Effect of fumigation of potato seed tubers with 2-aminobutane on plant growth and yield

From 1968 to 1973, 13 field experiments were carried out to discover any effects of fumigation of seed tubers with 2-aminobutane (used for tuber disease control) on subsequent plant growth and yield. Nine experiments were done with tubers treated within 1 month of harvest, the remaining 4 with tubers stored for several months before treatment. In general, fumigation did not have any substantial effect on the growth pattern or the yield of the crop obtained from treated seed, although in most cases it was probable that there were small increases in the number of sprouting eyes, percentage emergence, stem number and in weight and number of seed tubers at harvest. However, these effects rarely reached levels which gave a statistically significant increase over crops grown from untreated material.     

The effectiveness of using a minituber crop for selection of agronomic characters in potato breeding programmes

Summary Performance of 20 potato genotypes was studied for seven agronomic characters in crops raised from minitubers and normal seed tubers. Correlation coefficients were computed between minituber crop and normal seed crop in order to study the selection efficiency at minituber crop level. The performance of normal seed crop was significantly better than the minituber crop for various characters including tuber yield and its components. Correlation coefficients between minituber and normal seed crop were significant for various characters except number of stems and number of tubers. Highest correlation coefficient (r=0.86) was for tuber yield followed by average tuber weight (r=0.67) and number of nodes (r=0.63). The results suggest that selection for tuber yield can be practised at the minituber crop level in potato breeding programmes     

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.     

Seed Potato Performance after Storage in Light at Elevated Temperatures

In regions with short growth seasons, it is of great importance to use potato (Solanum tuberosum L.) seed tubers with a high growth vigour and a short growth cycle. Such qualities may be obtained by treatments advancing the physiological age of the seed tubers. In this study, we have exposed tubers from four cultivars to various combinations of temperature and light conditions (green-sprouting) for 3–7 months in controlled climate. Subsequent sprout quality, seed tuber health and performance were studied in laboratory, greenhouse and field trials. Satisfactory short, sturdy and leafy sprouts were produced even after 7 months storage at 15 °C under light exposure. An assay of black scurf (Rhizoctonia solani) on the tuber skin showed that light exposure significantly reduced the occurrence compared with dark-stored tubers, while the average effect of storage temperatures was insignificant. In general, green-sprouting advanced emergence and plant growth by 1–2 weeks, and showed early tuber initiation and growth, compared to untreated material. Yields, 107 days after planting in the field trial, did not deviate significantly from untreated tubers. However, plant development at harvest was in accordance with general responses to physiological ageing of potato seed tubers, i.e. still tall and immature plants from untreated tubers, and short and mature plants from aged tubers. Results demonstrated the possibility of successful long-term storage of potato seed tubers in light at elevated temperatures and a potential for earlier harvests and higher early yields from such treatments.     

Seasonal differences in the field performance of micropropagated potato under a short growing season in Quebec

Field performance comparisons between ex vitro plantlet-derived (EVPD) plants and seed tuber-derived (STD) plants ofRusset Burbank were conducted for two consecutive years under a short growing season in Quebec. The EVPD plants produced more potential seed tubers than STD plants although total tuber biomass of EVPD plants was less than that of STD plants. The frequency and weight distributions of tubers formed by the two types of propagates were different. The EVPD plants produced significantly more small sized tubers and fewer large sized tubers than the STD plants. Average tuber weight was less for EVPD than STD plants for each of five size categories. No significant differences were found in the fresh and dry weight of plants, leaves and stems at harvest time. However, plant height and growth habit differed between the two types of propagates. The EVPD plants had a unique appearance. They produced a single stem with extensive axillary bud development. The EVPD plants were apparently more susceptible to early water stress in the field than STD plants, probably due to an earlier production of stolons. No differences were found between ex vitro plantlet- or microtuber-derived plants, in plant growth or yield characteristics.     

Field performance of potato minitubers with different fresh weights and conventional seed tubers: Crop establishment and yield formation

Summary Field performance of five fresh weight classes of minitubers ranging from 0.13–0.25 g to 2.00–3.99 g and conventional seed tubers was studied in a short growing season (79 or 82 days) in two years. The heavier minitubers gave a more regular emergence, faster ground cover soon after emergence, higher dry-matter yields, and higher fresh tuber yields. Radiation conversion coefficient (RCC) did not differ. Higher tuber yields resulted from more radiation intercepted due to a faster ground cover, and a higher harvest index. All minitubers produced plants with one primary stem. In one experiment when heavier minitubers had long sprouts, time to 50% emergence decreased with tuber weight, whereas dry-matter concentration of progeny tubers increased. Conventional tubers appeared superior to minitubers in all characteristics mentioned except RCC, which was similar. Differences in performance between minitubers and conventional tubers were attributed to weight and age of seed tubers, presprouting method and crop husbandry.     

Soil water stress and the growth and yield of potato plants grown from microtubers and conventional seed tubers

Tuber yields of potato plants grown from microtubers in fields are more variable than yields from conventional seed tubers (CT). One reason could be their higher susceptibility to water stress. This study clarified the effect of soil water stress from 1 month after emergence on the growth and yield of plants grown from conventional seed tubers and microtubers in fields. Microtubers (0.5–3 g) and conventional seed tubers (50 g) were grown in Hokkaido, Japan, over three field seasons. One month after emergence, poly-shelters were placed over the plots to prevent rainfall, and either irrigated (wet plot) or non-irrigated (dry plot) treatments were formed. At mid-flowering (about 50 days after emergence) leaf area index (LAI) in microtuber plants was decreased relatively more due to soil water stress than LAI in conventional seed tuber plants. However, at maximum shoot growth (about 80 days after emergence) both microtuber and conventional seed tuber plants had a similar relative decrease in LAI due to soil water stress. At mid-flowering and maximum shoot growth microtuber and conventional seed tuber plants had reduced stomatal conductance due to soil water stress, but the reduction in stomatal conductance was greater in conventional seed tuber plants than in microtuber plants. Microtuber and conventional seed tuber plants had similar root development at maximum shoot growth. Tuber production from mid-flowering until plant maturity was similarly affected by soil water stress in microtuber and conventional seed tuber plants. At harvest, plants affected by soil water stress had about 87% of the tuber dry weight of irrigated plants. We conclude, that the greater variation on tuber yield of microtuber plants cannot be attributed to soil water stress from 1 month after emergence.     

A comparison of variability in storage behaviour of seed tubers from true potato seed and clonal tubers

Summary The tuber-to-tuber variability in storage behaviour of seed tubers from true potato seed was compared with that in clonal seed tubers after storage in the dark, in diffused light, or in diffused light with a single desprouting. The variability was estimated by calculating standard deviations of length, number and weight of sprouts, and tuber weight loss. After dark storage, the variability of these variables was greater in seed tubers from true potato seed than in clonal seed tubers. After storage in diffused light with a single desprouting, the variability of number, length and weight of sprouts of seed tubers from true seed was not statistically different from that observed in clonal seed tubers. All storage treatments resulted in a greater variability of tuber weight loss in seed tubers from true potato seed than in clonal tubers.     

Effect of gibberellic acid and multiple harvests on production and reproductive value of seed potatoes produced above ground on stem cuttings

Summary Potato plants of cvs Eersteling and Bintje were grown from stem cuttings and induced to form aerial tubers for use as seed. Spraying the plants with gibberellic acid in concentrations of 10, 25 and 50 mg/l to induce stolon formation in the leaf axils led to a decrease in the number of tubers formed per plant. Multiple harvesting of the largest tubers from plants treated with gibberellic acid or not, approximately doubled the number of tubers formed but halved their individual weight compared with only one harvest at plant senescence. After a storage period of about 1 year, with their vigour declining, the aerial tubers were planted in the field. Aerial seed tubers taken from multiple harvests during the previous year produced the same number of tubers as plants grown from above-ground tubers harvested at plant senescence only, but the tuber yields declined with earlier harvesting when small (5–13 mm) aerial tubers were used, compared to larger (14–19 mm) tubers.     

Physiological regulation of potato tuber dormancy

At harvest, potato (Solanum tuberosum L.) tubers are dormant and will not sprout. As the period of postharvest storage is extended, tuber dormancy is broken and sprout growth commences. The loss of tuber dormancy and onset of sprout growth is accompanied by numerous biochemical changes, many of which are detrimental to the nutritional and processing qualities of potatoes. Endogenous hormones have been proposed to play a significant role in tuber dormancy regulation. The involvement of all major classes of endogenous hormones in tuber dormancy is reviewed. Based on available evidence, it is concluded that both ABA and ethylene are required for dormancy induction, but only ABA is needed to maintain bud dormancy. An increase in cytokinin sensitivity and content appear to be the principal factors leading to the loss of dormancy. Changes in endogenous IAA and GA content appear to be more closely related to the regulation of subsequent sprout growth.     

Evaluation of new clones of Jerusalem artichoke (Helianthus tuberosus L.) for inulin and sugar yield from stalks and tubers

Six clones of Jerusalem artichoke, five new clones (coded as 17, 22, 56, 69 and 70) and the control cultivar “Violette de Rennes” were evaluated for variability in sugars yield, when the plant is utilised as stalk, tuber and “integral crop”.Among the above harvesting methods, the integral crop (stalks and tubers at flowering time), showed the highest yield potential of total sugars (fructose+glucose) and inulin (18.6 and 17.9 t/ha, respectively). This was obtained by the clone Violette de Rennes, which also had the greatest inulin chain length, in the text reported as average degree of polymerisation (DP).Clone 69 produced the highest yield of sugars and inulin, when the stalks are harvested at flowering (10.4 and 8.0 t/ha, respectively), while clone 17, with the conventional harvest of tubers at the end of crop cycle, reached 13.3 and 13.7 t/ha of total sugars and inulin, respectively. The average inulin chain length (DP) was highest at flowering time in both stalks and tubers with a range of 7.5–11.2 in the genotypes studied, while, at the final harvest of tubers, it significantly decreased reaching values ranging from 4.8 to 6.7. Among the organs analysed, the tubers at stalk harvest, showed both the highest inulin content and the longest inulin chain, expressed as DP.The genetic variability was very high among the clones for the other characters studied, such as flowering time, sugar content in different organs, photosynthesis activity, leaf chlorophyll content, etc. In particular, the “refractometrically measured” solids, in extracted tissue juice, expressed as the Brix-value (a very quick method), exhibited a significant positive relationship with the tuber inulin content (0.90^** and 0.85^**, n=6, in the first and second harvest, respectively), confirming its suitability as a fast screening method in breeding, avoiding time consuming and expensive laboratory analysis.     

Sprouting of seed tubers during cold storage and its influence on tuber formation, flowering and the duration of the life cycle in a diploid population of potato

Summary The influence of a short tuber dormancy and the subsequent sprout growth of the seed tubers during storage at 4 °C on the processes related to plant development and tuber formation was investigated in a diploid population with 238 genotypes, its crossing parents and seven tetraploid varieties. Sprout growth during storage at 4 °C was positively correlated to the duration of the dormancy period at 18–22 °C, the low temperature prolonging the dormancy period. Results show that the duration of the dormancy period and the sprouting of seed tubers during storage at low temperature did not have a determinant influence on plant development, tuber formation or the duration of the plant cycle in this large and highly diverse population of potato.     

Seed potato quality as influenced by high temperatures during the growth period. 2. Sprouting pattern in several cultivars in response to storage temperature

Summary Locally grown seed tubers of nine varieties developing in spring or in autumn in a semi-arid region were examined for length of dormancy and for sprouting response. In spring, high temperatures during the last part of tuber development markedly shortened the dormant periods of tubers in comparison with tubers of the same varieties developing in autumn. The sprouting behaviour of tubers indicated that it is a varietal characteristic influenced by the change in environmental conditions during tuber development and storage. On tubers developing in spring and stored at high temperatures, three sprouting patterns were defined: a) apical dominance, characterized by the evident development of the apical sprout and less than 10% sprouting of the non-apical buds; b) apical influence, the apical sprout well developed and 10–20% sprouting of the non-apical buds; and c) simultaneous sprouting of 3 or 4 sprouts of similar size per tuber. It is suggested that apical dominance is a relative rather than an absolute phenomenon. The extent of dominance depends upon the variety's response to the high temperatures during tuber growth and storage. Contribution from the Agricultural Research Organization, Beit Dagan, Israel, 1979 Series, No 301.     

Tetrazolium tests as indicators of tuber physiological age and yield potential

Seed tubers were treated by incubation of cut surfaces in solutions of 0.5%, 2,3,5-triphenyl tetrazolium chloride (TZ) for 30 or 90 min. Reaction rate, measured as change in surface reflectance (R/hr) and distance of transport in vascular tissue (mm/hr), were significantly correlated with tuber aging due to time (1, 2, 3 years) or temperature treatments and with sprout number per tuber. TZ results were significantly correlated with yield of U.S. no. 1 tubers in field tests. It was proposed that TZ be used in seed tuber testing and as a cytochemical probe in physiological studies.     

Tillage and seed-sprouting strategies to improve potato yield and quality in short season climates

Management practices that accelerate crop development and allow earlier harvest would be beneficial in short-season potato (Solanum tuberosum L.) production areas. Yield and quality of the potato cultivar ‘Russet Burbank’ were evaluated in a 2-yr study in northern Maine to determine effects of soil tillage and seedsprouting treatments designed to dry soil early in the spring and hasten seed emergence. The tillage treatments, consisting of fall raised bed (RB), fall ridge till (RT), and spring chisel plow (CH), were tested in combination with green-sprouted and non-sprouted seed tubers on a Caribou gravelly loam (coarse-loamy, mixed, frigid,Typic Haplorthod). Plants from green-sprouted seed emerged earlier than from non-sprouted seed tubers (87%-96% vs 21%-37%, respectively, at 18 days after planting [DAP] in 2000; and 73%-88% vs 18%-23%, respectively, at 20 DAP in 2001). Green-sprouted seed tubers in RB yielded 4.6 to 5.9 T ha^-1 more than nonsprouted seed tubers in RB. However, non-sprouted seed tubers yielded higher than green-sprouted seed tubers in RT by 2.9 to 4.2 T ha^-1 and in CH by 1.1 to 4.1 T ha^-1. Similarly, green-sprouted seed tubers in RB and nonsprouted seed tubers in RT and CH produced higher marketable yield, greater tuber length, and greater tuber diameter than the corresponding seed-sprouting treatment. In the comparatively wetter year (2000), the use of green-sprouted seed tubers in RB significantly increased total and marketable yields, and produced longer and larger tubers than all other treatments. However, in 2001 (relatively dry year), yield and quality from green-sprouted seed tubers in RB did not differ from non-sprouted seed in RT or CH. Green-sprouted seed produced fewer sunburned and rotten tubers, but more misshapen tubers than non-sprouted seed in RB tillage. The technique of producing Russet Burbank potatoes in raised beds is a promising system in regions with short growing seasons for enhancing early soil drainage during spring and improving soil water retention during critical periods of crop growth and development.     

马铃薯种薯芽条生育规律的研究

种薯萌发的芽条数不随萌芽时间的延长而增多,但在高温(22～28℃)下萌芽和种薯尚未完全通过休眠时催芽,会使萌芽数显著减少。品种、光照、温度、萌芽时间、赤霉素浸种等因素条件的不同,对芽条伸长速率和芽生长锥分化程度和速率有显著影响、而对芽条节间数、生根节数、顶芽萌发数的影响不明显。芽条根原基只有在黑暗潮湿的条件下才能仲长,以芽条基部1～3节的根系发生最早、最多、早长。芽生长锥分化程度与芽条其它各器官的发育程度呈显著正相关,它是衡量芽条发育水平的最具代表指标。     

Comparison of methods for measuring dormancy of potatoes

Comparisons were made of different methods of measuring length of the dormant period of Russet Burbank potato tubers as affected by time of planting and harvest. The study resulted in the following conclusions: 1) when measured from planting or tuber initiation to sprouting, the dormant period of tubers harvested on the same date was longer from an early planted crop than from a late planted crop. 2) When measured from harvest to sprouting, the dormant period was shorter for tubers from an early compared to a late planting. 3) With the same planting date and different harvest dates, when measured from planting or tuber initiation to sprouting, the dormant period was shorter for tubers from an early compared to a late harvest. 4) On the other hand, with the same planting date, when measured from time of harvest to sprouting, the dormant period was longer for tubers from an early compared to a late harvest. Planting date to sprouting was considered the best practical field measure of dormancy since it closely correlated with tuber initiation to sprouting, a method which was more accurate but difficult to determine. Both methods were much better than harvest date to sprouting which is commonly used. In addition, larger tubers from earlier planting had shorter dormancy than smaller tubers regardless of method of measurement due to a probable earlier set. From later plantings, tuber size had no relationship to length of dormancy. Moisture stress significantly reduced dormancy of Lemhi, Russet Burbank, and Nooksack but the Butte cultivar was only slightly affected.     

Serogroups ofErwinia carotovora involved in systemic infection of potato plants and infestation of progeny tubers

Enrichment techniques and serological strain typing methods were used to determine the source of stem and progeny tuber populations ofErwinia carotovora (Ec) in 1980 and 1981. Plots were established in a field that had been planted with potatoes since 1972. Seed tubers of cultivars Russet Burbank and Norgold Russet were assayed forErwinia carotovora pv.carotovora (Ecc) andErwinia carotovora pv.atroseptica (Eca) by tuber peeling and direct plating and plating following enrichment in a pectate-based broth. Levels of seed tuber infestation ranged from undetectable to 2.4 × 10⁴ colony-forming units per g peel tissue. Prior to planting Ecc was detected in soil samples from field plots by enrichment in a pectate-based broth. Ec was isolated from symptomless plants with increasing frequencies from 8 weeks following planting regardless of the level of Ec populations in seed tubers. At harvest progeny tuber recontamination was low and not related to levels of seed tuber Ec populations. In 1980, serological typing of representative Ecc isolates indicated serogroups III, XXIX, and unknown strains isolated from the soil but not the seed tubers prior to planting were isolated from stems and progeny tubers. Serogroup XXIX was isolated from soil, seed, stems and progeny tubers in 1981. Throughout both years, Ecc was isolated more frequently than Eca from seed, soil, stems, and progeny tubers. These data emphasize the potential for reinfestation of seed stocks and infection of plants by populations of Ecc that overwinter in soil under Wisconsin conditions.     

Comparative performance of different-sized seed tubers derived from true potato seed

The growth and yield of plants from different-sized seed tubers derived from true potato seed were evaluated on a per stem, per plant, and per unit area basis using either single or multiple-sprout tubers. In single-sprout tubers, haulm dry weight per stem 47 days after planting was greater in the 40–60 g tubers when compared with that in the 5–10 g or the 10–20 g tubers. This resulted in greater tuber weight per stem in the 40–60 g tubers throughout the growing season. The number of tubers per stem was not affected by seed tuber size. In multiple-sprout seed tubers of increasing size, total tuber number and total tuber weight, as well as weight of those tubers larger than 45 mm, increased on a per plant basis but decreased on a per stem basis. At different rates of planting, 1–5 g seed tubers produced smaller tubers than 5–10 g or 10–20 g seed tubers. Increased rate of planting resulted in non-significant yield increases per unit area in plots planted with 1–5 g seed tubers. The yield increases were significant when 5–10 g and 10–20 g seed tubers were planted at higher rates. The number of main stems per unit of seed tuber weight was five times greater in 1–5 g tubers compared with that in 40–60 g tubers. This resulted in low seed weights per hectare when small tubers were planted and in a high ratio of harvested to planted tuber weight.