Sugar and dry matter changes in potatoes stored in a clamp in a mountainous region of Northern Greece

Summary Potato tubers (cvs Fina, Marfona and Spunta) were stored in a clamp in the region of Mount Vermion in Northern Greece (altitude about 1400 m) from October 1985 to April 1986. No sprout inhibitor was applied. Tubers were analysed for dry matter and sugar content at 2–4 month intervals. Cultivar and date of sampling had a no significant effect on dry matter but had a significant effect on the total and reducing sugar contents. A significant interaction between cultivar and date of sampling was observed for dry matter and sugars. A continuous increase of total and reducing sugars from October to April was found in tubers of cv. Marfona. In tubers of cvs Fina and Spunta the total and reducing sugars increased, significantly only until March, and thereafter decreased.     

Sugar content and dry matter in potatoes stored under fluctuating temperatures in non-refrigerated stores in Greece

Summary Potatoes were stored in non-refrigerated stores in the Marmarini area (central Greece, altitude about 50 m) and in the Polymylos area (northern Greece, altitude about 900m). In Polymylos, the tubers (cvs Fina and Spunta) were harvested in October 1985 and stored until April 1986; the temperature in the store fluctuated between −1°C and 14°C (mostly between 3°C and 7°C). In Marmarini, the tubers (cvs Sebago and Spunta) were harvested in December 1985 and stored until April 1986; the temperature in the store fluctuated between 0°C and 18°C (mostly between 5°C and 10°C). Every 1–2 months tubers were analysed for dry matter (DM), total sugars (TS) and reducing sugars (RS). In Marmarini, a significant increase of TS and RS was found in both cultivars from December to January, followed thereafter by a significant decrease. In Polymylos, a continuous (from November to April) increase in TS and RS was observed in cv. Fina while in cv. Spunta the sugars increased only until January, followed thereafter until April by a significant decrease.     

Production of seed potatoes in Cyprus: the effects of roguing and planting date on the spread of potato leaf roll virus,tuber yield,and infestation by potato tuber moth

Summary Field experiments during 1984–6 tested the effects of planting date on the development of aphid infestations and the spread of potato leaf roll virus (PLRV) in rogued or unrogued plots of potatoes, cv. Spunta. Plantings were made each month from December to April, the customary time for planting being February. Aphid infestation in early-planted plots was severe throughout the growing season; plots planted in February were also severely infested early in the growing season but the populations later gradually declined to undetectable levels. Nevertheless, the incidence of PLRV in the latter plots was as high as in those planted in December-January. Late-planted crops escaped aphid infestation and PLRV infection, either in part (March planting) or completely (April planting). Such crops, however, were uneconomical due to poor yields and heavy losses from potato tuber moth infestation. Roguing significantly reduced the spread of PLRV in all years but its interaction with planting date was insignificant.     

Effects of drought on chlorophyll fluorescence in potato (Solanum tuberosum L.). II. Relations between plant growth and measurements of fluorescence

Summary Relations between measurements of the slow kinetics of chlorophyll fluorescence and growth and yield were examined in seven potato genotypes grown either fully irrigated or droughted from the time of plant emergence. Drought reduced total dry matter production and yields and increased tuber dry matter concentration. Drought increased harvest index in cv. Spunta, but decreased it in cv. Pentland Crown. Total dry matter production was correlated with each of constant fluorescence, variable fluorescence and the half life of the decay in variable fluorescence. These correlations were determined largely by the effect of treatment, and did not discriminate effectively between genotypes within a treatment.     

The effect of autumn fungicide application on spring dry matter accumulation in perennial ryegrass cv. S24

Fungicide applied to plots of perennial ryegrass cv. S24 in the autumn of 1981 significantly increased tiller number and total dry matter accumulation in February and March of 1982. However, fungicide application in the autumn of 1982 failed to increase tiller number or dry matter accumulation in the spring of 1983. It is suggested that fungicide application in autumn 1981 prevented the death of tillers caused by fungal attack after snow covered the plots in December 1981.     

Effect of seed source, presprouting and desiccation date on the processing quality of potato tubers for French fry production

Summary The effects of seed source, presprouting and desiccation date on processing quality parameters in the cultivars, Maris Piper and Rooster were investigated over four seasons. Tuber dry matter, sucrose, reducing sugar concentrations and fry colour were measured. Seed source did not affect sucrose concentrations, significantly affected tuber dry matter in three of the four seasons and had no effect on reducing sugar concentrations or fry colour. Presprouting seed, reduced sucrose concentrations during two seasons from four and increased dry matter concentration of cv. Maris Piper during one season from four and in cv. Rooster during two seasons from four; lowered reducing sugar concentrations following storage in one season from three and did not affect fry colour. Delaying the desiccation date decreased sucrose concentration in all seasons, increased tuber dry matter concentration during two seasons and induced higher reducing sugar concentrations and darker fry colours.     

Influence of growth conditions on the value of crisphead lettuce

Crisphead lettuce (Lactuca sativa L. varcapitata cvs.Marius andSaladin) were grown with a nitrogen supply from 50 to 200 kg N/hectare. Heads were stored for one or two weeks at 1 °C in cold storage or ice bank cooling. Samples were taken for measurement of dry matter, sugars, vitamin C and nitrate. The content of dry matter, sugars (glucose, fructose) and vitamin C decreased with increasing level of nitrogen, and the content of nitrate increased. Except for nitrate the contents of the other quality attributes decreased at all nitrogen supply levels during storage. No differences were found between the storage systems, and beside fructose no significant differences were found between the two cultivars. The content of dry matter, vitamin C, and nitrate decreased from the outer to the inner head fraction, while the content of sugars increased. Trimming decreased the content of dry matter, vitamin C and nitrate and increased the content of sugars. To obtain heads from storage with a relatively high content of dry matter, sugars and vitamin C, and a relatively low content of nitrate the nitrogen supply must be as low as possible. Except for nitrate where no distinct results were found in this experiment it must also be recommended to store the heads as short time as possible. Possibly the cv.Saladin has some advantage quality attributes after storage compared with the cv.Marius.     

Effects of temperature pre-treatment of transplants from in vitro produced potato plantlets on transplant growth and yield in the field

Summary In vitro produced potato plantlets, cvs Gloria and Spunta were planted in soil and exposed to day/night temperatures of 18/12 or 26/20°C for 14 days. They were then transplanted into the field in two experiments to assess after-effects of temperature on the performance of short-cycle crops. Accumulated intercepted radiation (AIR) was calculated from ground cover and incoming radiation, and dry matter production and fresh tuber yield were frequently recorded. Pre-treatment at 26/20°C caused higher leaf area at the end of the transplant production phase and resulted in a higher AIR at the end of the field phase than pre-treatment at 18/12°C. Higher AIR, however, was not associated with significantly higher yield. Initially, the proportion of dry matter partitioned to tubers was lower after 26/20°C, but this effect did not persist. High temperature pre-treatment may improve the performance of plantlets, especially of very early potato cultivars.     

The effect of storage conditions on chemical content of raw potatoes and texture of cooked potatoes

Summary Texture of boiled potato tubers (cv. Beate) was studied over several months of storage at either 4 or 8 °C, in relation to dry matter content, non-starch polysaccharides (NSP), methyl groups, glucose, starch and amylose. The dry matter content decreased significantly during storage at 4 °C, but increased at 8 °C due to evaporation. The insoluble NSP contained rhamnose, galactose, arabinose, xylose, mannose, fucose and glucose; the first three sugars decreased significantly after the first 7 weeks of storage. Fracturability and percent compression before break increased during storage at 8 °C, particularly percent compression after 15 weeks. The change in fracturability could partly be explained (R²=43.4%) by the content of the NSP and the increase in percent compression by dry matter (R²=91.8%). Changes in texture during storage at 4 °C, however, were not striking, and could not be explained by changes in the potato components that were analysed.     

Potato micropropagation: Growth of cultivars in solid and liquid media

Summary The effect of liquid and solid media on the growth of micropropagated potato shoots (cvs Spunta, Kennebec and Huinkul) was studied in relation to the availability of nutrients and water in the culture medium. Nitrogen and sugar assimilation in the shoot and the water content of the shoots were evaluated. The water content of the plant tissues was not affected by the physical state of the medium. The liquid medium caused a greater accumulation of dry matter in the shoot without changing assimilate partition. The liquid medium increased shoot growth without affecting the number of nodes. The higher growth rate of shoots in liquid medium was correlated with increases in their organic nitrogen and sugar contents, indicating that nutrient assimilation was favoured in liquid media.     

Evaluation of potato cooking quality in Argentina

Cooking quality of mature tubers was assessed for ten Argentine potato cultivars, two cultivars of foreign origin and three advanced clones. Specific gravity, dry matter and starch content, as well as quality of boiled potatoes and chips were determined Pampeana INTA had the highest dry matter content with 21.8 percent and would appear to be a very good cultivar for dehydrated products. The lowest dry matter values were obtained for three of the four most widely planted cultivars: Spunta, Bonaerense La Ballenera and Kennebec Kennebec demonstrated its good quality for chipping with a score of 6.9 points. Primicia INTA and Sureña INTA with high dry matter content and good features for chipping can also be used to produce chips Breeding under high temperatures during tuberization has proven to be a successful strategy in developing cultivars that are superior in dry matter contents to the cultivars currently imported from the northern hemisphere     

Dry matter content and mineral composition of potatoes grown in Cyprus

Summary The specific gravity and dry matter content of 193 tuber samples (cultivars: Arran Banner, Spunta, Up-to-Date, Cara) from crops grown at Kokkinochoria, the major potato growing area of Cyprus, were related to each other as follows: Dry matter (%)=−269.59+268.24×specific gravity. This regression accounted for 82.4% of the variation; the fiducial limits (P<0.05) for single determinations of specific gravity were±1.54 percentage units. The mineral contents of the tubers were similar to those reported in other countries.     

Influence of irrigation regimes on growth and yield of potato cv. Spunta

Summary The effect of furrow and drip irrigation giving 0, 33, 66, 100 and 133% of the maximum evapotranspiration (ETM) was studied on leaf transpiration, stomatal resistance, tuber growth, yield and yield response of cv. Spunta. The research was carried out in Sicily in 1988 and 1989 on early potato crops grown during the winter/spring cycle. Increased water supply increased leaf transpiration, plant fresh weight, tuber growth rate, yield and earliness, and decreased stomatal resistance and tuber dry weight. A higher yield response was obtained at the lower water regimes (ETM of 33 and 66%). There were no significant differences between the two methods of irrigation.     

Large scale commercial production of potato minitubers, using in vitro techniques

Summary Large scale, commercial production of potato minitubers, cvs Spunta, Jaerla and Kennebec, has been carried out in VITRO HELLAS S.A. since 1995, according to protocols based on in vitro methods. Apical meristems were cultured on MS medium supplemented with 1 μM IBA, 20 g/l sucrose and 6 g/l agar (pH 5.8). Subculture was carried out every 15 days. Multiplication rate was 4–5 per cycle. Self-rooted microplants were transferred into screen houses (200 plants/m²) in a mixture of peat and perlite 1∶1 (v/v). Cultivation period was 15 August to 15 November each year. During the period 1995–1997, the number of minitubers produced/plant was 2.07 for cv. Spunta, 1.85 for cv. Jaerla and 2.52 for cv. Kennebec and their average weights were 10.8 g, 10.9 g and 9.8 g, respectively. The percentage of minitubers<10 mm in diameter was 2%, 50.1% were 10–20 mm and 47.9% were>20 mm.     

THE PRODUCTION AND USE OF COCKSFOOT FOGGAGE FOR WINTER GRAZING IN SOUTH-WEST SCOTLAND

The production and use of cocksfoot foggage for winter grazing at the Hannah Dairy Research Institute in the period 1956–61 is described. Two acres of cocksfoot (S37) were sown broadcast in 1956 and two acres were drilled in rows 28 in apart in 1957. The average annual application of fertilizer nutrients was 118 lb. N, 51 1b. P2O5 and 142 lb. K2O per acre.
The mean yield of the broadcast section was 7450 lb. dry matter/acre/annum compared with 6090 lb. from the rowcrop section. Normally two crops of grass were harvested from the field in the summer, and one grazing was made in the winter. The yield of winter herbage dry matter was 28% and 26% of the total annual yield of the broadcast and the rowcrop sections, respectively.
The field was grazed for four successive winters by 5–10 bulling heifers each weighing 650–850 lb. They received no other feed during the grazing period. Grazing started in December and finished in February, March or April in different years. The mean intake of herbage dry matter was only 6 lb./day, and on average the heifers lost 80 lb. liveweight each winter. This loss was regained after 4–6 weeks when the winter grazing finished. Twenty-nine of the 30 heifers held to the first or second service while grazing the winter herbage.
On average the broadcast section gave 340 heifer-grazing-days per acre during the winter and the rowcrop section 260 days. The cost of a heifer-grazing-day was 3id. and 4id. on the broadcast and rowcrop sections, respectively.
The dry matter of the herbage cut on 19 December 1960 had a digestible crude protein content of 59% and a starch equivalent of 34.
It is concluded that on well-drained land the technique of foggage production and of winter grazing can usefully extend the normal grazing season and hence reduce the costs of winter feeding.     

Effects of spring defoliation and fertilizer nitrogen on the growth of white clover in ryegrass/clover swards

An examination was made of the effects of different spring treatments on the growth of white clover in a ryegrass/white clover sward. Plots were either cut once (in February, March or April) or twice (in February and April) or left uncut. Nitrogen was applied to half of the plots in each instance. The clover was sampled at intervals of approximately 3 weeks from February to June to determine numbers of leaves and growing points and weights of plant parts. Rates of leaf appearance were also observed and estimates were made of total herbage mass from ground-level cuts.
Percentages of white clover in the herbage were higher in unfertilized than in fertilized plots and in defoliated than in undefoliated plots. The percentage increases that followed defoliation were usually maintained into later regrowth, showing that clover content was not automatically reduced as herbage mass increased. Increases in growing points were recorded after the beginning of April in defoliated unfertilized plots but not in undefoliated fertilized plots or in plots fertilized and defoliated twice during the spring period, in which numbers fell substantially.
Inverse relationships were found between rates of leaf appearance, or the number of green leaves retained per stolon, and herbage mass, whereas heights of clover and grass leaves and the percentage of dry matter allocated to petiole rather than leaf in the clover increased with increasing herbage mass.
We suggest that the observed differences between spring treatments in clover percentage result primarily from their differential effects on the formation and death of tillers and growing points in the early stages of regrowth.     

热研7号柱花草的选育

进行了热研7号柱花草品种比较试验、区域试验和生产性试验的选育研究。研究结果表明:该品种具有高产、优质、抗病、耐寒、晚熟的特点。年平均干草产量14879.3kg·hm-2,年平均种子产量424.0kg·hm-2 ,分别比格拉姆柱花草增产84.0%、116.4%,与热研2号柱花草差异不显著。粗蛋白含量16.86%,粗脂肪含量2.65%,生育期为239d。可用于青饲料、干草粉生产等。适合我国热带、南亚热带地区种植。      

菠萝不同月份采收果实品质变化规律研究

以我国菠萝主栽品种‘巴厘’为试材,分析不同月份采收的菠萝果实Vc、可滴定酸、可溶性糖和可溶性固形物的变化,结果表明：不同月份成熟的菠萝果实Vc含量有差异,1～12月呈先降低后升高的趋势,11～4月较高,5～9月较低;可滴定酸含量与Vc含量变化趋势一致,11～3月较高,4～9月较低;不同月份成熟菠萝果实可溶性糖含量变化无明显规律,1、5、6、7、12月较高,其他月份较低;可溶性固形物含量表现出与Vc、可滴定酸含量变化相反的趋势,5～7月较高,其次为9、11,2、3月,可溶性固形物含量最低;各月份果实糖酸比情     

Effect of winter grazing date on yield components of Lolium perenne (L.)/Trifolium repens (L.) hill pasture

Perennial ryegrass/white clover pastures were grazed at different times in the winter to study the effect of time of grazing on subsequent plant growth. In 1983–84, 1984–85, and 1985–86, pastures were grazed to a residual of 400 kg dry matter ha^-1 by sheep once in early December (D), January (J), February (F), March (M), or April (A) and compared with an ungrazed control (C). Rates of herbage accumulation on C in the winter were low, averaging 6, -9, and 2 kg dry matter ha^-1 in December, January, and February, respectively. Little forage production occurred during the month immediately following winter grazing. Herbage accumulation rate then increased sufficiently to replace the forage removed from winter-grazed paddocks by early spring. By May, herbage mass on grazed treatments was similar to C except for D and A which averaged 20 and 47% less forage than C, respectively (P<0·01). Herbage accumulation rates of D were unique among winter grazing treatments in never exceeding those of C. By May 1986, D yielded less perennial ryegrass compared with C (P<0·05). Grazing reduced the number of leaves per ryegrass tiller for 1 to 2 months following grazing. By May, J, F and M had numerically more tillers m^-2 and more leaves per tiller than C. Similar May yields of J, F, M, and C resulted from fewer but larger and slightly less leafy tillers of ungrazed compared with winter grazed plants.     

Performance of Dimethomorph + Mancozeb Applied to Seed Potatoes in Early Management of Late Blight (<Emphasis Type="Italic">Phytophthora infestans</Emphasis>)

Treating seed potatoes with contact fungicides prevents infection of Phytophthora infestans from tuber to tuber during handling but does not prevent field infections in the young plant. Dimethomorph (DMM) 9% + mancozeb 60% (Acrobat MZ, BASF) can cover both aspects due to the contact and systemic action of mancozeb and DMM, respectively. Experiments were performed under greenhouse and field conditions (three seasons and two locations) with cvs Kennebec, Shepody, Spunta, Russet Burbank, and Ranger Russet. Immediately after cutting, seed pieces were treated with Acrobat MZ at doses equivalent to 2, 3, and 4 kg ha⁻¹. At any dose, Acrobat MZ protected healthy seed tubers against P. infestans infections. Acrobat MZ (4 kg ha⁻¹) also protected the foliage of all cultivars against artificial inoculation of P. infestans, assessed by the detached-leaf method. These effects were observed up to 30 days after emergence in greenhouse experiments and up to 28 days after crop emergence under field conditions in two growing seasons. In cv Spunta, significant foliage protection was observed up to 35 days after field emergence whereas in seed tubers of cv Kennebec planted in sandy soils, significant foliage protection persisted longer. Additional evidence for acropetal translocation of Acrobat MZ in field crops was also found. With this strategy, there is no need to apply contact or systemic fungicides early in the season, and spraying costs and environmental risks are also reduced.