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  • Author or Editor: Wallace G. Pill x
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Abstract

Nitrapyrin (NI) incorporation into a peat-vermiculite medium reduced shoot growth of tomato (Lycopersicon esculentum Mill. cv. Marglobe) but this reduction was less pronounced at higher NO3-N fertilization levels. An initial 50 ppm NI application caused less growth reduction than 7, weekly 7.14 ppm applications. While increasing NO3 level had little effect on shoot ion concentration, with the exception of increasing shoot K and NO3 concentration, the increased shoot total N, Mg, and K concentrations with NI were attributed to the concentrating effect of reduced growth. Single and multiple NI applications decreased and increased, respectively, both plant water stress and medium NO3 retention. Nitrapyrin consistently increased medium NO3 concentration at the 2 highest NO3 fertilization levels. With time, however, medium NO3 concentration decreased and increased with single and multiple NI applications, respectively, relative to each other. Nitrapyrin initially decreased leaf xylem pressure potential (ψp), but with time, water stress decreased below that of the control plants with the single NI application but remained consistently high with multiple applications. Since leaf diffusive resistance and ψp were lower and transpiration rate was initially higher with the single NI application relative to the control, and since plants given the multiple NI applications had the lowest ψp and transpiration rate values throughout the study, it is hypothesized that NI reduced water uptake. That NI decreased both NO3 assimilation and uptake was evidenced by decreased shoot total N content, increased shoot NO3 content, and increased medium NO3 concentration.

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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.

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Abstract

Parsley (Petroselinum crispum L.) seeds osmoconditioned in −1.2 MPa polyethylene glycol 6000 (PEG) for 3 weeks at 15°C emerged earlier and gave higher seedling shoot fresh weights 24 days after planting than raw seeds. Further improvement in earliness of emergence was achieved by fluid-drilling the nongerminated, imbibed seeds in hydroxy ethyl cellulose gel. Germinating the osmoconditioned seeds (42% germination after 4 days at 15° in aerated water) before fluid-drilling decreased the time to 50% emergence by 52% and increased shoot fresh weight by 192% relative to raw seed performance. As emergence rate increased due to treatment, shoot fresh weight increased but emergence synchrony decreased. Neither grading seeds into density classes nor daily PEG replacement during osmoconditioning influenced seedling performance to a practical extent.

Open Access
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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.

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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.

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Abstract

The granulated, insoluble acrylamide-based hydrophilic polymers, Terrasorb HB and Alcosorb AB3C, hydrated initially with all the essential nutrients (15 g gel solids/liter of 1-fold Hoagland solution), were effective media for the production of 3-week seedlings of tomato (Lycopersicon esculentum Mil.) in plug (modular) trays. Higher concentrations of the nutrient solution used to hydrate gels or incorporation of resin-encapsulated, slow-release fertilizer (Osmocote, 17N–3.9P–10.8K, 1.5 or 3.0 g·liter–1) in the hydrated gels decreased seedling growth. Daily application of fertilizer solution (100 mg N/liter) or water resulted in similar seedling growth. Seedlings were healthy, with roots permeating the voids between the hydrated granules of the entire gel mass. The gel mass adhering to the root system could be extracted readily and intact from the plug tray cell.

Open Access

We examined the efficacy of coir dust (CD)—the short fibers and dust from the mesocarp of coconuts (Cocos nucifera L.)—as an alternative to sphagnum peat (SP) in 50 SP : 50 vermiculite (% volume) medium. Shoot dry mass of coreopsis (Coreopsis lanceolata L.) or `Red Robin' tomato (Lycopersicon esculentum Mill.) after 5 weeks' growth in up to 50 CD : 50 vermiculite (% volume) was similar to that in 50 SP : 50 vermiculite and a commercial peat-lite (Pro-Mix BX). These growth responses depended on preplant controlled-release fertilizer (CRF) [Osmocote 17N-3.9P-10.8K at 11.5 lb/yd3 (4 kg·m−3)] and/or a post-transplanting weekly solution fertilization (SF) at 350 ppm (mg·L−1) N from 21N-2.2P-16.6K. Compared to SP, CD had lower bulk density and cation exchange capacity (volume basis) and higher C to N ratio, pH, total porosity, and container capacity. We conclude that CD is an adequate alternative to SP in soilless container media.

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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.

Free access

`Moss Curled' seeds of parsley (Petroselinum crispum L.) were primed osmotically in polyethylene glycol or matrically in fine, exfoliated vermiculite at -0.5 MPa for 4 or 7 days at 20 or 30 °C with 0 or 1 mm GA3. All priming treatments stimulated and hastened germination. Matric priming resulted in greater germination (89%) than osmotic priming (83%) when seeds were primed for 7 days at 30 °C, but priming agent had no effect on germination percentage following priming at 20 °C or for 4 days. In seeds primed for 4 days at 20 or 30 °C, matric priming hastened germination more than did osmotic priming. Germination was generally less synchronous with matric than with osmotic priming. Increasing priming time from 4 to 7 days increased the rate of germination, but increased germination synchrony only when seeds were primed a t 20 °C. Inclusion of 1 mm GA3 during priming had little or no effect on germination. All matric priming treatments (other than 4-day priming) were repeated to assess seedling emergence in a greenhouse (25°C day/22 °C night). Priming increased the percentage, rate and synchrony of emergence, and increased hypocotyl length at 3 weeks after planting. Priming at 30 °C with 1 mm GA3 resulted in the greatest emergence percentage, hypocotyl length, and shoot dry weight. We conclude that matric priming is a satisfactory alternative to osmotic priming of parsley seeds. Chemical name used: gibberellic acid (GA3).

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Seeds of `Ace 55VF' tomato were soaked in solutions of -1.0 MPa Instant Ocean™ (inorganic salt mixture) or -0.6 MPa polyethylene glycol 8000 (P.E.G.) at 25 C for 1 week. `Mary Washington' asparagus seeds were soaked in the same solutions for 2 weeks. In solutions of decreasing matric or osmotic potentials, primed seeds germinated faster than untreated seeds. Germination percentages of primed seeds generally were greater than those of untreated seeds when water stress exceeded -0.5 MPa. All primed seeds, whether dried to a low moisture content or not, germinated faster than untreated seeds after storage for up to 3 months at 4 C or 20 C. Primed asparagus seeds germinated most rapidly and synchronously after storage at 4 C and high moisture content. Storage temperature and seed moisture content had no effect on subsequent germination of primed tomato seeds.

Free access