Several soilborne diseases severely affect eggplants (Solanum melongena L.) in Japan. Therefore, eggplants are usually grafted on rootstocks of various species resistant to these diseases. For the control of verticillium wilt (Verticillium dahliae Klebahn), Solanum torvum `Torvum vigor' plants are used for rootstocks. However since the seeds started to emerge after 12 - 14 days at 25C and only 40% of them emerged after 30 days, it was difficult to obtain seedlings of uniform size.
In this experiment, matric priming treatment of seeds prior to planting was modified to improve the emergence of the seeds of `Torvum vigor'. Vermiculite powder was selected as the substrate to control the water potential of seeds during the treatment. First, samples of 0.25g seeds (235seeds on an average) were mixed with various amounts of vermiculite powder and water at 25C in the dark during 1 week. Thereafter, the treated seeds were planted in soil and incubated at 25C under a 12h daylength regime and the emergence and growth were monitored. Second, the temperature for the treatment, growth regulators added to water, air pressure and components, and the duration of the treatment were varied. Finally, the optimum treatment for improving the emergence of Solanum torvum seeds was developed.
of site on long-term growth, flowering, vigor, overall quality, and survival—horticultural performance traits that are pertinent to landscape use. Low-input conditions were used because typical garden conditions, in which moisture and nutrients are
Abstract
Butia fruit coloration at removal from the infructescence indicates the ability of the seeds to germinate. Seeds from yellow-green fruits had significantly lower germination percentages than seeds from bright to dark yellow fruits. Soaking cleaned seeds in deionized water or aqueous GA3 solutions at 1000 ppm for 24 hr following mechanical or acid scarification failed to promote germination. Butia seeds required 90 to 150 days after-ripening at 5° to 25°C before sowing. After-ripened seed sown at 40° and held there for 2 to 3 weeks and at 30° thereafter had 70% to 80% germination and superior vigor. Constant 40° temperature during germination reduced seedling growth. After-ripening and germination at 40° substantially increased total germination and reduced germination time. Time required for germination declined as after-ripening increased from 30 to 150 days.
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.
In developing countries, the use of True Potato Seed (TPS) technology offers some potential economic and biological advantages compared to using seed tubers. One problem with using TPS technology is the lack of seedling vigor, poor germination and non-uniformity of seedlings derived from TPS. Open-pollinated true seeds were divided into three classes based on differences in embryo morphology. Highly significant differences were observed among these seed classes for 100-seed weights, percent germination, rate of germination, 10-seedling weights and percent seedlings with leaves unfurled, ten days after sowing. Seed classes were quantified in terms of 100-seed weight with Seed class 1 having the lowest weight and Seed class 3 the highest; A significantly high r value (0.99) was obtained between seed classes and 10-seedling weight. High r values (0.93) and (0.94) were also obtained between seed classes and percent germination and percent seedlings with unfurled leaves, respectively. Results indicate that it may be possible to use these differences on embryo morphology as a basis for selecting vigorous true potato seeds.
The effect of fruit age (30 to 50 days after anthesis), fruit storage (seed extracted 0 to 20 days after harvest), and seed storage (0 to 12 months) on seed weight, emergence and vigor were studied in two tropical populations of pumpkin (Cucurbita moschata). In separate experiments fermentation of extracted seed was studied using several tropical and temperate genotypes. Emergence reached nearly 100% in seeds from fruit harvested 45 days after flowering, no matter how many days these fruits were stored. Seed weight and emergence markedly increased for seed extracted from less mature fruit (harvested 30 to 45 days after anthesis) when those fruits were stored for 15 to 20 days after harvest. Emergence improved during the first 3 months of seed storage, then leveled off during the remainder of the study. Fermentation of the seed and placental material for 48 hrs followering extraction does not damage seed. The seed extraction process is simplified and the emergence rate appears to increase possibly due to faster imbibition in fermented seed.
. Florida Agricultural Experiment Station Journal series no. R-02545. We express ourappreciationto R. Littell for assistance with statistical analyses and to Asgrow Seed Co. and Crookham Seed Co. for supplying the seed used in this investigation. The cost of
Abstract
Thirty random seedlings from each of 50 random parents of a sweet potato (Ipomoea batatas (L.) Lam.) mass selected population were evaluated in the greenhouse and their subsequent field performances were recorded. Simulated selection sequences were also studied. A sequence with mass selection first on maternal hill weight, high seed set, and high seed weight followed by a 50% culling level within families on the basis of low greenhouse seedling vigor resulted in average progeny field yields 45% above that of no selection. The results showed seed weight to be a potentially useful selection criterion for root yield. Individual seedling root weight in the greenhouse was not a good predictor of field yield.
Field experiments were conducted in 1996 and 1997 to examine the effects of plant density on yield and quality of fruit and seeds of muskmelons (Cucumis melo L.). Two open-pollinated cultivars, Noy Yizre'el (Ha'Ogen type) and TopMark (western U.S. shipper type), were grown at plant densities ranging from 0.5 to 16.0 plants/m2 under commercial conditions. The highest marketable fruit yields were achieved with plant densities of 2 to 4 plants/m2. In contrast, the highest seed yields were obtained at 8 to 12 plants/m2. Seed yield index [seed yield (g)/fruit yield (kg)] was used as a parameter to define seed production efficiency. High seed yield was closely related to high value of the seed yield index. High seed yield indexes resulted from high plant densities (up to 12 plants/m2), at which the crops produced many, but relatively small fruit. In all cases, the seed yield per fruit (seed number and seed size) increased with increasing fruit weight. However, the sum of the seed yield of two small fruit was always greater than the seed yield of one, double-sized fruit. There was a clear exception with extremely small fruit (<500 g), which produced both low seed yields and poor seed quality. A positive relationship was found between fruit size and seed size in both cultivars. Nevertheless, relatively small seeds (25 to 30 mg) extracted from relatively small fruit (500 to 1000 g) showed the best performance in terms of germination and emergence percentages and rates, and in the vegetative development vigor of the seedlings.
Sweet corn with the shrunken-2 (sh2) gene is characterized by poor seed emergence and low seedling vigor. Also, this variety is sensitive to flooded conditions. Our objective was to determine the effects of aeration, during priming treatment, on germination and vigor. Priming consisted of aerating sh2 maize seed during soaking then drying on a lab bench overnight under a fan. Fifty seeds at a time were soaked (25 ± 2C) in 100 ml deionized water. During this time they received either 75% O2: 25% N2, pure N2, pure CO2, or no gas (soak control) for up to 6 hours. The flow rates ranged from 0.35 to 2 standard liters per minute for 75% O2: 25% N2, 0.8 to 2.5 for N2, and 0.5 to 1.3 for CO2. Pressure was held constant at 1 psi. All samples were weighed before soaking, immediately after soaking, and again upon partial drying. Germination was counted after 7 days using the rolled paper towel method (25 ± 1C). Radicle lengths were measured after 72 hours. Oxygen (75%) increased vigor. Also, O2 permitted greater water absorption (P < 0.02). Carbon dioxide and N2 both decreased vigor. Data suggest that aeration conditions (75% O2) during the hydration treatment has beneficial effects.