Carrots and Related Vegetable Umbelliferae . V.E. Rubatzky, C. F. Quiros, and P. W. Simon. 1999. CABI Publishing, 10 E. 40 th St., Suite 3203, New York, NY 10016. 294 p., illustrated, softcover. $50.00. ISBN 0-85199-129-7.
‘Utah 52-70R’ celery (Apium graveolens L.) seedlings were grown in a N- and P-deficient soilless medium amended with N and P slow-release fertilizers (Osmocote) in greenhouses maintained at either 21° to 32°C (warm house) or 14° to 24° (cool house). Generally, as N rate increased from 1.25 to 10 g N/kg of medium, plant stands, chlorophyll, shoot number, plant height, leaf area, and shoot and root dry weights increased; but, from 10 to 20 g N/kg of medium, these variables decreased. As P rates increased from 2.5 to 10.0 g·kg−1 of medium, only chlorophyll content decreased linearly. Temperatures in the warm house generally reduced celery growth compared to the cool house. At the experiment's termination, it was determined that as N and P rates increased, media conductivity, nitrate-N, and phosphorus levels increased, but pH decreased. A N rate of 1.25 and 2.5 g P/kg of medium was adequate to produce quality celery transplants in a cool house.
`Moss Curled' parsley [Petroselinum crispum (Mill.) Nyman ex. A.W. Hill] schizocarps were osmotically primed in polyethylene glycol at -1.0 MPa for 7 days at 20 °C. The smaller of the two mericarps within a parsley schizocarp had lower germination percentage, but similar rate and synchrony of germination. Osmotic priming increased germination percentage, rate, and synchrony, irrespective of mericarp half. This promotive effect of priming on germination was associated with embryonic advancement as indicated by a doubling of radicle and cotyledon volumes, without changes in lengths of these organs. Periclinal divisions of the lateral expansion meristem, distinct in primed radicles but indistinct in nonprimed radicles, led to radial alignment of the cortical cells and a doubling of cortical volume and thereby increased radicle volume. Each embryonic cotyledon of primed mericarps had three distinct procambial bundles that differentiated along most of the cotyledon length, while nonprimed cotyledons had from zero to three that differentiated only a short way into the cotyledon. Priming increased coyledonary procambium length by 5-fold and volume by 11-fold. Increased embryonic growth due to priming was associated with greater endosperm depletion adjacent to the embryo. The schizocarps frequently separated or partially separated into component mericarps during priming, indicating a weakening of pericarp tissue along the commissural suture and possibly elsewhere.
Germination studies indicated that increasing priming duration (-1.0 MPa at 20 °C for 7, 14, or 21 days) increased `Moss Curled' parsley [Petroselinum crispum (Mill.) Nyman ex A.W. Hill] germination rate quadratically and seed moisture content linearly. A histological and anatomical study was conducted to identify and/or quantify principle mericarp organ or tissue volume changes influenced by priming duration. Embryo volume increased as priming duration increased from 7 to 21 days (0.014 to 0.034 mm3), and this was due more to radicle (0.007 to 0.022 mm3) than to cotyledon (0.006 to 0.011 mm3) growth. Concomitant with increased embryo volume was increased volume of the depleted layer (space formation, surrounding the embryo), from 0.038 after 7 days to 0.071 mm3 after 21 days, and increased hydrolysis of central endosperm (a thick-walled endosperm type). In nonprimed mericarps, central endosperm cells constituted 97% of the endosperm volume. The remaining 3% was comprised of 1% depleted layer and 2% distal endosperm (small, thin-walled, and irregularly shaped endosperm cells). During 7 or 21 days of priming, ≈10% or 40%, respectively, of central endosperm cells were hydrolyzed centrifugally around the embryo with a corresponding decrease in volume of central endosperm with thick cell walls. In addition, distal endosperm cells adjacent to the depleted layer, containing reserve materials, were digested of contents following 21 days priming, and sometimes, following 7 days priming. A long priming duration resulted in degradation of pericarp tissues, as indicated visually and by a decline in pericarp volume. We hypothesize that priming duration of parsley primarily influences radicle growth and centrifugal digestion and utilization of central and distal endosperm, resulting in a larger depleted layer required for embryo volume increases. Secondary events influenced by priming duration include cotyledon growth and degradation of pericarp tissues.
Fennel (Foeniculum vulgare Mill.) is grown commercially in Tasmania for the production of a steam-distilled essential oil, which is high in trans-anethole. Often, only the generative canopy is harvested since this contains the bulk of the oil and further this oil is higher in anethole than oil from other parts of the plant. Regardless of whether the whole crop is forage harvested or the generative canopy alone is removed using a combine-harvester, the most efficient oil production occurs when the greatest proportion of the canopy is generative, giving maximum oil yield from a minimum of fresh weight to be processed. A trial was conducted to examine the relationship between stand density and the various yield components of fennel in order to predict the likely effect on yield of increasing stem density as the short term perennial crop matures. As for most crops, planting density and biomass yield are closely related and the optimum planting density was predicted using a mathematical model. The results suggest that an initial stand density of 10 to 12 plants/m2, in a square layout, would produce the greatest yield of essential oil per unit area by maximising the production of the generative canopy. This density also maximises the yield of oil relative to the weight of material to be distilled.
Fruit set is a key component of essential oil yield from fennel (Foeniculum vulgare Mill.) under Tasmanian conditions. Fruit set in commercial crops is often low, possibly due to incomplete pollination. Fennel flowers are strongly protandrous and a series of flowers must be produced to ensure pollination. The hypothesis tested was that decreasing stand density increases the number of lateral branches, thereby increasing the number of higher order umbels and thus increasing the overlap between the periods of pollen production and stigma receptivity. A field trial was used to examine the number of umbels of each order produced under stand densities of 4, 12, 25, 50 and 100 plants/m2. Stand density influenced the ratio of pollen producing to pollen receptive umbels and stand densities of 50 and 100 plants/m2 showed a distinct imbalance between pollen production and stigma receptivity. The data collected supported the hypothesis and it is probable that, in commercial crops, fruit set is being reduced by a lack of synchrony between pollen production and stigma receptivity. The highest stand density tested reduced total oil production. We therefore recommend the inclusion of low stand-density strips within standard-density commercial crops.
Celery transplants (Apium graveolens L. cv. Florida 683) were fertilized with complete nutrient solutions at three N concentrations and three concentrations of P in a factorial combination, both with or without atmospheric CO2 enrichment. They then were planted on a muck soil and harvested at the end of July. Carbon dioxide enrichment increased the transplant leaf area as well as shoot and root dry weight and decreased the leaf area ratio (LAR), but had no significant effect on growth parameters at harvest. Nitrogen affected leaf area, dry weight, leaf area ratio, and dry matter content of transplant shoots together with root: shoot dry weight ratio. Total, marketable, and side shoot weights at harvest were significantly increased by the intermediate N concentration (400 ppm N) provided during transplant raising. Phosphorus had no effect on transplant growth but interacted with N on the weight of marketable shoots harvested.
Celery seedlings (Apium graveolens L. cv. Florida 683) were seeded in multicell styrofoam trays containing a commercial peat mix. They were irrigated with nutrient solutions containing three N fertilizations (150, 250, or 350 mg N/liter) and three NO3:NH4 ratios (1:1, 2:1, or 3:1) in factorial combinations. Growth measurements and saturated medium extracts were obtained on days 38, 45, and 52 after seeding. Increasing N fertilization increased leaf area and shoot dry weight, but decreased root dry weight and root : shoot ratio. The lowest NO3:NH4 ratio had increased the percentage of shoot dry matter by the end of the experiment. Nitrogen was preferentially taken up as NH4-N. The composition of the fertilizer solution had a greater effect on young celery seedlings than on older ones. A minimum of 250 mg N/Iiter at a NO3:NH4 ratio of 2:1 appears to be adequate for celery seedlings grown in multicells.
Celery seedlings (Apium graveolens L. cv. Florida 683) were seeded in multicell styrofoam trays containing a commercial peat mix. They were fertilized with nutrient solutions at two nitrogen fertilizations (150 or 350 mg N/liter), two NO3:NH4 ratios (2:1 or 3:1), and two urea-N levels (0% or 50%) in factorial combinations to determine main and interactive effects of urea on seedling growth, nutrient status, and crop yield. Urea used in combination with low N improved the percentage of shoot dry matter and increased leaf area, shoot and root dry weight, and root: shoot ratio of the seedlings. Urea proved beneficial in improving transplant yield potential under high-N fertilization.
Carrot (Daucus carota) L.) seed quality is affected by the environment in which it matures. Substantial differences in germination from year to year and from field to field have been recognized for many years for umbelliferae seed. Part of the explanation for low germination appears to be the harvest of immature seed. Data was collected for two years, from fields of the cultivars Chantenay and Nantes. Approximately 550 growing degree days were accumulated from anthesis until maturity for seed from the primary umbel. Growing degree days were calculated using a 10°C base temperature and without truncating for temperatures in excess of 35°C. Secondary, tertiary, and quaternary umbel seed maturity sequentially followed primary umbel seed. Secondary and tertiary umbels produced approximately 80 percent of the total seed yield while the primary and quaternary umbels produced approximately 20 percent. Seed maturity was determined by measuring the germination rate. Immature seed germinate at a slower rate than mature seed. The implications of these results for obtaining high quality carrot seed will be discussed.