The effect of stem population on tuber yield in a trial with single-stem seed pieces

Summary Excised eyes on 5 g of seed tuber tissue were used to grow plants with single stems. These were transplanted in the field at densities of 120 000, 180 000 and 240 000 plants/ha, with in-row spacings of 16 or 33 cm. Total tuber yield was not affected, although more tubers were produced at the high densities. Tuber numbers did not increase in proportion to the number of stems. This was due to the fact that the number of tubers per stem decreased from a mean of 4.8 to 2.9 with increasing stem populations.     

Rapid seed multiplication by planting into beds micro tubers and in vitro plants

Summary Micro tubers of 3 weight categories with means of 0.63 g, 1.25 g or 2.50 g and in vitro plants were planted in nursery beds at densities of 24 and 48 plants per m². The average tuber numbers and tuber weights were, respectively, 38% and 17% higher at 48 than at 24 plants per m². In vitro plants produced significantly more but smaller tubers than did plants grown from micro tubers. Plants grown from the larger micro tubers produced a similar number of tubers but larger ones than did plants grown from small micro tubers. Tuber yields and multiplication rates are discussed.     

Potato (Solanum spp.) production using apical cuttings and tuberlets under three contrasting environments of Vietnam

Potato production from rooted apical cuttings or from small tubers (l–20g) produced in high density beds has great potential in Asia. This is particularly important in non-traditional warmer environments. This research was conducted to assess the feasibility of producing many small tubers in high density beds. A second objective compared tubers from beds with transplanted rooted cuttings and traditional seed tubers for growth and yield in the field. Tuberlet production in beds exceeded 2000/m² with a density of 1000 plants/m² under optimal growing conditions while under high temperatures only about 1.25 tuberlets/plant were produced. In field experiments, transplanted cuttings yielded 20 t/ha in the mid and high elevation areas, only slightly less than tuberlets of 5–10g while at the hot site, yields were generally only 8 to 10 t/ha for both materials. Larger healthy seed tubers produced significantly higher yields at the low and high elevation sites. Tuberlets of 1–5g were also able to give yields of 20 t/ha in the mid-elevation site. These results indicate that cuttings and small tuberlets are two ways of growing potatoes which need to be further evaluated for socioeconomic assessment by farmers.     

Potato leafroll virus concentration in the vascular region of potato tubers examined by enzyme-linked immunosorbent assay (ELISA)

Summary Enzyme-linked immunosorbent assay (ELISA), used in conjunction with a new rapid extraction method, showed that potato leafroll virus (PLRV) concentration in the vascular region of infected potato tubers decreases from the heel to the rose end. Lower virus concentration at the rose than at the heel end was found not only in dormant tubers but also in tubers three weeks after breaking dormancy although the difference was then less pronounced. These results were obtained from plants with both primary and secondary infection by one of two French virus isolates which behave differently in respect of either accumulation in the ants or in their serological properties or both.     

Influence of time of application of maleic hydrazide on the yield and quality of Russet Burbank potatoes

A three-year study in central Wisconsin with timed foliar applications of maleic hydrazide at 3 lb/A (3.36 kg/ha) resulted in an improvement in quality and a favorable alteration in the shape of tubers of the Russet Burbank potato variety. Application in early and mid-July resulted in an increase in yield of U.S. 1 tubers and reduced yield of malformed tubers. Over 40 percent fewer misshapen tubers were produced when applications of maleic hydrazide were made during July when compared with tubers from untreated plants. Applications made in midor late July resulted in tuber development with a more favorable length to diameter ratio of U. S. 1 tubers, again compared with tubers from untreated plants. Maleic hydrazide applied in early or mid-June resulted in severely reduced yield and increased incidence of misshapen tubers. When applied in July or early August, no effect on tuber specific gravity was found. Maleic hydrazide functioned as an effective sprout inhibitor on tubers from all treatment dates except when applied in early June.     

Enzyme-linked immunosorbent assay (ELISA) for the detection of potato leafroll virus and potato virus Y in potato tubers after artificial break of dormancy

Summary Conditions necessary for the detection of potato leafroll virus (PLRV) and potato virus Y (PVY) in tubers from primary and secondary infected plants were investigated. Tubers were analysed before and after breaking dormancy by rindite treatment. PLRV was reliably detected indormant tubers whereas PVY was readily detected only when tubers had been rindite-treated and held for two to three weeks at 22°C and high humidity in the dark. PLRV occurred in higher concentration at the heel end than at the rose end of infected tubers and the concentration remained nearly unchanged during the experimental period of 35 days, whereas PVY was found to be more concentrated at the rose end and was rapidly accumulating in the tubers after the break of dormancy. In dormant tubers PVY concentration dropped during storage at 22°C. The use of ELISA for tuber indexing is discussed.     

Response of Russet Burbank potatoes to ethephon sprays

Ethephon ((2-chloroethyl)phosphonic acid) was sprayed on the foliage of Russet Burbank potatoes at tuber initiation in four separate field trials over two years. Rates were 0, 61, 122 and 183 g ai/ha. Total yield, yield of U.S. No. 1’s, hollow heart and brown center generally decreased at higher ethephon rates. Yield of undersized tubers increased. Ethephon sprays generally decreased specific gravity but the effect was minor and not consistent. In three of the four plantings where hollow heart and brown center in the untreated controls exceeded 8 t/ha, the low rate of ethephon increased the yield of non-hollow tubers ≥56 g in size.     

利用TPS夏播生产优质实生种薯的研究——夏播TPS生产实生种薯

本文是利用TPS夏播生产优质实生种薯的初步研究结果,它由种著大小试验、实生苗密度试验,夏播TPS生产实生种薯试验三部分组成.这三个试验是在1989~1992年进行的.试验揭示了种薯大小与后代生长发育的关系,认为3g以上的小整薯均可直接播于大田生产实生种薯,土壤肥力和实生苗密度是影响夏播生产实生种薯的主要因素,土壤肥力更重要.实生苗的定植密度应大于120株/m~2.初步证明,利用TPS夏播生产实生种薯是可行的.     

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.     

Effects of inoculum source and irrigation on black dot disease of potatoes (Colletotrichum coccodes (Wallr.) Hughes) and its development during storage

Summary In 1985 and 1986 plots were planted with seed tubers affected with black dot and with healthy seed inoculated or not with cultures ofColletotrichum coccodes at planting. Half the plots were irrigated from shoot emergence to the end of July. Seed tubers rotted more often when they were diseased than when they were not and rotting was increased by irrigation; by contrast, up to 18 weeks after planting irrigation decreased infection of stem-bases, roots and tubers. Tuber infection, first recorded in July, increased throughout the season and most rapidly from September, when the irrigation applied earlier increased disease. Soil-applied inoculum gave most disease in both years and tubers from healthy seed gave least in 1986 but as much as from diseased seed in 1985. Incidence and severity of black dot increased more during storage at 15°C than at 5°C and only on unwashed tubers.     

Position and date of seed tuber inoculation byErwinia carotovora ssp.atroseptica and appearance of potato blackleg

Summary The date of inoculation and the part of the potato seed tuber inoculated both influenced the number of blackleg plants appearing in June, July and August. In winter, inoculation of the heel end was more effective than inoculation of the rose end of seed tubers, but there were no significant differences following inoculation earlier, in autumn, or later, in spring.     

The dependence of internal brown spot development upon calcium fertility in potato tubers

Summary To determine calcium fertility and high temperature effects on internal brown spot development in potato, cv. Russet Burbank plants were fertilised with Hoagland's nutrient solution with or without calcium. Prevalence and severity of internal brown spot were greatest in tubers receiving no calcium fertilisation during growth. Internal brown spot was evident as early as tuber initiation. A high growth medium temperature (32°C) at tuber maturity with a lack of calcium increased internal brown spot incidence and severity. No tubers subjected to the high temperature and fertilised with calcium developed internal brown spot. Peel calcium concentration of tubers receiving no calcium fertilisation was lower (0.5–0.8 g/kg) than tubers receiving calcium (1.2–1.9 g/kg). Medullary tissue calcium concentration was similar under both calcium regimes. Calcium availability during early tuber growth was an influential factor in internal brown spot development, however high temperature effects may not be discounted in exacerbating the disorder. H/LA Paper No. 95-7. Project No. 1984, College of Agriculture and Home Economics Research Center, Pullman WA 99164, USA     

Microtuber and minituber production and field performance compared with normal tubers

Summary Microtuber and minitubers of cv. Monalisa were produced in the laboratory and compared with normal seed tubers in a field experiment. These tubers were planted at similar plant densities (13.6 sprouts per m²) with two distances between rows (60 and 90 cm). Final ground cover was almost complete only in the plots derived from normal tubers and decreased with the size of the mother tubers. Normal seed, mini- and microtubers yielded respectively 50.8, 31.7, and 17.0 t/ha (means of two spacings). At close and wide spacing between rows, microtubers yielded respectively 27.3 and 6.7 t/ha, and minitubers 38.9 to 24.4 t/ha. Row spacing did not influence the yields from normal seed tubers. Total number of tubers per m² was also affected and, as means of the two spacings, ranged from 107.8 with microtubers, 122.1 with minitubers, to 142.9 with normal tubers. Mother tuber type also affected the yield distribution in three tuber grades (<36, 36–55, and 55–80 mm) and micro and minitubers produced many small tubers. Multiplication rates and the possible use of different propagation sources are discussed.     

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.     

Myzus persicae (Sulzer) in diffuse light and dark rustic storages and resultant PLRV transmission

Population levels ofMyzus persicae (Sulzer) were studied on potato tubers in diffuse light and dark rustic storage houses in Peru. No differences in numbers of aphids/sprouted eye on potatoes infested naturally during storage in diffuse light or darkness were observed. Significantly more alate aphids were observed on tubers stored in darkness than in diffuse light storage houses. Viral transmission was occurring during the storage period. The incidence of viral transmission was not significantly influenced by storing tubers in diffuse light or dark storages. There were significantly more plants infected with virus from tubers that had not been sprayed for aphid control than from tubers that had been sprayed     

Effect of Potato Microtuber Size on the Growth and Yield Performance of Field Grown Plants

Abstract

To examine the effect of the size of the potato microtuber (MT) produced in vitro on the posterior field performance, we examined the growth and yield of the late maturity cultivar Norin 1 using four sizes of MT: 0.3–0.5 g, 0.5–1 g, 1–3 g and 3–5 g, and conventional seed tubers (CT) (approximately 50 g). The experiment was conducted at Hokkaido University, Sapporo Japan in 1998 and 1999. The tubers were planted in May of each year, in a randomized block design with three replications. Plants from MT lighter than 0.5 g showed a slower initial leaf and tuber growth than heavier MT, but around the full flowering stage there was no significant difference with the MT size in leaf or tuber growth. CT plants showed higher initial leaf and tuber growth compared with MT plants, especially in 1999. No differences in growing period, number of tubers, and tuber fresh and dry yield were observed with the MT size. However, in 1999, the growing period was longer and tuber fresh and dry yields at harvest were higher in CT plants. MT of all sizes used in the study can be used for direct field planting, but more studies are needed to increase the yield stability of MT plants.     

Effects of temperature and photoperiod on early growth and final number of tubers in potato (Solanum tuberosum L.)

Summary A phytotron experiment with all combinations of two photoperiod (12 or 18 h) and four temperature (18/12, 22/16, 26/20 or 30/24 °C; 12h/12h) treatments was carried out to analyse quantitative effects on early tuber growth, dry-matter partitioning and number of tubers of two cultivars. Higher temperatures and longer photoperiod delayed the onset of expolinear tuber growth and the onset of linear tuber bulking. Higher temperatures also gave lower absolute tuber growth rates. Photoperiod did not affect absolute tuber growth rate at lower temperatures. Higher temperature and longer photoperiod gave lower relative rates of partitioning of dry matter to the tubers. Differences between treatments in numbers of tubers initiated were inconsistent. This quantitative analysis of the effects of temperature and photoperiod on characteristics of tuber growth should prove useful in potato modelling.     

Growth and yield of potatoes as affected by severity of stem canker (Rhizoctonia solani)

Summary Different amounts ofRhizoctonia solani inoculum were applied to sprouted and non-sprouted seed tubers cultivar Désirée during planting in field experiments at Rothamsted in 1984 and 1985. Severity of stem canker and stolon infection increased with increasing amounts of inoculum; with small or medium amounts these infections were most severe on plants from sprouted seed. In 1985 plants grown from non-sprouted, seed had most stem canker when large amounts of inoculum were applied. Severe infection following high inoculum levels delayed shoot emergence, increased the variability in stem height and decreased the mean height of stems and weight of foliage but did not affect the number of stems per plant or final plant populations. Tuber initiation was delayed and tuber numbers slightly decreased by severe infection and at harvest the size distribution of tubers was altered. Tuber yields from severely infected plants were decreased by 15% (sprouted seed) and 19% (non-sprouted seed) in 1984 and by 17 and 28% respectively in 1985.     

Inhibition of potato tuber sprouting: Low levels of cytosolic pyrophosphate lead to non-sprouting tubers harvested from transgenic potato plants

Summary ExpressingE. coli inorganic pyrophosphatase in transgenic plants demonstrated that long distance sucrose transport is dependent on cytosolic pyrophosphate. It was speculated that removal of cytosolic pyrophosphate would impair sucrose utilization during storage of potato tubers and thereby prevent tuber sprouting. To explore this hypothesisSolanum tuberosum var. Désirée plants were transformed with a chimeric PPa gene. FollowingAgrobacterium mediated transformation, metabolite and carbohydrate contents of growing and stored tubers were measured. There was a large accumulation of soluble sugars and a decrease of starch at all developmental stages investigated. The PPase activity in PPaII tubers was parallel with a decrease of PPa, an increase of fructose-2,6-bisphosphate and an increase of UDP-glucose. As expected the amount of hexose-6-phosphates and glycolytic intermediates decreased. As a consequence PPaII tubers did not sprout even after a prolonged storage period of two years. Since the energy status of PPaII tubers is unaltered inhibition of sprouting is most likely due to reduced sucrose export and its subsequent utilization.     

Morphological changes and yield enhancement of superior potatoes by AC 243,654

AC 243,654, 1-(m)-methoxybenzyl)-3-nitroguanidine, represents a new family of plant growth regulators with cytokinin-like activity. This compound was tested at 1 and 4 kg/ha on greenhouse-grown potatoes (Solanum tuberosum L.), cultivar Superior. The treatments were applied two weeks after emergence. Morphological and yield effects of AC 243,654 were determined at 4, 7, 11, 14, 21, 42 and 70 days after treatment (DAT). Shortly after treatment, AC 243,654 stimulated plant height, branch number and stolon number. Plant weights were initially stimulated. At the final harvest, 70 DAT, the dry weight of treated plants was greater than that of the check plants; this is attributed to the anti-senescence effect of this compound on vine tissue. AC 243,654 induced tuber initiation at 14 DAT, whereas checks did not have tubers until one week later. Between 14 and 70 DAT, treated plants produced greater yield than check plants; the yield increases were primarily due to larger tubers. The yield of smaller tubers was decreased by the treatments. Although the number of larger tubers increased, total tuber number was decreased by AC 243,654. Observations on tuber number over time suggested that the check plants initiated more tubers than treated plants but most of these aborted. In treated plants, less tubers were initiated.