affected by seed piece population. As population increased, however, the number of harvested tubers increased and average tuber size decreased, which resulted in a decreased yield of premium tubers (greater than 284 g) and an increased yield of small tubers (less than 5.0 cm in diameter). Specific gravity, the incidence of hollow heart in maingrade (5 cm in diameter to 284 g in weight) and premium tubers, and fry color were not significantly affected by seed piece population. In the one trial tested, sucrose content decreased as population increased, however, this was not reflected in improved fry color after storage.     

Zinc experiments on potatoes in the San Luis Valley of Colorado

Seven field trials with Zn were carried out in 1965, 1966, and 1967 to determine source and placement effects of ZnEDTA (Zn ethylene-diaminetetraacetate) and ZnSO₄ on the yield and composition of potatoes grown in the San Luis Valley of Colorado. Application of Zn increased the yield of U.S. No. 1 potatoes from 16 to 95% on soils having less than 4.8 ppm of 0.1NHCI-extractable Zn. No yield response was obtained on soils having greater than 5.5 ppm of extractable Zn. Uptake of Zn was greater from soil-applied ZnEDTA than from soilapplied ZnSO₄. Banding ZnSO₄ approximately 3 inches (7.6 cm) directly below the seed piece was more efficient than discing it or sidebanding it 5 inches (12.7 cm) to the side and 3 inches (7.6 cm) below the seed piece. Two foliar sprays of either ZnSO₄ or ZnEDTA solutions (0.5%) were also effective in correcting Zn deficiency. Zinc content of the foliage was not a good indicator of the Zn nutrition of potato plants.     

Comparative effects of cut and treated seed tubers vs untreated whole seed tubers on seed decay, Rhizoctonia stem canker, growth, and yield of Russet Burbank Potatoes

Whole seed tubers have been reported to have performance advantages over seed tubers that have been cut, even if the cut tuber pieces are treated with a fungicide dust. For this study, whole seed tubers were compared to cut seedpieces and to cut seedpieces treated with four different commercial fungicide dusts for five consecutive seasons. A new field generation 3 Russet Burbank seed lot was used for each of the five years of this study. Both whole tubers and cut seedpieces were inoculated withFusarium spp., and the seedpieces were then treated with a fungicide dust. Inoculated and uninoculated untreated controls were also included. Emergence,Fusarium seed decay,Rhizoctonia stem canker, stem numbers, and vigor, as well as yield and grade data were obtained.Rhizoctonia stem canker in stems grown from whole seed tubers was significantly higher than in stems from seedpieces receiving fungicide treatment in several of the study years. Predicting whole seed tuber performance is difficult because performance varies more from year to year than performance of cut and treated seedpieces. Yield performance of whole seed tubers was not significantly better than cut and fungicide-treated seedpieces in any experimental year, and yield of large (over 280 g) tubers was significantly less than that recorded for two of the treatments when data from all five years were combined. This study demonstrated that untreated whole seed did not outperform cut and treated seedpieces for vigor, stem numbers, disease ratings, or yield in small plot comparisons for five consecutive seasons.     

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.     

Manipulating Stem Number, Tuber Set and Size Distribution in Specialty Potato Cultivars

Manipulating seed physiological age is an effective method to alter tuber set and size distribution for many cultivars. However, cultivars Cal White, Red La Soda, Chieftain, Yukon Gold, and Satina were largely insensitive to high temperature-induced age-priming treatments. Gibberellins (GA) also have potential for altering tuber set and size development. When applied to cut seed of the five cultivars, GA hastened plant emergence, increased stem and tuber numbers per plant, and decreased average tuber size. The optimum concentration of GA for shifting tuber size distribution to maximize crop value without decreasing total yield depended on cultivar. Total yields decreased substantially in all cultivars with 10 mg L^?1 GA but lower concentrations (0.5–4 mg L^?1) either increased yields of Red La Soda, Yukon Gold, Chieftain and Satina by 11, 13, 15, and 24 %, respectively, or had no effect (Cal White). GA-induced increases in tubers per hectare ranged from zero (Cal White, Satina) to 36 % (Chieftain) and associated increases in yields of premium priced creamer size potatoes (C size; 10–66 g, 28–51 mm diameter) ranged from 0 to 140 %, depending on cultivar and length of the growing season. Increases in total crop values ranged from 7 to 30 % (Chieftain) with the optimum concentrations of GA, which also varied by cultivar. Effective use of GA to alter tuber size distribution for increased value depends on cultivar, concentration, and harvest timing.     

Comparison of growth and yield parameters of Russet Burbank for a two-year period

The effect of three planting dates on stem, stolon, tuber number and size were compared throughout the 1979 and 1980 growing seasons. A relatively warm April and early May and a relatively cool late May and June in 1980 resulted in significantly higher stem and stolon numbers and a tuber population over double that of 1979. The highest average commercial yields ever recorded in the Columbia Basin were obtained with yields in some fields of 100 tons per ha on 48 hectare irrigation circles. On experimental plots tuber numbers increased from the latter part of May with successive sampling dates until late June and early July when a peak in number was reached after which a significant decline in number occurred. The decrease in tuber number was attributed to the phenomenon of reabsorption which was much greater with later planted potatoes. It occurred only in tubers of approximately 10 g size or smaller. Average tuber size in 1980 was one-half that of 1979 although total yield was 25 tons per ha higher because of significantly larger tuber numbers.