The application of locally available invasive algae biomass as a fertilizer for crop production in Hawaii is being investigated as a substitute for imported chemical fertilizers. Three closely related greenhouse trials were conducted to determine if the algae served as a source of potassium (K) on growth, yield, and K mineral nutrition in pak choi (Brassica rapa, Chinensis group). In the first trial, three algal species (Gracilaria salicornia, Kappaphycus alvarezii, and Eucheuma denticulatum) were applied at five rates of K, each to evaluate their effects on growth and K nutrition of pak choi plants. The pak choi was direct seeded into 0.0027-m3 pots containing peatmoss-based growth media. In trial 2, pak choi was grown in peat media at six rates of K provided by algae (E. denticulatum) or by potassium nitrate (KNO3). In trial 3, the six rates of K were provided through algae (K. alvarezii), KNO3, and potassium chloride (KCl) and were compared for growth and K nutrition. Results from the first greenhouse trial showed no significant differences among the three algal species in yield or tissue K content of pak choi. However, plant yield and tissue K concentration were increased with application rates. The maximum yield and tissue K were observed when K was provided within the range of 250–300 kg·ha−1. Similarly, in Expts. 2 and 3, there were no significant differences between commercial K fertilizers and algal K species for yield. Only K rates were significant for yields and tissue K concentrations. It was concluded that K in the invasive algae was similarly available as K in commercial synthetic fertilizers for pak choi growth in terms of yield and tissue K content under our experimental conditions.
Chandrappa Gangaiah, Amjad Ahmad, Hue V. Nguyen, Koon-Hui Wang, and Theodore J.K. Radovich
Elizabeth T. Maynard
Benefits of drip irrigation for jack-o-lantern pumpkins (Cucurbita pepo) in the midwestern United States are not documented. Field trials were conducted on a sandy loam soil to compare yield and fruit size of unirrigated pumpkins (NONE) with pumpkins irrigated when in-row soil water tension (SWT) 30 cm deep reached 20 kPa (HIGH) or 60 kPa (MED). The 2004 trial included two planting methods, direct seed (SD) and transplant, and two cultivars, `Gold Medal' (GM) and `Magic Lantern' (ML). GM typically has larger and more vigorous vines than ML. In 2005 the trial included only SD ML. Rainfall June through August totaled 38.4 cm in 2004 and 28.2 cm in 2005. In 2004 HIGH increased yield 13% compared to NONE (42.1 vs. 37.2 t·ha-1). MED (39.0 t·ha-1) did not differ from NONE. Neither planting method nor cultivar influenced the yield response to irrigation. The effect of irrigation on average weight per pumpkin depended on cultivar. In 2004, ML with HIGH averaged 7.76 kg per pumpkin, 16% heavier than NONE at 6.67 kg. MED averaged 7.17 kg. Irrigation did not affect average weight of GM: HIGH, MED and NONE averaged 12.6, 12.8 and 12.3 kg, respectively. For SD ML, combined analysis of 2004 and 2005 data showed an 18% increase in average pumpkin weight for HIGH vs. NONE (7.94 vs. 6.72 kg), but no significant effect of irrigation on yield (33.6, 29.8 and 28.4 t·ha-1 for HIGH, MED and NONE, respectively). Irrigation did not affect the number of pumpkins produced per hectare for either cultivar in either year. Results suggest that compared to no irrigation, maintaining SWT less than 20 kPA with drip irrigation may lead to 1) yield increase on the order of 10% or less, 2) 16% to 18% increase in average pumpkin weight for ML.
William Terry Kelley
Carrots (Daucus carota L.) have become an economically important vegetable crop for Georgia. Currently the harvest season extends from December through May. One possibility for extending the harvest season would be to produce carrots in the cooler mountain area of Georgia during the summer months. This study was undertaken to examine the potential for fresh-market carrot production on Georgia mountain soils and to evaluate which varieties of carrots might be most suitable for this area. Ten commercially available carrot varieties were direct seeded into a Transylvania clay loam soil on 28 May 1999 in Blairsville, Ga. Plots consisted of three twin rows of carrots each 20 feet in length. The twin rows were each three inches apart and there were 20 inches between each set of twin rows. Each plot was replicated four times. Base fertilizer of 20 pounds of nitrogen, potassium, and phosphorous were incorporated into the plots prior to seeding. Sidedress applications of 15 pounds each of N, P, and K were applied at 3-week intervals throughout the season. Recommended pest control practices were applied. A three-foot section of the center twin row was harvested on 23 Sept. 1999. The varieties `Pacific Gold' and `Topnotch' produced the highest marketable yield; however, all yields were below acceptable levels. Percent marketability was <60% for all varieties. Percent stand was extremely variable due to variability in seed size. All carrots had severe nematode damage although a nematicide was used preplant. The length of season for spring-planted carrots was too long for the life of the nematicide at the rate and method applied. Late summer–planted carrots would likely be a more viable option for this area.
Jeanine M. Davis and Jacqulyn T. Greenfield
Seventeen North Carolina farmers received $5000 grants to grow medicinal herbs as part of a research study to determine the economic feasibility of producing herbs in different regions of the state, including producing the quality and quantity of medicinal herbs required by the industry at a price that is competitive in a global market. With the help of five buyers in the natural products industry, four medicinal herbs were selected to be grown: California poppy, dandelion, Echinacea purpurea, and valerian. The growers experimented with new crops, learned new production methods, and adapted existing methods and equipment to these crops. These growers were also introduced to new markets and made connections with buyers, statewide and nationally, in an industry that can be difficult to enter. Growers were responsible for keeping detailed records of production, harvest, and postharvest handling. To produce a marketable crop in 1 year, some of the growers started seedlings in their greenhouses, while others direct seeded into the field. With the natural products industry moving toward a nonchemically grown product, growers in this project had to produce their crop without pesticides. Weed pressures were the biggest challenge to most of the growers. Prior to harvest, bioactive constituents were tested on the dried raw material to see if levels met buyers' requirements. Other testing methods determined percentage of ash, moisture content, microbial limits, and heavy metal accumulation. For postharvest handling, tobacco farmers who had drying facilities experimented with different temperature regimes to produce a uniformed dried material. Buyers and growers were then introduced to each other to complete the sale of goods.
L. Brandenberger, L.K. Wells, and B. Bostian
Because of the limited number of herbicides in spinach, beet, and swiss chard, a screening study was initiated to identify new preemergence herbicides. Field soil at the study was a fine sandy loam. The study was initiated on 8 Apr. 2004 at Bixby, Okla. Each plot had four direct seeded rows of spinach, beet and chard. 22 treatments were replicated four times in a RBD that included a nontreated check. Treatments used 12 preemergence herbicides. Herbicides were applied PRE with a research sprayer at 20 GPA in a 6-ft swath perpendicular to crop rows. The experimental area received 0.5 inch of irrigation after application. Callisto (mesotrione) and V10146 (Valent exp. compound) both resulted in 100% death of beet, chard and spinach seedlings. Herbicides that had injury at or below Dual Magnum included Pyramin (pyrazon), Nortron (ethofumesate), Lorox (linuron), and Bolero (thiobencarb) tank-mixed with Bio-Power. Yields were zero for the nontreated check and several treatments due to weed competition and the lack of crop plants in some plots. Treatments with the highest beet yields included Dual Magnum at 0.5 lbs/acre, Pyramin at 3.6 lbs/acre, and Outlook (dimethenamid-P) at 0.25 lbs/acre (11,822, 8,034, 8,010 lbs/acre respectively). Highest chard yields were from Dual Magnum at 0.5 lbs/acre, Pyramin at 3.6 lbs/acre, Outlook at 0.5 lbs/acre + Bio-Power, and Outlook at 0.5 lbs (12,753, 12,596, 11,495, and 10,563 lbs/acre, respectively). Spinach yields were highest for Dual Magnum at 0.5 lbs/acre, Define (flufenacet) at 0.3 lbs/acre, and Outlook at 0.5 lbs/acre + Bio-Power (4,465, 4,259, and 3,207 lbs/acre, respectively).
Olivia Riffo and Monica Ozores-Hampton
The nursery industry in Florida relies entirely on peat as a major component in potting soil. Escalating peat costs are a major concern, so alternative media are attractive in Florida. The objectives of the project were to study the feasibility of using food waste compost (FWC) to replace peat in different annual ornamental crops. The experiments were conducted in Spring 2004 at the University of Florida/SWFREC Immokalee, Fla. The crops basil (Ocimum basilicum L.), marigold (Calendulaofficinalis L.), and periwinkle (Vincarosea L.) were grown in mixes of FWC. The treatments were: 1) 100% FWC; 2) 60% FWC, 25% vermiculite, 15% perlite; 3) 30% FWC, 30% peat, 25% vermiculite, 15% perlite; and 4) 0% FWC, 60% peat, 25% vermiculite, 15% perlite, by volume. Basil `U.H' was direct seeded; marigold and periwinkle were transplanted (5 cm tall) in pots (2 inches). All treatments received 4 g per pot of Osmocote (19-6-12) for 4 months. Percentage of basil germination and biomass were higher in mixes with 60% and 30% FWC as compared with 100% FWC and the control. Lower basil biomass in the control media was due to high weed biomass grown in the peat control media. There were no differences in biomass and number of flowers per plant among marigold treatments. But, periwinkle dry biomass and number of flowers per plant were higher in the control and 30% FWC than in 60% and 100% FWC, indicating a negative effect of FWC in periwinkle. It can be concluded that FWC may become a viable alternative to replace peat in basil and marigold when included in potting mixes between 30% and 60% by volume, but a negative effect was reported in periwinkle production.
L.P. Brandenberger and R.P. Wiedenfeld
Melon growers in the Lower Rio Grande Valley of Texas have observed in the past that particular sizes of melons and the earliness of melons had a direct effect upon economic returns. A replicated study was carried out during two seasons to determine what specific effects plant density, row arrangement, and cultivar would have on fruit size and yield. The study combined six spacing treatments with three cultivars in a randomized design utilizing five replications on top of raised beds on 80-inch centers. Work was initiated by direct seeding and then thinning to the desired spacing interval in plots located in a commercial field. Plots were harvested by commercial harvesting crews. Results indicate that different plant spacings and honeydew cultivars can result in differences in fruit size, earliness, and returns/acre over different seasons and environments although spacing and cultivar acted independent of one another. Lower plant populations resulted in the production of larger fruit and higher plant populations resulted in the production of smaller fruit. Cultivar did affect the size of fruit produced, with some cultivars resulting in larger melons and others producing more small melons. In both seasons, the double-row 24-inch spacing resulted in an earlier harvest and exhibited a higher percent harvest for the first harvest in both years. Cultivar Sure 7050 was significantly later than either `Honeybrew' or `Morning Ice'. Returns/acre were significantly different between spacing treatments for a majority of harvests. The double-row 24-inch spacing resulted in the highest returns/acre. Both `Morning Ice' and `Sure7050' had significantly higher returns when compared to `Honeybrew'.
M.R. McDonald, M.H.Y. Hovius, and C. Sirjusingh
Resistance to Sclerotium cepivorum was investigated over 3 years at field sites with known histories of white rot in the Holland Marsh, Ontario, Canada. Onion lines from three sources (Petoseed, Asgrow Ltd., and Univ. of Wisconsin), including commercial cultivars, were direct-seeded (1995) or hand-transplanted (1994 and 1996) and the bulbs were assessed for white rot incidence at harvest. The incidence of white rot in 1994 was low (0% to 2.6%) and not significantly different among lines and cultivars. In 1995, white rot incidence was moderate at sites 1 and 2 (maximum 21.5% and 24%), but low at site 3 (0% to 6.3%). In 1996, white rot incidence ranged from 0.8% to 41.1% at site 1, but was not observed at sites 2 and 3. The results of the 1995 and 1996 assessment suggested that the breeding lines could be divided into two major groups with high (Univ. of Wisconsin) or low (Asgrow Ltd. and Petoseed) resistance to the fungus. Scale segments of harvested bulbs from the 1995 field trial and 35 commercial cultivars were inoculated with mycelial plugs of two isolates of Sclerotium cepivorum. The resulting lesions were measured. Significant differences in lesion diameters among onion lines (9.1–22.4 mm) and cultivars (10.5–26.75 mm) were found within isolates. There was a significant, high, and positive correlation between diameters of lesions formed by the two isolates on the 23 lines (r 2 = 0.76, P = 0.05) and 35 cultivars (r 2 = 0.62, P = 0.005). Both techniques demonstrated a wide range of resistance to white rot. This suggests a strong potential for increasing resistance through breeding.
Dan Drost, Rich Koenig, and Terry Tindall
Nitrogen (N) losses can be substantial in furrow-irrigated onions (Allium cepa L.). Polymer-coated urea (PU) may reduce N losses and result in an increase in productivity. In this study, we investigated the effects of different rates and blends of urea and PU on onion yield and N use for two cropping seasons. Nitrogen was applied at 112, 168, and 224 kg·ha-1 as PU or urea. In addition, three PU/urea blends equal to 224 kg·ha-1 of N were compared. Plant growth and N concentration, soil nitrate concentrations, and bulb yield were evaluated each year. Onion yield decreased by 95 Mg·ha-1 for each 25% increase in the proportion of urea in the fertilizer blends. Reducing the N rates from 224 to 112 kg·ha-1 had minimal effect on bulb yield when all the fertilizer was supplied by urea. A reduction of N applied from 224 to 168 kg·ha-1 had little effect on yield, although a further reduction to 112 kg·ha-1 did significantly reduce bulb yield when the entire N was supplied from PU. Nitrogen source and rate had no effect on bulb maturity and only minor effects on leaf area and storage potential. Soil sampling indicated that more N was retained in PU-treated onion beds than in urea-treated beds, which improved nitrogen use efficiency. In addition, N use efficiency improved when there was more PU in the blend and when PU was compared with urea at the same rate. We conclude that the use of PU can dramatically improve N use efficiency and productivity in direct-seeded onions.
H.C. Wien, B.S. Orenstein, and L.A. Ellerbrock
Although it has been known since the 1930s that long photoperiods and high temperatures hasten bulb formation in onions, the time at which onion cultivars under field conditions in New York start forming bulbs has not been previously reported. In the 1997 and 1998, onion cultivars were seeded in three commercial onion production areas at normal early spring planting dates. In 1998, a time-of-planting study was carried out in Ithaca, N.Y., in which three transplanted crops and three direct-seeded crops were established at monthly intervals beginning at the end of March. Bulb ratios (bulb diameter: neck diameter) were measured at 2-week intervals during the season in all plantings. Initiation of bulbs (assumed to occur 3 weeks before bulb ratio reached 2) was then related to the photoperiod and air temperature up to that point. A comparison of early, mid-season, and late cultivars indicated that bulbs are initiated in commercial plantings in New York at close to the longest day of the year (15.6 h), at a time when mean temperature is still rising. In the time of planting study, delay of planting resulted in fewer days from emergence to bulb initiation and a reduction in growing degree-day accumulation. If planted later than 15 June, some cultivars failed to initiate bulbs, but others, such as `Quantum' and `Winner', initiated bulbs but did not mature them. The results indicate that photoperiod appears to be the primary factor for the initiation of bulbs, but that bulb initiation can be modified strongly in some cultivars by temperature.