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  • Author or Editor: Daniel J. Cantliffe x
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Abstract

Fruit development from pollinated flowers of cucumber (Cucumis sativus L.) on early nodes inhibited fruit set on later nodes. Application of chlorflurenol (methyl-2-chloro-9-hydroxyfluorene-(9)-caroxylate) overcame this inhibition and increased the number of fruit which developed from both pollinated and nonpollinated ovaries. In nonpollinated flowers, chlorflurenol promoted fruit set through parthenocarpy. In chlorflurenol treated plants, approximately 80% of the fruit from pollinated flowers produced seed, while the remaining 20% were parthenocarpic. However, chlorflurenol reduced the quantity of seed in the nonparthenocarpic fruit by 30%. This included fruit set from flowers that had been pollinated up to 5 days before chlorflurenol application. Pollination tended to improve the effectiveness of chlorflurenol to increase fruit set.

Open Access

Since the establishment of the land-grant systems in the late 1800s, universities and experiment station systems have sought out and tested vegetable germplasm for its suitability in regional and local areas across the United States. The private seed industry continued to grow, both in number and volume of sales through the early half of the twentieth century. It was during this time that many of the public breeding programs at land-grant universities began corollary plant breeding programs in variety development for vegetables. For many years it was a cooperative coexistence between the private seed industry and the public programs, wherein the seed industry derived much of its germplasm for new variety releases from the public sector. Beginning in the 1970s, the numbers of public breeders began to decline, while the numbers, especially of PhD plant breeders in the private sector, began to proliferate. Throughout this 100-year period university personnel were actively involved in vegetable variety trials, both on main campuses as well as at experiment stations, and in many cases in locales in various counties through cooperative efforts with county agents. Up through this period much credit could be given to individual faculty members for their involvement in such endeavors. In the past 10 to 20 years, many things have changed in university operations and perspectives, namely faculty are only given credit for refereed publications, regardless of the area in which they work. Moreover, they must constantly procure money to support their programs. In the past, vegetable variety testing generally did not lead to refereed publications and was not supported by the industry. Moreover, as previously mentioned many of the public programs in germplasm improvement for vegetables across the United States have ceased, thus ending a direct need for variety testing to support these programs. The critical issue for today's faculty is the relative importance of variety testing and delivering information to the general public versus how they would support such a program and eventually get academic credit for conducting such a program.

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Seed germination is a critical step to achieve economic success in a transplant operation. Total germination of a seed lot dictates total plant sales by the producer, while uniformity of germination dictates the quality of the transplant crop. Using high vigor seed will help to achieve uniform stands, as well as maximize stands, in the transplant house or field. In order to maintain the highest seed quality, transplant producers should store unused seeds at recommended temperature and relative humidity for the crop species. Methods to promote uniformity and optimum stands under a wide range of conditions include the use of seed priming, film coating with fungicides, and pelleting for ease of planting.

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Abstract

Five pickling cultivars and a breeding line of cucumber (Cucumis sativus L.) were grown under varying environmental conditions to determine the influence of light and temperature on sex expression. More staminate flowers were produced under 17,200 lux light intensity than 8,600,12,900 or 25,800 lux, whereas more pistillate flowers reached anthesis under the highest 2 light intensities. A gynoecious line, MSU 713-5, produced no staminate flowers under varying light intensities, however gynoecious hybrids did. Altering the length of the photoperiod or red and tarred light exposure at the end of the light period had no influence on sex expression. Few staminate flowers were produced when the plants were grown at a constant 16° or 22°C, but all lines or cultivars produced some staminate flowers at 30°. The largest number of pistillate flowers reached anthesis at 26° or 30°. Temperature influenced sex expression more than light intensity or photoperiod.

Open Access

Abstract

Different preplant and sidedress N fertilizer rates from NH4NO3 or urea were applied to pickling cucumbers (Cucumis sativus L.) grown for once-over harvest to determine the effect of N rate, source and time of application on cucumber yield, sex expression, and fruit quality. Nitrogen preplant rates of 67 or 134 kg/ha resulted in greater yields ($/ha and MT/ha) than no N preplant fertilizer. Preplant rates of 201 or 268 kg N/ha gave lower yields. The preplant source of N, NH4NO3 or urea had no effect on yield. Sidedress N as NH4NO3 or urea generally did not influence yields ($ and MT) when preplant N was used at rates of 67 or 134 kg/ha. The addition of preplant N fertilizer up to 134 kg/ha resulted in a slightly greater number of pistillate flowers per plant. The percentages of off-shape fruit were higher for the highest rate (268 kg/ha) of preplant N. Fruit quality evaluation (shape and color) and length:diameter ratios were generally not influenced by preplant N fertilizer.

Open Access

Abstract

Pickling cucumbers (Cucumis sativus L.) were grown at high plant population (250,000 plants/ha) for once-over harvest. Nitrogen was applied preplant, 0 to 268 kg/ha, and sidedress, 0 to 112 kg/ha, from 2 N sources, NH4NO3 and urea. The effects of N fertilization practices on mineral nutrient composition of the tissue was studied. The concentration of NO3-N in leaf blade and petiole tissue rapidly decreased during the last 2 to 3 weeks before harvest (fruit sizing period). Preplant and sidedress N fertilizer applications led to increased tissue concentration of NO3-N and total N. Petiole tissue concentration less than 0.8% NO3-N or greater than 1.5% at harvest usually reflected reduced yields. Optimum yields generally occurred when blades contained 4 to 5% total N. The source of N fertilizer used had little influence on tissue concentration of NO3-N and total N. Nitrogen fertilization practices had a direct influence on the mineral nutrient composition of the leaf tissue at harvest. Tissue concentration of K, Ca, Mg, Fe and Mn were higher in tissue that received preplant fertilizer N rates from 67 to 201 kg/ha compared to plants that received no preplant N, while the Na concn was reduced. Sidedressing N fertilizer had little influence on cation and anion accumulation in the tissue.

Open Access

Abstract

No NO3 accumulated at any photoperiod in leaves or roots of table beets when N was not added to the soil. When N was applied at rates from 100 to 400 lb./acre less NO3 accumulated in both plant parts as photoperiod was extended from 8 to 20 hr. Addition of N to the soil increased the total N content of leaves and roots. Larger total N concn were observed in plants grown under an 8-hr photoperiod than in plants grown under longer photoperiods.

Various radish, spinach, and snap bean cultivars were grown at different soil N rates and harvested 0, 6, and 12 hr after the initiation of the light period. Radish leaves and snap bean pods contained less NO3-N as the plants were harvested further into the light period. Nitrate concn of radish roots and spinach leaves were not changed by harvesting at 6 AM, 12 noon or 6 PM. The addition of N fertilizer increased the NO3-N concn of radish and spinach but decreased the NO3-N concn of snap bean pods. Cultivars differed in their capacity to accumulate NO3 in all 3 species. Nitrite accumulation was proportional to the quantity of NO3 in the tissue.

Open Access

Abstract

Nitrate accumulated in spinach plants that did not receive additional fertilizer N when temp was increased above 15°C. When 50 mg N/kg soil was added the NO3 concn increased above 10°C and with 200 mg N/kg soil NO3 increased with temp increments above 5°C. When N fertilizer was added the NO3 concn decreased with a subsequent increment in temp from 25°C to 30°C. The effect of N fertilizer on NO3 accumulation became more apparent with each 5°C rise in temp to 25°C. Either N fertilizer or a temp rise from 5°C to 25°C led to a significant increase in the total N concn of the plants. Changes in total N were correlated with changes in NO3-N when N fertilizer was added to the soil or when the temp was changed. Nitrite did not accumulate appreciably at any of 6 temp or 3 N fertilizer levels used.

Open Access

Abstract

‘Winter Bloomsdale’ spinach plants were grown in a growth chamber with a light intensity of 2400 ft-c until 2 weeks before harvest when light intensity treatments of 600, 1600, 2400, and 3500 ft-c were imposed. The total N and NO3 concn of the leaves were increased by the addition of N to the soil and by reduction of light intensity. At 600 ft-c the plants accumulated NO3-N and total N at all soil N levels, but response to soil increments of N was greater at higher light intensities. The concn of K in the tissue increased with a reduction in the light intensity from 2400 to 600 ft-c or application of N fertilizer to 200 mg/kg of soil. Less P was found in spinach leaves as N fertilizer was added to 100 mg/kg of soil. The P content was variable with light intensity.

Open Access