Glucosinolates are secondary plant products of the Brassicaceae that may influence vegetable flavor and human health. Soil moisture levels and plant water status are thought to influence cabbage head glucosinolate levels. However, no information is available on the effect of irrigation timing relative to plant developmental stage on glucosinolate concentrations in cabbage. To address these gaps in the literature, cabbage (cv. Bravo) was grown in 2002 and 2003 at The Ohio State Univ., Ohio Agricultural Research and development Center in Wooster, Ohio. The four irrigation treatments, arranged in a RCB design, were: 1) irrigation throughout development [no stress (NS)], 2) irrigation only during head development [frame stress (FS)], 3) irrigation only during frame development [head stress (HS)], and 4) no irrigation [frame and head stress (FHS)]. Irrigation was supplied via drip tape and scheduled by the hand-feel method. Differential soil moisture levels among treatments were confirmed with gypsum block, time domain reflectometry (TDR) and gravimetric measurements. Analyzed across years, irrigation timing significantly affected total glucosinolate concentrations, with levels 36% greater in cabbage not irrigated during head development (HS, FHS) relative to cabbage receiving irrigation during head development (NS, FS). Concentrations were highest (29.4 mmol·kg-1) and lowest (19.4 mmol·kg-1) in FHS and FS cabbage, respectively. Irrigation effects were greater in 2002, when air temperatures were higher and rainfall and relative humidity lower than in 2003. We conclude from the data that head development is the critical stage at which irrigation should be applied in order to influence cabbage glucosinolate levels at maturity.
T.J.K. Radovich, M.D. Kleinhenz*, and J.G. Streeter
T.J.K. Radovich*, M.D. Kleinhenz, J.G. Streeter, and M.A. Bennett
Cabbage (cv. Bravo) was grown in 2002 and 2003 at The Ohio State Univ., Ohio Agricultural Research and development Center in Wooster, Ohio. The four irrigation treatments, arranged in a RCB design, were: 1) irrigation throughout development [no stress (NS)], 2) irrigation only during head development [frame stress (FS)], 3) irrigation only during frame development [head stress (HS)], and 4) no irrigation [frame and head stress (FHS)]. Irrigation timing relative to crop stage significantly affected all head characteristics except density, with the greatest differences between cabbage receiving irrigation during head development (NS, FS) and cabbage not irrigated during head development (FHS, HS). On average, heads from NS and FS plots were heavier (38%), larger (15%), less pointed and had less volume occupied by the core than heads from HS and FHS plots. Combined head fructose and glucose concentrations were significantly greater in cabbage receiving irrigation during head development than in cabbage not irrigated during head development (47% vs. 41% dwt, respectively). Sucrose concentrations were significantly greater in cabbage not irrigated during head development than cabbage receiving irrigation during head development (8% vs. 6% dwt, respectively). The higher ratio of sucrose: fructose+glucose observed in HS and FHS relative to NS and FS treatments was interpreted as an osmo-regulatory response with potential implications for cabbage flavor. Overall, it was concluded that physiological responses elicited in cabbage by differential irrigation can affect important head traits, and that targeted applications of water during specific stages of crop development may be utilized to maximize water use efficiency and crop quality.
Vincent A. Fritz, Veronica L. Justen, Ann M. Bode, Todd Schuster, and Min Wang
concentrations in six commercial cultivars of cabbage ( Brassica oleracea L., Capitata group) HortScience 40 106 110 Rosen, C.J. Fritz, V.A. Gardner, G.M. Hecht, S.S. Carmella, S.G. Kenney, P
Charles F. Forney and Michael A. Jordan
Methanethiol (MT) is a volatile compound responsible for the unpleasant odor evolved when fresh broccoli (Brassica oleracea L., Italica group) is held under anaerobic conditions. Inductive atmospheres can develop in storage, transportation containers, or modified atmosphere packages, resulting in reduced quality. To determine if related vegetables are capable of producing MT, 12 different vegetables from the genus Brassica were cut into ready-to-eat forms. Fifty-gram samples were sealed in 500-mL glass jars and flushed with N2. After 24 h in the dark at 20 °C, headspace samples from the jars were analyzed for MT and other volatiles. Headspace concentration of MT was greatest in broccoli florets, followed by pak choi (Brassica rapa L., Chinensis group) leaf blades, savoy cabbage (Brassica oleracea L., Capitata group), broccoflower (Brassica oleracea L., Botrytis group), and green and red cabbage (Brassica oleracea L., Capitata group). Broccoli stems, kale (Brassica oleracea L., Acephala group), Brussels sprouts (Brassica oleracea L., Gemmifera group), pak choi petioles, rutabaga (Brassica napus L., Napobrassica group) root, cauliflower (Brassica oleracea L., Botrytis group) florets, Chinese cabbage (Brassica rapa L., Pekinensis group), and kohlrabi (Brassica oleracea L., Gongylodes group) tubers produced <3% of the MT produced by broccoli florets. Green tissues appeared to have a greater capacity to produce MT than nongreen tissues. Anaerobic production of CO2 and ethanol did not relate to the vegetable's ability to produce MT. The production of dimethyl disulfide (DMDS) and dimethyl trisulfide (DMTS) were also induced by the anaerobic conditions. Green cabbage produced the greatest concentration of DMDS, followed by savoy cabbage and broccoli florets. Production of DMTS was similar to the pattern observed for MT, but DMDS production was not highly correlated with MT production.
David W. Still
Brassica crops have indeterminate growth and flower over an extended period of time. Harvested seed is therefore comprised of seed of varying degrees of physiological maturity and quality. Using population-based threshold models, broccoli (Brassica oleracea L. Group Italica), brussels sprouts (B. oleracea L. Group Gemmifera), red cabbage (B. oleracea L. Group Capitata), and rapeseed (B. napus L.) were characterized during seed development with respect to sensitivity to abiotic stress (reduced water potential) and shelf life. Using these models our data suggests that the physiological patterns of seed development are the same in all brassica crops we have tested to date. These population-based models can be used to provide a biological basis in which to evaluate cultural, postharvest and storage practices to ensure the production and maintenance of seed vigor.
Mark W. Farnham
A collection of collard (Brassica oleracea L., Acephala group) germplasm, including 13 cultivars or breeding lines and 5 landraces, was evaluated using randomly amplified polymorphic DNA (RAPD) markers and compared to representatives of kale (Acephala group), cabbage (Capitata group), broccoli (Italica group), Brussels sprouts (Gemmifera group), and cauliflower (Botrytis group). Objectives were to assess genetic variation and relationships among collard and other crop entries, evaluate intrapopulation variation of open-pollinated (OP) collard lines, and determine the potential of collard landraces to provide new B. oleracea genes. Two hundred nine RAPD bands were scored from 18 oligonucleotide decamer primers when collard and other B. oleracea entries were compared. Of these, 147 (70%) were polymorphic and 29 were specific to collard. Similarity indices between collard entries were computed from RAPD data and these ranged from 0.75 to 0.99 with an average of 0.83. Collard entries were most closely related to cabbage (similarity index = 0.83) and Brussels sprouts entries (index = 0.80). Analysis of individuals of an OP cultivar and landrace indicated that intrapopulation genetic variance accounts for as much variation as that observed between populations. RAPD analysis identified collard landraces as unique genotypes and showed them to be sources of unique DNA markers. The systematic collection of collard landraces should enhance diversity of the B. oleracea germplasm pool and provide genes for future crop improvement.
Jose R.A. Santos and Daniel I. Leskovar
Poor seedling emergence and stunted growth were observed in cauliflower (Brassica oleracea L., Botrytis group) and cabbage (Brassica oleracea L., Capitata group) crops when planted after three consecutive monocrops of broccoli (Brassica oleracea L., Italica group). This study was conducted to assess seed, seedling, and plant growth responses of broccoli, cabbage, and cauliflower to broccoli residue (leaves, stem + roots, and whole plant) extracts, broccoli residue incorporation, or soil previously cropped to broccoli. Osmotic potential, electrical conductivity, and pH of extracts were measured, rate (T50) and total germination were determined. Filter-sterilized leaf extract delayed T50(7.5 d) and reduced total germination (22%) of cauliflower compared to broccoli or cabbage. Similarly, plant height, shoot dry weight, and leaf area of cauliflower were significantly reduced when grown on broccoli soil in the greenhouse. Cabbage and cauliflower had low total marketable yields with more culled heads when grown in the field previously cropped to broccoli. Therefore, a potential growth inhibition of cabbage and cauliflower exists when following a continous cropping of broccoli.
Richard L. Parish and Regina P. Bracy
Two studies were conducted on bed and row configurations. The first compared erosion effects on stand count with single and double drill plantings; the second evaluated bed heights. Vegetables are usually planted on raised beds in the Deep South. Both single and double drills per bed are common. The double drills offer higher yields in some cases, but may be difficult to maintain because of erosion on the bed sides after heavy rainfall. A series of plantings of cabbage (Brassica oleracea L. Capitata group) and broccoli (Brassica oleracea L. Italica group) was made over a period of nearly a year to compare stands from single and double drills. Heavy rainfall did not occur after any of the 18 plantings, so bed erosion did not occur. Differences in percent stand were few, although in a few cases the double drill planting resulted in higher stands. A field study was conducted to determine the optimum bed height for leafy greens crops grown on shaped beds. Bed heights of 5, 10, 15, and 20 cm (2, 4, 6, and 8 in) were evaluated with crops of mustard [Brassica juncea (L.) Czerniak.] and turnip (Brassica rapa L. Rapifera group) during three crop seasons. Few significant differences in stand count, yield, or product quality resulted from the different bed heights. A trend toward lower yields, quality, and reduced efficacy of precision cultivation was noted with the 5-cm (2-in) bed height.
Regina P. Bracy and Richard L. Parish
Stanhay, Carraro, and Gaspardo precision vegetable seeders were evaluated for seeding uniformity with seeds of five vegetable crops—cabbage (Brassica oleracea L. Capitata group), carrot (Daucus carota L.), cucumber (Cucumis sativus L.), onion (Allium cepa L. Cepa group), and spinach (Spinacia oleracea L.). Five measurements [mean, percentage of misses, percentage of multiples, quality of feed, and precision (defined as the coefficient of variation after misses and multiples were discarded)] were used to evaluate seeder uniformity. Using all five measurements provided a more complete determination of the metering uniformity of the seeders than was possible in prior work when only mean and coefficient of variation were used. The belt seeder (Stanhay) was effective at singulating spherical seeds (cabbage) and nearly spherical seeds (onion)as the most precise vacuum seeder (Carraro). Seeding uniformity of all seeders with elongated (carrot and cucumber) or angular (spinach) seeds was inadequate for precision seeding.
Rogério L. Cansian and Sergio Echeverrigaray
Randomly amplified polymorphic DNA (RAPD) markers were used to discriminate among 16 commercial cultivars of cabbage (Brassica oleracea L. Capitata Group). A set of 18 decamer primers was selected from 100 random sequences and used to characterize cultivars and to evaluate distances. The selected primers produced 105 (54%) polymorphic bands ranging in size from 100 and 2500 base pairs, out of a total of 195 bands, which allowed for discrimination of all cultivars. Similarity indices between cultivars were computed from RAPD data, and ranged from 0.72 to 0.87 with an average of 0.82. Unweighted pair-group method with arithmetic average (UPGMA) cluster analysis revealed two groups, one formed by two cultivars recommended for summer cropping, and the other by 14 cultivars. This large group was additionally divided into two subgroups. RAPD analysis provides a quick and reliable alternative for the identification of cabbage cultivars and for determination of the relationships among them.