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- Author or Editor: Oyette L. Chambliss x
‘Freezegreen’ southernpea, (Vigna unguiculata (L.) Walp.) has been released by the Auburn University Agricultural Experiment Station to fill a need in the processing industry for a cultivar which maintains its green seed color to maturity. ‘Freezegreen’ should have added consumer appeal because of a more uniformly green frozen pack and an enhanced green color.
Reciprocal crosses were made between `White Acre-BVR', resistant to blackeye cowpea mosaic virus (BICMV), and the susceptible `California Blackeye No. 5' cowpea [Vigna unguiculata (L.) Walp.]. Seedlings from `California Blackeye No. 5', `White Acre-BVR', F1, F2, and backcrosses were mechanically inoculated with BICMV, and evaluated 4 weeks later for symptom expression in the greenhouse. Plants were assayed by enzyme-linked immunosorbent assay. The resistance observed in the F1 and progeny from the backcross to the resistant parent indicated that resistance to BICMV in `White Acre-BVR' was dominant. Furthermore, a 1 resistant: 1 susceptible segregation of progeny from the backcross to the susceptible parent and a 3 resistant: 1 susceptible segregation of the F2 progenies suggested that the resistance to BICMV in `White Acre-BVR' was conferred by a single dominant gene.
Correlation analysis was used as an aid in developing a scoring system to determine superior lines among 288 entries evaluated for resistance to cowpea curculio, southern green stink bug, and leaffooted bug. The following selection criteria were used (min/max values): days to harvest (58 to 111); sound pods (17% to 100%); curculio larval weight (3.3 to 10.4 mg) and mortality (0% to 80%); larval exit holes per pod (0.0 to 2.2) in a random sample of 25 pods; larval exit holes per pod (0.0 to 8.6) in a 10-pod sample selected for presence of punctures; punctures per pod (one to 15); punctures per exit hole (one to 14); exit holes per puncture (zero to one); curculio damaged seed (0% to 93%); stinkbug damaged seed (0% to 71%); sound seed (0% to 98%); pod length (8 to 25 cm); pod weight (1.3 to 9.2 g); seed per pod (five to 19); and average seed weight (10 to 327 mg). Lines ranking best for pod insect resistance were UCR212 = BAMBEY-5, UCR306 = IT82D-713, UCR194 = BBR-42, PI-218122, UCR90 = T W-3046, UCR200 = 24-lA, PI-115679, PI-145198, AU9lP3 = CCR-20, UCR202 (BROWN SEED), and IT83S-911.
Twenty-two southernpea (Vigna unguiculata L. Walp.) cultigens were evaluated in field plots in southern, central, and northern Alabama to establish a set of varieties that would reach harvest stage sequentially. As first pods reached the dry stage, subjective ratings were made to estimate percentages of the following pod maturity stages: presnap, snap, mature green, and dry. Mature-green and dry stages were combined to give the total percentage of mature pods. From a general linear model analysis on SAS, lines were highly significant sources of variation in percentage of mature pods up to 83 days after planting. At least three maturity groups were apparent: >80%, 50% to 80%, and <50% mature pods. These are represented by `Santee Early Pinkeye', `Coronet', `Texas Pinkeye', and `Pinkeye Purplehull BVR'; `C.T. Pinkeye Purplehull', `Epoch', and `Pinkeye Pinkpod'; and `Mississippi Pinkeye' and `Corona', respectively. All the plant introductions were in the late category and generally are not characteristic of commercial pinkeyes; they may be valuable in breeding for lateness in southernpeas.
The average frequency of observable outcrossing among 6 genotypes of southernpea (Vigna unguiculata (L.) Walp.) in a population of 9,987 plants was 0.59% and varied from 1.42% in AU 70.4 to 0% in Ala. 963.8G1-4. Outcrossing as high as 4.26% was recorded in a single plot of ‘Giant Blackeye’.
Axillary buds of gynoecious cucumber (Cucumis sativus L.) were cultured on a semisolid medium containing Murashige and Skoog salts plus thiamin, pyridoxin, nicotinic acid, myo-inositol, and sucrose with 0.1 mg/liter naphthaleneacetic acid (NAA) and 0.1 mg/liter kinetin. Both shoots and roots were proliferated with little callus formation. Plants produced in vitro were successfully transferred to soil.
Compounds active as feeding stimulants for cowpea curculio (Chalcodermus aeneus Boheman) were quantitatively determined by laboratory bioassays in pods of 5 cultivars of southernpeas (Vigna unguiculata (L.) Walpers). Feeding response was tested on intact sections of fresh pods and on filter paper wrapped plugs of agar and water-extracts of hulls with seeds removed. Water extracts were partitioned with ether and the tests of the activity of both fractions indicated that the active compounds were lipid in nature. Active compounds extracted from a susceptible cultivar were added to the extract of a resistant cultivar and feeding response was increased nearly 10 fold.
Quantitative and qualitative differences in fatty acid composition between resistant and susceptible cultivars were shown by gas chromatography. The amounts of eicosenoic acid were directly related to curculio feeding response to the cultivars.
A single recessive gene, blc, controls resistance to blackeye cowpea mosaic virus (B1CMV) in progeny from a cross between southernpea (cowpea) cultivars ‘Worthmore’ (homozygous resistant) and ‘California Blackeye No. 5’ (homozygous susceptible). All F1 plants and backcrosses to the susceptible parent were susceptible, indicating that resistance is recessive to susceptibility. Backcrosses to the resistant parent segregated 1 susceptible: 1 resistant and F2 plants segregated 3 susceptible:1 resistant.
Resistance to the cowpea curculio (Chalcodermus aeneus Boheman), in 16 F5 lines of southern peas [Vigna unguiculata (L.) Walp], was found to be dependent on various levels of nonpreference, a pod factor inhibiting penetration through the pod wall by the adult, and antibiosis. Each of the 3 mechanisms appeared to be under genetic control and capable of being transmitted to progeny. Probably a line 99% more resistant than ‘California Blackeye’ can be produced by combining the highest levels of the components of resistance; however, selection must be independent for each of the 3 resistance factors.
Volatile extracts were isolated from pods of southernpea by vapor-phase ether extraction. In bioassays conducted with freshly emerged adult curculios Chalcodermus aeneus (Boh.), the insects were significantly more attracted to extracts of the susceptible ‘California Blackeye No. 5’ than to air with no extracts. Extracts of the breeding lines Ala. 963.8 and CR 22-2-21 were repellent to the insects as evidenced by directed travel away from the extracts towards air alone. Gas chromatographic profiles of the 3 extracts showed obvious qualitative and quantitative differences.