Seeds of `Champion' collard (Brassica oleracea L. var. acephala) were hydrated in water or a fluid-drilling gel (N-gel, hydroxyethyl cellulose) for 1 or 2 days at 20C (50 seeds/ml) before they were fluid-drilled into peat-lite in a greenhouse. Time to 50% seedling emergence from these seeds was more than 2 days earlier than from dry-sown untreated seeds, although emergence synchrony and percentage were unaffected. A second greenhouse study revealed more rapid seedling emergence from hydrated seeds that then were fluid-drilled than from dry-sown untreated seeds even when the delivery gel contained up to 25 g 9N-19.8P-12.5K/liter. Increasing fertilizer from 5 to 25 g·liter-1 led to increased shoot fresh weight 6 weeks after planting. When sown on two dates into field plots, hydrated seeds (1 day in either water or gel at 20C, 50 seeds/ml) that were fluid-drilled in 1.5% (w/v) N-gel containing 5 or 15 g 9N-19.8P-12.5K/liter yielded 42% greater final shoot fresh weights than untreated seeds sown dry.
Ahmet Korkmaz and Wallace Pill
Achievement of head size uniformity at final harvest reduces loss and increases profitability for the hydroponic lettuce grower. Shoot fresh weight of `Cortina' lettuce (Lactuca sativa L.) at 7 or 21 days after planting (DAP) was inversely proportional to the number of days required for seedling emergence, and was greater for raw than for pelleted seeds. Head fresh weight at final harvest (61 DAP) was directly proportional to seedling length at 21 DAP, but raw and pelleted seeds produced equal head weights. Thus, initial seed (seedling) vigor differences were maintained to final harvest. Osmotic seed priming (–1.5 MPa KH2PO4, 20 h, dark) led to increased germination rate at 15, 25, and 35C; had no effect on germination synchrony; and increased germination percentage only at 35C. Covering raw or pelleted seeds sown in depressions of the phenolic foam trays with fine (No. 5) vermiculite compared to leaving the seeds uncovered, and soaking the trays in hydroponic solution rather than water, increased seedling shoot fresh weights. Seeds sown on their first day of germination or primed seeds gave greater seedling shoot fresh weights than pelleted seeds. However, the more uniform seedling shoot fresh weights from germinated seeds than from primed seeds was associated with more rapid and synchronous seedling emergence.
Wallace G. Pill
Seed treatments, gels, and planters associated with fluid drilling are reviewed in detail. The future of fluid drilling likely lies predominantly in the sowing of primed seeds rather than germinated seeds in the carrier gel. The primed seeds may be hydrated before fluid drilling to enhance germination and seedling emergence. The gel can carry a variety of chemical or biological additives appropriate for the crop and seedbed conditions. The positional advantage resulting from additive incorporation in the fluid-drilling gel represents a more eflicient, cost-effective, and environmentally sound application method than others such as binding or spraying.
Bing Shi and Wallace Pill
Kenaf (Hibiscus cannabinus L.), native to east Africa, is an annual herbaceous member of Malvaceae cultivated primarily for its bast fibers. One of many potential uses of kenaf is that of a growth medium component. Kenaf stems (xylem plus phloem) were ground and sieved to 2 to 5 mm diameter particles. The particles were combined at various volumetric percentages with other components (perlite, vermiculite, calcined clay) in 70% Sphagnum pest moss which received standard preplant fertilization. To avoid growth suppression, the kenaf must be enriched with nitrogen (soaked in NH4NO3 solution for 5 days). Impatiens and tomato bedding plant shoot growth was proportional to both the N concentration of the soak solution and the percentage of N-soaked kenaf in the medium. The N soak solution should be £ 2000 mg N/liter with 30% kenaf or £ 4000 mg N/liter with 10% kenaf. Physical properties (bulk density, total porosity, air porosity and container capacity) of kenaf media were similar to those of a commercial peat-lite. The optimal medium for bedding plant production was 70% pest + 15% calcined clay + 15% kenaf soaked in 2000 mg N/liter. The N-soaked kenaf served successfully both as a medium bulking component and as a slow-release N supply.
Cynthia Crossan and Wallace Pill
Seeds of purple coneflower (Echinacea purpurea (L.) Moench were osmotically primed (OSP) in polyethylene glycol (PEG) or matrically primed in expanded vermiculite No. 5 (solid matrix priming, SMP). With both OSP or SHP at 15C, 10-day exposure to -0.4 MPa resulted in lowered time to 50% germination (T,) and higher germination percentage than shorter exposure (5-day) or lower water potential (-1.5 MPa). SMP- and OSP-seeds performed similarly in a greenhouse trial, resulting in 80% and 34% seedling emergence at 23C and 37C, respectively, compared to 58% and 27% for non-primed seeds. Seedling emergence rate and synchrony from primed seeds were greater than from non-primed seeds at both temperatures. An incubator study established that adding 10-4M GA3 and 10 mN ethephon (2-chloroethylphosphonic acid) to the PEG or vermiculite resulted in lower T50 and higher germination percentage than priming without these growth regulators. A further incubator study established that less-expensive trade products (Pro-Gibb Pius 2X) and Florel could substitute for the reagent-grade growth regulators. Seeds primed in PEG or vermiculite containing 10-4M GA3 from Pro-Gibb Plus 2X and 10 mM ethephon from Floral had lower T50 and higher percentage emergence in a greenhouse trial than seeds primed without growth regulators. Compared to the non-primed seeds, these treated seeds had 29% greater seedling emergence and 61% less time to 50% emergence.
Wallace Pill and Bing Shi
Kenaf stems were ground and sieved to yield fine (<2mm), medium (2 to 6 mm) or coarse (6 to 12 mm) grades. These grades were mixed at 25, 50 or 75% volumes in sphagnum peatmoss and then provided standard basal fertilization. Tomato and impatiens shoot fresh weights 4 weeks after transplanting (50 mg N.liter-1 daily liquid feed) were greatest in 25% medium kenaf, being 68 and 89%, respectively, those in peat-lite (ProMix BX). In a further study, medium kenaf was soaked for 3 days in 5000, 10000 or 15000 mg N.liter-1 from 20N-4. 3P-8.6K then mixed at 25% volume in peatmoss. Tomato seedlings transplanted into these media were provided 0, 100, 300 or 500 mg N.liter-1 daily liquid feed (LF) from 20N-4.3P-8.6K. With ≥100 mg N.liter-1 LF, soak solution concentration had no effect on shoot fresh weight. With 0 mg N.liter-1 LF however, kenaf media soaked in 10000 or 15000 mg N.liter-1 yielded greater shoot fresh weights than ProMix with 100 mg N.liter-1, LF.
Garrett Goyette and Wallace Pill
The utility of Ironrich (IR), a tertiary mineral co-product from TiO2 production, as a growth medium component was investigated. All complementary bulking components (10 to 50% volume) gave reduced shoot fresh weights of tomato, impatiens or perennial ryegrass relative to Fairgrow (FG, co-composted solid waste and sewage sludge). Shoot fresh weights of impatiens and tomato grown in 50% IR with FG were similar to those grown in commercial peat-lites. When provided 200 mg N litre-1 daily, chard shoot fresh weights, beet root fresh weights, and tomato fruit fresh weights from plants grown in 50% IR plus 50% FG were not significantly different from those grown in 50% silt loam plus 50% FG. Tissue Cd, Cr, Ni, and Pb concentrations from plants grown in 50% combinations of FG with IR or silt loam were below the limits of detection. IR plus FG with N-P-K fertilization provided a satisfactory greenhouse growth medium. We project that IR + FG will constitute a satisfactory synthetic topsoil.
Wallace G. Pill
Kenaf core (xylem) particles (2 to 4 mm in diameter) were submersed in ammonium nitrate solutions (0 to 5000 mg N/liter) for 5 days. The kenaf was incorporated into complementary components as 30% kenaf: 70%. sphagnum moss or 10% kenaf: 10% vermiculite: 10% calcined clay: 70% sphagnum moss. These media received standard preplant fertilizer additions. Tomato and impatiens bedding plant shoot dry weights increased with up to 5000 mg N/liter in media containing 10% kenaf and with up to 3000 mg N/liter in media containing 30% kenaf. By selecting the N concentration of the kenaf soak solution, shoot growth could be matched to that achieved with commercial peat-lites after any post-transplanting period (2 to 9 weeks). A further study revealed that kenaf was an effective carrier for Bonzi and Sumagic growth regulators. By combining N-soaked kenaf with growth-regulator-soaked kenaf in the growth medium, bedding plant shoot growth was healthy but restricted.
Jonathon I. Watkinson and Wallace G. Pill
Following dry storage for 5 or 11 months (new and old seeds, respectively) at 5 °C, less than 10% of the seeds of Indiangrass germinated as determined by a standard germination test. We attempted to increase germination by subjecting seeds to dormancy-breaking treatments, including sodium hypochlorite soak (5.25% v/v NaOCl; 20 or 60 min), prechilling (5 °C for 2 weeks), gibberellic acid during germination (GA3, 1000 mg·L-1), and combinations thereof. Treatment with NaOCl increased the germination of non-prechilled seeds only when they were germinated in GA3; a 60-min soak in NaOCl increased germination to 53% and 65% in new and old seeds, respectively. Prechilling increased germination to 65% and 47% in new and old seeds, respectively. Germination of new, prechilled seeds was increased further to 86% by either a 20-min soak in NaOCl or germination in GA3. Germination of old, prechilled seeds was not promoted further by treatment with NaOCl, but was increased to 67% by germination in GA3. Since NaOCl treatment alone failed to promote germination, we examined the effects on seedling emergence and growth of providing GA3 at 1000 mg·L-1 during the 2-week prechilling period. While prechilling alone increased emergence to an average 34% for new and old seeds, prechilling with GA3 increased emergence to 75% and 50% for new and old seeds, respectively. These treatments did not influence seedling shoot dry mass. Seed exposure to GA3 during rather than after prechilling was more effective in promoting Indiangrass establishment.
Paul L. Owen and Wallace G. Pill
The influence of two drying regimes and two storage temperatures of primed asparagus (Asparagus officinalis L.) and tomato (Lycopersicon esculentum Mill.) seeds on germination after storage up to 3 months was examined. Seeds of `Mary Washington' asparagus and `Ace 55' tomato primed in synthetic seawater (-1.0 MPa, 20C, 1 week, dark) were surface-dried at 20C and 50% relative humidity (RH) for 2 h (42% to 49% moisture) or dried-back at 20C and 32.5% RH for 48 h (moisture = 13% tomato and 22% asparagus). These and nonprimed seeds were stored in tight-lidded metal cans and heat-sealed plastic pouches at 4 or 20C for up to 3 months before germination at 20C. After 3-month storage, primed surface-dried asparagus seeds stored at 4C had greater germination percentage and rate than nonprimed seeds, surface-dried seeds stored at 20C, or primed dried-back seeds. Dried-back primed tomato seeds had higher germination percentage than surface-dried primed seeds after 2 or 3 months of storage, with storage temperature having no effect on germination perecentage or rate. In a further study, primed surface-dried and primed dried-back seeds stored at 4 or 20C for 1.5 months in sealed containers were germinated at 15, 25, or 35C under low (-0.05 MPa) or high osmotic stress (-0.4 MPa). Primed surface-dried asparagus seeds stored at 4C, compared to nonprimed seeds, surface-dried seed stored at 20C, or primed dried-back seeds, had greater germination percentage at 15 and 35C and low osmotic stress, and higher germination rate at 15 or 25C. Primed tomato seeds had greater germination percentage than nonprimed seeds only at 35C and low osmotic stress, and higher germination rate at 15 or 25C. Storage of primed tomato seeds at 4C rather than 20C increased germination rate at 15 or 25C, and increased germination percentage at 35C and low osmotic stress. For maximal seed viability and germination rate after 1.5 to 3 months of storage, primed asparagus and tomato seeds should be stored at 4C rather than 20C; however, asparagus seeds should be surface-dried, and tomato seeds should be dried-back.