J. L. Halderson

Zone-subsoiling effects on potato yield and grade

Soil compaction and erosion are problems in many Pacific Northwestern potato fields. We wanted to determine if zone-subsoiling would reduce these problems and improve potato yields and or grade without adversely impacting other production practices. Studies were conducted in Southern Idaho at six locations over two years on different soils and with different irrigation methods to assess the effects of zone-subsoiling immediately after planting on tuber yield and grade. Reservoir-tillage comparisons were made at three locations where sprinkler water application rates were higher than soil infiltration rates. Russet Burbank was represented by eight location-years and Russet Norkotah by two. Zone-subsoiling consistently improved tuber grade or increased tuber size. The biggest improvement was under furrow irrigation. Zone-subsoiling also tended to increase total yield in eight of ten location-years. Reservoir-tillage improved yield and grade, but zone-subsoiling did not without reservoir-tillage when water application rates were high. At no location did zone-subsoiling significantly decrease tuber grade or yield. Zone-subsoiling had no appreciable effects on hill configuration or seed-piece dislocation. Surface cracking and “water piping” occurred under furrow irrigation but were not significant problems. Results were similar for both cultivars. Additional studies will be needed to successfully incorporate zone-subsoiling into commercial production practicesCompendioLa compactación y erosión del suelo son problemas presentes en muchos de los campos de papa del noroeste del Pacífico. Se quería determinar si una aradura profunda zonal podría reducir estos problemas y mejorar los rendimientos de papa y/o su grado sin impactar negativamente sobre otras prácticas culturales de producción. Se condujeron estudios al Sur de Idaho, en seis localidades, durante dos años, con diferentes suelos y métodos de irrigatión, para determinar los efectos, de una aradura profunda zonal efectuada inmediatamente después de la siembra, sobre el rendimiento en tubérculos y su grado. Se efectuaron comparaciones de acumulación-aradura en tres localidades donde las tasas de aplicación de agua por aspersión eran más altas que las tasas de infiltración en el suelo. Russet Burbank fue considerada durante ocho localidades-años y Russet Norkotah en dos. La aradura profunda zonal mejoró consistentemente el grado de los tubérculos o incremento el tamaño de los mismos. La mejora más notable se efectuó bajo irrigación por surcos. La aradura profunda zonal también tuvo la tendencia a incrementar el rendimiento total, en ocho de las diez localidades-años. La acumulación-aradura mejoró el rendimiento y grado, pero no sucedió lo mismo con la aradura profunda zonal sin acumulación-aradura cuando las tasas de aplicación de agua fueron altas. En ninguna de las localidades la aradura profunda zonal disminuyó significativamente el grado de los tubérculos o el rendimiento. La aradura profunda zonal no tuvo efectos apreciables sobre la configuratión del lomo del surco o sobre la localizatión de las secciones de los tubérculos-semillas. Bajo irrigación por surco se produjeron grietas superficiales y aguda licuefacción (‘water piping’), pero no constituyeron problemas significativos. Los resultados fueron similares para ambos cultivares. Se requieren estudios adicionales para incorporar exitosamente la aradura profunda zonal entre las prácticas de productión comerciales.

Measurements for determining potato tuber maturity

A device and procedure have been developed for measuring tuber skin strength of Russet Burbank potatoes. Tests were designed to quantitatively measure the effects of: 1) various vine killing methods, 2) elapsed time between digging and testing, 3) tester tip hardness and 4) skin strength changes for three weeks following vine kill. Results show that no differences in skin strength can be detected between vine killing methods. Skin strength values of 2160 g-cm or greater are estimated to provide adequate resistance to harvest and handling damage. Location of the test area on the tuber influences results as well as does the elapsed time between digging and testing. Some commencai users find this testing device to be advantageous.

Chemical desiccation of potato vines

Potato (Solanum tuberosum L., ‘Russet Burbank’) vine desiccation was compared with sulfuric acid (89 kg ha−1 sulfur), dinoseb [2-(1-methylpropyl)-4, 6-dinitrophenol] (2.4 kg ha−1), diquat (6, 7-dihydrodipyrido [1,2-α:2′,1′-c] pyrazinediium ion) (0.28 kg ha−1) and endothal (7-oxabicyclo[2.2.1] heptane-2,3-dicarboxylic acid) (1.1 kg ha−1). All treatments were field-applied in southern Idaho during August and September. Vine (stem and leaf) desiccation was most rapid and consistent with sulfuric acid which averaged 42% desiccation at day one after treatment. Dinoseb and diquat at rates used were similar with desiccation of 19% and 17%, respectively, at day one. Endothal followed with 9% desiccation at day one. As diquat rates increased from 0.28 kg ha−1 to 0.55 kg ha−1, desiccation increased from 16% to 21% at day one. As diquat rate was further increased to 1.65 kg ha−1 vine desiccation was 25%. Major differences in desiccation rate occurred the first day. After the first day, rates of desiccation were mostly similar. Immature vines were desiccated more slowly than mature vines that were beginning to senesce. This difference between mature and immature vine desiccation was least with sulfuric acid. Several crop oils and surfactants evaluated with dinoseb and diquat were similar, except Mor-act that slightly increased dinoseb activity. Changes in tuber yield and quality were not associated with chemicals except as expected from desiccation.CompendioSe comparó el desecado de plantas de papa (Solanum tuberosum L., ‘Russet Burbank’) con ácido sulfúrico (0.89 kg ha−1 de azufre), dinoseb [2-(l-metilpropil)-4,6-dinitrofenol] (2.4 kg ha−1), diquat (6,7-dihidrodipirido [1,2-α:2′, 1′-c] pirazinediium ion) (0.28 k ha−1)y endotal (7 oxabiciclo 2.2.1 heptano-2,3-ácido dicarboxílico (1.1 kg ha−1). Todos los tratamientos se aplicaron en campo en el sur de Idaho durante Agosto y Setiembre. La desecación de la planta fué más rápida y consistente con ácido sulfúrico, con un promedio de desecación de 42% al día uno, después del tratamiento. El dinoseb y el diquat a las dosis usadas fueron similares, con desecación de 19% y 17% respectivamente, al día uno. El endotal fué el siguiente con 9% de desecación, al dia uno. A medida que se incrementaron las dosis de diquat de 0.28 kg ha−1 a 0.55 kg ha−1, la desecación aumentó de 16% a 21% al día uno. Cuando se incrementó aún más la dosis de diquat a 1.65 kg ha−1, la desecación de la planta fué de 25%. Las mayores diferencias en la velocidad de desecación ocurrieron el primer día. Después del primer día, las velocidades de desecación fueron generalmente similares. Las plantas inmaduras se desecaron más lentamente que las plantas maduras, las cuales empezaban ya a envejecer. Esta diferencia entre la desecación de plantas maduras e inmaduras fué menor con ácido sulfúrico. Diversos aceites agrícolas y surfactantes evaluados con dinoseb y diquat fueron similares con excepción del Mor-act, que aumentó ligeramente la actividad del dinoseb. Los cambios en rendimiento y calidad de los tubérculos no estuvieron asociados con los productos químicos, excepto como se esperaba de la desecación.

Influence of seed placement on Russet Burbank potato yield and grade

Potato seed pieces were hand planted with different spacings in the row and percentages of doubles to determine the effects on total yield and tuber size distribution. The objective was to determine acceptable performance levels for commercial potato planters. Average tuber size increased as the percentage of double seed pieces decreased or as the in-row spacing between single seed pieces increased. Yield of tubers smaller than 113 g was the most sensitive parameter and they increased as in-row spacing decreased and as the percentage of double seed pieces increased. Yield of tubers larger than 283 g increased as in-row spacing increased but only for the first year. Total yield was not affected by the change of in-row spacing or the percentage of doubles.CompendioSe sembró, a mano, semillas cortadas de papa a diferentes distancias en el surco y porcentajes de doble número de secciones, para determinar los efectos sobre el rendimiento total y la distribución por tamaño de los tubérculos. El objetivo fue determinar niveles aceptables de comportamiento para los productores comerciales de papa. El tamaño promedio de tubérculo aumentó conforme disminuyó el porcentaje del doble número de secciones de semilla o conforme se incrementó en el surco el espacio entre las secciones unitarias de la misma. El rendimiento de los tubérculos con menos de 113 g fue el parámetro más sensible y se incrementó conforme disminuyó la distancia en el surco y aumentó el procentaje de doble número de secciones de semilla. El rendimiento de los tubérculos con más de 283 g se incrementó con la mayor distancia en el surco, pero sólo en el primer año. El rendimiento total no fue afectado por el cambio de distanciamiento en el surco o el porcentaje de doble número de semillas.

Determining potato tuber resistance to impact damage

Results of potato tuber impact damage tests depend primarily upon velocity and energy of impact. Blackspot and shatter indexes correlated poorly with tuber mass, storage time and each other. However, the shatter index became much less variable with increased storage time. Impact velocity and energy correlated quite well with rebound angle (r = 0.92 for each) and shatter index (r = 0.99 and 0.98 respectively). However, the size of the surface of the impact head correlated poorly with rebound angle and shatter index. The rebound angle: 1) correlated with tuber mass (r = 0.83), 2) was random over storage time, 3) correlated poorly with shatter index (r = 0.40), and 4) had no correlation with blackspot index.CompendioEl resultado de las pruebas de golpe de los tubérculos de papa depende principalmente de la velocidad y fuerza del impacto. Los índices de mancha negra y de fraccionamiento correlacionaron pobremente con la masa del tubérculo, el tiempo de almacenamiento y entre ellos mismos. Sin embargo, el indice de fraccionamiento result6 mucho menos variable con el mayor tiempo de almacenamiento. La velocidad y fuerza del impacto correlacionaron bastante bien con el ángulo de rebote (r = 0,92 para cada una) y el índice de fraccionamiento (r = 0,99 y 0,98 respectivamente). Sin embargo, el tamaño de la superficie impactada correlaciono pobremente con el ángulo de rebote y el índice de fraccionamiento. El ángulo de rebote: 1) correlacionó con la masa del tuberculo (r = 0,83), 2) no estuvo correlacionado con el periodo de almacenamiento, 3) correlacionó pobremente con el índice de fraccionamiento (r = 0,40) y 4) no tuvo correlatión con el indice de mancha negra.

Potato vine kill: Pulling, chemical killing and rolling effects on yield and quality of Russet Burbank

Pulling of potato vines in Idaho was compared to three chemical vine killing methods for a period of three years. Rolling was examined alone or in combination with chemicals. Effects on yield, grade, specific gravity and stem-end discoloration of the Russet Burbank variety were determined. Rolling increased desiccation overall by 6% but was not a satisfactory vine kill method when used alone. Pulling reduced yields by 14% compared to control plots and 7% compared to sulfuric acid treatments. Specific gravity was reduced overall by 0.002 for all vine killing treatments compared to the control. Pulling and rolling did not affect the amount of stem-end discoloration.

Measurement of diurnal changes in potato tuber growth

A system was developed for continuous,in situ measurement of potato tuber growth. The system consists of a linear variable differential transformer (LVDT) attached to a nylon line which is looped around a developing tuber. Tension is applied to the line so that changes in tuber circumference can be measured with the LVDT and recorded at selected time intervals with a datalogger. Measurements of tubers from potted plants grown in the greenhouse show that tubers follow a diurnal pattern of expansion and contraction. Expansion occurs primarily during the late night and early morning hours when turgor recovery normally occurs.

Potato vine kill: Stem-end discoloration effects on Russet Burbank

The relationship of potato (cv. Russet Burbank) tuber stem-end discoloration to speed of vine kill and maturity of vines when killed was studied for three years at several sites in Idaho. Discoloration due to leafroll was separately determined. Vine killing with sulfuric acid, dinoseb, endothall and hand pulling produced a range in killing speeds from fast to slow. Vine kill speed alone did not affect amounts of discoloration. Vines that died naturally from frost or other causes had as much discoloration (14% over all treatments) as from any chemical or mechanical vine killing method. The tendency for tuber discoloration increased when vines were less mature when killed.

Zoned Tillage for Potato Production

Studies in southeastern Idaho evaluated the potential of tillage under the potato row (zoned tillage) to influence tuber yield and grade. Such tillage is estimated to provide significant improvement in control of water erosion. The ‘Russet Burbank’ variety was grown on silt loam soil under sprinkler irrigation. Major variables included 1) depth of tillage; 2) timing of tillage; 3) amount of irrigation; 4) amount and timing of nitrogen applications; and 5) depletion of soil moisture. Zoned tillage with the Tye Paratill was also compared to that of a conventional chisel. Zoned tillage did not generally affect total yield, but sometimes reduced the amount of malformed tubers. Zoned tillage tended to perform better as plant stress conditions became more severe. Late application of zoned tillage can reduce yield due to plant root disturbance. Lower soil bulk density persisted longer after zoned tillage than after conventional chiseling. The most suitable depth of zoned tillage appears to be 38 to 46 cm. Field traction conditions for zoned tillage are not favorable for large drawbar pull which will limit machine width.

Mechanical vine killing of potatoes

Six chemical and mechanical vine killing methods were compared for their effects during tuber maturation and subsequent harvesting of commercially-produced Russet Burbank potatoes. Pulling of vines resulted in tuber specific gravities which were equal to those of other vine killing treatments even though pulling terminated plant growth more abruptly. Dehydration tests show no significant difference among treatments and that the tuber maturation period could be less than the customary 21 days. Overall results suggest that pulling of vines might be done several days later than for other vine killing methods. An experimental vine puller placed pulled vines between adjacent rows to entirely eliminate subsequent harvester pickup. Pulling increased the amount of vine fragments in the harvested tubers compared to chemical vine killing methods. The number of tubers exposed to light was greatest for the vine pulling treatments.