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- Author or Editor: Wallace G. Pill x
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.
`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).
Seed treatments with paclobutrazol (PB), a triazole growth retardant, were examined for seedling growth suppression without exerting a deleterious effect on germination or emergence. Seeds of `Salmon Picotee impatiens (Impatiens wallerana Hook f.) and `Marglobe tomato (Lycopersicon esculentum Mill.) were soaked for 24 or 48 hours at 22 °C in 0, 50, 500, or 1000 mg·L-1 PB or were primed in polyethylene glycol 8000 or grade 5 exfoliated vermiculite (both at -1.0 MPa for 7 days at 22 °C) containing these PB solutions. Any PB seed treatment of impatiens (including a series of lower concentrations up to 50 mg·L-1 PB) that elicited seedling growth suppression also reduced germination and emergence. For tomato, soaking seeds for 24 hours in up to 1000 mg·L-1 PB had little or no effect on germination or emergence, and yet shoot height or dry weight was not decreased further by exceeding 50 mg·L-1 PB. At any PB concentration, soaking seeds for 48 hours or priming seeds resulted in lower percentage of germination or emergence than soaking seeds for 24 hours. Soaking tomato seeds in 50 mg·L-1 PB for 24 hours resulted in similar shoot growth suppression until at least 31 days after planting as a growth medium drench (1 mg·L-1 PB) or as a shoot spray (10 mg·L-1 PB), both applied at 14 days after planting. Beyond 31 days after planting, however, the latter two treatments gave greater shoot growth suppression than the PB seed soak treatment, which had lost its growth suppressive effect. Chemical name used: (+)-(R *,R *)-[(4-chlorophenyl)methyl]- -(1,1,-dimethyl)-1H-1,2,4-triazole-1-ethanol (paclobutrazol).
`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 at 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).
Abstract
Metalaxyl, etridiazole, and captan were incorporated at 0, 50, 450, and 850 mg active ingredient per liter of magnesium silicate (Laponite 445) gel to ascertain fungicide efficacy in controlling damping-off [Pythium aphanidermatum (Edson) Fitzp.] in fluid-drilled ‘Heinz 1350’ tomato (Lycopersicon esculentum Mill.). Metalaxyl and etridiazole at 50 and 450 mg a.i./liter, respectively, gave percentage emergence values in infested growth media equal to those in control media. Captan at 850 mg a.i./liter gave lower percentage emergence values in Pythium-infested media than in control media. Thus, damping-off control efficacy was in the order metalaxyl > etridiazole > captan. Seedling growth reflected fungicide efficacy in controlling Pythium, since plant fresh weight and infection index values were inversely related. Fungicides incorporated in gel were nonphy to toxic.
Abstract
The effects of 0.02, 0.06, 0.18, and 0.54 kg P/m3 incorporation as superphosphate (0-9-0) in peat–vermiculite and of NO3-N and NH4-H liquid feeds were investigated with tomato (Lycopersicon esculentum Mill. cv. Marglobe). Increasing P rate decreased shoot and root dry weights but increased total fruit fresh weight. NH4-N, relative to NO3-N nutrition, decreased shoot growth but had no effect on fruit yield. Decreased vegetative growth with increasing P rate and NH4-N nutrition was associated with decreased leaflet xylem pressure potential, increased transpiration rate, and increased leaf NH4-N concentration. Leaf P and medium water-soluble P concentrations increased with increasing P rate but were unaffected by N form. During time of fruit development, leaf P content decreased at the 2 lowest P rates but increased at higher P rates. Net P export from leaves ceased and luxury P consumption began between 0.06 and 0.18 kg P/m3.
Abstract
Germinated seeds of ‘Heinz 1350 VF’ tomato (Lycopersicon esculentum Mill.) were subjected to short-term (through 5 days) low temperature (0° or 5°C) storage suspended in 2 fluid-drilling gels (Natrosol 250 HHR or Laponite 445). Following storage, a greenhouse emergence assay and respiratory characterization via double inhibitor titrations (0.4/mM KCN and 10.0/mM salicylhydroxamic acid) were conducted. After 3-day storage in Natrosol or moist cheesecloth, emergence was about 90% but had decreased to <60% following 3-day storage in Laponite. With 5-day storage in Natrosol, 0° drastically reduced seedling vigor relative to that at 5°. Total O2 consumption by all stored germinated seeds was less than that of unstored germinated seeds. Consumption of O2 via both the cytochrome and alternative respiratory pathways was not affected differentially by storage temperature or gel. The maximum inducible rate of oxygen consumption via the alternative pathway decreased during storage in Natrosol at 0° or Laponite at 5° relative to that of unstored seeds or seeds stored in Natrosol at 5°.
Abstract
The effects of storage of pregerminated tomato seed (Lycopersicon esculentum Mill. cv. Marglobe) at 0° and 5°C for 0, 4, 8, 12, 16, and 20 days in 4 gels or in moist cheesecloth on percentage emergence (PE) and emergence rate index (ERI) were examined. The PE and ERI values of freshly germinated (unstored) seeds were statistically equal and high in all gels and much greater than the values of dry seed. After 4 days storage, both PE and ERI were unaffected by storage temperature but were significantly affected by gels in order of emergence magnitude: Moist cheesecloth = Natrosol 250 HHR > Laponite 508 = SGP104K > Vittera II Hydrogel. With ≥ 8-day storage, storage temperature interacted with gels so that 0° compared to 5° storage gave greater PE and ERI in Natrosol 250 HHR and Laponite 508 but lower values in moist cheesecloth. Pregerminated tomato seed storage in Natrosol 250 HHR at 0° is an acceptable alternative to 5° moist storage providing, even after 12 days of storage, a distinctly higher PE and ERI than dry seed. To avoid unacceptably low emergence, chitted seed storage in Vittera II hydrogel should be avoided and storage in Laponite 508 or SGP104K should not exceed 4 days.
Abstract
Nitrapyrin (NI) at 10 ppm, compared to water control, added to a soil-sand-peat medium decreased shoot growth of tomatoes (Lycopersicon esculentum Mill. cv. Marglobe) grown with NO3-N nutrition but had no effect on growth with NH4-N nutrition. While plant water stress was decreased by NI compared to the control with NO3-N nutrition, the toxic effect of increased uncombined NH4 concentration in the shoots may have caused the growth reduction. Denitrification suppression by NI with NO3-N nutrition was evidenced by increased media and shoot NO3 concentrations. Nitrification suppression by NI with NH4-N nutrition was evidenced by increased media and shoot NH4 concentrations. Nitrapyrin, irrespective of N form, decreased shoot Ca concentration, increased shoot K and uncombined NH4 concentrations, and had no effect on shoot Mg concentration. Plant water stress was decreased by NI with both N forms at the third and fifth weeks after final transplanting. While NI decreased the differential effect of N form on transpiration rate and leaf diffusive resistance (RL), in NI’s absence, NH4-N nutrition decreased transpiration and increased RL relative to NO3-N. Decreased shoot growth with NH4-N relative to NO3-N nutrition, both in the presence and absence of NI, was associated with increases in plant water stress, root hydraulic resistance, and shoot uncombined NH4 concentration, but a decrease in shoot Ca concentration.
Switchgrass (Panicum virgatum L.) is one of the perennial, native, warm-season grasses recommended as a component of wildflower meadows. Seed treatments to alleviate low seed vigor and seed dormancy of switchgrass would enhance establishment of either plug transplants or seedlings after direct sowing into the meadow. “Heavy” seeds (45.5 mg/50 seeds) of open-pollinated switchgrass stored under cool and dry conditions (average 13 °C, 30% relative humidity) for 24 months had higher germination percentage than “light” seeds (26.0 mg per 50 seeds). In factorial combination, the heavy seeds were subjected to acid scarification (8 M H2SO4 for 5 min), sodium hypochlorite treatment (5.25% NaOCl for 15 min), and moist chilling (prechilling in 0.2% KNO3, for 14 days). Acid scarification followed by NaOCl treatment additively increased germination, a response that was associated with marked corrosion of the lemma margin in the distal region of the caryopsis, as observed by scanning electron microscopy. Prechilling the seeds following acid scarification and NaOCl further increased germination. All three treatments combined (acid scarification, NaOCl, and prechilling) almost doubled the final emergence and greatly increased seedling shoot dry mass in both a warm and cool postsowing environment. However, the effectiveness of these seed treatments was lost after 32 months of dry storage.