The effect of nitrogen on the coumarin-induced tuberization of potato axillary shoots culturedin vitro

Coumarin-induced tuberization was studied on axillary shoots excised from etiolated potato sprouts each of which was cultured in vitro. Sprouts grown on culture medium with high nitrogen concentrations produced axillary shoots which elongated and would not readily tuberize. Sprouts cultured on medium low in nitrogen produced axillary shoots which tuberized with limited elongation. Carbohydrate concentration of the culture medium for the excised axillary shoot could significantly modify the nitrogen effect of the potato sprout medium. Axillary shoots growing on high nitrogen medium did not tuberize except in cases where the carbohydrate concentration was increased.     

The effect of the inhibitors of protein and nucleic acid synthesis on the coumarin-induced tuberization and growth of excised axillary shoots of potato sprquts (Solanum tuberosum l.) culturedin vitro

The inhibitors of protein and nucleic acid synthesis; chloramphenicol, para-fluorophenylalanine, actinomycin D, and 5-fluorouracil were evaluated for their effectiveness in inhibiting coumarin-induced tuberization, tuber growth, and the inhibition of.root and shoot growth of excised axillary shoots of potato sprouts culturedin vitro. To date, it has been demonstrated that both kinetin and coumarin readily effect 100 percent tuberization of the shoots culturedin vitro. The results of the present study demonstrate that with the exception of 5-fluorouracil, the inhibitors significantly inhibited the coumarin-induced. tuberization, tuber growth, and root growth whereas in previously published data by Palmer and Smith (6), the inhibitors merely delayed kinetin-induced tuberization. It is suggested that both protein and nucleic acid synthesis are required for the coumarin-induced tuberization processes, and the mode of action of coumarin is distinctly different from that of kinetin.     

Effects of photoperiod on kinetin-induced tuberization of isolated potato stolons culturedin vitro

Are short-day (SD) conditions inductive or permissive for potato tuberization? This question was addressed using anin vitro culture system. Kinetin induction ofin vitro tuberization in potato stolons cultured in the dark can be partially inhibited by light treatments. Photoperiod required for a major inhibition varied with cultivars: 8 hours for cv. Red Pontiac and 16 hours for cv. Kennebec. Short photoperiods decreased kinetininduced tuberization for all cultivars. Stolons cultured on kinetin-free medium generally did not tuberize, regardless of light treatment. Effects of kinetin and photoperiod on stolon and tuber development are observed. Relationships among kinetin, photoperiod and tuber-inducing stimulus produced under short days are discussed.     

Potato minitubers: Technology validation in Mexico

The effects of four previously reportedin vitro tuber-inducing modified culture media on the potato cultivars Atzimba and Juanita were studied under three illumination regimes. Tuberization from stem segments started 7–18 days after transfer for all the cultivar-light-medium combinations, but this early start was not related to tuber yield. Atzimba tuberized more than Juanita (1.0 and 0.8 tubers/plant respectively), and 8 h light was optimal. The medium by Wang Hu (WH) promoted the greatest tuberization for cultivar Atzimba (1,198 mg/plant) and that by Palmer-Smith (PS) for Juanita (290 mg/plant). The modified Stallknecht’s (ST), on the contrary, slightly stimulated tuberization under all illumination conditions. The presence of cytokinins and light favored the tuberization process. Dormancy was not observed in any of the microtubers, regardless of the tuber-inducing treatment.     

Variability for photoperiodic reaction among diploid and tetraploid potato clones from three taxonomic groups

The photoperiodic behaviour of 18 potato clones from three taxonomic groups (Andigena, Phureja, and Tuberosum diploid and tetraploid) was studied under controlled environments. Day lengths of 11, 13, 15, and 17 hours were provided with all other environmental conditions common. Six characters were studied: tuber formation, stem height, haulm weight, tuber number, tuber weight, and tuberization efficiency (tuber weight/haulm weight). All clones showed well defined critical daylength values at which tuberization was either absent or irregular. A wide variability for critical day length was observed among clones, the higher values corresponding to Tuberosum tetraploid and the lower values to the Phureja group. Stem height and haulm weight increased as photoperiod increased. Tuber number remained practically the same for all groups but Phureja which showed an inverse relationship. Tuber weight decreased as daylength increased for the groups Andigena, Phureja, and Tuberosum diploid which on the average showed a short day reaction for tuber yield. Tuberosum tetraploid did not show any significant change, behaving as a day neutral type. Tuberization efficiency was, in general, decreased as daylength increased suggesting a short day behaviour for all groups. A regression analysis of tuber yield and tuberization efficiency on photoperiod indicated that, in general, tetraploid genotypes were less sensitive to drastic increases in daylength than diploids.     

Anatomy and compositional variation within potatoes

Re-examination of the histological development of the potato tuber supports Artschwager’s view that tuber growth is predominantly due to enlargement of the perimedullary zone and is of procambial origin. Pith (medulla) and cortical regions are differentiated from the ground or fundamental meristem derived from the apical meristem of the stolon apex, even before tuberization has been initiated. The procambium gives rise to external phloem, primary xylem, internal phloem and associated parenchyma, and likewise to interfascicular parenchyma. Those parenchyma cells so formed inwardly to the xylem “ring” contribute to the growth of the perimedullary zone. The sequence of tissue origins is diagrammed and discussed from the viewpoint of modern concepts of histogenesis.     

Comparison of nitrogen and phosphorus requirements between PVX free and regular Russet Burbank potato seed stocks

A Potato Virus X (PVX) free seed stock resulted in higher total yield and U.S. No. 1 potatoes than regular seed stock which carried PVX. Petiole samples from PVX free seed stock were higher in 2% acetic acid extractable PO₄-P than those from regular seed at all rates of fertilizer phosphorus. A high positive correlation was found between petiole phosphate and yield at early tuber set. Increasing rates of nitrogen increased higher total and U.S. No. 1 yields of potatoes, but also slightly decreased specific gravity. The results of this study indicate that phosphorus fertilizer recommendations for growers using Russet Burbank seed low in PVX will necessarily be different from those made for growers planting ordinary seed.     

Light and genotype effects on in vitro tuberization of potato plantlets

Summary In vitro tuberization responses of eleven clones of potato were evaluated under different photoperiods and light intensities. No growth regulators were added to the medium to avoid the potential modification of the response to the environmental stimuli. Plantlets were grown on MS medium containing 3% sucrose for four weeks under long days (16 h). Tuberization was induced by short days (8 h). Five photoperiodic combinations and three light intensity treatments were applied. Light applied after the tuber induction phase delayed or inhibited tuber initiation (at proper photoperiods both at 111 and 55 μmol m⁻² s⁻¹ light intensities at 24/15 °C day/night temperature). Darkness following the induction stage accelerated and synchronized tuber initiation after high light intensity. However, these effects of dark treatment depended on light intensity applied in short days before dark treatment. There was an interaction between the duration of darkness applied in photoperiodic treatments and the light intensity applied in short days on tuber initiation. No relationship was observed between the maturity groups of clones tested and their tuber initiation responses. Tight interaction (P≤0.01) of treatments and clones was proved by statistical analysis. Reliable tuberization and high rate of tuberization (1.20–1.52) can be reached using these hormon-free systems.     

In vitro induction of potato tuberization by organic acids

Summary Potato microtubers are usually induced in media containing growth regulatory, typically cytokinins and growth retardants. However, since these substances may imbalance the physiology of the cultured explants and cause adverse carry-over effects on the subsequent performance of the microtubers, the potential acid-induction of in vitro-mass tuberization was investigated as an alternative. For this purpose, a range of explant types (stolons, single-node or apex-containing multinodal sections), organic acids (acetic, propionic, ascorbic, acetylsalicylic or salicylic acid), and photoperiods (continuous dark, 8 or 16 h photoperiod) were established. Gellified medium or raft membranes on liquid medium were also tested. Although variations due to explant type, photoperiod, organic acid supplemented, and medium type were found, all organic acids tested under the different experiments caused tuberization. Multiple tuber formation or bigger tubers did not develop on multinodal explants. In terms of tuberization rate and mean tuber weight, gellified medium performed better than liquid medium with rafts. The recently established role of the salicylic and acetylsalicylic acids on tuberization is corroborated by our system. The results with the acetic, propionic and ascorbic acids show that in vitro hormone-free tuberization can be easily and rapidly achieved.     

Protein,starch, and non-protein nitrogen accumulation in high protein hybrids and low protein cultivars

Tuber protein, starch, non-protein nitrogen and percent dry matter content were measured during tuber development of four Phureja-Tuberosum-Andigena hybrids and two Tuberosum cultivars. Percentages of starch and protein in the tuber dry matter were curvilinearly related to tuber size in all six clones. The amounts of starch and protein in a tuber were linear functions of tuber size. Rates of protein accumulation in some of the hybrids were higher than those of either cultivar. Starch accumulation rates were similar among all six clones. The high protein character of at least one of the hybrids was associated with starch containing storage tissue. Differences between high and low protein clones were mainly related to quantitative differences in the subunit composition of the protein. The ratio of non-protein nitrogen to protein N was similar among the six clones. Relationships between percent dry matter and starch content were not consistent among the six clones.     

Localization of the photoperiodic perception in potatoes

Summary It was found that probably all the leaves of young potato plants played a part in perceiving the photoperiodic stimulus which induces tuberization. The importance of the mature leaves in the photoperiodic perception is emphasized by the large tuber yield which could be obtained by subjecting these leaves to inductive photoperiods while the growing tip and young leaves were subjected to non-inductive photoperiods. Tubers were produced under non-inductive photoperiods when the young leaves and meristematic stem apices were removed. Tuberization in these plants could be inhibited by application of gibberellic acid. The developing leaves, therefore, seem to produce a substance, probably gibberellin, which prevents tuberization under long-day conditions. If a specific tuberforming substance is involved it is present in active concentrations even under non-inductive photoperiods. The results are in agreement with the theory that a balance between endogenous gibberellins and another substance(s) controls tuberization.     

Response of Nooksack potatoes to nitrogen fertilizer

The Nooksack cultivar because of differing characteristics may have different responses to grower management practices developed principally for Russet Burbank. This study was conducted to determine the effects of nitrogen on yield, grade, and specific gravity of the Nooksack cultivar. In irrigated field experiments, N fertilizer was sprinkler-applied daily on Quincy sand soil. In other experiments, on a Warden silt loam soil all N was broadcast and incorporated before planting. Fertilization rate did not significantly affect tuber grade or specific gravity. Short term shifts in N supply did not cause tuber deformities and poor grades as they commonly do with Russet Burbank. Nooksack, while responsive, did not have a strong positive response to N fertilization. Tuber yields were depressed at fertilizer plus residual N levels above 200 kg/ha on Warden silt loam and above 300 kg/ha on Quincy sand. This difference was because of variation in NO₃ leaching and soil N mineralization and was reflected in calculation of optimum N rates. Nooksack may require less N fertilization than Russet Burbank partially because of the strong dormancy of Nooksack tubers that retards emergence and shortens growing season. Management to promote more rapid dormancy break and lower N nutrition during tuber initiation could result in earlier establishment, earlier tuber bulking, and greater yields of Nooksacks.     

Influence of nitrogen supply on micropropagation and subsequent microtuberization of four potato cullwars

A medium containing low amounts of nitrogen (19–23 meq.l^?1) produced optimum results in micropropagation as revealed by the number of nodes, internode length, chlorophyll content, and leaf area of four potato cvs. belonging each to four different maturity groups. Decreasing amounts of nitrogen also increased chlorophyll content in all four cultivars tested. The NH ₄ ⁺ concentration did not have an effect on micropropagation for low nitrogen supplies. In all cvs., except Baraka, there was a “carry over” effect of the nitrogen content in the micropropagation medium onto subsequent tuberization, the lower nitrogen (23 meq.l^?1) advancing tuber initiation. Microtuberization of cv. Jaerla was earlier in darkness than under short days regardless of the propagation medium used.     

Inheritance of tuber traits from phureja in diploid phureja - Tuberosum hybrids

Heterosis and combining ability for tuber number, average tuber weight, and total yield were evaluated in Phureja - haploid Tuberosum diploid hybrids. Heterosis estimates suggest dominance for high tuber number and low average tuber weight in Phureja. Total yield of the hybrid population exceeded the high parent. The higher-yielding segment of hybrids had a significantly higher number of smaller tubers per plant. Breeding value could be improved by attaining high yield with a lower number of larger tubers per plant. General combining ability was the only significant source of variation for tuber number and average tuber weight indicating high heritability. Phenotypic recurrent selection should be an effective approach to manipulating these traits. General and specific combining ability were significant for total yield. Full exploitation of genetic variance for yield will require test-crossing.     

Recurrent selection for heat tolerance in diploid potatoes (solanum tuberosum subsp.phureja andstenotomum)

The response of diploid potatoes to growing seasons of high temperatures was studied at two locations in eastern North Carolina. The responses measured were survival, tuberization, and yield. One cycle of phenotypic recurrent selection for yield resulted in increases of 3% for survival, 15% for tuberization, and 27% for yield. Heritability of yield, estimated from selection response, was 0.07 for the combined locations. There was a small positive phenotypic correlation between the responses.     

A reevaluation of bromoethane in comparison to rindite for the post-harvest detection of potato virus Y in tubers by ELISA

A reevaluation of breaking tuber dormancy with bromoethane to increase the concentration of potato virus Y in the tuber revealed a positive response, by ELISA testing, to the treatment. The degree of response increased with the maturity of the tuber. Response to treatment with rindite was generally stronger, although differences were slight.     

Influence of slit plastic mulches and nitrogen fertilization rates on potato yield and quality

Clear and black slit plastic mulches had little effect on tuber yields when compared with unmulched controls during two growing seasons. Mulching films significantly increased the incidence of pinkeye, caused byPseudomonas spp. and varius types of soft rot in 1974 but not in 1975. The incidence of tuber greening was higher than normal both years due to inability to hill with mulch films in place. Under these conditions, black plastic reduced the incidence of greening. Significant yield responses were observed for an increase in nitrogen fertilization rate from 100 (45.36 kg) to 140 (63.5 kg) but not from 140 to 180 1b, (81.65 kg) N/A. Plastic mulches did not affect the nitrogen response. Higher post-harvest inorganic soil nitrogen levels were found under both mulches compared with unmulched controls.     

温度影响马铃薯块茎形成的研究进展

块茎是马铃薯的商品和营养繁殖器官,而温度是影响块茎形成最重要的环境因素之一.针对温度对马铃薯块茎诱导和起始、膨大和成熟生长发育阶段表型变化的影响,对光合特性、源库平衡和渗透调节物质等生理生化变化影响,对调控块茎形成的光周期、植物激素、sRNA和糖类物质通路的影响,以及马铃薯耐热性评价和遗传改良研究等方面进行了综述,以期...     

Changes in endogenous abscisic acid,soluble sugars and proline levels during tuber dormancy inSolanum tuberosum L.

Abscisic acid (ABA), sucrose, reducing sugars and proline contents were monitored over an eleven-month period in tubers of three potato cultivars that varied in tuber dormancy. ABA and proline levels increased after top pulling the haulms and were not affected by harvest date. Proline did not change in either a storage temperature or cultivar-specific manner. The highest concentrations of ABA were found in tubers stored at 2°C while the lowest concentrations occurred in tubers stored at 20°C. At 10°C, the end of tuber dormancy in the cultivars Kennebec and Nooksack (but not Sebago) coincided with the decline in ABA content. There was no evidence of a threshold concentration of ABA below which sprouting would occur. Tuber samples of 10 different cultivars were removed from 10°C and placed in 20°C storage (in darkness). Initial ABA concentrations (i.e., at the time of removal from 10°C storage) were positively correlated with duration of dormancy and negatively correlated with subsequent rates of sprout elongation at 20°C. Sucrose content was negatively correlated with duration of dormancy. Reducing sugars responded primarily to storage temperature and did not appear to be related to dormancy or sprouting.     

Influence of Colorado potato beetle sample counts and plant defoliation on potato tuber production

Field experiments were designed to subject Superior potato plants to various levels of defoliation by the Colorado potato beetle (CPB)Leptinotarsa decemlineata (Say), Coleoptera: Chrysomelidae. Defoliation occurred during each of five consecutive plant growth periods and CPB population, plant leaf area, and tuber weight data were recorded for each period. A visual defoliation rating scheme provided an accurate estimate of actual potato plant leaf area of defoliated plants. Data generated from regression analysis demonstrated a significant dependence of leaf area on CPB numbers per plant during some plant growth periods, but numbers of CPB accounted for very little of the total variation in tuber weight. Plant leaf area was the most important independent variable in the tuber weight regression model.