with 14.8% MC were used (Seed Lot 2). The hilum of the seeds was covered by a layer of Vaseline, and the seeds were placed in a petri dish inside an electronic humidity control box set at 3% RH. To prevent the seeds from rolling around and having
Chia Ting Han, Yu Sung, and Ming-Tung Hsueh
Susumu Maekawa and William J. Carpenter
The germination of verbena (Verbena × hybrids) seed was found to be sensitive to high substrate moisture content. Cultivars varied in sensitivity to excessive substrate moisture content, with `Romance Scarlet' having higher total germination (G) in the presence of free water than `Showtime Blaze' or seedling `Red A'. Hilum cavity measurements of dry seeds showed larger hilum apertures with reduced depths for seeds of `Romance Scarlet' than for the others. Seed imbibition resulted in a rapid and extensive thickening of the hilum wall. The extent of hilum aperture closure varied among cultivars and the quantity of water present. Free water reduced hilum apertures 45% for `Romance Scarlet', 60% for `Showtime Blaze', and 86% for `Red A'. Seeds of `Romance Scarlet' and `Showtime Blaze' failed to germinate with lanolin covering the hilum, while seeds coated with lanolin, except for the hilum, had 67% to 78% G of nontreated seeds. This difference indicates that essential oxygen for the embryo was obtained through the hilum and micropyle of the seeds. Total germination varied with substrate moisture content, with seeds placed horizontally on 2%, 1%, or 0.5% agar having 80%, 75%, and 65% germination, respectively, for `Romance Scarlet' and 59%, 41%, and “24%, respectively, for `Showtime Blaze'.
Mark J. Bassett
The inheritance of corona and hilum ring color of common bean (Phaseolus vulgaris L.) was investigated in the reciprocal cross `Wagenaar' (a Canario market class dry bean) × `Mayocoba' (Mayocoba market class dry bean), where both parents were known to have seedcoat color genotype P [C r] gy J g b v lae Rk. `Wagenaar' has greenish yellow (GY) seedcoat (due to gy) except for purple (dark) corona (due to v lae) and reddish brown hilum ring (due to J), whereas `Mayocoba' has an entirely GY seedcoat. Seeds produced on the F1 progeny plants had GY corona and reddish brown hilum ring. The F2 segregated for three phenotypic classes, the two parental classes and the F1 class, but the segregation did not fit a 1:2:1 segregation ratio due to disturbed segregation. F3 progeny tests of 35 randomly selected F2 parents demonstrated that the two parental classes were true breeding and the F1 class segregated again (as in the F2) for the same three phenotypic classes. In spite of variable expressivity of GY color and disturbed segregation, the data support a single gene hypothesis, for which the tentative symbol Chr is proposed. Chr is dominant for changing purple corona to GY, but recessive for changing reddish brown hilum ring to GY. Thus, only one gene, Chr, controls the difference in seedcoat color between the market classes Canario and Mayocoba. An allelism test between Chr and Z (hilum ring color factor) is needed before a formal proposal for Chr can be made.
Mark J. Bassett, Colleen Shearon, and Phil McClean
Inheritance of two phenotypes, the virgarcus pattern of partly colored seedcoats and the margo d seedcoat pattern, were studied in common bean (Phaseolus vulgaris L.) materials that segregated jointly for genes controlling the two phenotypes to test the hypothesis of allelism of two genes, D and Z. The F2 progeny from the cross j margo BC3 5-593 × t z virgarcus BC3 5-593 produced an unexpected phenotypic class, margo d, suggesting possible allelism of D and Z. The F2 also produced another unexpected phenotypic class, white seedcoat, for which the genetic hypothesis t j z was made. The F2 from the cross t j marginata BC3 5-593 × t z virgarcus BC3 5-593 provided supporting evidence for the new genotype, t j z, for a white seedcoat. Analysis of the F2 and F3 progenies of 80 random F2 plants from the cross t z virgarcus BC3 5-593 × d j (margo d) BC3 5-593 provided support for the hypothesis that the D and Z loci are allelic. Production of two different phenotypes (white vs. white with two tiny pale gray dots, one each at the raphe and micropyle) for t J/j z in two different genetic and cytoplasmic backgrounds is discussed. The F2 from the crosses d j (margo d) BC2 5-593 × j v margo BC2 5-593 and d j (margo d) BC3 5-593 × j margo BC3 5-593 segregated for d (vs. D) phenotypes, which were found not to be independent of a randomly amplified polymorphic DNA (RAPD) marker (AM10560) associated (1.4 cM) with the Z locus. Because the Z gene symbol has priority, we propose to retain Z for the locus.
Menahem Edelstein and Haim Nerson
-Berman et al., 1989 ), the hilum was found to be the main pathway for gas exchange, and sealing the hilum prevented germination because oxygen diffusion through the seedcoat surface was not sufficient. Similar results were reported in ‘Noy Yizre'el’ (NY
A.K. Forney, D.E. Halseth, and W.C. Kelly
Four planting and harvest dates yielded 16 lots of `Ruddy' red kidney beans (Phaseofus vulgaris L.) that were canned immediately after harvest in the fall and from storage in January and April. Late planting resulted in a high percentage of acceptable beans, but time of harvest had little effect on subsequent canning quality. The most important defect was transverse splitting from the hilum. Hilum splits, drained weight, cooked weight, and seed size were all negatively correlated with acceptability. Seed size was the most important factor determining quality, with the smallest seeds exhibiting the fewest splits. Length of storage had significant but small effects on canned seed quality.
Mark J. Bassett
The inheritance of hilum ring color in common bean (Phaseolus vulgaris L.) was investigated using various genetic tester stocks developed by backcrossing recessive alleles into a recurrent parent stock 5-593 with seedcoat genotype P [C r] D J G B V Rk, viz., mar BC2 5-593, mar BC3 5-593, mar v BC2 5-593, mar d BC2 5-593, and mar d BC3 5-593. The current hypothesis is that the margo character is controlled by mar and hilum ring color is controlled by d but expresses only with mar. The V locus controls flower and seedcoat color. The allelism test crosses `Citroen' (P C d j g b v lae) × mar BC3 5-593 and `Citroen' × mar d BC3 5-593 demonstrated that mar is allelic with j and that the putative d in mar d BC3 5-593 is allelic with the d in `Citroen'. Thus, the former genetic tester stocks mar BC3 5-593 and mar d BC3 5-593 are reclassified as j BC3 5-593 and d j BC3 5-593, respectively, because mar is a synonym for j. Similarly, the former genetic tester stock mar v BC2 5-593 is reclassified as j v BC2 5-593. The interaction of j with d expresses as loss of color in the hilum ring. The development of the white-seeded genetic tester stock P c u d j BC3 5-593 was described in detail, where the all-recessive tester `Prakken 75' was used as the source of the recessive alleles. The previously reported work showing that the partly colored seedcoat gene t interacts with mar to control seedcoat pattern is now interpreted to mean that the joker (J) locus interacts with t to produce partly colored seedcoat patterns. The genetic loci D and V were found to segregate independently. The common gene for dull seedcoats (asper, asp) is discussed and contrasted with j.
William J. Carpenter and Susumu Maekawa
Verbena (Verbena × hybrida Voss) seed germination varied with the water content of the substrate. Total germination percentages (G) were highest when substrates were 75% to 100% saturated and progressively declined with increased free distilled water (FDW) on the blotter paper substrate. Natural differences in G among cultivars at favorable substrate moisture levels increased when free water was present. Removing the seed hilums did not increase G of `Romance Scarlet' on a substrate with FDW, but significantly increased the G of `Showtime Blaze' and `Red A'. Au inverse relationship was found between seed moisture contents and G at high substrate moisture levels. `Romance Scarlet', `Showtime Blaze', and `Red A' had 64%, 73%, and 84% seed moisture contents and G of 72%, 18%, and l0%, respectively. The period of sensitivity to excessive water during germination was day 2 for `Red A' and days 2 and 3 for `Showtime Blaze'. The G of `Romance Scarlet' seed was not reduced when placed on a substrate containing FDW for 1 day. Removal of seed hilums from `Red A' significantly increased G during day 2 for seeds on a substrate containing FDW.
T. A. Nell, P. M. Marsh, and D. J. Cantliffe
No differences were observed in water uptake, respiration rate and seed coat morphology of ‘New Era Bright Red’ and ‘New Era Dark Red’ geranium. Water uptake in some seeds was rapid in the first 12 hours following initiation of imbibition. Radicle emergence and germination occurred 3 days after swelling and respiratory activity began as soon as seeds imbibed water. Nonswollen seeds did not germinate. Seed coat surfaces appeared wax-like in both cultivars and no relationship between occlusion of the hilum fissure and germination was observed. Dipping seed in concentrated H2SO4 or hot water, or removing a portion of the seed, increased germination rate and germination to nearly 100%. Results suggest the seed coat in geraniums can be impervious to water uptake.
M. H. Dickson, K. Duczmal, and S. Shannon
Transverse cracking of cotyledons, (TVC), varied from 0 to 95% among bean cultivars and was enhanced by planting dry seed in wet soils. A more reliable indication of TVC potential was obtained if the seed was placed in small beakers and covered with water. Covering the hilum with grease slowed imbibition and reduced TVC in tolerant lines. Soaking for 45 minutes in ethanol prior to imbibition in water accelerated imbibition and increased TVC. Seed coat removal prior to imbibition further enhanced imbibition and increased TVC. None of these 3 treatments changed the relative amount of TVC, but seed coat nicking or removal prior to imbibition gave the most reliable test.
Potassium and Mg in cotyledons were negatively correlated with cultivar susceptibility. Calcium was sometimes significantly correlated with TVC in seed grown in a given location, but the correlations could be lacking or of opposite sign in seed grown elsewhere.