Influence of temperature and length of storage on resistance of potato to tuber rot induced byErwinia chrysanthemi

Tubers of 11 clones ofSolanum tuberosum subsp.andigena (andigena) and 12 cultivars ofS. tuberosum subsp.tuberosum (tuberosum) were inoculated with water suspensions (5.5 × 10⁴ 5.5 × 10⁵, 5.5 × 10⁶ CFU/ml) ofErwinia chrysanthemi. Tubers were inoculated immediately after harvest and after 6 and 16 wk of storage at 4 and 23°C. Tuber rot incidence in andigena and tuberosum increased as inoculum concentration increased. Based on tuber rot severity, clones of andigena were classified as resistant, intermediate, or susceptible and cultivars of tuberosum were classified as intermediate or susceptible. Rot severity increased in all tubers stored at 4°C and in tubers of tuberosum stored at 23°C; rot did not increase in tubers of andigena stored at 23°C. Electrolyte leakage (EL), total sugars (TS), reducing sugars (RS), non-reducing sugars (NRS) and dry matter (DM) were determined in non-inoculated tubers. There was a significant positive correlation between the rate of EL, concentration of RS and tuber rot in andigena and tuberosum. Tuber rot and DM were negatively correlated in tubers of andigena; but they were not correlated in tuberosum. Clones of andigena with low EL, TS, RS, and high DM were resistant to tuber rot, and the incidence of tuber rot in these clones was much less influenced by temperature and length of storage. The influence of temperature and length of storage on susceptibility toE. chrysanthemi may be explained by increased cell membrane permeability; increased leakage of accumulated sugars in potatoes stored at 4°C could favor bacterial proliferation resulting in more disease.     

Eradication of potato virus X from potato by ribavirin treatment of cultured potato shoot tips

Ribavirin treatment of cultured potato shoot tips was tested as a means of eradicating potato virus X (PVX) from two potato cultivars. Shoot tips were cultured on liquid medium containing 0, 1, 10 or 100μg/ml ribavirin. Cultures were evaluated periodically for viability, and scored for vigor on a relative growth scale. Developed plantlets were assayed for PVX by transmission tests toGomphrena globosa. Ribavirin treatment was phytotoxic at all tested concentrations, and lethal to all cultivars treated at 100 μg/ml. Treatment also delayed plantlet development by up to 2 months at 1 and 10 μg/ml as compared with nontreated controls. PVX assays indicated that 80 and 83% of the plantlets were free of PVX following treatment with 10 μg/ml for cultivars Russet Burbank and Red McClure, respectively. Five and 6% of the plantlets developed from the 1 μg/ml treatment were PVX-free, whereas 0 and 2% of the controls were PVX-free for the same cultivars. Six to 8 months were required to develop plants from shoot-tip cultures treated with 10 μg/ml ribavirin.     

Management of the Colorado potato beetle using the entomogenous fungusBeauveria bassiana

Small field plots of Katahdin potatoes on Long Island, NY were treated 6 times in 1980 for control of Colorado potato beetle (CPB)Leptinotarsa decemlineata (Say), Coleoptera: Chrysomelidae, using either the entomogenous fungusBeauveria bassiana (Balsamo) Vuill. (Bb) at 5x 10¹³ colony forming units/ha or fenvalerate at 0.227 kg active ingredient/ha. No significant differences were found between Bb and fenvalerate treatments in egg mass size and viability or in the total foliage consumed by first generation CPBs. First generation CPB larval populations were significantly higher in Bb plots. Oviposition by first generation adults and second generation beetle populations were higher in fenvalerate plots. Average yield was 29.4 metric tons/ha in fenvalerate plots and 24.6 metric tons/ha in Bb plots (a 16% reduction), but nearby untreated plots were completely defoliated by July 24 and yielded <7 metric tons/ha (> 60% reduction).     

Seed set in 4x x 2x crosses as related to 2n pollen frequency

Seeds per fruit following 4x × 2x crosses in potato are roughly related to the frequency of 2n pollen. Our goal was to examine precisely the relationship between frequency of stainable 2n pollen and seeds per fruit (s/f) in 4x × 2x crosses. A 4x cultivar with high female fertility and 21 2n pollen producing 2x hybrids were used as seed and pollen parents, respectively. 2n pollen frequencies varied from 1 to 99% in the 2x hybrids and seed set ranged from 0 to 305 s/f in 4x×2x crosses. Mean seeds per fruit increased in response to increases from 1 to 50% 2n pollen, but did not increase in response to using a pollen sample with a 2n pollen frequency over 60%. Seed set averaged 11 s/f corresponding to pollen samples with 1–5% 2n pollen, 50 s/f at 10–20%, 125 s/f at 20–30%, and over 170 s/f at 2n pollen frequencies over 60%. Seed set in 210 control 4x × 4x crosses indicated that equivalent seed set occurs in 4x × 2x crosses when 2n pollen frequencies are over 20–30%. The 2x hybrids differed in mean and variation of 2n pollen frequencies and seed set in 4x × 2x crosses. One 2x hybrid with a meiotic aberration (sy-3) resulting in all univalents at Metaphase I (ordinarily leading to male sterility) and parallel spindles (ps) at Anaphase II had close to 100% 2n pollen (of the stainable pollen) and gave equivalent s/f in 4x × 2x crosses to s/f in 4x × 4x crosses. It is apparent that ample seed set occurs for using the 4x × 2x breeding scheme with 2n pollen frequencies over 10% and that even very low 2n pollen frequencies (1–10%) provide seed for the 4x×2x breeding approach.     

Effect of short term ingestion ofTelfaria occidentalis (fluted pumpkin) on the liver

Four groups of female mice (18–22g) were fed for at least 10 days on a control diet or diets with addedTelfaria occidentalis (10% w/w) vegetables. Group 1 were the control animals. Group 2 were fed the vegetable diet alone. Group 3 were fed the control diet and injected with aflatoxin B₁(AFB₁, 0.35 mg/kg/day) in the last 3 days. Group 4 were fed with the vegetable diet and similarly treated for 3 days with AFB₁. No effects attributable to treatment were encountered in body weight, food intake, water intake and relative liver weight (g/100 g body weight). Decreases (17–40%) in PB sleeping time in the vegetable fed animals were not significant (P>0.05) in comparison to the control. Microsomal proteins increased by 2 fold in group 2 but were apparently normal in groups 3 and 4. In group 2 the activities of liver microsomal glucose-6-phosphatase and NADH-cytochrome c reductase increased but those of NADPH-cytochrome c reductase and aniline hydroxylase decreased. Increases were observed in the activities of all of these enzymes in groups 3 and 4. The highest increases were observed in glucose-6-phosphatase activity in mice fed the vegetables and also injected with AFB₁.     

Reaction of potato tuber slices toPhytophthora infestans in relation to physiological age

Tuber resistance toPhytophthora infestans was studied in relation to physiological age in tubers of the cultivars Atzimba, Katahdin, Kennebec, and Sebago. Resistance to race1,2,3,4 was evaluated in freshly harvested tubers, and tubers stored at 5 C for up to 215 days. Atzimba tubers were highly resistant when freshly harvested but became increasingly susceptible as they aged physiologically. Tubers of the other three cultivars were susceptible when freshly harvested and also when aged. Further, 57 tuber selections from among 11 crosses initially gave resistant reactions. However, after storage for six months at 5 C, 26.3% of the selections remained resistant, 22.8% were moderately resistant, 31.6% moderately susceptible, and 19.3% fully susceptible.     

Albinism of potato spindle tuber viroid-infected Rutgers tomato in continuous light

Potato spindle tuber viroid (PSTV) caused albinism in the new growth of Rutgers tomato under continuous light. The albinism response was obtained with 4 isolates causing severe symptoms in tomato and with 1 mild isolate which is normally symptomless. Rutgers tomato inoculated with the 4 severe strains of PSTV developed typical ‘bunchy top’ symptoms in 12 to 16-hr day lengths. Symptoms developed slower and much less distinctly on plants incubated in 6-hr days. New growth in PSTV-infected plants was green in short days (12-hr illumination) and chlorotic to white in continuous light. Infectivities of extracts from white portions of plants were from 3 to 10 times greater than those from green portions of infected plants. Albino symptoms also developed in other tomato varieties when inoculated with PSTV and kept under continuous light. Albinism was most pronounced under continuous light at 30°C, somewhat less intense at 24°, and at 16°, new growth of infected leaves and stems remained green. Albinism did not develop in otherSolanum species which are symptomless hosts of PSTV nor in seedling potato plants grown in continuous light.     

Phytophthora erythroseptica in Peru: Its identification and pathogenesis

EightPhytophthora isolates cultured from diseased potato plants and tubers in Peru were identified asPhytophthora erythroseptica Pethyb. var.erythroseptica. This pathogen was not previously reported from South America. The isolates were pathogenic to potato plants but they differed in virulence. Injuring roots prior to inoculation enhanced infection and disease development but all isolates infected noninjured roots. Continuous high soil moisture during incubation favored disease development. Under these conditions, disease developed at soil temperatures from 10 C to 30 C, but most rapidly at 25 C and 30 C. Plants grown 60 days before inoculation developed symptoms earlier and more rapidly than plants grown 15-, 30-, and 45 days. Four concentrations of mycelial-suspension inocula did not alter disease development, but zoospore inoculum induced symptoms and plant death more rapidly than mycelial suspensions at 25 C.     

Chemical vine desiccation of two potato cultivars

Russet Burbank and Onaway potato (Solanum tuberosum L.) vines were desiccated with diquat (6,7-dihydrodipyrido (1,2-a:2′1′-c) pyrazinediium ion), ametryn (N-ethyl-N-methylethyl)-6-(methylthio)-1,3,5-triazine-2,4-diamine), paraquat (1,1′-dimethyl-4,4′-bipyridinium ion), and endothall (7-oxabicyclo (2.2.1) heptane-2,3-dicarboxylic acid) applied at various rates alone or combined with surfactants, drift retardant, copper, or ammonium sulfate. Diquat and paraquat at 0.28 and 0.56 kg ha^?1 plus nonionic surfactant thoroughly desiccated Onaway and Russet Burbank potato vines. Only Onaway vines were thoroughly desiccated by ametryn at 1.3 and 2.3 kg ha^?1. Endothall at 0.87 kg ha^?1 provided thorough desiccation of Russet Burbank vines. The addition of a drift retardant did not reduce the effectiveness of diquat, while combining either ammonium or copper sulfate with diquat slowed the dieback of potato vines in 1987. Combining copper sulfate with diquat also slowed the dieback of Onaway vines in 1988. Both copper and ammonium sulfate, combined with diquat and nonionic surfactant, slowed the dieback of Russet Burbank vines when evaluated two days after application, but seven days later, no difference in vine dieback was evident. Crushing plants by rolling the field prior to desiccant application quickened vinekill by 18%. Applications of diquat using flat fan nozzles at 333 kPa provided vinekill equivalent to applications using hollow cone nozzles on a 25 cm spacing at 833 kPa, when spray volume for both applications was 467 L ha^?1. Potato yield, percentage of U.S. No. 1 potatoes, and stemend discoloration were unaffected by chemical desiccation.     

Kinetin,thermotherapy, and tissue culture to eliminate potato virus (PVX) in potato

PVX infected plantlets from two potato cultivars grownin vitro with 0.3, 3, 30 or 300 ppm kinetin were exposed to temperatures of 28 or 35 C. After 3 wk, axillary buds were isolated and grown aseptically in organogenic media, followed by PVX testing by ELISA. The serological test was also run on whole plantlets at the end of the kinetin-temperature exposure. No donor plants exposed to 28 C nor the plantlets derived from their buds gave an ELISA (-) reaction, regardless of the kinetin content of the media or that of the cultivar. At 35 C the virus was suppressed to undetectable levels in several whole plantlets. In the cultivar Alpha, 2 out of 6 resulting plantlets after isolation of buds were virus-free in the presence of 3.0 mg/1 kinetin during the treatments. From Atzimba, about 15–40% of the regenerated plants were ELISA (-), without any relationship to the cytokinin content in the media. Heat had a stronger influence on virus elimination than kinetin and the results varied with the cultivar.     

籼稻绿芽悬浮细胞原生质体再生成株

采用籼稻Hu-18绿芽为外植体,在N6附加2 mg/L 2,4-D的培养基上诱导愈伤组织。加20 d后转人AA 培养基进行悬浮培养。继代培养45 d左右形成了分裂旺盛的胚性细胞悬浮系。即从绿芽诱导至胚性细胞悬浮系的建立仅用了65 d左右。继代后前6 d,细胞干重几乎每2 d增加1倍,而培养液的渗透压及pH 值迅速下降。取继代后4 d的悬浮细胞游离原生质体,产率为8.74X10⁶/g鲜重。纯化后的原生质体在KPR培养基中进行琼脂糖包埋培养,原生质体植扳率为12.0％ 。将20 d后的小愈伤组织(0.1 mm)转入 N6附加0.5 mg/L 2,4- D、1 mg/ L BA、1 mg/L KT、0.3 mg/L ZT的培养基上增殖,待长成直径2～3 mm 左右时,用N₆附加1 mg/L BA,1 mg/L KT,0.3 mg/L ZT的培养基进行分化培养, 5 d后同时出现芽根生长,最终再生成绿色植株,绿苗分化率为3.5株/10000个原生质体。     

Production of somatic hybrids between frost tolerantSolanum commersonii andS. Tuberosum: Protoplast fusion,regeneration and isozyme analysis

Mesophyll protoplasts ofSolanum commersonii, a frost tolerant wild species not crossable with the cultivated potato, were fused with either dihaploid or tetraploid S.tuberosum. Protoplasts were aggregated by means of alternating current (AC) or polyethylene glycol (PEG), and electrofused with three direct current (DC) pulses. The treatments with PEG/DC generally resulted in very low heterofusion frequency and protoplast viabiity. On the other hand, AC/DC fusion conditions were optimized by increasing the fusion density of protoplasts and adding CaCl₂ to fusion medium. When a density of 4.8 × 10⁵ protoplasts ml^?1 was used in the fusion medium containing 0.2 mM Ca⁺⁺, AC/DC treated protoplasts showed heterofusion frequencies and plating efficiencies of about 10 and 3%, respectively. Fast growing calli from AC/DC fusion experiments were further cultured for regeneration. Fifty-seven plants were regenerated and clonedin vitro as shoot cultures. Compared to parents they showed heterotic vigor and could be identified as hybrids, based on isozyme analysis.     

Dry-matter production,and nutrient uptake and removal bySolanum andigena in the Peruvian Andes

A Field experiment withSolanum andigena (cv. Renacimiento) at three levels of fertilization was conducted in the Mantaro Valley (Central Sierra) of Peru during the 1967–68 growing season. Dry matter and nutrient accumulation in tops and tubers of Renacimiento potatoes were determined at 3-week intervals between 72 and 172 days after planting (42 and 142 days after emergence). Tuber initiation took place during the interval 116–137 days after planting, and top growth reached its maximum shortly thereafter. Total growth rates of 200 kg/ha/day⁴ (178 lb/a/day) where estimated under medium and high fertilization, and tuber dry matter accounted for 70–75% of the total dry matter produced. Final tuber yields (fresh, 21% dry matter) ranged from 10m.t./ha (89 cwt/a) without fertilizer to 41 m.t/ha (366 cwt/a) when fertilized with 160 kg each of N, P₂O₅ and K₂O/ha (143 lb/a). Under high fertilization, total N, P, and K accumulation was estimated at 141, 19, and 403 kg/ha (126, 17 and 359 lb/a), respectively, with 77 kg (68 lb/a) of N, 14 kg (12 lb/a) of P, and 224 kg (200lb/a) of K being removed in the tubers.     

Petiole nitrate content of Maine-grown Russet Burbank and Shepody potatoes in response to varying nitrogen rate

Russet Burbank and Shepody potatoes were grown with at-planting nitrogen fertilizer rates varying from 0 to 270 kg ha^?1 following small grains and red clover. Petiole samples were collected from the 4th and 5th leaflets at four to six dates each during the 1986 to 1989 growing seasons. The samples were dried and analyzed for NO ₃ ^? N content. Petiole NO ₃ ^? N levels were strongly related to nitrogen rate regardless of cultivar, growing season, and cropping system. Differences among treatments and NO ₃ ^? N content varied substantially as the growing season progressed with petiole NO ₃ ^? N levels declining rapidly in underfertilized plots as the plants aged. Petiole NO ₃ ^? N levels were higher at midseason following red clover than following small grains. Sampling 50 to 60 days after planting (DAP) is most appropriate as a tool for scheduling supplemental nitrogen applications. At 50 DAP, critical petiole NO ₃ ^? N levels were 1.6 and 1.7% for Russet Burbank and Shepody, respectively. Petiole NO ₃ ^? N levels above 2.2% at 50 DAP resulted in lower yields of Russet Burbank than when petiole NO ₃ ^? N levels were in the 1.6 to 2.2% range. Petiole NO ₃ ^? N testing should be particularly useful as a diagnostic tool in management strategies which make maximum use of previous crop residues, organic amendments, and soil reserves as nitrogen sources.     

Inheritance of glandular trichomes in crosses withSolanum berthaultii

The inheritance of trichome density and droplet size was investigated in diploid and tetraploid crosses. In haploidTuberosum ×Solanum berthaultii and (S.phureja ×haploid Tuberosum) × S.berthaultii crosses, droplet size on type B trichomes was small or droplets were lacking on F₁ hybrids. Parental phenotypes were recovered in the F₂ and backcross generations. Trichome density was more variable within a clone that was droplet size. Density of both type A and type B trichomes appears to be under the control of small numbers of genes, as parental phenotypes were recovered in the F₂ and backcross generations. The variation observed for each of the three traits studied could not be explained by hypotheses based on the segregation of one or two loci. The insect resistance ofSolanum berthaultii appears to be due to the interaction of several chemical and physical factors, thus potato breeders should handle it as a quantitatively inherited trait.     

Effect on man's serum lipids of a faba-bean protein concentrate

The hypocholesterolemic effect of a vegetable dietary protein was studied by comparing egg white protein and faba-bean protein concentrate in 4 hyperchol-esterolemic persons (3 type IIA, 1 type IIB) and 1 normal individual. To maintain stable body weight, participants were kept for 1 month on an isocaloric diet (20% protein, 48% CHO, 32% fat, P/S=2) and then hospitalized for two consecutive cross-over periods of 18 days each, when they again received an isocaloric diet but of different composition (15% protein, 59% CHO, 26% fat, P/S=2), with the two protein sources as the basis of the cross-over. Serum total, LDL-, VLDL- and HDL-cholesterol and total and VLDL-triglycerides were analyzed every three days. Compared to baseline values, serum total and LDL-cholesterol decreased during both diets, reaching statistical significance for the egg white diet; serum HDL-cholesterol significantly decreased on the faba-bean diet; serum total and VLDL-Tg did not show any significant changes. Comparisons of lipid values at the end of each diet (faba-bean vs. egg white) showed small differences in mean values, none statistically significant. In conclusion, evidence was not obtained that the faba-bean diet produced a significant lowering of serum total and LDL-cholesterol.     

Utilization of potatoes for life support systems in space: III. Productivity at successive harvest dates under 12-H and 24-H photoperiods

Potatoes are among several crops under consideration for use in controlled ecological life support systems (CELSS) being proposed for space colonies. Efficient crop production for such life support systems will require nearoptimal growing conditions with harvests taken when production per unit area per unit time is maximum. To determine this maximum for potato, cv. Norland plants were grown in walk-in growth rooms under 12-h and 24-h photoperiods at 16 C and harvested at 42,63, 84,105,126 and 148 days from planting. At 42 days, plants were encaged in wire fence cylinders with a cross-sectional area of 0.2 m². The dry weights (dwt) of tubers and of the entire plants increased under both photoperiods until the final harvest date (148 days), reaching 572 g tuber dwt and 704 g total dwt under 12-h, and 791 g tuber dwt and 972 g total dwt under 24-h. At a spacing of 0.2 m² per plant, the 148-day tuber production from plants under continuous light would equate to nearly 40t ha^-1 dry matter (200t fresh weight), approximately twice that of exceptionally high field yields. Tuber productivity (g m^-2 day^-1) under the 24-h photoperiod reached a maximum of 29.4 g dwt m^-2 day^-1 at 126 days, but continued to rise throughout the experiment under the 12-h photoperiod, reaching 19.5 g dwt m^-2 day^-1 at 148 days. With a productivity of 29.4 g tuber dwt m^-2 day^-1, approximately 25 m² would continuously provide the daily dietary energy requirements for one human.     

The Use of Mineral Oil in Potato Protection: Dynamics in the Plant and Effect on Potato Virus Y Spread

The focus of this study was to evaluate two mineral oils (Superior 70 and Vazyl-Y) in reducing the seasonal spread of Potato Virus Y (PVY). Three concentrations of oil (0, 5, and 10 L ha^?1 of Superior 70; 0, 7.5, and 15 L ha^?1 of Vazyl-Y) and three spray regimes for both oils (every 3–4, 7, and 10–11 days) were tested. Two weeks after top-kill, two tubers from each of 49 plants free of virus at emergence were harvested from treatment plots, sprouted, and tested for PVY with enzyme-linked immunosorbent assay (ELISA). Results revealed that in the case of Superior 70, PVY spread in mineral oil treated plots ranged from 2.1 to 12.2 %, while in the control plots it ranged from 20.4 to 37.7 % across three cultivars. In the case of Vazyl-Y, PVY spread in mineral oil treated plots ranged from 2.1 to 26.5 %, while in the control plots it ranged from 49.9 to 85.7 % across three cultivars. These data show that there was a significant reduction in PVY due to spray of mineral oils. In addition, mineral oil was quantified in plants from the Superior 70 treated and the control plots to understand the dynamics of mineral oil during the season. While there was little to no oil measured in the leaves at the early stages of plant growth, a considerable amount of mineral oil was detected close to plant maturity. A basic model of the concentration of oil in the treated foliage was formulated to confirm our understanding of the factors at play. The model could explain from 50 to 90 % of the variation in oil content observed in the field. Plant growth and size are important factors affecting oil content in mineral oil treated foliage.     

Inheritance of tuber initiation in tuber bearingSolanum as influenced by photoperiod

Eight potato clones (three day-neutral (DN) Tuberosum, one dayneutral and four short-day (SD) Andigena) were used as parents. Eight genetic sets bearing P₁, P₂, P_1?, P_2?, F₁, F₂, BC₁, and BC₂ generations were developed. Two sets were DN×DN crosses, four SD×DN, and two SD×SD. Tuber initiation (TI) was evaluated in growth chambers with daylengths of 11, 13, and 15 hours. The stolons of each genotype were examined every eight days between the 38th and 86th day after planting. F₁ generation means from SD×DN crosses showed complete dominance of SD reaction (late TI) over DN reaction (early TI). F₁ generation means from DN × DN and SD× SD crosses showed either no dominance or a slight tendency towards the late TI parent. Within plot variances of the selfed generations suggested a variable degree of parental heterozygosity for the loci controlling TI. Andigena clones showed the greatest heterozygosity. Bell shaped frequency distributions in the segregating generations indicated that TI was under the control of several genes. It appears also that major and minor genes were involved. Broad sense heritability estimates of about 90% at 11 hours and 55% at 15 hours of daylength were computed.