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S. Shannon

Abstract

Application of equimolar solutions of (2-chloroethyl)phosphonic acid and the mono-2-chloroethyl ester of the acid to monoecious cucumber (Cucumis sativus L.) plants resulted in equal retardation of internode growth and equal conversion to gynoecious flowering habit for the first 8 nodes. However, the effects of the ester persisted for 4 or more nodes longer than those of the acid for both parameters. Both peroxidase activity and ethylene evolution were 10-fold greater in plants treated with the acid than in those treated with the ester.

Open access

S. Shannon

Abstract

Changes in soluble solids, red pigment, and firmness of 2 table beet cultivars with growing time were evaluated during 3 seasons. In 1969 and 1970 there were significant cultivar differences in soluble solids. There were significant changes in soluble solids with growing time all 3 seasons due primarily to drought. Highly significant differences existed in the red pigment content of cultivars. Red pigment content of the roots increased with growing time during 2 seasons, but the opposite was true during the 3rd season. Firmness of the processed product increased greatly with growing time during all 3 seasons. There was a highly significant difference in firmness of 2 cultivars grown all 3 seasons. All 3 quality attributes varied with root size, small roots having higher soluble solids and red pigment contents and slightly lower firmness than medium sized roots.

Open access

M. H. Dickson and S. Shannon

Abstract

An analytic procedure using spectrophotometry permitted quantitative estimation of chlorophyll and carotenoids in wax beans. Crosses studied demonstrate a wide range for chlorophyll and carotenoid content, with heritability of about .60 for both pigments. Seed chlorophyll was correlated (r=.54) with pod chlorophyll! content in large pods. The results show it is just as important to select for carotenoid content as for early degradation of the chlorophyll in wax beans.

Open access

M. H. Dickson and S. Shannon

Abstract

The arg y gene combination in beans (Phaseolus vulgaris L.) normally produces white pods, but pods with desirable yellow wax bean color can be developed by selection within this genotype for high cartoenoid levels and low chlorophyll levels. These pods exhibit acceptable yellow color at all stages of growth, unlike normal wax pods which are green initially but turn yellow in color only as they approach full size.

Open access

S. Shannon and R. W. Robinson

Abstract

Foliar application of 50 or 100 ppm 2-chloro-9-hydroxyfluorene-9-carboxylic acid (chlorflurenol) to plants of cucumber (Cucumis sativus L.) increased the number of fruit per plant 2- to 3-fold at a single harvest, particularly the more valuable small fruit. Higher and lower concentrations were less effective, and repeated applications were often more effective than a single application. In 2 of 4 field trials there were significant increases in value of treated over untreated plots, and in none of the trials was fruit shape affected.

Open access

S. Shannon and R. W. Robinson

Abstract

Recommended rates of (2-chloroethyl)phosphonic acid (ethephon) application did not prevent staminate flower formation on summer squash (Cucurbita pepo L.) sufficient to permit hybrid seed production without defloration. The field experiments were conducted in commercial fields in which flower development occurred during warm long day conditions, which promote maleness in squash. A strongly female ‘Cocozelle’ inbred, a strongly male ‘Straightneck’ inbred and a very strongly male ‘Crookneck’ inbred were treated at several seedling stages with rates up to 600 ppm ethephon. Two applications of 400 to 600 ppm ethephon resulted in development of the fewest staminate flowers without significantly reducing seed yield or quality. The ‘Crookneck’ inbred was least responsive to ethephon.

Open access

M. H. Dickson, K. Duczmal, and S. Shannon

Abstract

Transverse cracking of cotyledons, (TVC), varied from 0 to 95% among bean cultivars and was enhanced by planting dry seed in wet soils. A more reliable indication of TVC potential was obtained if the seed was placed in small beakers and covered with water. Covering the hilum with grease slowed imbibition and reduced TVC in tolerant lines. Soaking for 45 minutes in ethanol prior to imbibition in water accelerated imbibition and increased TVC. Seed coat removal prior to imbibition further enhanced imbibition and increased TVC. None of these 3 treatments changed the relative amount of TVC, but seed coat nicking or removal prior to imbibition gave the most reliable test.

Potassium and Mg in cotyledons were negatively correlated with cultivar susceptibility. Calcium was sometimes significantly correlated with TVC in seed grown in a given location, but the correlations could be lacking or of opposite sign in seed grown elsewhere.

Open access

P. M. Gorski, A. Jaworski, S. Shannon, and R. W. Robinson

Abstract

Two rapid methods for estimating cucurbitacin C (Cuc C) in cucumber cotyledons are described. Both methods require a single cotyledon extracted with methanol. The filtered extract is injected into a C18 HPLC column with methanol-water (55:45) solvent, and quantitative estimates of Cuc C are obtained by UV detection at 254 nm. In the 2nd method, the extract is concentrated for spotting on silica gel TLC plates, the TLC plates are developed with ethylacetate : benzene (75:25), and visualized with vanillin-orthophosphate to give a semiquantitative estimate of Cuc C. The 2 methods are quick and suited for screening seedlings for cucurbitacin levels in segregating populations to select for cucumber beetle resistance and for nonbitter fruit.

Open access

D. L. Garwood, F. J. McArdle, S. F. Vanderslice, and J. C. Shannon

Abstract

The T5125 × 1453’ hybrids of maize (Zea mays L.) homozygous for the sugary (su), amylose-extender (ae) dull (du) waxy (wx) and ae wx genotypes plus the related shrunken-2 (sh2) commercial hybrid were compared for processing and fresh market characteristics. Sensory panel evaluation and U.S. Department of Agriculture grading showed that both the ae du wx and sh2 genotypes produced high quality canned and frozen products. The processed sweet corn (su) hybrid had a high pericarp content resulting in lower quality. The ae wx canned and frozen products scored low in texture and flavor and were unacceptable. Kernel sucrose values (percent dry weight) in unstored ears were 36.5% for sh2 , 24.8% for ae du wx, 18.5% for ae wx, and 14.4% for su. Only minor changes were observed in reducing sugar, sucrose, water soluble polysaccharide (WSP), and starch measured after 24, 48, and 96 hours of storage at 4°C. After 96 hours of storage at 27°, sucrose content decreased from initial levels by 83% in su, 67% in ae wx, 63% in sh2 , and 55% in ae du wx. In spite of these decreases, ae du wx and sh2 sucrose content after 96 hours at 27° was almost as high as that found in unstored su ears demonstrating superior postharvest sugar retention for ae du wx and sh2 . Corresponding with the decrease in su sucrose during storage at 27°, WSP increased and the starch decreased. In contrast, starch increased in sh2 and tended to increase in ae du wx while WSP declined. The processing, carbohydrate, and postharvest storage data indicate that the ae wx T5125 × 1453’ hybrid cannot be used for sweet corn quality improvement, while ae du wx and sh2 show definite potential for processing use. Furthermore, ae du wx can be considered as a high sugar genotype for fresh market use along with currently grown sh2 hybrids.

Open access

G. Tehrani, H. M. Munger, R. W. Robinson, and S. Shannon

Abstract

Genetic variation in foliar symptoms of B deficiency in the seedling stage of red beet was observed among inbred lines and commercial cultivars grown in sand culture in growth chambers. F1, F2 and backcross populations between the most susceptible and tolerant lines, tested at .001 ppm B, indicated that susceptibility was conditioned primarily by a single dominant gene. No linkage was established between this gene and the gene controlling red leaf color.

The most susceptible line was inherently more vigorous than the most tolerant line but this relationship was not evident among the other inbreds and cultivars tested.

Boron deficiency sumptoms on leaves of both tolerant and susceptible lines were significantly accentuated by reducing the Ca(NO3)2 content of the nutrient solution from 8 to 7 mEq/litre without altering B content. At both Ca levels the B content was greater in the tolerant than in the susceptible line. When supplied with adequate Ca but low B the susceptible line contained higher Ca, Na and P and lower Mg than the tolerant line.