Search Results
Abstract
The effects of kinetin—(6-furfuryl-amino-purine), thiourea, thiourea dioxide, light and heat on germination of kola seeds were studied. The effect of chemicals on the germination of kola seeds was found to be highly significant. High temperatures and light seem to have no direct effect on germination. Seedlings from both fresh and stored kola seeds were normal at growth but the subsequent growth was enhanced in seedlings from stored kola seeds. None of the chemicals appear to have completely substituted for the postharvest requirement of fresh kola seeds. Germination of kola seeds by this method would considerably reduce the time required for producing seedlings for planting and grafting and would provide a higher percentage of uniform seedlings.
Abstract
Blueberry seeds (Vaccinium ashei Reade cv. Tifblue) were aspirated into several terminal velocity (TV) grades in an elutriation column. Different light and temperature environments were used to germinate the seeds. In all tests, germination was best at TV grades 2.23 and 2.45. Seed remaining in the air columns after aspiration did not germinate. Light was necessary for germination.
Abstract
There are differences among Kalmia species in their requirements for germination: pregermination treatments are effective with 3 of the species. Kalmia hirsuta seeds require a heat-humidity treatment, whereas those of K. latifolia and K. cuneata respond to stratification. Gibberellin (GA) can substitute for stratification. Soaking seed for 24 hr in 100 ppm of GA is sufficient for K. latifolia, where dormancy is partial, but for K. cuneata 1,000 ppm GA is required. The dormancy of fresh K. latifolia seed disappeared following storage for a year or more; seeds remained viable for 9 years. Seed of K. angustifolia, K. polifolia, and K, microphylla germinated well in three weeks at 22°C without pretreatment. Germination of K. angustifolia, K. polifolia, and K. cuneata was good between 18 and 30°C, but K. latifolia was sensitive to temperatures above 26°. Light was required for germination of K. hirsuta, K. angustifolia, K. polifolia, and K. latifolia and is probably a requirement of the other species. This information about germination should facilitate the growing and testing of Kalmia seedlings for ornamental and other purposes.
Pollen viability, in-vivo pollen tube growth, fruit ripening, seed germination, seed weight, whole plant vigor, and natural flower senescence were investigated in homozygous and heterozygous transgenic ethylene-insensitive CaMV35S::etr1-1 petunias (Petunia ×hybrida `Mitchell Diploid'). Homozygous or heterozygous plants were used to determine any maternal and/or paternal effects of the CaMV35S::etr1-1 transgene. All experiments except for those used to determine natural flower senescence characteristics were conducted in both high and low temperature greenhouses to determine the effect of temperature stress on transgenic plants when compared to wild-type. Results indicated that ethylene-insensitive plants had a decrease in pollen viability, root dry mass, seed weight, and seed germination. Fruit ripening, seed germination, and seed weight were maternally regulated. In contrast, the CaMV35S::etr1-1 transgene is completely dominant in its effect on natural flower senescence.
Abstract
The endocarp of ‘Manzanillo’ olive (Olea europaea L.) seeds was subjected to several treatments in order to determine its effect on germination of the olive seed. The endocarp inhibited germination in stratified as well as unstratified olive seeds. Removing the endocarp resulted in high percentages of germination, but only when it was completely removed or when the radicle end was removed. The endocarp did not inhibit germination by preventing imbibition, since water uptake occurred in the seed through the untreated endocarp and through the clipped cotyledon end. The endocarp also did not contain water soluble inhibitors that prevent germination. Rather, the endocarp seemed to inhibit germination through mechanical resistance. High percentages of germination can occur only when the structure of the endocarp is altered, reducing its resistance to embryo expansion.
Abstract
Seeds of tomato (Lycopersicon esculentum Mill.) and pepper (Capsicum annuum L.) were either germinated before planting, primed (immersed in an aerated solution of potassium phosphate and ammonium phosphate for 72 hours (tomato) or 120 hours (pepper) and dried), or left untreated (raw) and then planted with gel in loamy sand and sandy soils. There was little difference in response from the tomato seed treatments. In pepper, germinated seeds emerged much earlier and established heavier plants. Differences in emergence due to seed treatments generally were greater in loamy sand than in sandy soil.
A tissue culture protocol was developed that increased the germination percentage and decreased the lag time to germination for strawberry (Fragaria x ananassa Duch.) achenes. This technique involved cutting surface-sterilized achenes across the embryo axis then placing the shoot apex/radicle-containing sections on semisolid Murashige and Skoog medium lacking hormones. Cut achenes began germinating 5 days after culture and achieved maximum germination (97% to 100%) in less than 2 weeks, compared to whole achenes, which began to germinate 7 to 10 days after sowing and required more than 7 weeks for maximum germination (<50%). Enhanced germination of cut achenes was a general phenomenon since achenes from 231 hybrid crosses responded similarly. Following placement on culture medium, cut achenes could be stored up to 8 weeks at 4C then removed to 27C, where germination and seedling development occurred at percentages and rates comparable to freshly cut achenes. Achenes did not require stratification before cutting to exhibit increased germination. Nearly 100% of the achenes from freshly harvested red-ripe, pink and white strawberries germinated after cutting and culture, although cut achenes from white and pink berries germinated more slowly than those from red-ripe berries. Achenes from green berries, whether whole or cut, did not germinate. This method of “embryo rescue” could be used to generate more seedlings from poorly germinating hybrid crosses, would considerably decrease the time from sowing to seedling production compared to traditional means, and would produce seedlings of uniform age for subsequent field evaluation.
Seeds of tickseed (Coreopsis lanceolata L.) and purple coneflower [Echinacea purpurea (L.) Moench] were primed in aerated solutions of distilled water or 50 or 100 mM salt (potassium phosphate, pH 7.0) at 16C for 3, 6, 9, or 12 days. Coreopsis seeds primed in the 50 mM buffer germinated the most rapidly and uniformly, and, under stress conditions in the greenhouse, resulted in a faster-growing, more-uniform crop than other treatments. Seeds primed in distilled water and the 50 mM buffer germinated faster and at higher rates at suboptimal temperatures in the laboratory than nonprimed seeds. Priming of Echinacea purpurea seeds for 6 or 9 days in distilled water or in the 50 mM buffer resulted in faster, more-uniform germination than other treatments. Seedling emergence under stress conditions was improved by all priming regimes, with best emergence occurring in treatments that lasted > 3 days. Priming also increased germination rates of E. purpurea at suboptimal temperatures in the laboratory.
Seed yield and quality of carrot (Daucus carota var. sativa DC.) were influenced by a wide range of water application regimes and levels. Irrigation treatments were imposed beginning at the time of extension of the primary umbel and extending throughout the reproductive development period. The three application regimes used were: 1) a high-frequency, low water deficit treatment [100% of daily accumulated crop evapotranspiration (ETc)]; 2) a series of five low-frequency (irrigated after 30 mm of accumulated ET,) application treatments with a range of water deficits from moderate to minimal (40% to 120% of ETc applied); and 3) a series of three treatments that had rapidly developing water deficits applied by terminating irrigation at 7, 5, and 2 weeks before harvest after being grown under low-stress conditions. Pure live seed (PLS) yield was optimized by different treatments within each of the three application regimes. Maximum yields were achieved with short-term (2-week) rapidly developing water deficits near harvest, moderate deficit irrigation with 60% to 80% of ETc applied after 30 mm of ETc, or with a low water deficit, high-frequency application. Seed germination percentage decreased as the amount of applied water increased. This effect was more pronounced in the later-developing umbel orders. However, seed quality measured as seedling root length was improved with increasing water application.
Flower and fruit production by the columnar cactus, Stenocereus queretaroensis (Weber) Buxbaum, occurred during the dry season in the late winter and spring, and the relatively small annual stem extension occurred primarily during the fall. Thus, reproductive growth does not directly compete with vegetative growth for resources such as reducing sugars, which increased during the wet summer season, a period when total sugars were decreasing. Stem extension, reproductive demography, fruit quality, seed size, and seed quality were not influenced by irrigation. Final fruit size and seed germination, however, were enhanced by applying water. The times from flower bud differentiation to flower opening and from anthesis to fruit ripening were relatively short and unaffected by irrigation.