Tadesse Mebrahtu

Omega-three fatty acids in purslane (Portulaca oleracea) Tissues

Total lipids and omega-3 fatty acids in purslane(Portulaca oleracea) were determined in leaves, stems and whole plants at three ages. Significant differences (P<0.05) existed in levels of total lipids among ages and between leaves and stems, but no relationship of age to plant part (>O5) was found. Contents of 18:3ω3,20:5ω3, 22:5ω3,22:6ω3,18:2ω6 and 18:loω9 showed that leaves were the richer source of omega-3 acids at each age.

Effects of ozone on soybean resistance to the mexican bean beetle (Epilachna varivestis mulsant)

Abstract Two soybean [Glycine max (L.) Merr.] cultivars, Forrest and Essex, were exposed to incremental levels of O3 in open-top field chambers during the 1986 growing season. Treatments consisted of chambers receiving carbon-filtered air or non-filtered air to which either 0.00, 0.03 or 0.06 ppm (μl/l)O3 was added continuously for 7 hr/day. After 3 weeks of exposure, the feeding preference of Mexican bean beetle (MBB) adults (Epilachna varivestis Mulsant) was determined by placing plants in a carbon-filtered chamber enclosed by an aluminum screen. Defoliation was visually determined after the MBB had fed for 6–8 days. Leaves from the remainder of the plants were brought to the laboratory and fed to MBB larvae. The larvae were reared in plastic boxes until pupation, and developmental time, pupal weight and mortality were determined. Visible O3 injury increased significantly with increasing O3 concentration and Forrest was significantly more sensitive than Essex. No cultivar differences were found in MBB adult feeding preference, but defoliation increased significantly with increasing O3 concentration. Results, although not as definitive as in the feeding preference study, indicated that MBB larvae tended to weigh more and develop faster on ozonated foliage. Implications of this pollutant × pest interaction are discussed relative to its potential impact on crop production.

Supercritical fluid extraction of Vernonia galamensis seeds

Abstract Vernonia galamensis is an excellent source of a seed oil rich in vernolic acid. However, the seeds of this plant exhibit a high lipase activity in the dormant state. The activity of this enzyme is apparent as vernonia oil will undergo lipolysis when the seeds are crushed prior to extraction. In this study, supercritical fluid extraction (SFE) utilizing carbon dioxide has been examined as an alternative solvent, at different pressures, temperatures and cosolvent concentrations. The use of supercritical fluid carbon dioxide (SC-CO2) as the extraction fluid under high temperatures and pressures has the potential to inhibit the lipolysis reaction during the extraction by reducing the activity of the enzyme, and hence the production of undesired fatty acids. Vernonia seeds were ground with dry ice prior to extraction to minimize any nascent lipase activity. Selective SFE was conducted at various pressures, temperatures, modifier concentrations, and total CO2 volume used to determine whether the vernolic acid content of the resultant extract could be enriched. An increase in pressure and temperature significantly increased the amount of extracted oil as well as the vernolic acid content. In addition, a significant reduction in the free fatty acid content of the oil from 69 to 8 mg/g oil was present with increasing extraction pressure. Exhaustive extraction of the oil could be attained via SFE with neat CO2 and with ethanol-modified CO2. However, regrinding the matrix after the initial extraction, followed by re-extraction of the seed matrix was necessary in these cases. The resultant oil and extracted meal were characterized with respect to free fatty acid, phospholipid, and percent protein contents.

Nutrient composition and anti-nutritional factors in selected vegetable soybean (Glycine Max [L.] Merr.)

The genetic variation in the nutrient composition and anti-nutritional factors of 17 vegetable soybean genotypes were determined and a wide variation in protein %, total phosphorus (TPi) and available phosphorus (AP) was found among these genotypes. Variations in Ca, K, Fe, Mn, and Cu were also documented. Variation was also found for trypsin inhibitor (TI) activity and Phytate (PA) content. A highly significant and negative correlation (r=−0.533,P<0.01) was observed between TI and total protein. Strong positive correlation (r=0.90) was also found between TPi and AP. Several genotypes (Sooty, Emperor, Wilson-5, PI 416771, PI 417322) showed good nutritional potential and can be used in the breeding program. High protein %, TPi, and minerals are desirable qualities for vegetable-type soybeans that make it as food with high nutrient density. Studies on the nutritional evaluation of immature vegetable type soybean seeds at different reproductive stages are also underway.

Accumulation of phytate in vegetable-type soybean genotypes harvested at four developmental stages

A total of 17 vegetable-type soybean (Glycine max [L.] Merr) genotypes were planted in four-row plots arranged in a randomized complete block design in 1988 and 1989 at Petersburg, Virginia. Each genotype was harvested at four developmental stages and evaluated for phytate content. Highly significant differences for phytate content were observed among the stages of harvest and genotypes, and there was an interaction between genotype x stage of harvest. The significant differences observed for phytate content among genotypes indicated that genetic variation exists among the tested genotypes for selection and improvement through hybridization. Among the genotypes, ‘Kingston’ and PI 423852 had the highest phytate content in most stages of harvest while PI 416771, ‘Emperor’, and PI 416982 had the lowest phytate values. A heritability estimate of 81 percent was observed for phytate content. This high heritability value indicates that selecting genotypes for lower phytate content would be effective. Significant correlations were observed for phytate content among genotypes harvested at R6, R7, R8, and overall. The magnitude of association of R6 with the overall phytate mean was especially high. These results illustrate that determining the phytate content of genotypes at the R6 growth stage would be a good predictor of the overall genotypic performance.

Leaf Peltate Glandular Trichomes of Vernonia galamensis ssp. galamensis var. ethiopica Gilbert: Development, Ultrastructure, and Chemical Composition

Plants from the genus Vernonia produce a variety of flavonoids and bitter sesquiterpene lactones important for agriculture and human health. Leaf glandular trichomes of Vernonia galamensis ssp. galamensis var. ethiopica Gilbert (VGAE) were investigated for ultrastructural development and content composition because sesquiterpene lactones that impart a bitter taste to the leaves have been associated with the presence of these glands. Trichome ultrastructure was examined using LM, SEM, and TEM. Glands were removed from the leaf surface, and the chemical composition of gland contents was determined using HPLC and high‐resolution mass spectrometry. Immature and mature 10‐celled peltate biseriate glandular trichomes were present only at the abaxial side of the leaf. A large subcuticular space (head) developed from the most distal cell pair of the mature trichome and gradually filled with an osmiophillic substance. Mass spectrometry analysis revealed that the peltate trichome is a major source of prevernocistifolide‐8‐O‐isobutyrate. This glaucolide‐type sesquiterpene lactone was previously identified as a major constituent of the aerial parts of VGAE.

Inheritance of ambient ozone insensitivity in common bean (Phaseolus vulgaris L.)

The inheritance of ozone (O(3)) insensitivity in common bean (Phaseolus vulgaris L.) was evaluated using F(2) and F(3) populations under ambient conditions. This study was conducted over two growing seasons (1987, 1988) at Virginia State University, Randolph Research Farm, Petersburg, Virginia. Two populations were obtained by crossing insensitive plant introductions with sensitive commercial cultivars. Ratings on the scale of 1 to 5 (1 = 0 to 20% leaf injury, 2 = 21 to 40%, 3 = 41 to 60%, 4 = 61 to 80%, and 5 > 80%) were made on 160 F(2), F(3) progenies, and parental lines. Population mean injury ratings were recorded and estimates of genotypic, environmental, and phenotypic variances were computed. Estimates of heritability in the broadsense and of genetic advance were calculated for each population using F(2) and family component variance methods. Population means of the F(2) and F(3) progenies were not significantly different from their mid-parent values, suggesting that genetic variance was primarily additive. Broad-sense heritability estimates using F(2) variance method ranged from 51.4 to 70.5% and using family component variance method ranged from 62.1 to 75.6%. In this study, the computed genetic advance values closely parallel those of heritability estimated values. The high heritable nature of insensitivity would indicate that effective levels of insensitivity could be transferred to agronomically superior cultivars in a relatively short time.

Genetic Variation for Green Pod Yield and Quality Among Vegetable Soybean Genotypes

Abstract Few studies have evaluated vegetable soybean (Glycine max [L]. Merr.) for green pod yield and individual and total sugar when harvested at green pod stage (R6 to R7). The purpose of this research was to assess the amount of genetic variation that existed among vegetable soybeans for green pod yield (GPY), hundred pod weight (HPW), pod length (PL), plant height (PH), and individual sugars (glucose, fructose, sucrose, raffinose, and stachyose) and total sugar, and to determine the association of GPY with the individual and total sugars. Thirty-one vegetable soybean genotypes from maturity groups (MGs) III, IV, V, and VI were planted at Virginia State University Research Farm during 1996,1997, and 1998. Each genotype was harvested at green pod stage. There was substantial genetic variation for GPY, PH, and PL as indicated by relatively large genotypic variance components. Heritability (h2) estimates of 0.85, 0.68, 0.81, and 0.85 were observed for GPY, HPW, PL, and PH, respectively. These high h2 estimates imply that selection for improved GPY along with PL and HPW can be achieved in a breeding population. Correlation values of HPW with sucrose and total sugar content were 0.598 and 0.447, respectively. Pod length had correlations of 0.598 and 0.447 with sucrose and total sugar, respectively. The PL was positively correlated (0.766) with HPW. The PL σ2 g variance was 22 times larger than σ2 gy variance, suggesting that selection for PL should be effective. Because pod length reaches the maximum size 30 days after flowering, it could be used an indirect selection criterion to identify genotypes with high sucrose and total sugar contents.

Analysis of Nutritional Contents in Vegetable Soybeans

ABSTRACT In addition to oil and soyfoods, soybean [Glycine max L. (Merr.)] is also produced for vegetable use. The importance of consuming vegetable soybean for the prevention of chronic diseases is well documented. The objectives of this study were to determine the magnitude of genotype x year interactions (GYIs) for nutritional values, to estimate broad-sense heritability (h2 BS), and to identify genotypes that have stable nutritional values. Thirty-one soybean genotypes from maturity groups (MGs) III to VI were grown at Randolph Research Farm of Virginia State University, Petersburg, Virginia, during three years. The genotypes were harvested at immature green pod stage (R6-R7) and analyzed for nutritional values (lipid, protein, fatty acid profile, and carbohydrate). Significant (P < 0.01) differences among the genotypes were found for protein, ratio (18:1/18:2 + 18:3), and carbohydrate (CHO). The GYIs were also significant (P < 0.01) for all the seed traits analyzed, indicating that the performance of the genotype changed from year to year. Moderate h2 BS estimates of 56%, 61%, and 69% were observed for protein, ratio, and CHO, respectively. These h2 BS indicated the seed traits analyzed were equally influenced by environments and genetic factors. In general, the percentage contribution of genotype to the total sum of squares was higher than that of the GYIs for all seed traits analyzed with the exception of lipid. Among the genotypes tested Akiyoshi ranked high in protein, ratio, and, CHO and PI 379621 ranked high in protein and CHO. These genotypes could be used as genetic source in improving nutritive values of vegetable soybean genotypes. The rank correlations between G ×; Y model analysis mean ranking and cultivar superiority performance measure (CSPM) value ranks for lipid, ratio, protein, and CHO were 0.912**, 0.979**, 0.987**, and 0.973**, respectively. This suggested that either method of analysis could be used in identifying genotypes with stable performance.

Generation mean analysis of inheritance of insensitivity to ozone injury in two crosses of beans (Phaseolus vulgaris L.)

The inheritance of bean (Phaseolus vulgaris L.) foliar insensitivity to ozone (03) was studied using generation mean analyses (GMA) as the genetic design. The following GMAs were evaluated: ‘Bush Blue Lake (BBL) 290’ x PI 304833, and ‘BBL 254’ x PI 300657. The six populations (P,, P2, F,, F2, F, x P,, and F, x P2) comprising a GMA from each cross were planted in 15 cm plastic pots as a randomized complete block design with three replications. When unifoliate leaves were about two-third expanded and maximally sensitive to 03 they were fumigated with non-filtered ambient (NF) + 0.06 ppm 03 concentration in open top field-fumigation chambers. Data on percent leaf 03 injury were recorded. The mean rated values of the incidence of O, injury in the F, generation were lower than the mid-parent values in both crosses, suggesting that insensitivity may be dominant over sensitivity. A genetic model with additive-dominance effects was fitted to generation means in ‘BBL 290’ x PI 304833, and ‘BBL 254’ x PI 300657 and...