Abstract
Thirty-six climbing accessions of lima bean (Phaseolus lunatus L.) were grown on trellises with minimal chemical inputs in 5 trials at 4 Colombian sites. Mean dry-seed yield of all accessions at all 4 sites was 2.6 mt/ha. Mean yield at the least favorable site was 1.7 mt/ha; at the most favorable site it was 4.8 mt/ha. Although growth was affected adversely on a soil with pH 4.2, the mean yield was 2.5 mt/ha. Mean daily dry-seed productivity rates of all accessions ranged from 15.1 kg/ha/day to 44.1 kg/ha/day for the several locations, in some cases exceeding rates reported for common beans and other legumes at the same location. Mean yield and number of pods per plant varied significantly among sites, dependent upon temperature and soil differences. Days to flower and to dry-seed harvest were relatively stable traits. No relationship was found between yield and seed-coat color. Production constraints were rainfall distribution and acid, phosphorus-deficient soils. These studies demonstrated high productivity of lima beans under adverse and favorable climatic and soil conditions in Colombia
Abstract
Attempts to select for flower bud chilling requirement (CR) at the seed stage were made in 58 families obtained from crosses and open-pollination of low chill selections and cultivars of peach and nectarine [Prunus persica (L.) Batsch] from the Florida breeding program. A nonsignificant correlation (r = 0.08) between midparent bud CR and family seed CR was obtained. A low significant correlation (r = 0.21**) was obtained between individual seed CR and the CR of the resultant seedling. Seed coat removal had no effect on these correlations. Narrow sense heritability for bud CR as determined by parent-offspring regression was 0.50 ± 0.06. The small range in CR of the seed and pollen parents, 300 to 450 and 200 to 400 chill units, respectively, may explain the low correlation values obtained. The data suggest that it is impractical to screen for seedling CR based on seed CR where the CR for climatic adaptability must be held within a range of less than 300 chill units.
The USDA, Louisiana State University, and Lincoln University have released a new southernpea cultivar named WhipperSnapper. The new cultivar is the product of a plant breeding effort to incorporate genes conditioning superior yield and seed characteristics of Asian vegetable cowpeas into American snap-type southernpeas. The new cultivar was developed for use by home gardeners and market gardeners as a dual-purpose cultivar that can be used to produce both fresh-shell peas and immature, fresh pods or snaps. Typical ready-to-harvest WhipperSnapper snaps are green colored, 6.4 mm in diameter, 7.6 mm in height, and 24 cm long; the pods are slightly curved at the attachment end. Typical mature-green pods suitable for fresh-shell harvest exhibit an attractive yellow color, are 25 cm long, and contain 14 peas. Fresh peas are cream-colored, kidney-shaped, and weigh 24.5 g/100 peas. Dry pods exhibit a light straw color, and the dry peas have a smooth seed coat. The quality of WhipperSnapper seed is excellent. In replicated field trials, WhipperSnapper produced significantly greater yields of both snaps and peas than the snap-type cultivar Bettersnap. WhipperSnapper has potential for use as a mechanically-harvested source of snaps for use by food processors in mixed packs of peas and snaps. Protection for WhipperSnapper is being sought under the Plant Variety Protection Act.
Watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai] is a diverse crop, with much variability for fruit and seed traits. This study measured the inheritance of scarlet red flesh color, egusi seed type, yellow belly (ground spot) rind pattern, and intermittent stripes on the rind. Scarlet red is a dark red flesh color found in `Dixielee' and `Red-N-Sweet'. Egusi seed is an unusual mutant having a fleshy pericarp adherent to the seed coat found in PI 490383 and PI 560006. Yellow belly is found in `Black Diamond, Yellow Belly'. Intermittent stripes are found in `Navajo Sweet', which has narrow dark stripes that are irregular or nearly absent across the fruit. In order to study the inheritance of these traits, six generations, including parents, crosses, and backcrosses (Pa, Pb, F1, F2, BC1Pa, BC1Pb), were produced in each of seven crosses. Phenotypic data were recorded in the field, and analyzed with the Chi-square method for the segregation of Mendelian genes. Scarlet red color in `Dixielee' was allelic to scarlet red color in `Red-N-Sweet'. Four new genes were identified and named, in conformance with gene nomenclature rules for Cucurbitaceae: Scr for scarlet red, eg for egusi seed, Yb for yellow belly, and ins for intermittent stripes. Thus, we have added four new genes to the 52 morphological and disease resistance genes already published.
Abstract
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.
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.
Little scientific information is available describing morphological development of pawpaw during seed germination. To provide this information, a study was designed to outline important developmental stages and describe seedling characteristics within each stage. Stratified pawpaw seeds were sown in vermiculite and germinated at 25°C in a growth chamber. Ten seedlings were randomly chosen and destructively harvested at 5-day intervals starting at radicle protrusion. Length (mm), fresh and dry weight, and percentage of total dry weight were determined for seedling components. Pawpaw seeds have a small rudimentary embryo with all food reserves stored in a ruminate endosperm. Dry weight measurements showed a dramatic reallocation of reserves from the storage tissue to developing seedling parts. Initial embryo length was less than 3 mm, but within 70 days seedlings exceeded 350 mm. Twelve days after planting, simultaneous radicle and cotyledon growth occurred (3.4 and 3.0 mm, respectively), but neither hypocotyl nor epicotyl was visible. Radicle protrusion was observed at 15 days with radicle, cotyledon and hypocotyl lengths increasing to 4.4, 4.0, and 3.2 mm, respectively. Endosperm comprised 99.1% of total dry weight at this stage. The hypocotyl hook emerged after 30 days and endosperm comprised 76.1% of total dry weight. Cotyledons reached maximum length (29.0 mm) at day 40 and the epicotyl was discernible. At 55 days, the seed coat containing cotyledons and residual endosperm abscised and the average radicle, hypocotyl and epicotyl lengths were 182.0, 61.1, and 7.3 mm, respectively. It is suggested that the cotyledons primary function is absorption of food reserves from the endosperm for transfer to the developing seedling.
Seed coats of developing fruit of peach [Prunus persica (L.) Batsch cvs. Redkist, Redskin, and Loring] were punctured at 31, 33, and 38 days after full bloom (DAFB), respectively. Injections of water, 390 mg GA3/liter, or 390 mg GA4+7/liter were made immediately following seed puncture. Seed puncture and water injection following puncture resulted in abscission of all fruit. Injection of GA3 and GA4+7 delayed abscission of `Redkist' and `Redskin' fruits of punctured seeds by 6 to 10 days. Both GA treatments resulted in normal growth into Stage II and increased fruit retention through Stage III in `Loring'. About 100 μl of 250, 500, or 1000 mg GA3/liter was injected into the locule of `Loring' fruits following seed puncture at 30, 40, or 50 DAFB. GA treatments at 30 DAFB resulted in≈ 75% fruit set in comparison to seeded control fruit, while fruit treated at 40 and 50 DAFB abscised by the end of Stage II. Increasing GA concentration from 250 to 1000 mg·liter-1 had no additional effect. Movement of the GA was examined by injecting 3H-GA1 into the locule following the puncture treatment. More than 97% remained in the fruit after 96 hours. The percentage of 3H recovered in the seed cavity decreased over time, whereas recovered label increased in both endocarp and mesocarp. The results suggest a potential regulatory role for seed-produced gibberellins during early Stage I of development. We have identified an apparent change in tissue sensitivity to gibberellin induction of seedless fruit development between 30 and 40 DAFB in `Loring' peach.
Abstract
Food-quality comparisons between tropically adapted genotypes of dry bean (Phaseolus vulgaris L.) and accessions from domestic breeding agencies showed there is sufficient variability in important nutritional and canning traits among tropical beans to justify their use in temperate-climate breeding programs. Specifically, tropical bean germplasm may be of use to transfer stress tolerance and lodging resistance to commercially acceptable genotypes while the breeder is simultaneously breeding to maintain or improve nutritional composition and canning quality. Seed of 35 bean accessions representing plant introductions, breeding lines, and cultivars were screened for proximate chemical composition, yield, and several horticultural characters. Seventeen of these accessions, including several commercial dry bean cultivars, were selected for canning evaluations. Beans were adjusted to 16% moisture before soaking and processing. Soaked and processed beans were evaluated for water uptake, texture (with a Kramer Shear Press), and general canning quality. Protein content was highest in domestically adapted beans (31%) and lowest in the nonblack tropical array of genotypes (22%). Tropical beans showed a greater tendency to clump in the can after cooking. This indicates excessive breakdown of tropical beans during thermal processing. Nonsignificant correlation coefficients indicated that textural differences and soaking properties of the beans were not associated; however, textural differences were correlated with the final moisture percentage in processed tropically adapted beans. Several tropical genotypes were much firmer or much softer after cooking than ‘Sanilac’, which is considered the industry standard for making canning comparisons. Further evaluation of texture by examining Kramer Shear Press tracings showed that textural differences among genotypes could be broken down into a configuration showing a large shear force component, and a curve characterized by mostly compression. The curve types appeared to be a characteristic of the genotype rather than of seed-coat color, size of bean, or final moisture percentage.
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.