A seaweed/humus extract (ROOTS) was tested as a propagation biostimulant. Transplants from seed showed enhanced root, root hair, and shoot growth. Cultivars tested included: Broccoli `Bonaza', Coleus `Park's Bril1iant', Dahlia `Redskin', Eggplant `Early Bird', Gazania `Pinata', Geranium `Earliana' and `Hybrid Orbit', Impatiens `Shady Lady' and New Guinea `Tango', Marigolds `Gay Ladies' and `Climax', Nicotiana `Nikki', Pepper `Park's Whopper', Petunia `Total Madness', and Tomatoes `Sweet Million', `Good n Early', `Better Boy', `Early Girl', `Lady Luck' and `Super Steak'. Cuttings from citrus cultivars showed improved rooting (Lemon `Ponderosa', Lime `Bearss', and Orange `Calamondin'). Cuttings from succulents also showed improved propagation (Pedilanthus tithymaloides cucullatus, Senecio deflersii, and an unknown stapeliad species). Seaweed extracts, known growth stimulants, when fortified with humic acid, offer promise as a propagation biostimulant.
Raymond P. Poincelot
Hector Valenzuela, Robin Shimabuku, and John Cho
Pink root (Phomaterrestris) is among the major limiting factors for the production of sweet onions on Maui, Hawaii. Few management options exist for the control of pink root in onions. Two split-plot experiments were conducted in the area of Kula, Maui, over 2 years to evaluate several alternative management practices. In Expt. 1, the main plots were a rotation with cabbage, solarization with a clear plastic mulch, and a fallow period. Subplots were plus or minus Vapam fumigation. Sub-subplots were biomass application of Sudex or rape, inoculation with an EM biostimulant, and control. Each treatment had four replications for a total of 96 plots. In the follow-up experiment, the main plots were Vapam fumigation, rotation with either a Sudex or rape cover crop, and controls. The subplots were plus or minus EM biostimulant application. In Expt. 1, three separate treatments: solarization, cabbage rotation, and Sudex incorporation had a synergistic effect with Vapam fumigation. Fumigation and solarization also decreased pink root incidence. Rape contributed to a decreased disease incidence while EM contributed to increased bulb size. In Expt. 2, EM and rape contributed to increased yields. Rape and sorghum rotations contributed to decreased pink root incidence. EM inoculation had differential effects on several diseases, contributing to reduced bacterial bulb rot levels. The data indicate that growers may have several alternative management tools at their disposal, in addition to proper varietal selection, to improve yields and reduce disease incidence in sweet onions.
J.P. Morales-Payan and B.M. Santos
Greenhouse experiments were conducted in the Dominican Republic to determine the effect nitrogen (N) and the biostimulant folcysteine on the yield of `Black Seeded Simpson' lettuce. Plants were individually grown in plastic containers filled with loamy soil and treated with combinations of N and folcysteine. N rates (35, 70, 105, 140, 175, and 210 kg/ha) were applied at planting, while folcysteine (0, 100, 200, 300, and 400 ppm) was applied as a foliar spray when the plants had five true leaves. Plants were harvested 50 days after planting. The results show that there was an interaction of the effects of N and folcysteine on lettuce yield. The highest yields were obtained with combinations of 300–400 ppm of folcysteine and 140–210 kg N.
Jose Pablo Morales-Payan and Bielinski M. Santos
Field experiments were conducted in the Dominican Republic to determine the effect of combinations of N with folcysteine and gibberellic acid 3 on cilantro (Coriandrum sativum) yield. Nitrogen levels (0, 36, 55, 73, 91 kg·ha–1) in soil application at sowing were combined with foliar spray of the biostimulant folcysteine or gibberellic acid (0, 100, 200, 300, and 400 ppm) 15 days after emergence. Treatments were applied in a factorial arrangement on a randomized complete block design with three replications. Fresh weight of the aerial part of the plants was determined 40 days after emergence. No significant difference was found due to folcysteine treatment. Nitrogen had a significant effect, with optimal yield at 55 kg·ha–1. Significant interaction was detected for the combinations of gibberellic acid and N, with yield increasing as the rate of the two factors increased.
Jose Pablo Morales-Payan
Flowering plants of `Kapoho' papaya were sprayed with aqueous solutions of kinetin and folcysteine. Plants were treated four times at 3-week intervals with 0-, 50-, 90-, or 130-ppm solutions of either biostimulant or their combinations. Fruit number, size, and weight were recorded weekly during 15 weeks after treatment. Folcysteine treatment at 90 to 130 ppm significantly increased `Kapoho' papaya yield. Kinetin treatment alone did not significantly affect fruit yield at any rate tested. Moreover, none of the kinetin plus folcysteine combinations significantly differed from the control in terms of fruit yield. These findings suggest that folcysteine rates of 90 to 130 ppm can increase fruit yield in this cultivar, and that kinetin had an antagonistic effect on the activity of folcysteine on the yield of `Kapoho' papaya.
Jose Pablo Morales-Payan
Field experiments were conducted in the Dominican Republic to determine the effects of different rates of the biostimulants folcysteine and kinetin on fruit yield of `Sunrise' papaya. Aqueous solutions of either 50, 70, 90, 110, or 130 ppm. Four applications were made at 3-week intervals. Fruit number, size, and weight were recorded weekly during 15 weeks after application. Yields for the control and kinetin-treated plants were not significantly different. Significant yield increase was found in plants treated with 70 and 90 ppm of folcysteine solution. Fruit yield in plants treated with 30, 50, 110, or 130 ppm of folcysteine did not differ significantly from that of the control. These results indicate that folcysteine treatment at 70 and 90 ppm at flowering can significantly increase fruit yield in `Sunrise' papaya.
J. Pablo Morales-Payan and William M. Stall
Experiments were conducted to assess the effects of rate combinations of nitrogen (N) and a soil-applied biostimulant based on seaweed (Ascophyllum nodosum) extract (SSE) on the growth of papaya seedlings for transplant production. Seedlings were grown in 180-mL Styrofoam containers filled with a sphagnum/vermiculite/perlite growing medium. N (0 to 2 g per plant) and SSE (drench, 0 to 1 mL per plant) were applied at sowing and 15 days after emergence. N and SSE rates affected overall growth as well as time to attain adequate size for transplanting. In general, increasing N rates resulted in increased growth, and adding SSE enhanced N effects. In terms of increasing overall transplant growth and decreasing the time required from emergence to adequate transplanting size, the best results were found at the highest N and SSE rates.
M.D. Richardson and K.W. Hignight
Seed coating has been effectively used in the agricultural and horticultural industries for over 100 years. Recently, several turfgrass seed companies have been applying seed coating technologies to commercial seed lines, but there have been limited studies that have demonstrated a positive benefit of seed coating to turfgrass seed. The objective of this study was to determine the effects of two commercially available seed coating technologies, including a fungicide/biostimulant coating and a starch-based polymer coating, on tall fescue (Festuca arundinaceae) and kentucky bluegrass (Poa pratensis) in three soil types. Coated seeds were obtained from a retail outlet. Non-coated seed samples were developed by removing the coating from the seed just before planting. Neither coating technology had an effect on tall fescue speed of germination or total germination percentage in any of the soil types. Seed coating did have a positive effect on the speed of germination of kentucky bluegrass in a sandy loam soil, but did not improve the speed of germination or percentage emergence in the other soil types. These results support earlier findings that seed coating has minimal effects on establishment of turfgrass species. However, these coatings may provide benefits when attempting to establish turfgrasses in less than ideal conditions.
J. Pablo Morales-Payan and William M. Stall
Experiments were conducted to determine the effect of the biostimulant amino levulinic acid (5-ALA) on canopy and root competition of transplanted sweet and purple basils with the weed slender amaranth (Amaranthusviridus). Before transplanting, basil plants were sprayed with an aqueous solution of 5-ALA (0 and 15 mg·L-1 a.i.). Basil and amaranth were grown in plastic 19-L containers either: 1) individually (one plant per container = no interference); 2) one basil plant and one amaranth plant together in the same container (= full interference); 3) one basil plant and one amaranth plant together in the same container, training the shoots apart to avoid canopy interference (= below ground interference); or 4) basil and amaranth grown in different containers set side by side (= above ground interference). When 5-ALA was not applied, full-interference from slender amaranth reduced sweet basil shoot yield by 33%, and purple basil shoot yield by 48%. Above ground interference from slender amaranth was about 65% of the total interference effect. Basil plants treated with 5-ALA were less affected by amaranth interference than untreated basil plants, but the magnitude of the 5-ALA effect was greater in sweet basil than in purple basil. 5-ALA increased the yields of weed-free sweet basil and purple basil by about 15% and 10%, respectively.
Xunzhong Zhang, E.H. Ervin, and R.E. Schmidt
A variety of organic materials such as humic substances, seaweed extracts (SWE), organic matter, and amino acids are being used as fertilizer supplements in commercial turfgrass management. Among them, SWE and humic acid (HA) are widely used in various biostimulant product formulations. These compounds have been reported to contain phytohormones and osmoprotectants such as cytokinins, auxins, polyamines, and betaines. Manufacturer claims are that these products may supplement standard fertility programs by reducing mineral nutrient requirements while improving stress tolerance. There is a lack of season-long, field-based evidence to support these claims. This study was conducted to investigate the influence of monthly field applications of SWE, HA, and high and low seasonal fertilization regimes on the physiological health of fairway-height creeping bentgrass (Agrostis stolonifera L.). Plots were treated monthly with SWE at 16 mg·m-2 and HA (70% a.i.) at 38 mg·m-2 alone, or in combination, and were grown under low (20 kg·ha-1/month) or high nitrogen (50 kg·ha-1/month) fertilization regimes during 1996 and 1997. Endogenous antioxidant superoxide dismutase (SOD) activity, photochemical activity (PA), and turf quality were measured in July of each year. Superoxide dismutase activity was increased by 46% to 181%, accompanied by a PA increase of 9% to 18%, and improved visual quality of bentgrass in both years. There was no significant fertilization × supplement interaction. Although not part of our original objectives, it was noted that significantly less dollar spot (Sclerotinia homoeocarpa F.T. Bennett) disease incidence occurred in supplement-treated bentgrass. Our results indicate that increased SOD activity in July due to SWE and/or HA applications improved overall physiological health, irrespective of fertilization regime. This suggests that these compounds may be beneficial supplements for reducing standard fertilizer and fungicide inputs, while maintaining adequate creeping bentgrass health.