Search Results
Abstract
A modular assimilation chamber (MAC) was developed for rapid examination of CO2 exchange rate (CER) of multiple turfgrass replicates. Kentucky bluegrass (Poa pratensis L. ‘Enoble’) and tall fescue (Festuca arundinacea Schreb. ‘Houndog’) were grown in Cone-tainers with attached base plates under greenhouse conditions. A chamber top was sealed to the base plate to complete the MAC. It then was used under laboratory conditions to measure CER by an open, differential CO2 method or by closed chamber-syringe sampling method. The two-module concept provided a relatively simple tool for making rapid, multiple measurements of CER when used as part of a closed system. However, a larger chamber volume is needed for closed system measurements because: 1) CER values were significantly larger with the open system, rapid drops in CO2 concentration occurred during closed-system measurements, and CER measurements after 2 min of closure were significantly lower than those made after 1 min of closure.
Abstract
Potential benefits of priming seeds were first indicated by Levitt and Hamm in 1943 (14), reported for vegetable seed in 1963 by Ells (7), and summarized in 1975 by Hey-decker et al. (11). Effective priming causes the treated seed to germinate earlier and with greater uniformity than untreated seed (11). To date, the technique of priming seeds has been used to solve problems concerning thermodormancy (9), cold soil temperatures (15), and to increase the rate and uniformity of crop emergence (7, 10, 11). However, the methodology of priming, especially for PEG solutions, has not been readily adaptable to handling the large amounts of seed that would be required for commercial use (4, 10). Although the successful use of the SPS to ‘bulk’ prime carrot (12) and pepper (3) seeds has been reported, the design of the SPS and the methodology of its use have not been adequately described. Therefore, this report describes the SPS and the methodology that makes it functional.
Abstract
Thirty-six-day-old ‘Dodd’ pecan seedlings [Carya illinoensis (Wangenh) C. Koch] were flooded for 31 days or not flooded in factorial combinations with 0, 215, or 430 g P per m3 of media. Flooding decreased leaf number, leaf area, leaf and root dry weight, and induced stomatal closure. Flooding also reduced leaf, trunk, and root K, Ca, Mg, Zn, Fe, and Mn concentrations. Nitrogen was lower in the leaves and trunk of flooded trees, but higher in the roots of flooded trees than unflooded trees. Flooding decreased the leaf P concentration, but did not affect the P concentration in the roots. Phosphorus application increased leaf P concentration in unflooded trees, but not flooded trees.
Abstract
‘Forest Green’ parsley ( Petroselinum crispum L.) seeds were leached for 3 days in aerated water at 25°C and then primed in aerated polyethylene glycol (PEG) 8000 solutions for 4.5 days at 25°. Priming improved earliness of germination at all temperatures of the tests (5°, 15°, 20°, and 25°), with the largest improvement at the coolest temperature. Uniformity of germination, as measured by the mean time between 25% and 75% germination, was not significantly affected by priming. Primed seeds germinated significantly faster than unprimed seeds when water stress was applied by low osmotic potentials (PEG solutions, -0.25, -0.5, or -0.75 MPa, were substituted for water). The latter result supports the hypothesis that priming induces the development of low cellular osmotic potentials. The priming effect was not lost during 8 months of storage, indicating a good treatment longevity.
Abstract
Periodic seismic (shaking) stress influenced the growth of sexual and asexual reproductive structures of three cultivated species. It delayed anthesis of Lycopersicon esculentum Mill. ‘Patio’ but not of Tagetes erecta L. ‘Jubilee’ or Solanum tuberosum L. ‘Kennebec’. Shaken ‘Jubliee’ marigold plants produced the same number of flowers as undisturbed plants, but flowers of shaken plants were smaller. In contrast, seismicstressed ‘Patio’ tomato produced fewer buds and flowers, but fruit set was enhanced relative to that of controls. Seismic stress also reduced tuber weight of ‘Kennebec’ potato, whereas tuber number was unaffected. The overall effect of seismic stress was to reduce the growth of reproductive structures and, in some cases, the number of reproductive structures that developed.
Abstract
The design and operation of a system is described in which small plants can be grown under controlled environment conditions. Important features of this “Minitron” system include precise control of temperature and CO2 concentration in a flowing atmosphere. Plants can be grown either hydroponically or in solid root support medium. For either culture method, nutrient solution or water is added from an external reservoir, altering neither atmospheric composition nor temperature equilibrium within a closed Minitron chamber.
Abstract
Osmotic priming effects on stand establishment and yield were evaluated for ‘Forest Green’ parsley (Petroselinum crispum Mill.) seed sown on three dates in the field. Stand establishment occurred under progressively higher temperatures for early, middle, and late plantings. Seed priming enhanced early seeded stands 78% at one site and 76% at a second site in comparison with untreated seed. This priming effect on seedling establishment for the earliest planting led to a 67% increase in early yield (96 days from seeding) and a 28% yield increase over untreated seed at a later harvest. Stands of primed seed sown at later dates were enhanced to a lesser extent and yields were not affected by osmotic priming.