Muscadine grape industry in the southeastern United Sates is expanding in recent years. To provide necessary information for the growing industry, 50 muscadine grape cultivars were evaluated for vigor and fruit characteristics at Florida A&M Univ., Tallahassee, Fla. Vine vigor was measured by winter pruning weight and varied from 5.4 lb/vine to 35.7 lb/vine. Among these cultivars, Triumph, Summit, and Tara were the least vigorous, while `Carlos', `Fry Seedless', and `Gold Isle' produced the most pruning weight. Dry scar ranged from 60.6% (Darlene) to 97.7% (Dixie Red). Among the most important table grapes, `Nesbitt', `Alachua', `Jumbo', `Fry', `Triumph', and `Scarlete' showed more than 70% of dry scars. Fruit rot ranged from 0.3% (Gold Isle) to 31.8% (Dixie Land). `Noble', `Scarlet', `Nesbitt', and `Carlos' were the important cultivars with less than 5% rotted fruits. Commercial fruit index were different significantly among the cultivars, ranged from 45.5% to 96.4%. Higher commercial fruit index of table grapes were found with `Magnolia', `Rosa', `Scarlet', and `Tara', while `Dixie Land' (45.5%) was the least. Seeds per fruit varied among the cultivars, ranging from 2.4 to 4.9. Fewer fruit seeds were found in `Fry' and `Nesbitt', while `Granny Val', `Senoria', `Darlene' and `Triumph' had more seeds per fruit than the others. Seed size also differed among the cultivars. `Sugar Pop' had the largest seeds (0.144 g/seed), which was twice as the size of the smallest seeds of `Welder' (0.056 g/seed). Fruit soluble solids content (SSC) ranged from 11.7% to 16.9% among the cvs. evaluated. Higher SSCs were found in `Welder', `Fry Seedless', `Scarlet', and `Cowart', while `Senoria' and `Jumbo' had relatively low SSC.
1 Currrent address: Louisiana State Univ. Sweet Potato Research Station, P.O. Box 120, Chase, LA 71324-0120. 2 Assistant professor, welbaum@vt.edu . 3 Associate professor. We are grateful for the gift of broccoli seeds from Petoseed Co. Inc
Abstract
‘Sumter’ cucumber plants (Cucumis sativus L.) were grown in an acid-washed sand with a modified Hoagland's solution containing calcium (Ca) at 160 (control), 80, or 40 mg·liter−1. Fruits grown under low Ca levels developed water-soaked and necrotic lesions on the epidermis and pericarp of the distal end of the fruits. Some Ca-stressed fruits also developed a placental disruption near the stem-end forming a cylindrical air pocket. Fruit fresh and dry weights from 40 mg Ca/liter were lower than those of the control between weeks 4 to 7 of development. The Ca content of the fruit pericarp sections decreased with increased Ca stress. Regardless of treatment, the proximal peduncle portion contained the highest level of Ca, while the distal section contained the lowest. Seed quality was also reduced from Ca stress. Almost all dry seeds from the control but only 70% of those from 40 mg Ca/liter germinated with the standard germination test. Drying seed at 25C for 5 days reduced the viability of Ca-stressed seeds, when compared to undried seed (72% vs. 99% germination). The vigor of the control seeds was significantly higher when dried. Seeds from the 40 mg Ca/liter treatment produced a significantly higher proportion of abnormal seedlings than the control seeds (58% vs. 4%).
Multiple electroconductivity readings (μAmps) of leachates from individual seeds during the first 6 hr of imbibition was examined as a possible predictor of seed quality. Readings from each sample of 100 seeds were formed into frequency distributions and the mean, median. and internal slope were calculated using an automated computer retrieval system. Internal slope is a non-central tendency measure based on the slope of a line tangent to the inflection point of the S-shaped cumulative frequency distribution (CFD) of μAmps. Radicle lengths (3 days) and germination (7 days) percentages were regressed on each of the two measures of central tendency and also the CFD shape indicator, internal slope. None of the three predictors were satisfactory for estimating seed vigor (root lengths) of maize (Zea mays L.) or wheat (Triticum aestivum L.) or germination of wheat seed lots. Internal slope was useful in estimating viability of artificially aged maize seeds (r2= 0.91), which compared favorably with our previous results using naturally aged red clover (Trifolium pratense L.) seed lots. Overall the seed quality of the unaged wheat lots was fairly high and the electrolyte leakage test was not sensitive enough to detect differences within these lots.
All of the major California almond varieties are self-incompatible necessitating the interplanting of pollinizer varieties. The incorporation of self-compatibility into the dominant variety Nonpareil through mutation or genetic engineering would greatly improve cropping efficiency. Negative effects of inbreeding on resultant seed and seedling quality could negate production advantages. Inbred seed of Nonpareil were obtained by: a) enclosing mature trees in pollination cages containing bees at flowering, and, b) controlled crosses to a Nonpareil mutation (Jeffries) which is unilaterally compatible when used as the seed parent. Selfed seed set from caged trees was less than 0.001% of available flowers. Seed set from crosses to the Jeffries mutation averaged 34.4% which was not significantly different than outcrossed controls. No significant loss in kernel weight and dimensions were observed in any of the inbred material when compared with outcrossed controls though a higher proportion of the inbred seed and seedlings failed to develop fully. Both average tree height and trunk diameter after 1 year of growth was significantly lower in inbred vs. outcrossed material. Results suggest no major penalty to kernel quality following self-pollination, though losses in progeny vigor should be a concern when utilizing selfed seed in variety development programs.
We thank Katarzyna Kolenda for her technical assistance. Appreciation is also extended to Bob Maloney and Tom Williams (Syngenta Seeds, Inc.) for providing the triploid seed materials. Mention of a trademark, proprietary product or vendor does not
141 POSTER SESSION 21 (Abstr. 833-841) Seeds and Seedlings
Abstract
Live oak (Quercus virginiana Mill.) acorns harvested for commercial seedling production frequently are heavily infested by larvae of Curculio spp. (2). Many nurserymen routinely soak acorns for 30 min in 49°C water to kill weevil larvae before planting the seed (4). Microwave radiation is effective against some stored products pests, but it is too damaging for use against acorn weevil larvae (2). Crocker and Morgan (1) measured the short-term (12-day) effects of hydrothermal treatments of tree-harvested acorns on survival of weevil larvae and seed germination, using 0- to 60-min immersion of the seed in 43.3° to 60.0° baths. Treatment for any of the tested times at a minimum of ≈49° controlled 100% of the weevils; it also produced dosage-related plant mortality and reduction in the short-term growth of seedlings. In the present research, we examined the survival and long-term vigor of acorns that were exposed to a 49° hydrothermal treatment.
Abstract
‘Haggith’ (Prunus armeniaca L.) is a new apricot cultivar introduced in 1974 as a seed source for apricot rootstocks. Trees of ‘Haggith’ are cold hardy, consistently productive, self-fertile and disease tolerant. The seeds of ‘Haggith’ germinate readily as fall planted pits or as spring planted stratified seeds. ‘Haggith’ seedlings are quite uniform in the nursery row, attain buddable size by August and are compatible with a broad range of scion cultivars. Scions on ‘Haggith’ seedlings appear to be comparable in vigor, precocity and disease response with those on seedlings of ‘Alfred’ or ‘Morden 604’. However, there is a tendency for scions on ‘Haggith’ seedlings to have wider crotch angles, a more spreading growth habit, and slightly higher yield than on ‘Alfred’ seedlings. The ‘Haggith’ seedling rootstock is being introduced to meet the need for a reliable, cold hardy rootstock for apricot. ‘Haggith’ is not recommended as a scion variety.
A seedling disorder of broccoli (Brassica oleraceae L. var. italica) characterized by chlorotic cotyledons and delayed seedling growth is described. This disorder, termed “yellow cotyledon”, has been observed in field plantings under high temperatures with some broccoli seed lots. Yellow-cotyledon disorder can be observed in laboratory germination tests if they are conducted under illumination, where unaffected seedlings will develop green cotyledons. Little relationship was found between overall seed vigor and the expression of yellow cotyledon by use of early germination counts and accelerated aging tests, although the most severely affected seed lots had been stored for several years. Field trials in 2 years showed that although seedlings with yellow-cotyledon disorder developed into normal plants, maturity was delayed and total yields were reduced.