Casimir A. Jaworski

Canopy photosynthesis, stomatal conductance and yield ofSolanum tuberosum grown in a warm climate

Selected potato (Solanum tuberosum L.) genotypes were grown in the field from May to September during 1984 and 1985, to study their growth and gas exchange responses in a warm climate. The parameters measured were leaf area index (LAI), canopy photosynthesis on ground area basis (CPn-Ga), stomatal conductance, dry matter partitioning and yield. The LAI ranged from 1.40 for Dakchip to 6.60 for Pungo during August 1984. The LAI also differed significantly among the potato genotypes for the three samplings during 1985. Atlantic, Chipbelle and DTO-33 showed no decline in their LAI up to 73 days after planting (DAP), indicating a better heat-stress tolerance response than the other genotypes. During both years, CPn-Ga differed significantly among the genotypes and Pungo had higher CPn-Ga than all the other genotypes. Mean CPn-Ga rates were 1.72 and 4.34 g CO2 m−2hr−1 during 1984 and 1985, respectively. Mean adaxial and abaxial stomatal conductances were 0.86 and 1.46 cm sec−1, during 1984, and stomatal conductances were similar for both years. Stomatal conductance did not appear to limit gas exchange in potato leaves. Dry matter partitioning to tubers ranged from 8.9% for Pungo to 55.5% for Atlantic 67 DAP during 1984. At final harvest, July 19, 1985, dry matter partitioning to tubers varied from 47.5% for Pungo to 69.9% for Chipbelle. The tuber yield ranged from 9.6 to 27.8 MT/ha. This study indicated that Atlantic and La Chipper have potential for growing in a warm climate.CompendioDe mayo a setiembre, durante 1984 y 1985, se cultivaron genotipos selectos de papa (Solanum tuberosum L.), para estudiar su crecimiento y la respuesta al intercambio de gases en clima cálido. Los parámetros medidos fueron el índice de área de hoja (LAI), la fotosíntesis del follaje expuesto en base al área de terreno (CPn-Ga), la conductión estomática, la repartición de la materia seca, y el rendimiento. Durante agosto de 1984, la LAI varió de 1,40 para “Dakchip” a 6,60 para “Pungo.” Durante 1985, la LAI también fue significativamente diferente entre los genotipos de papa para las tres muestras estudiadas. “Atlantic,” “Chipbelle” y DTO-33 no mostraron declinatión en su LAI hasta los 73 días después de la siembra (DAP), indicando una respuesta mejor para la tolerancia al estrés al calor en comparación con los otros genotipos. Durante ambos años, la CPn-Ga difirió significativamente entre los genotipos y “Pungo” tuvo una CPn-Ga más alta que todos los otros genotipos. Durante 1984 y 1985, las tasas de CPn-Ga fueron l,72 y 4,34 g CO2 m-2hr-1,respectivamente. La conductión estomática media para las caras superior e inferior de las hojas, durante 1984, fue 0,86 y 1,46 cm sec-1, respectivamente, y fue similar para ambos años. La conductión estomática aparentemente no limitó el intercambio gaseoso en las hojas de papa. La repartición de materia seca a los tubérculos varió de 8,9% para “Pungo” a 55,5% para “Atlantic” 67 DAP, durante 1984. A la cosecha final, julio 19, 1985, la repartición de materia seca a los tubérculos varió de 47,5% para “Pungo” a 69,9% para “Chipbelle.” El rendimiento en tubérculos varió de 9,6 a 27,8 t/ha. Este estudio indicó que “Atlantic” y “La Chipper” tienen potential para ser cultivadas en clima cálido.

Relative resistance of potato cultivars to bacterial wilt

Fifty-one potato cultivars were evaluated for reaction to infection byPseudomonas solanacearum Sm. under high disease pressure in a field plot near Tifton, Georgia during the spring of 1978 and 1979. Plots were infested by clipping beds of thickly seeded tomato plants with a rotary mower contaminated with the wilt baterium in 1975, 1976, 1977 and 1978. The plants were incorporated into the soil following disease development. In addition to the use of infested soil, one stem on each potato plant was inoculated in late May by cutting with a knife blade dipped in a bacterial suspension. Most of the cultivars evaluated were highly susceptible to bacterial wilt. Ontario was the only cultivar highly resistant to the disease, with only 1% and 8% dead or dying plants in 1978 and 1979, respectively. Based on tuber infection, Ontario and Snowchip were the most resistant, with 9% and 14% infection, respectively, in 1978 and both 4% in 1979. Saco, Green Mountain and Sebago also showed some resistance.ResumenSe evaluaron para su reacción a infección porPseudomonas solanacearum Sm. 51 cultivares de papa bajo presión alta de la enfermedad en una parcela de campo cerca de Tifton, Georgia durante la primavera de 1978 y 1979. La infestación de la parcela fué realizada cegando camas de tomate densamente sembrado con una cegadora de césped rotativa contaminada con la bacteria en 1975, 1976, 1977 y 1978. Después del desarrollo de la enfermedad se incorporaron las plantas al suelo. Además de usar suelo infestado, se inoculó un tallo de cada planta de papa a fines de Mayo con una cuchilla sumergida en una suspensión de la bacteria. La mayoría de los cultivares fureon altamente susceptibles a la marchitez bacteriana. El único cultivar altamente resistente fué Ontario, con sólo 1% y 8% plantas muertas o moribundas en 1978 y 1979, respectivamente. En base a infección de tubérculos, Ontario y Snowchip fueron las mas resistentes con 9% y 14% de infección, respectivamente en 1978 y ambos con 4% en 1979. Los cultivares Saco, Green Mountain y Sebago también mostraron cierta resistencia.

Effect of storage temperature and duration on quality and survival of potato transplants

Potato transplants (Solanum tuberosum) were harvested and stored at 1.7, 7.2, 12.8, 15.6 and 18.3°C between 4 and 8 days. The transplants were evaluated after storage for leaf color and drop, wilt, tuberization, and stolonization. After transplanting, the plants were evaluated for survival. At 1.7 and 7.2°C storage, the leaves were greener with less drop than at the higher temperatures. During storage above 7.2°C, the development of tubers and stolons continued. Plant survival was generally higher at 1.7, 7.2 and 12.8°C than at 15.6 and 18.3°C.ResumenLas plántulas de papa (Solanum tuberosum) fueron sacadas del almácigo y mantenidas durante 4 a 8 días en 1.7°, 7.2°, 12.8°, 15.6° y 18.3°C. Luego fueron evaluadas por el color y la caída de sus hojas y por marchitez, tuberización y estolonización. Después del trasplante, las plántulas fueron evaluadas por su sobrevivencia. Con una exposición a 1.7° y 7.2°C, las hojas estuvieron más verdes y cayeron menos que a temperaturas más altas. Con una exposición a más de 7.2°C, el desarrollo de los tubérculos y de los estolones continuaba. En general, la sobrevivencia de las plantas fue mayor en las que habian estado expuestas a 1.7°, 7.2° y 12.8°C que en las expuestas a 16.6° y 18.3°C.

Emergence and plant stand of pregerminated true potato seed in warm climate

Pregermination of true potato seeds obtained from open pollination of breeding lines and F1, hybrids improved the emergence and stand in a warm climate. Considerable differences in emergence existed within the breeding lines and F1 hybrids. With proper selection of breeding lines and pregermination of seeds, it would be possible to obtain a desirable plant stand in a warm climate.ResumenLa pregerminación de la semilla sexual de papa mejoró la emergencia y la densidad en muchas lineas avanzadas de mejoramiento y de híbridos F1 en un clima caliente. Hubo diferencias considerables en emergencia dentro de las líneas de mejoramiento y de los híbridos F1. Con una selección apropiada de lineas de mejoramiento y con la pregerminación de las semillas, séria posible obtener una densidad satisfactoria de plantas en clima cálido.

A Field Inoculator for Potatoes

ABSTRACT A device was developed for field inoculation of potato plants with Pseudomonas solanacearum E. F. Smith. A prerequisite wound induced by sand blasting, followed by a spray of bacterial suspension, produced severe wilt of potato even under suboptimal environmen-tal conditions.

Performance of Precooled Tomato Transplants

FIELD grown bare root tomato transplants packed in commercial shipping crates were precooled in a batch type precooler by forced air cooled with liquid carbon dioxide (L-C02). The precooled transplants were shipped via commercial truck from Tifton, GA to Fremont, OH. Some of the precooled and nonprecooled transplants were immediately planted in the field upon reaching destination and some were planted after 5 days of storage either at ambient or at 7°C temperatures. The technique of precooling using L-C02 was successful but there was nonuniform cooling between crates. The precooled transplants went through a heating and cooling cycle in transit because of the heat load of nonprecooled transplants. The survival and fruit yield data indicated that the performance of precooled and nonprecooled transplants was similar when they were not stored. The performance of stored transplants was worse than unstored transplants and the performance of precooled-stored transplants was worse than nonprecooled-stored transplants. Successive heating and cooling of precooled tomato transplants caused damage.

Physical Properties of Ethephon-Treated Tomato Transplants

ABSTRACT PHYSICAL properties of tomato transplants including pulling force, dry matter content, stiffness and the ultimate tensile strength for six cultivars treated and untreated with (2-chloroethyl) phosphonic acid (ethephon) were evaluated 0, 3, 10 and 14 days after treatment. Considerable difference in response existed within cultivars. Ethephon treatment generally reduced the pulling force and stiffness of the tomato transplants and increased the dry matter content. The ultimate tensile strength was by and large similar in treated and untreated samples. Shipment of tomato transplants later than 10 to 12 days after ethephon treatment could result in increased damage in harvesting and packaging because of the reduced plant strength in lateral direction..