Excluding seeded offspring at an early stage could be of great value to the breeder concerned with the development of seedless grapes (Vitis vinifera L.). We used the random amplified polymorphic DNA (RAPD) technique to identify molecular genetic markers, analyzing 82 individuals of a progeny resulting from a cross between `Early Muscat' (seeded) and `Flame Seedless'. Seven variables representing the traits of seedlessness were analyzed: mean fresh weight of one seed, total fresh weight of seeds per berry, perception of seed content, seed size categories evaluated visually, degree of hardness of the seed coat, degree of development of the endosperm, and degree of development of the embryo. Among 160 10mer primers, 110 gave distinct band patterns. Twelve markers yielded significant correlations with several subtraits of seedlessness, mainly with the mean fresh weight of one seed and the total fresh weight of seeds per berry. Multiple linear regression analysis resulted in high coefficients, such as R = 0.779 for fresh weight of seeds per berry, when the seven markers were included as independent variables in the model. Most of the seeded individuals, about 44% of the progeny, could be excluded using a two-step process of marker assisted selection.
M.J. Striem, G. Ben-Hayyim, and P. Spiegel-Roy
Ross J. Traverse and Jerald W. Riekels
Soaking tomato seeds in MnS04 solutions of concentrations greater than 0.5 and 1 M MnS04 inhibited germination during treatment without affecting the viability of the seeds. The emergence and early growth of tomato seedlings and the emergence of onion seedlings in soil was greater using seeds previously treated with 1 M MnS04 than with untreated seeds or with seeds treated with 2 and 2.5 M MnS04. These treatments had no effect on onion seedling growth. Soaking seeds in 1 M MnS04 was effective in supplying the Mn requirements of tomato plants grown in Mn deficient solutions for Approx 40 days. Shorter periods of normal growth were obtained by treating the seeds with less than 1 M concn of MnS04.
The amount of Mn retained after desorption and washing was greater with each increase in the soaking temp (0, 10, 20, and 30°C). A substantial amount of the Mn retained by the tomato and onion seeds after soaking appeared to be located on the seed coat or in the “outer space” of the tissue. With onion seeds, an additional portion of the Mn retained after soaking was located on the exchange sites of the seeds.
Remi Bonnart, Anthony Koski, and Harrison Hughes
Native turfgrasses have received greater attention in recent years because of their usefulness in growing in areas where many other grasses cannot. Saltgrass (Distichlis spicata) has good salt tolerance, but the natural germination rate for the seed is low. This is most likely due to the thickness of the seed coat inhibiting normal imbibition of water. Previous research in our laboratory has demonstrated increased germination with hand-scarification. The purpose of this research was to compare germination rates of machine-scarified, hand-scarified, and nonscarified seed. Scarifying the seeds by hand results in greater uniformity, but the operation is tedious and time-consuming. Machine scarification is quick, but the seeds have reduced uniformity. Two seed lots, one designated “Modoc” and one designated “Granite,” were compared in laboratory and field germination tests. Preliminary observations have shown that “Granite” seed had somewhat higher viability and vigor than the “Modoc” seed. Significantly greater germination occurred with scarification when seeds were germinated at 14 h of light at 30 °C and 10 h of darkness at 20 °C in the laboratory. Although scarification treatments were similar with the “Granite” seeds, near 80% germination, there were significant differences between hand and machine scarification with the”Modoc” seeds; hand scarified seed had greater germination. The field germination experiment had similar results to the laboratory experiments with “Granite” seed. However, scarification did not aid germination of “Modoc” seed. This is thought to be due to low vigor and associated death of seedlings prior to emergence. Preliminary data confirm the low vigor of the “Modoc” seed as compared to “Granite” seed.
John McCallum, Gail Timmerman-Vaughan, Tonya Frew, and Adrian Russell
Developmental, environmental, and genetic factors affecting seed color were studied in the progeny of a cross between two white-flowered (aa) green cotyledon (ii) field peas (Pisum sativum L.): the pale large-seeded Marrowfat cultivar Primo and the greener small-seeded Prussian Blue OSU442-15. Changes in chlorophyll and carotenoid content during seed development of the parental genotypes were determined by high performance liquid chromatography analysis. Both cultivars accumulated similar pigment quantities per seed, but pigment loss was greater during maturation of `Primo'. Bleached and unbleached mature seed tissues also were compared for pigment composition. Lutein was the predominant pigment in bleached cotyledons of both cultivars. Only trace amounts of pheophytins were detected in unbleached seed. In both genotypes, chlorophyll A : B ratios were ≈1:1 in seed coats compared to 3:1 in cotyledons. Objective measurements of seed color in terms of luminance (lightness) and chrominance (hue and saturation) were made in YUV color space by video image analysis. Inheritance of seed color was studied in an F2 population derived from the `Primo' × `OSU442-15' cross and inbred descendants. Quantitative trait loci (QTL) for seed color were localized by interval mapping using a linkage map of 199 molecular markers spanning most of the genome and by bulked segregant analysis and selective genotyping. Four genomic regions affecting seed color were detected. A major gene accounting for 61% of the phenotypic variance in seed lightness (Y luminance component) was identified on linkage group V linked to r locus. Another major gene, which accounted for 56% of the phenotypic variance in seed hue (U chrominance component), was mapped to a linkage group containing group III and IV markers. A QTL with smaller effect on seed hue (U and V chrominance components) was detected on linkage group VII. Support for overdominant allelic interaction for a QTL on linkage group I, adjacent to the legumin locus Lg-J, was obtained by selective genotyping of the seed lightness distributional extremes.
S. Grange, D.I. Leskovar, L. Pike, and G. Cobb
Triploid watermelon [Citrullus lanatus (Thunb.) Matsum & Nakai] consumption is increasing in the United States However, some of the original problems, poor and inconsistent germination, still exist. Seeds of several triploid and diploid watermelon cultivars were subjected to a variety of treatments to improve germination. Control and scarified seeds, by nicking, were incubated at 25 or 30 °C in either 5 or 10 mL H2O or hydrogen peroxide (H2O2). Triploid seed germination was strongly inhibited in all cultivars when seeds were at 10 mL of H2O or H2O2; both nicking and H2O2 increased germination but not equal to rate of the control in 5 mL H2O or H2O2. Germination of diploid cultivars was unaffected by any treatment. Seed morphological measurments indicated that triploid seed has a smaller embryo with a large and highly variable (cv = 105%) air space surrounding the embryonic axis as compared with the diploid seed. These data suggests that triploid watermelon seed germination is not inhibited by the seed coat thickness alone. Seed moisture plays a significant role in germination, emergence, and stand uniformity.
Kenna E. MacKenzie
The effects of pollination treatments on fruit set and five berry characteristics [mass, diameter, number of apparently viable seeds (well-developed, plump with dark seed coat), total seed number (includes apparently viable and partially developed seeds), and harvest date] were examined on three highbush blueberry cultivars. Pollination treatments included unpollinated, open pollinated, emasculated, and three hand pollinations that used pollen from the same flower, from the same cultivar, or from a different cultivar. Berries matured earliest and were smallest with the most apparently viable seeds in `Northland', `Patriot' had the greatest fruit set and smallest seed number, and `Bluecrop' matured the latest. Fruit set was greater, berry size larger, seed number smaller, and maturation later in 1990 than 1991. For all three cultivars, berries were generally smallest, latest maturing, and had the fewest seeds when pollination was prevented and were largest with the most seeds and earliest maturing in open visitation. Emasculation resulted in berries similar to those from unpollinated flowers. For berry characteristics, cross-pollination was of benefit for `Patriot' and possibly `Northland' but not `Bluecrop'. Thus, commercial highbush blueberry planting designs must be based on the pollination requirements of the particular cultivar. `Northland' berries almost always had seeds, while `Patriot' showed high levels and `Bluecrop' low levels of parthenocarpy.
Faisal A. Al-Mukhtar and Dermot P. Coyne
The accessions, PI 255960 (P1) (purple flowers, colored seed, curved pod tip, large seed) and G-19007 (P2) (white flowers, straight pod tip, white seed) of Phaseolus vulgaris L., both late maturing with many ovules and seeds per pod, were crossed with each other and with 2 early maturing, white flowered, white seeded, straight pod tip, low ovule number/pod parents, ‘Great Northern (GN) Emerson’ (P3) and ‘GN UI#59’ (P4). P1 and P2 appeared to possess the same genes for high ovule number/pod. The continuous distributions of ovule number/pod, seed number/pod, and seed weight in the F2 generations of the other crosses indicated quantitative inheritance. However, segregation data in their F3 generations suggested that ovule number/pod may be determined by additive action of the alleles of a single major gene. Moderately high broad sense heritability estimates were obtained for these traits. Purple flower color and seed-coat color were controlled by 2 different complementary dominant genes. Striped pod color and curved pod tip shape (Ct) were each controlled by different single dominant genes. Days to flowering was controlled by a single completely dominant gene; pod maturity was controlled by a single incompletely dominant gene for lateness. Linkage occurred between genes for flower color and pod color pattern, flower color and pod tip shape, and flower color and maturity. High seed number/pod was associated with purple flowers, colored seeds, and late maturity in the F2 of P3 × P1. Late maturity and high seed number/pod were also associated in the F2 of P4×P1, P3× P2 and P4 × P2. Moderately large negative correlations were found between number of seeds/pod and seed weight in all crosses involving P1 and P2. High ovule number/pod was associated with indeterminate growth habit and moderately late flowering in the F2 progeny from the indeterminate cultivar ‘G.N. Nebr. # 1’, crossed with a determinate isoline. No association between seed weight & seed-coat color was observed in the F2 of P3 × P1, and P4 × P1, but there was association between large seed and both late maturity and flower color.
Sharon Sowa and Eric E. Roos
Infrared spectroscopy was used to measure biochemical changes during bean (Phaseolus vulgaris L.) seed imbibition. Transmission spectroscopy of excised embryonic axes revealed changes in lipid phase (gel to liquid crystalline) and protein secondary structure within the first 15 min of hydration. Spectral changes in seed coats, cotyledons, and axes during the first 2 hr of imbibition (measured in vivo) were detected using photoacoustic sensing. Onset of seed respiration could be detected as early as 15 min after addition of water. CO2 production, demonstrated by the appearance of a double peak centered at 2350 cm-1, increased with time of imbibition. Infrared photoacoustic spectroscopy of intact seeds holds promise as a method for non-invasive viability assessment.
Tim D. Davis, Wayne A. Mackay, and Daksha Sankhla
Seeds of Lupinus havardii Wats. (Big Bend bluebonnet), a potential cut flower crop, were subjected to a variety of scarification and temperature treatments. Without scarification, only 10-20% of the seeds germinated within one week. Germination percentages increased sigmoidally as scarification time in concentrated sulfuric acid increased. Nearly 100% germination was obtained within one week after seeds were placed in sulfuric acid for 120 min. Nicking the seed coat with a razor blade also resulted in near 100% germination. Soaking the seed in water for 24 h failed to enhance germination. Soaking the seed in ethanol, methanol, or acetone for 2 h likewise failed to enhance germination. Total germination of scarified seed was >90% between 21 and 33C within 28 h. The most rapid germination occurred within a range of 24-29C. Above or below this range germination was delayed. At 35C, seedling, mortality was observed and total germination was reduced to <50%. Our data indicate that seed of this species requires scarification for optimum germination but the seed can germinate over a relatively wide temperature range.
Janusz Prusinski and Anwar A. Khan
1 Research Fellow on leave from Plant Cultivation Dept., Technical-Agricultural Univ., Bydgoszcz, Poland. 2 To whom reprint requests should be addressed. This work was partially supported by a grant from the Ferry Morse Seed Co., Modesto, Calif