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- Author or Editor: Daniel J. Cantliffe x
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.
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.
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.
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.
Shoot and root growth changes in response to handling and storage time in `Sunny' tomato (Lycopersicon esculentum Mill.) transplants were investigated. Transplants, 45 days old, were stored either in trays (nonpulled) or packed in boxes (pulled) for 0, 2, 4, 6, or 8 days at 5 and 15C. Also, 35-day-old nonpulled and pulled transplants were kept in darkness at 20/28C for 0, 1, 2, or 3 days. At SC, pulled transplants had longer and heavier stems, a higher shoot: root ratio, higher ethylene evolution, and lower root dry weight than nonpulled transplants. At 15C, pulled transplants had more shoot growth than nonpulled transplants. Nonpulled, initially 35-day-old transplants had heavier shoots and roots and higher (7.0 t·ha-1) yields of extra-large fruit than pulled transplants (4.1 t·ha-1), but there were no differences in the total yields of marketable fruits.
ABA and drought stress were evaluated on growth morphology and dry weight of pepper (Capsicum annuum L.) seedlings subjected to continuous watering (CV) or alternate watering (AW) subflotation irrigation. When ABA (10-4 m) was sprayed on to leaves 28, 32, or 37 days after seeding (DAS), leaf growth was limited relative to the controls. Root dry weight, basal root count, and diameter decreased in AW compared with CW-treated seedlings. ABA did not influence root growth of the transplants or subsequent total fruit yield. When ABA was applied to leaves at 20,23, or 29 DAS, there was a transient inhibition of leaf weight increase, but root growth was unaffected. Exogenous ABA may have a practical application as a substitute for drought stress to control transplant growth in the nursery. Chemical name used: abscisic acid (ABA).
Transplants produced with overhead or subirrigation and plants from direct seeding using primed or nontreated `Jupiter' bell pepper (Capsicum annuum L.) seeds were evaluated for growth and yield in the field for 3 years. Early in development, overhead-irrigated (01) transplants had more basal root elongation than subirrigated (SI) transplants; however, root growth differences caused by irrigation systems in the greenhouse were minimized during late ontogeny in the field. Basal, lateral, and taproot dry weights accounted for 81%, 15%, and 4% of the total for transplants and 25%, 57%, and 18% of the total for direct-seeded plants. Direct-seeded plants maintained a more-balanced root, stem, leaf, and fruit dry matter partitioning than transplants, which allocated more dry weight (per unit of root growth) to stems, leaves, and fruits. Over all seasons, transplants exhibited significantly higher and earlier yields than direct-seeded pepper plants, and total yields were similar between SI and OI transplants and between primed and nontreated seeds.