The South Carolina Agriculture Experiment Station and the United States Department of Agriculture announce the joint release of ‘Carolina’ collard Brassica oleracea L. (Acephala group). ‘Carolina’ offers potential because of its resistance to downy mildew incited by Penospora parasitica (Pers.) ex Fr., because of its desirable horticultural characteristics, and because it broadens the genetic base of collard.
A field study was conducted to determine the effects of rhizobial inoculation (cowpea ‘EL’ mixed strain) and N-fertilization with 100 kg/ha nitrate nitrogen (CaNO3 — 15.5% N) on seed and biomass yield in cowpea [Vigna unguiculata (L.) Walp.]. Four indeterminate cultivars, ‘Mississippi Silver’, ‘California Blackeye #5’, ‘Lady’, ‘Brown Crowder’, and one determinate, early maturing cultivar, ‘Bush Purple Hull’, were used. Seed yield in inoculated and N-fertilized plants was significantly greater than that of the unfertilized, uninoculated control treatment. Generally, yield of inoculated plants was equivalent to or greater than that obtained with 100 kg N. The indeterminate cultivars yielded more biomass than did ‘Bush Purple Hull’ in all 3 treatments. Seed yield was higher in the indeterminate cultivars with inoculation or N-fertilization than in ‘Bush Purple Hull’; however, there were no significant differences in seed yield among cultivars in the control treatment. Harvest index in the indeterminate cultivars was increased by inoculation but not by N-fertilization. Harvest index of ‘Bush Purple Hull’ was at least 3 times higher than the indeterminate cultivars. Among the major seed yield components, only pods/plant was influenced by all 3 treatments, whereas seeds/pod and seed weight were fairly stable and cultivar specific. Standardized regression analysis revealed that pods/plant was the major component which accounted for the variability in seed yield of inoculated plants within a cultivar, but not in ‘Bush Purple Hull’, where dry matter accumulation/plant/day was the major component. Factor analysis on the yield and N2 fixation components also indicated that cowpea cultivars behaved differently in the expression of traits which influenced seed yield. A measure of genetic divergence among these cultivars using Mahalanobis distances confirmed that the 5 cowpea cultivars differed significantly.
Plant growth aspects of field-grown cowpea [Vigna unguiculata (L.) Walp.] were investigated under four N regimes: No N, rhizobial inoculation (cowpea “EL” inoculum), 100 kg fertilizer N/ha (NO3-N) at planting, and inoculation + 50 kg fertilizer N/ha at flowering. Five indeterminate cultivars, Brown Crowder, California Blackeye No. 5, Mississippi Silver, Tennessee White Crowder, and Lady, and one determinate cultivar, Bush Purple Hull, were compared. Plant growth variables were measured biweekly starting at the 4th week. Dry matter and leaf area per plant reached maximum at 56 days after planting in all five indeterminate cultivars, and 1 week later in the determinate cultivar. Large-seeded cultivars, California Blackeye No. 5, Mississippi Silver, Brown Crowder, and Tennessee White Crowder, generally produced larger leaves throughout the season than did ‘Bush Purple Hull’ and ‘Lady’. The relative growth rate (RGR) declined linearly with harvest time, irrespective of N treatment. The RGR of ‘Bush Purple Hull’ was lower than that of the indeterminate cultivars throughout the growth period. The net assimilation rate (NAR) of the indeterminate cultivars declined slowly from maximum values at 4 weeks and became negative during pod development. However, ‘Bush Purple Hull’ NAR increased during pod development, but declined very rapidly during late pod development. The leaf area ratio (LAR) declined curvilinearly with time in all N treatments and cultivars. The LAR values were lowest for the determinate cultivar, and the differences among indeterminate cultivars were not significant. Total dry matter, leaf area per plant, and average leaf size of inoculated and N-fertilized plants were greater than the uninoculated and unfertilized control. Nitrogen treatments did not affect physiological components RGR, NAR, and LAR.
The effect of Biozyme™, a commercial germination stimulant, on emergence of bean and sweet corn seeds, treated with four levels of Carbofuran and Chlorothalonil, and grown under suboptimal field temperatures, was evaluated. Half the seeds from each treatment were treated with Biozyme™ Two planting dates were selected to provide suboptimal temperatures during emergence. Pesticide overdoses caused significant detrimental effects to all emerging seedlings. These effects were magnified under the low temperatures of the first planting. Biozyme™ treatment significantly improved emergence rate, percent emergence, final stand and number of ears of sweet corn in the first planting, and the percent emergence final stand, plant dry weight, and number of ears in the second planting. In beans, however, Biozyme™ treatment significantly reduced emergence rate, percent emergence. and final stand in the first planting, while significantly increasing percent emergence, plant dry weight, and seed dry weight in the second planting. The beneficial effects of Biozyme™ appeared to be independent of the negative effects of pesticide overdoses.
Rhizobial inoculation with commercial cowpea ‘EL’ mixed strain inoculant as compared to noninoculation, and effects of four levels (0, 14, 28, and 84 kg·ha−1) of fertilizer N (CaNO3–15.5% N) on yield and N2 fixation components in cowpea [Vigna unguiculata (L.) Walp.] were investigated in a field study. Plants were grown on a vertic albaqualf, fine, montmorillonitic, thermal soil with a pH of 6.7. Three high (H) and two low (L) N2-fixing, indeterminate cowpea cultivars, ‘H-California Blackeye No. 5’, ‘H-Brown Crowder’, ‘H-Tennessee White Crowder’, ‘L-Lady’, and ‘L-Mississippi Silver’, were used. In inoculated plants, N2 fixation was significantly reduced with increasing N levels. Although high-fixing cultivars produced more and larger nodules and expressed higher nitrogenase activity than the low fixers, no significant differences in top dry weight and total N/plant were observed between these groups at the time of flowering. Seed yield was greater in rhizobia-inoculated plants than in the noninoculated, fumigated controls. A significant linear increase in seed yield was observed with increasing N levels in the noninoculated, fumigated controls. The addition of fertilizer N to cowpeas inoculated at planting did not increase seed yield. In high-fixing cultivars, N2 fixation did not directly influence seed yield, but increased vegetative matter was produced. Seed and biomass yield were influenced by N2 fixation in low-fixing cultivars.
Antioxidants are important to human health, as they are responsible for reduced risk of diseases such as cancer, hence motivating researchers to examine crop plants for available antioxidant compounds. There is also increasing interest in the use of antioxidants from plants instead of synthetic products. In order to evaluate variability of antioxidant activity (AOA) in cowpea, 697 cowpea accessions from the U.S. Cowpea Core Collection obtained from the Regional Plant Introduction Station, Griffin, Ga., were analyzed for AOA expressed as μg trolox equivalents/gdw. Two grams of dry seed from each accession were ground, extracted in methanol and analyzed for AOA using the free radical, 2,2-Diphenyl-1-picrylhydrazyl (DPPH), method. A large variation in AOA within the core collection, ranging from 1859 μg·g–1 dw (PI 180355, pigmented seed coat) to 42.6 μg·g–1 dw (PI 583100, cream seed coat), was observed. A least significant difference of 131.5 (p =0.05) was obtained. Higher AOA was manifested by accessions with pigmented seed coats. Accessions that were speckled, striped or had a pigmented eye were moderate in AOA, while the cream types were generally low. Variability in AOA observed among cowpea accessions suggests that breeding for high AOA can be successfully conducted. Accessions with high AOA could also be used to extract antioxidants for industrial purposes. Some accessions were a mixture of various colors and patterns, making it difficult to classify them into a particular category. Therefore, there is need to ensure purity of these accessions by ascertaining whether the mixtures are physical, i.e., combination of different varieties, or are composed of segregating material.
Potatoes are stored to ensure a continuous supply; however, losses due to shrinkage and sprouting can be large. It is believed that ionizing irradiation will become more prominent for sprout inhibition due to the increasingly higher operating costs of low-temperature storage and possible phase-out of chemical sprout inhibitors. The effects of storage and ionizing irradiation (gamma and electron beam) on antioxidant activity (AOA), phenolic content, and carotenoid content were analyzed using the potato cultivar Atlantic. Tubers were subjected to 0, 75, and 200 Gy γ-irradiation doses, stored at 20 °C, and analyzed after 0, 10, 20, 75, and 110 days. Tubers from another harvest were subjected to a surface dose of 0 or 200 Gy e-beam irradiation, stored at 20 °C, and analyzed after 0, 10, 20, 75, and 110 days. AOA was measured via the DPPH method; phenolic content via the Folin-Ciocalteau method and individual phenolics via HPLC; and carotenoid content via absorbance at 445 nm and individual carotenoids via HPLC. During early storage, higher doses resulted in higher AOA, while, during longer storage, lower doses produced greater AOA. Phenolic content increased in storage during the γ-irradiation study, but decreased in the e-beam study, partly due to increases in chlorogenic acid in the former and decreases in caffeic acid in the latter. The e-beam dose of 200 Gy resulted in significantly greater total phenolics than 0 Gy. Total carotenoids and lutein decreased with storage, but were not affected by irradiation. Storage exerted a much greater influence on AOA, phenolic content, and carotenoid content than either irradiation treatment.
Two cowpea cultivars, Pinkeye Purple Hull and Royal Blackeye, were evaluated for their ability to produce a ratoon crop. Dry weight and pod yield were measured following harvest from two different cutting heights (second and fourth node), and stages of pod maturity (green and dry). The cultivar Royal Blackeye produced more green manure or returned biomass following ratooning than did Pinkeye Purple Hull. Cutting height and sampling at different pod maturities influenced ratooning potential. These results suggest that cowpea ratooning appears to be economically feasible and that further screening of cowpea cultivars for ratooning ability is warranted.