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Carlos A. Parera and Daniel J. Cantliffe

Seeds of two shrunken-2 (sh2) sweet corn (Zea mays L.) cultivars, Crisp N' Sweet 711 and How Sweet It Is were used to analyze seed quality factor differences between the cultivars. Negative correlations occurred among germination percentage and imbibition, electric conductivity, potassium concentration and total soluble sugars of the seed leachate. Imbibition and total soluble sugar in the leachate significantly increased as imbibition temperature increased from 5°C to 25°C in both cultivars. A significant increase in conductivity of the leachate also occurred in `Crisp N' Sweet 711' when temperature increased. Cracks in the seed coat were more frequent in `How Sweet It Is' than `Crisp N' Sweet 711'. The higher concentrations of soluble sugars in the seed, greater imbibition rate, leakage conductivity, potassium and sugar concentration in the leachate may have been directly related to the poorer seed quality of `How Sweet It Is'. The alteration in cell membrane structure caused by a rapid water uptake in `How Sweet It Is' may have led to the high concentration of electrolytes in the seed leachate. This, in turn, might provide a greater nutritive subtrate for fungi development.

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Ebrahim M. Khah, Konstantinos A. Akoumianakis, and Harold C. Passam

As good quality irrigation water becomes increasingly scarce in the Mediterranean region, especially in coastal areas where greenhouses are located, methods of economizing water consumption are essential. Therefore, the effect of the duration of irrigation on the quality and yield of seed of two cultivars of dwarf green bean (`Larma' and `Montano', Phaseolus vulgaris L.) was studied during fall and spring in Greece. Seeds were sown on 11 Sept. 2000 (fall crop) and 23 Feb. 2001 (spring crop) in peat compost and when the plants had two expanded leaves (11 and 20 days after sowing, respectively), they were transplanted to the soil of an unheated, plastic-covered greenhouse. The following irrigation treatments were applied: 1) irrigation for the entire duration (control), 2) irrigation until the first pods were dry, 3) irrigation until ≈50% of the pods had filled, and 4) irrigation till flowering. Fall cultivation was not suitable for seed production due to low yield and reduced seed quality. By contrast, the spring crop had a higher yield, seed size and good germination. Stopping irrigation of the spring crop at the drying of the first pods achieved an ≈20% saving in water without significantly affecting seed yield or quality. Earlier discontinuation of irrigation to achieve greater savings of water caused a reduction in yield, but did not affect seed quality.

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Jianhua Zhang and Miller B. McDonald

Varietal identification of cyclamen and petunia is important for flower seed production because these crops are marketed as hybrids and genetic purity determinations assure the purity of the seed lot and the success of hybridization. Random amplified polymorphic DNA (RAPD) banding patterns have been shown to be useful in identifying genotypes of various crops. This molecular biology technique was applied to five commercial cyclamen and six petunia hybrids. Using bulk seed/seedling samples, the varieties could be differentiated. However, when individual seeds of the cyclamen hybrid were tested, differing polymorphisms were observed. These variations were attributed to genetic variability in the inbred parents. We conclude that the genetic purity of cyclamen seeds can be improved and that the use of RAPDs can assist breeders of hybrid flowering crops in better monitoring seed quality.

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Mike Murray and Steve Temple

Significant industry interest exists for evaluating the lower Sacramento Valley as a production region for specialty dry beans. This interest is being driven by erratic or inconsistent production in the existing commercial production regions, mostly in the Pacific Northwest and the Mid-West regions. The environmental conditions in the Sacramento Valley are favorable for producing consistent yields of high-quality dry beans. Specialty beans are generally typified by limited markets and relatively high producer returns, and offers an attractive rotation crop for local growers.

Variety evaluations including many of the most popular or likely candidates for a local specialty bean industry were conducted in 1991 and 1993. Parameters evaluated included plant architecture, flowering dates, pod set and retention, maturity dates and seed yield. Additional qualitative evaluations to determine varietal quality were also conducted. Many varieties were identified that had both acceptable yield and seed quality potential.

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Richard O. Hampton

Blackeye cowpea mosaic potyvirus is the most easily observable seed-borne virus in cowpeas, but is typically seed-transmitted at lower rates (i.e., 0.1 to 2%) than the less conspicuous cowpea severe mosaic comovirus or cucumber mosaic cucumovirus. All three viruses are readily vector transmissible after seed-borne inoculum reaches the field, perpetuating and spreading the viruses. Individually and particularly in mixtures, these viruses are capable of decreasing both seed quality and yield. Disease-tolerant cultivars are available, but fail to control viral diseases. Development of superior new cowpea cultivars with multiple viral-disease resistance is clearly within reach and has become essential to long-term, sustainable, profitable cowpea production. This breeding objective requires public-research supported efforts by the combined cowpea seed and processing industries. Southern bean mosaic sobemovirus is also recognized as an important cowpea pathogen, but was encountered at a much lower frequency than the above three viruses in both plant and seed samples, in 1992 and 1993.

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Vladimir Orbović, Manjul Dutt, and Jude W. Grosser

The effects of fruit age on the seed quality and germination percentage of ‘Duncan’ and ‘Flame’ grapefruit and ‘Hamlin’ sweet orange were investigated. Our results suggested that seed germination varied from 98% to 100% for the two grapefruit cultivars and 85% to 100% for ‘Hamlin’ regardless of time of harvest. Within the first 5 months of the harvest season, chilling of ‘Duncan’ and ‘Hamlin’ seeds at 4 °C for 7 days after fruit sampling resulted in a lower germination percentage only with the ‘Hamlin’ seeds. Seed moisture content of all three cultivars varied slightly through the season and remained steady at 60% and 70% for batches of fresh seeds stored at room temperature or at 4 °C. Our results suggest that high seed viability and germination percentage can allow the use of these seeds for experimentation regardless of the time the fruit were picked during the harvest season.

Open access

Michael A. Raymond, Jeffrey C. Stark, and Glen A. Murray

Abstract

Seed yield and quality of four spring pea cultivars (Pisum sativum L.) were evaluated when subjected to deficient, optimal, and excessive irrigation levels. Irrigation at 100% of the estimated optimal irrigation amount (IR) resulted in the greatest seed yields, whereas irrigation at 60% or 140% IR reduced yields by 468 and 222 kg·ha−1, respectively. Yield reductions for individual cultivars were as large as 694 and 350 kg·ha−1 for deficient and excessive irrigation, respectively. Increased yields for the 100% IR treatment resulted from increases in pods per plant and seeds per pod. Irrigation at 140% IR reduced germination of pea seed by 5% to 13%. Deficient irrigation reduced seed yield more than did excessive irrigation, whereas excessive irrigation caused the greatest reduction of seed quality.

Open access

Kar-Ling Tao, Anwar A. Khan, Gary E. Harman, and Charles J. Eckenrode

Abstract

Several chemicals applied to dry seeds by means of organic solvents were successful in preserving seed quality as determined by germinating capability of seeds or ATP content. The fungicide (pentachloronitrobenzene)-treated, injured or healthy pea (Pisum sativum L. cv. Alaska) seeds were highly resistant to infection by Aspergillus ruber (Konig, Spiekerman and Bremer) Thom and Church (NRRL 52), a storage fungus. The insecticide, Chlorpyrifos caused the lima bean (Phaseolus lunatus L. cv. Fordhook 242) seeds to produce seedlings with reduced levels of damage from the seed-corn maggot, Hylemya platura (Meigen). The antibiotics, chloramphenicol and puromycin, slowed down the rate of deterioration of lettuce (Lactuca sativa L. cv. Grand Rapids) seeds stored under accelerated aging conditions [43°C & 85% Relative Humidity (RH)].

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A.G. Taylor, D.B. Churchill, S.S. Lee, D.M. Bilsland, and T.M. Cooper

Color sorting was performed to upgrade seed quality by removal of fluorescent coated seeds. The fluorescent coating was attributed to sinapine leakage from nonviable seeds. Nine seedlots, three seedlots each of cabbage (Brassica oleracea L. Capitata group), broccoli, and cauliflower (B. oleracea L. Botrytis group) were custom coated. Seed samples were pretreated before coating with or without 1.0% NaOCl for 10 minutes to enhance leakage. All samples revealed a percentage of seeds with fluorescence. The light emission from selected fluorescent and nonfluorescent coated seeds was quantified by fiber-optic spectrophotometry. Fluorescence was expressed from 400 to 560 nm, with peak emission being from 430 to 450 nm. These data confirmed our visual interpretation of blue-green fluorescence. The ratio of light emission from fluorescent compared to nonfluorescent coated seeds ranged from 4.5 to 7.0 for all samples and averaged 5.7. An ultraviolet (UV) color sorter was employed to separate fluorescent (reject) from nonfluorescent (accept) coated seeds. The percentage of nonfluorescent coated seeds (averaged over seedlot and NaOCl pretreatment) before and after sorting was 89.5% and 95.9%, respectively. Therefore, color sorting was able to remove a high percentage of fluorescent coated seeds with an average loss (rejection of nonfluorescent coated seeds) of 6%. An increase in the percent germination was recorded in eight of the nine seedlots following color sorting, and the greatest improvement was obtained with seedlots of medium quality. Germination of three medium quality lots was increased by 10 to 15 percentage points. The average increase in germination with or without NaOCl pretreatment was 8.2 and 5.5 percentage points, respectively. In conclusion, the germination of Brassica seedlots could be improved by separating (removing) fluorescent from nonfluorescent coated seeds. UV color sorting technology was employed to demonstrate that seed conditioning could be conducted on a commercial basis to upgrade seed quality.

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Samuel Contreras, David Tay, and Mark A. Bennett

Among the factors affecting germinability of a seed lot are the environmental conditions under which the seeds are produced. The objective of this study was to determine the effects of temperature during seed development on seed quality of two Asteraceae species. Seeds of lettuce cv. Tango and Helianthus debilis cv. Vanilla Ice and sp. cucumerifolius were produced in a greenhouse under one of two treatments: i) hot (27, 40, and 20 °C temperatures average, max, and min, respectively), and ii) cool (23, 33, and 18 °C temperatures average, max, and min, respectively). In both species, heavier seeds were produced under the cool conditions and no differences were observed in standard germination. In lettuce, germination percentage and rate were both affected by increased levels of exogenous ABA concentrations and reduced water potential (PEG solutions), and, in both cases, seeds from cool treatments were more affected. Germination at 30 °C and constant light was higher for seeds from the hot treatment. Lettuce seed showed a strong light requirement for germination. However, seeds from the hot treatment gave better dark germination at 13 and 19 °C. Seeds of H. debilis did not required light for germination, and the germination percentage and rates were evaluated at 13, 21, and 29 °C. For both lines, seeds from each treatment behave similarly; however, the germination of H. debilis cv. Vanilla Ice at 29 °C was higher when seeds were produced in the hot conditions. The results showed that temperature during seed development affected aspects of seed quality that are not detectable by the standard germination, but by germination at suboptimal conditions. Within the Asteraceae family, differences varied among and within species.