Variations in stolon length and in incidence of tuber roots among eight potato cultivars

The stolon length and percentage of tubers with tuber roots were compared for eight cultivars ofSolanum tuberosum L. over two growing seasons. Although stolon lengths varied considerably within cultivars, there were significant differences in the average stolon lengths among cultivars. The cultivars Norchip and Monona had the shortest stolons whereas Norland had the longest average stolons. The length of the stolon did not appear to be related to color type or time of tuber maturity. Since there was no significant difference in stolon length between years, stolon length appears to be a consistent genetic trait. There was no significant correlation between the stolon length and tuber size. The incidence of tuber roots also showed variation among cultivars, although there was significant variability between times of sampling. Recent studies have demonstrated that to maximize calcium uptake by tubers, the calcium must be placed around the tubers and stolons. Since stolon length determines the location of the tubers in the hill, the stolon length of different cultivars may need to be considered for fertilizer application, cultivation or hilling procedures. Thus, to get maximum benefit from supplemental calcium for Norchip and Monona, application would need to be made close to the main stem. However, in the other cultivars, the majority of the hill would have to be enriched in calcium to effectively supply calcium to the various tubers in the hill.     

Parenchyma cell growth in potato tubers I. Different tuber regions

Enlargement rates of starch-storage parenchyma cells during growth of Kennebec and Russet Burbank potato cultivars were determined for cortical, perimedullary, and pith tissuues of bud ends, midsections, and stem ends of tubers. Average volumetric size of parenchyma cells increased 7 to 18x during growth of Russet Burbank tubers, with the greatest increases occurring in cortical and perimedullary cells of bud ends and midsections, and the least in stem ends and pith tissues. In Kennebec tubers parenchyma cells in both stem end and midsection increased only 5 to 8 x, whereas increases in bud ends ranged from 8 to 20 times. Cell enlargement to tuber enlargement ratios appproached unity early in growth of Russet Burbank tubers. As tubers increased beyond the 45 g size, cell enlargement and tuber enlargement rates were essentially equal. Calculations of cells per unit tissue volume agreed with ratio determinations. The timing of such unity appeared to be delayed in Kennebec tubers, and was not quite as pronounced as in Russet Burbank tubers. This may have been due to differences in growth rates of individual tubers in response to cultural conditions. In general, cells of harvestmature Kennebec tubers were about 60% as large as similar cells of Russet Burbank tubers.     

Cell size in Russet Burbank potato tubers with various levels of nitrogen and soil moisture tensions

Russet Burbank potatoes were grown at levels of added nitrogen of 0, 135, and 270 kg/ha and soil moisture tensions (SMT) of 0.5 and 1.0 atm. With all combinations, there was a consistent gradient of larger to smaller starch-storage parenchyma cells from stem end to bud end of mature tubers. Stem and bud ends of tubers grown at a SMT of 0.5 atm with N had smaller cortical and pith (innermost medullary or water-core) cells than did ends of tubers grown without N. Perimedullary tissues of bud ends of tubers receiving N likewise contained smaller cells than did corresponding tissues of tubers grown without N. No pronounced differences in cell size were found in tissues from the midsections. In bud-end tissue of tubers grown at a SMT of 1.0 atm, there were no consistent differences in cell size with respect to N levels. However, pith, perimedullary, and cortical tissues of the midsections and stem ends of tubers receiving N had smaller cells than did corresponding tissues from tubers without N. The different patterns of cell size in tubers grown at different SMT indicate that the effects of N may be influenced by soil moisure.     

White clover growth patterns during the grazing season in a rotationally grazed dairy pasture in New York

White clover (Trifolium repens L.) is an important stoloniferous pasture legume in the Great Lakes region of the United States, but it often has limited persistence. Researchers in New Zealand and Wales have found that in spring, compared with other seasons, white clover plants have reduced branching complexity and have the fewest buds that produce leaves. They therefore suggested that in spring the plants are most vulnerable to grazing and climatic stress. Because of severe winter and cool, wet spring weather in New York State, it was hypothesized that white clover plants would also be of low branching complexity, smaller and have low axillary bud activity in spring compared with later in the grazing season. To test this, growth of white clover was monitored in an orchard grass (Dactylis glomerata L.)/white clover pasture in New York that was rotationally grazed with dairy cows during the 1993 and 1994 grazing seasons. Three sets of plants were sampled. The first set consisted of forty random plants sampled before each grazing event. Stolon branching order, number of each stolon branching type and area the plant occupied were determined. Approximately each month before one grazing event, a separate set of 32 random plants was measured in the field to determine the area they occupied; these plants were then removed to the laboratory for the measurement of stolon order, number of each stolon type, stolon lengths, total number of growing points, number of taproots and adventitious roots, root position and above-ground dry matter. Once a month, 12 additional plants were removed to measure axillary bud activity at each node. Leaf development from nodes tended to increase from spring to summer. However, the stolon branching order of white clover plants was not simpler in spring compared with summer or autumn. In 1994 during and after a dry and hot period, white clover plants were smaller, of lower stolon branching order and had fewer roots. Climate and associated soil organism activity appear to explain the different white clover growth patterns observed in New York and New Zealand. Severe winters in New York limit earthworm activity and stolon burial, which is important in contributing to stolon/plant breakdown in New Zealand. During the years of this study in New York, a hot and dry period had the most negative effect on the growth pattern of white clover.     

Comparative field performance of potatoes from seedlings and tubers

A field trial was conducted at Freeville, NY to compare yields from hybrid families ofSolanum tuberosum L. with yields from their corresponding full sib, first clonal generation tubers. Unselected tubers were saved after harvesting transplanted seedlings of four Neo-Tuberosum × Tuberosum hybrids in 1982. The following year these tubers were planted for comparison with seedlings of the same hybrids in a split plot design. Total yields and yields of tubers ≥ 38 mm in diameter were respectively 34% and 38% higher from tuber propagated plants than from seedlings. The biggest difference was in tubers ≥ 63 mm diameter, where plants from tubers gave yields more than double those from seedlings. Seedlings had twice as many large axillary branches per stem as plants from tubers. Uniformity of tuber size and shape, and overall appearance ratings of tubers were better with seedling propagation; however, these comparisons are biased by the tendency of seedlings to produce smaller tubers, which inherently receive higher ratings.     

Electron microprobe and neutron activation analysis for the determination of elemental distribution in hollow heart potato tubers

Electron microprobe and neutron activation analysis were used to evaluate the distribution of elements within potato tubers having the physiological disorder hollow heart. Both methods of analysis correlated well for all elements tested. In hollow heart tubers, there were significantly higher Ca⁺⁺ levels in the stem end than in the bud end; however, a Ca⁺⁺ gradient in the control was not evident. The stem to bud end ratios for Ca⁺⁺ were highest in the hollow heart tubers. A Cl^? gradient from stem to bud end was obvious in both the hollow heart and control tubers. In the control tubers, K⁺ was highest in the bud end and lowest in the stem end. There was no K⁺ gradient in hollow heart tubers, but in the area adjacent to the hollow it was higher than at both ends.     

The effect of early drought stress on numbers of tubers and stolons of potato in controlled and field conditions

Summary Potatoes were grown in plots, pots or containers in a glasshouse or under a rainshelter. Water was withheld from emergence onward or from tuber initiation onward in some treatments. The number of stolons per stem was greatly reduced but the number of tubers + tuber initials per stolon remained unchanged (cv. Radosa) or increased (cv. Bintje) as a result of the earliest drought treatment. The later dry period did not affect numbers of stolons and tubers (+ initials). These findings correspond well with data from field trials which were sampled for 13 consecutive years and which showed a highly significant linear relationship between the number of tubers per stem and total rainfall during the first 40 days after planting, which ranged from 17.5 to 120 mm.     

Infection of potato stem bases,stolons and tubers byPolyscytalum pustulans (Owen & Wakef.) Ellis and development of sclerotia

Summary Polyscytalum pustulans spread from infected buds of seed tubers on the nodal scale leaves of elongating stems and stolons. More eyes were infected at the apical end of developing tubers than at the stolon end. Sclerotia, first found within the agar of ageing cultures, appeared to form from thickened hyphal rings within the aerial hyphae and conidiophores. As infected plants senesced, sclerotia developed within single or groups of host cells in diseased stem bases and remained viable for seven years in undisturbed soil. Sclerotia were also found after harvest in skin spots on decayed seed tubers.     

马铃薯脱毒试管苗无土栽培高产机理研究

在防虫网室中无土栽培马铃薯脱毒试管苗生产微型薯。用 9次剪尖和 8次培土的办法 ,180d平均单株结薯达 2 12 8个 ,2 10d商品粒数 (≥ 1g)达 158 2个 ;且剪尖和培土的次数与匍匐茎数、腋芽枝数和单株结薯个数有正相关关系 ,后两者均达极显著水平r1=0 90 2 3,r2 =0 94 70     

Effects of auxin and calcium on phosphate partitioning in induced potato (Solanum tuberosum L.) cuttings

Summary Single-node leaf cuttings, from plants originated from apical cuttings on sprouted potato tubers (Solanum tuberosum L.), were used to study phosphate transport following hormone (IAA) and calcium treatments. Phosphate accumulation in tubers was significantly enhanced by axillary bud pretreatment with calcium followed by a subsequent treatment of the tuber formed with IAA. The results suggest that calcium may be necessary for the regulatory action of auxin on phosphate transport into the tuber.     

Potato cuttings as models to study maturation and senescence

Summary Single leaf cuttings with their subtended axillary buds proved to be useful models to study maturation and senescence in potato (Solanum tuberosum L.). Senescence was more rapid if the cultivar was early maturing or if plants were exposed to short days before cuttings were taken. Rooting was decreased by short days before cutting; excision of the buried bud only partially overcame the effects on senescence and rooting. High rates of N to mother plants in the field delayed senescence of cuttings in a way analogous to the delayed senescence of field plants. The tuberization of cuttings from late maturing cultivars was decreased by high rates of N. The color of crisps made from bud tubers was positively correlated with the color of crisps made from ordinary tubers of the same cultivars. Sugar concentrations in bud tubers decreased as cuttings became more senescent and increased after cold storage. Bud tubers harvested while ‘immature’ had greater concentrations of reducing sugars after 90 d at 10°C than did ‘mature’ bud tubers. Paper No. 878, Department of Vegetable Crops, Cornell University. This research was supported through HATCH project NYS161414, a contributing project to Regional Project NC150, and through HATCH project NYS161407.     

The effect of some environmental factors on potato tuber numbers

Summary Five experiments studied the effects of shading, temperature and stolon growth medium on stolon and tuber formation. The lowest numbers of stolons and tubers were produced at the higher and lower nodes. Numbers of primary stolons and tubers were relatively stable across nodes and treatments and variation in total numbers was largely due to changes in numbers of lateral and branch stolons. In the field, 70% shading reduced numbers of stolons and tubers by reducing lateral and branch stolons, while in hydroponics, 45% shading and temperatures at initiation had no effect on tuber numbers. In both environments later planting tended to reduce numbers of stolons and tubers. There were large effects of the physical environment, with compost producing three times as many tubers as dry vermiculite. The potential number of tubers may be determined by the number of stolons and the environmental conditions affecting stolon formation and development.     

晋薯9号马铃薯结薯规律的研究

经三年的试验资料表明,晋薯９号马铃薯的结薯规律,与地上部生长有着密切的关系。如株高生长最快时期是在块茎膨大盛期前夕;分枝生长最快时期是在花期左右,与块茎膨大盛期同步。复叶生长最快时期是和匍匐茎发生与生长同时进行。当植株茎叶鲜重生长进入高峰时期,块茎也进入膨大盛期。匍匐茎的发生是伴随着根和芽的生长而发生。在幼苗期考察,已有匍匐茎３～５条,出苗３０ｄ后基本全部形成,约７条左右。现蕾期后一周,匍匐茎顶端形成小块茎,单株出现１０～５０ｇ块茎,即块茎形成期。出苗后４０ｄ左右,正是初花,单株出现５０～１００ｇ块茎,地下部块茎进入膨大期。当株高、茎叶鲜重达到全生育期最大值时,单株出现１００ｇ以上块茎,当时正是花期后的两周,即出苗后６０ｄ左右,单株块茎日增量增至１８～２７ｇ,块茎进入膨大盛期。     

Effect of second growth on the quality of tubers as seed in the cultivar Record

Summary Seed quality in a crop harvested in 1984 was compared in tubers which either, (a) were unsprouted prior to harvest (normal), (b) had formed secondary chain tubers prior to harvest (primary), (c) secondary chain tubers. Normal and primary tubers formed substantial sprout growth during storage, while there was little sprout growth from secondary tubers. Plants derived from these seed tuber types differed, in terms of emergence, number of emerged stems, and tuber number. It is concluded that the tuber types can be considered to vary in terms of physiological age; normal and primary tubers appear to be physiologically older than the secondary tubers. This variability in seed condition can lead to variability in the performance of the subsequent crop.     

Possible mechanisms of size hierarchy among tubers on one stem of a potato (Solanum tuberosum L.) plant

Summary The tubers on one potato stem vary greatly in size and their size distribution may be described by their number and their average size and its variation. These components are mutually and closely related. The variation is partly caused by stolon characteristics, including their date of initiation, position and size. Tuber size is therefore partly determined before tuberization. Tuber-specific factors, such as the position and activity of the tuber initial also play a role, but the date of initiation of an individual tuber is not crucial. Later on, during tuber bulking, the activity of enzymes involved in starch metabolism, the levels of hormones, the mineral composition and the turgor potential are associated with the tuber growth rate. The growth characteristics of individual tubers may also vary since they are exposed to different conditions because of differences in position or growing period.     

Production of above-ground seed tubers on stem cuttings from eight potato cultivars

Summary The formation of above-ground tubers on stem cuttings of eight potato cultivars was studied over three seasons. To promote tuber formation in the leaf axils, stems grown from single node cuttings were exposed to short day conditions. Tuber formation underground was reduced by covering the soil with a plastic sheet and by using single node cuttings planted with the leaf axils several centimetres above the soil surface. With all cultivars except Alpha, which produced mis-shapen tubers in all experiments, an average of 11 (maximum 40) tubers per cutting were harvested. Significant cultivar × year interactions were observed.     

Differences in free and protein-bound tyrosine among potato genotypes and the relationship to internal blackspot resistance

Twelve potato clones were selected to represent the full range of internal blackspot response in order to determine the relationships between tuber protein, free tyrosine, and blackspot susceptibility. The blackspot reaction for each clone was consistent over five growing seasons, including tubers grown over a normal season (mature), and short season (immature) during one year. The blackspot index, determined by either an abrasive peel test or an impact bruise test, was highly correlated with the tyrosine content of the tubers (r = 0.90 p = 0.001 for the means of each clone over five location-years). Tubers with free tyrosine levels below 4 μmole/g dry weight consistently showed a resistant blackspot response. The relationship between tyrosine and blackspot susceptibility was also found in stolon and bud ends from five of the clones which represented the extremes of blackspot reaction and genetic diversity. Bud end samples of each of the clones had lower tyrosine content and a corresponding reduction in blackspot compared with stolon ends. Phenols, other than tyrosine, showed no consistent relationship to the blackspot reaction. There was a very high negative correlation between free tyrosine and estimated protein-bound tyrosine. R values ranged from ?0.85 to ?0.97 (p = 0.001) for mature tubers of the 12 clones over 4 growing seasons. Total tyrosine (free, plus protein-bound) remained relatively constant. There were no significant differences in mean total tyrosine content among the 12 clones over five location-years of testing; and there were no significant differences among the five growing seasons except for the short season (immature) tubers which were 14% lower in total tyrosine content. These results indicate a remarkably constant level of total tyrosine production in the twelve clones studied, that represented diverse genetic backgrounds. Mature tubers of all genotypes contained 26 ± 1 μmole/g dry weight total tyrosine. Partitioning of tyrosine between tuber protein and the free amino acid pool varied with genotype and appeared to be a major determinate of blackspot resistance.     

Calcium translocation and accumulation into potato tubers

Summary Calcium uptake into potato plants was examined using test solutions containing 5% safranin dye (C₂₀H₁₉N₄C1 mw 350.85) and the radiotracer⁴⁵CaCl₂. When minitubers were suspended in test solutions for up to 5 days, safranin moved into the outer pith tissues while⁴⁵Ca²⁺ was located throughout the pith. Ca²⁺ is apparently taken up directly from the tubersphere by a slow diffusion process. Plantlets with one microtuber were used to investigate calcium uptake via basal roots.⁴⁵Ca²⁺ was well ahead of the safranin dye front in all plantlet stems.⁴⁵Ca²⁺ in shoot tips was significantly greater than in microtubers and no safranin entered the microtubers. Greenhouse-grown ex vitro plantlets with minitubers attached were used to determine the relative uptake by basal and stolon roots. Basal root feeding contributed significantly more⁴⁵Ca²⁺ to shoot tips and tubers than stolon root feeding while combined feeding gave the greatest shoot tip and tuber⁴⁵Ca²⁺ levels.     

Changes in seed tubers after planting

Summary The changes after planting in weight and dry matter content of seed tubers were studied. The weight was found to increase after planting owing to uptake of water from the soil. The dry matter content decreased rather rapidly. The changes in weight varied within wide limits for individual tubers, showing great differences in water uptake between the tubers. These differences were also demonstrated in a soaking experiment. The variation in water uptake between tubers could partly be explained by variations in the soil but the variation between the seed tubers seemed to be more important.     

Effects of shoot,root and stolon temperature on the development of the potato (Solanum tuberosum L.) plant. III. Development of tubers

Summary The cultivars Bintje and Désirée were growth with their shoots, roots and stolons at different temperatures, to study the effects on tuber development. More tuber sites were initiated in ‘Bintje’ when the air, root or stolon temperature was increased but a combined increase of air and root temperature greatly reduced the number of sites. In contrast, each temperature increase reduced the number of tuber sites in ‘Désirée’ but an increase in temperature in one compartment usually increased the number of tubers set. The relative tuber set was enhanced by a combination of high stolon temperature and low root temperature. Especially an increase in air temperature reduced tuber yield and tuber dry-matter content, but increasing stolon temperature had the largest effects on the induction of second growth. Stolon and tuber development, dry-matter partitioning and initiation of second growth responded differently to variation in temperature around different plant parts suggesting that these processes are affected by different regulation mechanisms.