Seeds of two shrunken-2 (sh2) sweet corn (Zea mays L.) cultivars, `Crisp'n Sweet 710' and `Camelot', were used to relate volatile production to seed quality and seedling establishment. The five seed treatments evaluated were a hydration and drying cycle, a biological control of Pythium, a hydration and drying cycle followed by a biological control, a fungicide treatment, and an untreated check. For the aldehyde assays, 50 seeds were germinated in a flask for 24 h with a test tube of a 3-methyl-2-benzo-thiazolinone hydrazone (MBTH) solution. One ml of the solution was then reacted with FeCl3, diluted with acetone, and absorbance read at 635 nm. A field study was run under cool soil conditions (10-16°C) for seedling emergence and growth. Aldehyde production from the seeds did not correlate with field results for seed treatments, but did show a distinct difference between cultivars. The biological control with the hydration and drying cycle significantly reduced aldehyde production. This may contribute to the effectiveness of biological treatments since Pythium spores can be stimulated by volatile compounds released from germinating seeds.
Ginseng is an herbaceous perennial that is cultivated for its highly valued root. It is used as a cure-all, wonder drug and aphrodisiac, the active principles being saponins (ginsenosides). The essential features of the cultural system are shade, a mulch and the growing of plants on raised beds. The plants are obtained either by direct seeding or by seeding into a nursery bed and transplanting. The established crop requires spraying for diseases, insects and weed control. Although ginseng has been cultivated in North America for over 100 years associated research on mechanisms controlling growth and development of the plant has been minimal. Crop establishment is a highly vulnerable stage in the life cycle of ginseng growing yet we know little about fruit and seed set, seed quality, stratification and germination. The growing environments for ginseng have only recently been precisely defined. However, we need to know more about environmental variables and their inter-relationship particularly in relation to photosynthesis and dry matter partitioning. Disease control is the central problem in world ginseng production and requires an integrated approach.
The purpose of color sorting by fluorescence was to upgrade seed quality by removal of fluorescent coatings that were attributed to sinapine leakage from nonviable seeds. Nine seed lots (three seed lots each of broccoli, cabbage and cauliflower) were custom coated. Seed samples were pretreated prior to coating with or without 1.0% NaOCl for 10 minutes to enhance leakage. Fluorescence, as measured by fiber optic spectrometry, was expressed from 400 to 560 nm with peak emission being from 430 to 450 nm. A UV color sorter was employed to separate fluorescent (reject) from non-fluorescent (accept) coatings. The percent non-fluorescent coatings (averaged over seed lot and NaOCl pre-treatment) before and after sorting was 89.5 and 95.9, respectively. There was a six percent loss of non-fluorescent coatings after sorting (averaged over all treatments). An increase in the percent germination was recorded in 8 of the 9 seedlots following color sorting and the greatest improvement was obtained with seed lots of medium quality. The germination of three medium quality lots was increased from 10 to 15 percentage points. The average increase in germination with or without NaOCl pre-treatment was 8.2 and 5.5 percentage points, respectively. In conclusion, the combination of coating technology with seed conditioning by UV color sorting was effective in improving Brassica seed performance.
Six experimental pigeonpea (Cajanus cajan (L.) Millsp.) lines were evaluated during 1992 for their agronomic performance at Petersburg, Virginia under the New Crop Development Program of Virginia State University. The germination and stand establishment of indeterminate lines was poor due to low seed quality. The final seed yield varied from 349 to 2042 kg/ha with determinate types yielding significantly higher than indeterminate types. The experimental line GA#2 produced the highest yield. The protein content in mature seeds, harvested 175 days after planting (DAP), varied from 17.0 to 18.5 percent whereas the oil content varied from 1.7 to 2.3 percent. The seed yield was positively correlated with harvest index, seeds/pod, and seed weight. At 130 DAP, the 3 determinate lines yielded more than 10 metric tons of green beans per hectare (70 percent moisture). The protein and oil content of immature seeds from these pods varied from 18.1 to 21.2 and 2.1 to 2.2 percent, respectively. Pigeonpea, depending upon the variety, can also be used as an ornamental or vegetable plant in home gardens. The results of these experiments were quite encouraging.
Abstract
The effects of soil moisture deficit on yield and quality of head lettuce seed (Lactuca sativa L.) were studied. Three moisture levels (−0.3, −0.8 and −5.0 bars) were imposed upon lettuce plants continuously or in various combinations during vegetative and reproductive growth. Highest seed yields were obtained from treatments of intermediate water deficit during vegetative growth. Severe stress significantly reduced seed yields when introduced during either vegetative or reproductive growth. These treatments resulted in the lowest average number of seeds/seed head and seed heads/plant. Average seed weights were highest from plants exposed to severe stress for extended periods. Lowest average seed weights were produced on plants grown in adequate moisture treatments. Seed length, width, thickness and volume correlated with seed weight in response to soil moisture deficits. Germination was high in all treatments (97-100%). The lowest percentage abnormal seedlings observed during germination were obtained from seed developed on plants in severe and intermediate water deficit treatments. Seeds from these same treatments also produced the most vigorous seedlings, based on radicle length. Moisture levels conducive to highest seed yield generally produced lower quality seeds. Intermediate water deficits during vegetative and reproductive growth of lettuce plants appear to produce highest seed yields together with adequate seed quality.
Seed production in the family Cucurbitaceae is more complicated than in dry-seeded grain crops because seeds mature within a moist fruit and are often held at high moisture content for several weeks before seed harvest. Muskmelon (Cucumis melo L.), a member of this family, was used as a model system to contrast seed development with crops that are dry at maturity. A detailed time course for `Top Mark' fruit and seed development is presented based on previous studies. In muskmelon fruit, precocious germination is inhibited osmotically by the low water potential of the surrounding fruit tissue. Muskmelon seeds exhibit primary dormancy that affects viability very early in development but has a greater effect on seed vigor and is removed by afterripening during dry storage. Osmotically distended or fish-mouth seeds are dead seeds that occur in cucurbit seed lots after aging kills the embryo without disrupting the semipermeable endosperm that completely surrounds and protects the embryo. Cucurbit seed crops should be harvested before the onset of fruit senescence to prevent aging of the seeds inside. Open-pollinated cucurbit seed crops are frequently once-over mechanically harvested. Mechanical harvesting combines seeds from many stages of development into a single seed lot, which may adversely affect quality and increase seed to seed variability. Hand harvesting cucurbit fruit at the optimal stage of development could improve seed quality in some instances but is more costly and time consuming and would increase production costs.
Carrot (Daucus carota) L.) seed quality is affected by the environment in which it matures. Substantial differences in germination from year to year and from field to field have been recognized for many years for umbelliferae seed. Part of the explanation for low germination appears to be the harvest of immature seed. Data was collected for two years, from fields of the cultivars Chantenay and Nantes. Approximately 550 growing degree days were accumulated from anthesis until maturity for seed from the primary umbel. Growing degree days were calculated using a 10°C base temperature and without truncating for temperatures in excess of 35°C. Secondary, tertiary, and quaternary umbel seed maturity sequentially followed primary umbel seed. Secondary and tertiary umbels produced approximately 80 percent of the total seed yield while the primary and quaternary umbels produced approximately 20 percent. Seed maturity was determined by measuring the germination rate. Immature seed germinate at a slower rate than mature seed. The implications of these results for obtaining high quality carrot seed will be discussed.
The influence of plant density on yield of three confectionery seed pumpkin accessions was investigated under non-irrigated field conditions. Seeds of Golden Delicious (GD), open-pollinated Chinese snow-white seed (CS), and a selection from Austrian hull-less (HL) pumpkin were planted 30, 60, and 90 cm apart in rows that were 127 cm apart with seedlings thinned to one plant per hill. Plants were grown from 23 May to 18 Sept. One fruit per plant was harvested from five plants for each of the three replications. The number of seeds (and dry weight of seed) per fruit were 242 (59 g), 304 (87 g), and 334 (106 g), respectively, at 30, 60, and 90 cm spacing for GD. The number of seeds (and dry weight of seed) per fruit were 219 (108 g), 266 (108 g), and 258 (106 g), respectively, at 30, 60, and 90 cm spacing for CS. The number of seeds (and dry weight of seed) per fruit were 376 (76 g), 404 (94 g), and 304 (82 g), respectively, at 30, 60, and 90 cm spacing for HL. Highest seed yield was at 60 cm plant spacing for CS and HL, whereas GD produced highest seed yield at 90 cm plant spacing. The differences in total seed yield, seed size, and confectionery seed quality, as influenced by plant density and seed source, were also characterized.
Both seed viability and vigor directly affect the performance of seeds planted to regenerate the crop. Although seed quality can influence many aspects of performance (e.g., total emergence, rate of emergence), this presentation will primarily examine the relationship of seed vigor to one aspect of performance - crop yield. Reductions in yield can be indirectly related to low seed vigor if the low vigor seed results in plant populations that are below a critical level. Thus, we investigated the direct effects of seed vigor on yield in the absence of population differences for annual crops that are harvested at three stages; during vegetative growth, early reproductive growth or at full reproductive maturity. Seed vigor affects vegetative growth and is frequently related to yield in crops that are harvested during vegetative growth or during early reproductive growth. However, there is usually no relationship between vigor and yield in crops harvested at full reproductive maturity because seed yields at full reproductive maturity are usually not closely associated with vegetative growth. The use of high vigor planting seed can be justified for all crops; however, to insure adequate plant populations over the wide range of field conditions which occur during emergence.
programs and international working groups.” “Mark explained relationships among seed quality, stand establishment, and system productivity and helped steer improvements in all through independent and collaborative efforts. Mark bridged research, real