Kris Pruski

Field-scale validation of an automated soil nitrate extraction and measurement system

One of the many gaps that needs to be solved by precision agriculture technologies is the availability of an economic, automated, on-the-go mapping system that can be used to obtain intensive and accurate ‘real-time’ data on the levels of nitrate nitrogen (NO3–N) in the soil. A soil nitrate mapping system (SNMS) has been developed to provide a way to collect such data. This study was done to provide extensive field-scale validation testing of the system’s nitrate extraction and measurement sub-unit (NEMS) in two crop (wheat and carrot) production systems. Field conditions included conventional tillage (CT) versus no tillage (NT), inorganic versus organic fertilizer application, four soil groups and three points in time throughout the season. Detailed data analysis showed that: (i) the level of agreement, as measured by root mean squared error (RMSE), mean absolute error (MAE) and coefficient of efficiency (CE), between NEMS soil NO3–N and standard laboratory soil NO3–N measurements was excellent; (ii) at the field-scale, there was little practical difference when using either integer or real number data processing; (iii) regression equations can be used to enable field measurements of soil NO3–N using the NEMS to be obtained with laboratory accuracy; (iv) future designs of the SNMS’s control system can continue to use cheaper integer chip technology for processing the nitrate ion-selective electrode (NO3−–ISE) readings; and (v) future designs of the SNMS would not need a soil moisture sensor, ultimately saving on manufacturing costs of a more simple system.

Tissue culture propagation of Mongolian cherry (Prunus fruticosa) and Nanking cherry (Prunus tomentosa)

In vitro culture establishment, shoot proliferation and ex vitro rooting responses of Mongolian cherry (Prunus fruticosa L.), and Nanking cherry (Prunus tomentosa L.), were examined using various combinations of growth regulators. Dormant buds, taken during winter months, were used as explants. In both species, Murashige and Skoog Minimal Organic (MSMO) solid medium supplemented with 0.49 μM indole-3-butyric acid (IBA) and either 4.44 or 8.88 μM 6-benzylaminopurine (BA), was the best for culture initiation, and with 8.88–15.16 μM BA for shoot proliferation. Good rooting responses were also obtained with shoots produced on media containing 0.91 μM thidiazuron (TDZ). Auxin treatments were required for ex vitro rooting of approximately 20 mm long shoots in peat/perlite (1:1 v/v) mixture, at 25 °C, under mist. The best rooting (79%) was obtained with IBA/NAA (naphthaleneacetic acid) (9.80/2.69 μM) combination. A commercial rooting powder, Rootone F, containing IBA/NAA (0.057/0.067%), was also effective (73%). The ex vitro rooted plantlets did not require any additional acclimatization prior to transplanting to the regular greenhouse conditions.

Jasmonate effects on in vitro tuberization and tuber bulking in two potato cultivars (Solanum tuberosum L.) under different media and photoperiod conditions

SummaryJasmonic acid (JA) effects on in vitro tuberization of potato nodal explants cvs. Sangre and Russet Burbank were tested under liquid and solid media conditions and 0,8, and 16h photoperiod. Explants taken from stock plants grown on 2.5μM JA-supplemented medium tuberized first, particularly in darkness. The most pronounced benefits of the JA pretreatment were recorded under 16h photoperiod, which is known to inhibit tuberization. Cultivar Sangre benefited from the JA preconditioning of stock plants more than Russet Burbank. Russet Burbank required the JA supplement in tuberization media to reach the same degree of stimulation. Overall, microtubers produced either from JA preconditioned stock plants or on the JA-containing tuberization media were more uniform and larger than from other treatments. Eight hours photoperiod was by far the best treatment for the production of high-quality uniform microtubers. JA conditioning of stock plants prior to taking explants for tuberization is being proposed as a treatment enhancing the quality of microtubers.

Use of Jasmonate for conditioning of potato plantlets and microtubers in greenhouse production of minitubers

A two-year study was conducted to determine the effects of (1) jasmonic acid (JA) pre-treatment, (2) JA supplement in culture media, (3) cultivar (Amisk, Atlantic, Russet Burbank, Shepody, and Umatilla Russet), (4) light (0 h, 8 h), and (5) dormancy breaking treatment (Rindite, gibberellic acid) on greenhouse production of minitubers from microtubers andin vitro plantlets. The microtubers were produced under short day (8 h) light conditions and in darkness, from stock plantlets pre-treated with JA and untreated, and on tuberization media with or without JA.In vitro plantlets (the industry choice in nuclear seed potato production) of all five cultivars performed well, meeting the standard criteria for greenhouse production of minitubers. Production of minitubers from microtuber-derived plants of cvs Amisk, Russet Burbank, and Umatilla Russet was similar to that of plantlet-derived plants with regard to number of minitubers. Yields (weight), however, were lower than those from plantlets. Microtuber responses to JA varied with cultivar. Amisk produced the highest number of minitubers per plot from microtubers derived from JA pre-treated plantlets. Jasmonic acid-pretreated microtubers also gave significantly more minitubers in Russet Burbank and Umatilla Russet than the microtubers from other treatments. Shepody did not benefit from JA treatments and JA pre-treated Atlantic microtubers performed poorly, producing significantly lower yields of minitubers than other cultivars. Independently of cultivar, microtubers produced under 8-h photoperiod gave significantly higher yields of minitubers than microtubers produced in the dark. Dormancy release was the key factor influencing microtuber performance. Rindite proved to be a much more effective dormancy breaking treatment than gibberellin. JA conditioning of stock plants prior to tuberization is being proposed as a treatment in production of microtubers for greenhouse production of minitubers.

Sucrose and light effects on in vitro cultures of potato, chokecherry and saskatoon berry during low temperature storage

Cultures of potato (Solanum tuberosum) cv. Atlantic, chokecherry (Prunus virginiana L.) cv. Garrington and saskatoon berry (Amelancher alnifolia Nutt.) cv. Northline grown in vitro for 3 weeks at 24/22 °C, 16-h photoperiod, 150 μmol m−2 s−1 photosynthetic photon flux density (PPFD) mixed fluorescent/incandescent light were stored for 6, 9 and 12 weeks at 4 °C under 0 (darkness) and 3 μmol m−2 s−1 PPFD (690 nm red light continuous illumination). Growth regulators free MSMO medium either with or without 30 g l−1 sucrose was used to store the cultures. All cultures retained capacity to re-grow after storage. Tested factors, sucrose, light and the length of the storage period had an impact on shoot quality and re-growth capacity of the cultures. For either light treatment sucrose was essential for the low temperature maintenance of vigorous stock plants of potato, if stored for over 6 weeks. Chokecherry and saskatoon cultures stored well without sucrose; although chokecherry benefited from sucrose in the storage medium when the stock cultures were kept at the low temperature for 12 weeks. Low light significantly improved quality of the stored potato cultures, but had very little effect on both chokecherry and saskatoon berry cultures. The woody plant cultures grew during storage, and the longer the stock plants were stored, the more vigorous cultures they generated. The results indicate that growers can successfully use their existing facilities, small refrigerators and coolers with low light intensity, set at 4 °C, for short term storage of potato, chokecherry and saskatoon berry cultures. The potato cultures, which are known to be sensitive to prolonged low temperature storage, should be frequently monitored and subcultured as required. On the other hand, the woody plant stock cultures do not require any special attention when kept at 4 °C and re-grow the most vigorous shoots if stored for at least 12 weeks.

Manipulation of Microtubers for Direct Field Utilization in Seed Production

A two-year field study was conducted to determine the effects of jasmonic acid (JA), light (duringin vitro explant production andin vitro tuberization phases), and dormancy-breaking treatment on performance of microtubers in the production of seed tubers (pre-elite) in five potato cultivars. Microtubers were produced under short day (8-h) conditions and in darkness, from stock plantlets pre-treated with JA and untreated, and on tuberization media with or without JA. Microtuber performance was compared to invitro plantlets transplanted directly to the field. Yields of tubers from microtubers were 30% to 40% of those from plantlets.Microtubers of cultivars Amisk and Russet Burbank produced the highest yields of pre-elite tubers. Atlantic microtubers performed poorly in the field. JA pre-treatment of stock plantlets, prior toin vitro tuberization, enhanced seeds tuber production from microtubers in Russet Burbank and lowered in Shepody. JA presence in media duringin vitro tuberization significantly lowered production of tubers while exposure to 8-h light resulted in microtubers performing significantly better in the field than microtubers produced in the dark. Dormancy release was the key factor influencing microtuber performance. Unlike greenhouse studies, gibberellic acid (GA3) was more effective than Rindite. A further refinement of the production and handling methods is required before microtubers can be recommended for field production of seed tubers.

Micropropagation of four cultivars of Saskatoon berry (Amelanchier alnifolia NUTT.)

In vitro culture establishment, shoot proliferation, ex vitro rooting and dormancy breaking of the newly rooted plantlets were examined on Saskatoon berry (Amelanchier alnifolia NUTT.) cultivars Northline, Pembina, Smoky and Thiessen. Shoot-tip explants taken from actively growing plants were better for culture initiation than dormant buds. MS gave the most satisfactory results of the media formulations. Optimal shoot proliferation occurred at 8.8 and 13.3 μM BA. Higher BA concentrations caused culture deterioration during long-term maintenance. Auxin treatments significantly stimulated ex vitro rooting of shoots in all cultivars. The best rooting was achieved with IAA/NAA (2.8/1.1 μM) mixture. Satisfactory results were also obtained with commercial powder formulation, Rootone F, containing IBA/NAA mixture. Foliar application of BA and GA4+7 was successful in breaking dormancy of newly rooted plantlets. Combinations of these two growth regulators caused formation of axillary shoots and vigorous plant growth. There were significant differences in the cultivar responses to culture conditions and treatments with growth regulators. The best culture establishment and the highest rate of shoot proliferation was observed in cv. Thiessen; the best rooting and the most vigorous post-dormancy growth was recorded in cv. Smoky. Cultivar Northland gave the most erratic responses.

Jasmonate effect on in vitro tuberization of potato (Solanum tuberosum L.) cultivars under light and dark conditions

SummaryEffects of jasmonic acid (JA) on in vitro tuberization of six potato cultivars were examined. Tuberization was carried out in the dark, or with 8 h photoperiod on MS media with vitamins, 8% sucrose, 0.6% agar and either 2.5 μM JA (JAMed) or no JA using explants either preconditioned with 2.5 μM JA (JAPret) or not. Cultivars Amisk, Russet Burbank, Sangre and Umatilla Russet produced the most (1.0–1.7) and the largest microtubers per explant. Tuberization was inconsistent in Shepody and poor in Atlantic. All cultivars tuberized significantly better in 8 h than in the dark. JA effects were cultivar specific and larger in the dark than in light. In the dark, Amisk, Atlantic and Umatila Russet tuberized better in JAMed than in JAPret. These cultivars did not benefit from JA treatments in light. Russet Burbank and Sangre tuberized in the dark better from JAPret cuttings than on JAMed medium. JA had no effect on tuberization in Shepody. JA double treatment in light vs. control and individual JA treatments significantly reduced tuberization in Shepody and Russet Burbank.

Growth-room and field studies with seed tubers treated with ethylene and 1-methylcyclopropene (1-MCP) during storage

Based on ethylene management in potato storage, we hypothesized that the applied treatments would modify number of sprouts per seed tuber. Thus, in combination with in-row spacing (closer for seed, wider for processing) in the field treatments will give either (1) a high number of small tubers destined for seed use, or (2) a relatively smaller number of large, uniform tubers suitable for processing. A three-year study (2001–2003), conducted with two french fry processing cultivars, Russet Burbank (RB) and Shepody (SH), aimed at the development of a novel modified atmosphere seed tuber storage treatment. Seed tubers were stored at 4 C from October to May of each year in a cold room under five modified atmospheric regimes: (1) air ventilation only (Control); (2) 4 µl L−1 ethylene applied continuously beginning in November and (3) beginning in February; (4) 1 µ1 L−1 MCP (1-methylcyclopropene) applied as a gas for 48 h only in early December followed by continuous 4 µl L−1 ethylene and (5) MCP alone applied as above. Each year, once a month (mid-January until end of April), a number of seed tubers was taken from each storage treatment, planted to pots and grown for 4 wk in a growth-room. In these studies, shoot emergence from the ethylene-treated seeds of both cultivars occurred significantly earlier, giving higher number of stems per tuber and stolons per stem than Control and MCP treatments. Moreover, the time to emergence after planting decreased with the increased length of storage. Field studies that were conducted from the end of May (planting) until October each year, produced similar trends (although not significant atP≤0.05) and resulted in a higher number of tubers per stem. In RB at the closer in row spacing (30 cm) used for seed production, ethylene enhanced yield of smaller tubers in the 30- to 115-g and 115- to 300-g categories. The ethylene storage treatments also increased tuber number per plant, but not the total mass of harvested potatoes. The MCP treatment, in combination with the wider in-row spacing (40 cm) used for the production of processing tubers, significantly increased the percentage of large tubers (>300 g). In SH, contrary to RB, the ethylene treatments did not alter tuber size distribution and the application of MCP reduced tuber size rather than increasing it. Results from this study suggest that both ethylene and MCP can be used in seed potato storage to influence the tuber size distribution of the crop from that seed.ResumenBasado en el manejo de etileno para el almacenamiento de papa, hemos asumido la hipótesis de que los tratamientos aplicados modificarían el número de brotes por tubérculo semilla, así en combinación con el espaciamiento en el campo (corto para semilla y largo para procesamiento) nos dará ya sea (1) un gran número de tubérculos pequeños destinados a semilla o (2) un número relativamente pequeño de tubérculos grandes y uniformes adecuados para procesamiento. Se realizó un estudio de tres años (2001 a 2003) con dos cultivares para procesamiento de papa frita, Russet Burbank (RB) y Shepody (SH), destinado al desarrollo de un novedoso tratamiento de atmósfera modificada para el almacenamiento de tubérculos semilla. Los tubérculos semilla fueron almacenados a 4 C de octubre a mayo de cada año en un ambiente frío bajo cinco regímenes atmosféricos modificados: (1) solamente ventilación de aire (Testigo); (2) 4 Llq de 1 etileno aplicado continuamente a partir de noviembre y (3) comenzando en febrero; (4) 1 Llq de 1 MCP (1-metilcloropropeno) aplicado como gas por 48 horas solamente a principios de diciembre seguido de 4 Llq de 1-etileno y (5) MCP solo aplicado en la forma anterior. Cada año, una vez al mes (mediados de enero hasta fines de abril), se tomaron unos cuantos tubérculos semilla de cada tratamiento de almacenaje, fueron sembrados en macetas y llevados a la cámara de crecimiento por 4 semanas. En estos estudios, la emergencia de brotes de las semillas tratadas con etileno se realizó en ambos cultivares mucho más antes, con un número mayor de tallos por tubérculo y estolones por tallo que en el testigo y los tratamientos con MCP. Más aún, el tiempo de emergencia después de la siembra disminuyó con un mayor tiempo de almacenamiento. Los estudios de campo que se realizaron desde fines de mayo (siembra) hasta octubre de cada año mostraron tendencias similares (aunque no significativas aP≤0.05) y dieron un mayor número de tubérculos por tallo. En RB a menor espaciamiento (30 cm) usado para la produción de semilla, el etileno elevó el rendimiento de tubérculos más pequeños en las categorías de 30–115 g y 115–300 g. Los tratamientos de almacenamiento con etileno también incrementaron el número de tubérculos por planta, pero no la masa total de papa cosechada. El tratamiento con MCP, en combinación con un mayor espaciamiento entre plantas (40 cm) usado para la producción de papa para procesamiento incrementó significativamente el porcentaje de tubérculos más grandes (>300 g). En SH, contrariamente a RB, los tratamientos con etileno no alteraron la distribución de tamaño y la aplicación de MCP redujo el tamaño del tubérculo en lugar de incrementarlo. Los resultados de este estudio sugieren que tanto el etileno como el MCP pueden usarse en almacenamiento para influenciar la distribución de tamaño del tubérculo del cultivo a diferencia de lo que se quiere para semilla.

Photoautotrophic micropropagation of Russet Burbank Potato

The photoautotrophic micropropagation of potato cv. Russet Burbank was investigated. Single node microcuttings were grown for four weeks on Murashige and Skoog (MS) medium with or without sucrose (30 g l−1) in the growth room at 21/19 °C day/night temperature, with 16-h photoperiod at 150 μmol m−2 s−1, with or without supplemental CO2 at 1500 μl l−1. A 20% increase in the number of nodes per stem (from 7.5 to 9.4) and a 50% increase in stem dry weight were observed in cultures grown on media with sucrose and in CO2 enriched atmosphere comparing to the conventionally micropropagated cultures or the cultures grown photoautotrophically on media without sucrose but in air supplemented with 1500 μl l−1CO2. Stems of these cultures (from media with sucrose in CO2 enriched air) almost doubled in length the stems of cultures from the other two treatments. No significant differences were observed between Control (MS medium supplemented with sucrose, 30 g l−1) and photoautotrophic cultures coming from MS medium with no sucrose grown under 1500 μl l−1 of CO2. Photoautotrophic cultures produced stems averaging 43.3 mm, with 7 nodes and weighing 9.2 mg (dry weight), similar to conventionally grown in vitro cultures (47.9 mm with 7.5 nodes, 9.7 mg dry weight). Growers may consider photoautotrophic culturing of potato in areas where the high sterility levels are difficult to maintain. Supplementing air in the growth room with 1500 μl l−1 of CO2 could be beneficial for potato plantlet production even on media containing sucrose since it significantly improved quality, size and biomass of produced plantlets, speeding up the multiplication.