Abstract
Seeds of winged bean, accessions TPt-1 and ‘Chimbu’, treated in dilute H2SO4 (8:1 by volume in H2O) for 5 minutes at 62°C followed by a 5 minute rinse under running tap water gave 96-100% germination with no apparent injury to the emerging seedlings.
`Verina' leek (AIlium porrum L.) seed germination is normally reduced at temperatures > 25C. Leek seeds were primed in aerated solutions (1.5 MPa, 10 days at 15C) of d-mannitol (mannitol), polyethylene glycol-8000 (PEG), KNO, and a nonaerated solution of PEG-8000 (PEG). At high temperatures mannitol, PEG, and PEG significantly enhanced germination percentage relative to KNO, or the control. At constant 30C, the mannitol, PEG, and PEG treatments increased final germination almost 10 times and the coefficient of velocity (COV) was improved compared to KNO, and the control. 10 growth chambers with alternating day/night temperatures (38 to 28C or 32 to 22C, 10 to 14 hours, respectively), primed seeds had significantly higher emergence and a larger COV than the control. In a greenhouse study under good conditions for germination, total emergence of primed and nonprimed seeds was similar; however, mannitol, PEG, and PEG led to a significantly higher COV than the control or KNO, treatments. These controlled-environment results demonstrate that priming leek seeds via mannitol, PEG, and PEG may promote early emergence at high temperature and improve stand uniformity for container transplant production.
A study was conducted to improve the seedling emergence rate of lettuce (Lactuca sativa) seeds at high temperatures using a convenient postsown priming method. Seeding mixtures adjusted to 35%, 45%, or 55% moisture content were sown with lettuce ‘Patriot’ in cell trays. Postsown priming was performed at 20 °C for 1 day and at 30 °C for 3 or 5 days. After the treatment, trays were moved to an emergence room kept at 32.5 °C, a temperature assumed to be typical of non-air-conditioned rooms in nurseries. Emergence of nonprimed controls was 9% to 16% after 2 days in the emergence room and was 59% to 75% on day 6. In contrast, seedling emergences on day 2 were 95%, 76%, and 78% to 79% in 55% moisture at 20 °C for 1 day, 55% moisture at 30 °C for 3 days, and 45% to 55% moisture at 30 °C for 5 days, respectively. Therefore, the treatment with 55% moisture at 20 °C for 1 day appeared most effective; however, post-sown priming with 55% moisture at 30 °C for 3 days or 45% to 55% moisture at 30 °C for 5 days may be more practical due to lower temperature-control costs.
Onions (Allium cepa) in southeastern Georgia are almost exclusively transplanted, with the associated high costs and labor requirements. This study was undertaken to evaluate direct-seeded onions as an alternative production method. This study evaluates variety, sowing date, and fertility on direct seeding short-day onions in southeastern Georgia. Sowing dates, early or mid-October (5 and 15 Oct. 2001 and 7 and 21 Oct. 2002), did not affect total, jumbo (≥3 inches diameter), or medium (≥2 inches and <3 inches diameter) yields. Late October sowing (29 Oct. 2001) did not produce sufficient stand or yield to warrant harvesting. Variety also had no affect on yield of direct-seeded onions. Seedstems (flowering), an undesirable characteristic, was significantly greater with the early October sowing date across all varieties compared with the mid- or late- October sowing dates. Neither variety nor sowing date significantly affected plant stand or plant spacing. Fertilization treatments of 150 or 195 lb/acre nitrogen (N) with various application timings and fertilizer sources did not affect total or medium yields. Jumbo yield was affected in only 1 year with calcium nitrate as the primary N source at 195 lb/acre total N having the highest yield, but did not differ from some treatments at 150 lb/acre N. In addition, fertilization treatments did not affect seedstems, plant stand, or plant spacing. Based on this study, we are recommending that growers should direct seed onions in southeastern Georgia in mid-October, plus or minus 1 week depending on field accessibility. In addition, current fertilizer recommendations for transplanted dry bulb onions should be followed, which includes 150 lb/acre N. This eliminates all of the cost and resources required for transplant production.
Abstract
Seeds of table beet (Beta vulgaris L.) were soaked in either water or a 1% (v/v) solution of a seaweed extract prepared from members of species within the families Laminariaceae and Fucaceae (Cytex) prior to germination at 10°, 15°, 20°, 25°, and 30°C. Germination of the seaweed extract-treated seeds was superior to that of the water controls at all temperatures except 25°. Promotion of germination was attributed to the known cytokinin-like properties of the extract.
Abstract
Seeds of ‘Valmaine’ romaine lettuce (Lactuca sativa L.) were very sensitive to high temperature during laboratory germination. Priming seeds in −5.1 bar K3PO4 or polyethylene glycol osmotic solutions was more effective for increasing the germination rate over nonprimed seeds at 30°C than priming seeds in water. When planted in the field in 1978 and 1979, primed ‘Valmaine’ lettuce seeds emerged more rapidly and uniformly than nonprimed seeds. At harvest, plants from priming treatments which had emerged sooner, were at a more advanced and uniform stage of maturity than plants from nonprimed seeds.
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.
The effects of incorporating plant growth regulators into the priming solution on low temperature germination and emergence percentage performance of sweet pepper (Capsicum annuum `Demre') seeds before and after seed storage were investigated. Seeds were primed in 3% KNO3 solution for 6 days at 25 °C in darkness containing one of the following: 1, 3, 5, or 10 μm methyl jasmonate (MeJA) or 0.05, 0.1, 0.5, or 1 mm acetyl salicylic acid (ASA). Following priming, seeds were either immediately subjected to germination and emergence tests at 15 °C or stored at 4 °C for 1 month after which they were subjected to germination test at 15 °C. Priming pepper seeds in the presence or absence of plant growth regulators in general improved final germination percentage (FGP), germination rate (G50) and germination synchrony (G10-90) at 15 °C compared to nonprimed seeds which had an FGP of 44%, G50 of 7.3 days and G10-90 of 7.3 days. Priming seeds in KNO3 solution containing 0.1 mm of ASA resulted in the highest germination percentage (91%), fastest germination rate (G50 = 2.2 days) and the most synchronous germination (G10-90 = 6.1 days). Emergence percentages were the highest for the seeds primed in the presence of 0.1 mm ASA (85%) and 3 μm MeJA (84%) while nonprimed seeds had an emergence percentage of 40%. Fastest emergence rates (E50) were also obtained from seeds primed in KNO3 supplemented with 3 μm MeJA (E50 = 15.2 days) and 0.1 mm ASA (E50 = 15.2 days). Shoot fresh and dry weights of pepper seedlings were significantly affected by priming treatments and priming in the presence of 0.1 mm ASA resulted in highest seedling shoot fresh and dry weights. Although all priming treatments improved germination performance of pepper seeds at 15 °C following 1 month of storage, inclusion of 0.1 mm ASA into the priming solution resulted in the highest germination percentage (84%) and germination rate (G50 = 3.8 days). These results indicate that priming seeds in 0.1 mm of ASA or 3 μm MeJA incorporated into the KNO3 solution can be used as an effective method to improve low temperature performance of sweet pepper seeds and that these seeds can be stored for 1 month at 4 °C and still exhibit improved germination performance at 15 °C.
Abstract
‘Minetto’ lettuce seeds (Lactuca sativa L.) were germinated at 35°C after different initial imbibition periods at 20°. No germination occurred at 35° in untreated seeds when the imbibition period was less than 6 hours. Maximum germination occurred after the seeds were imbibed for 16 hours. Most seeds primed in 1% K3PO4 at 15° for 9 hours then redried, germinated at 35°. However, germination increased gradually by increasing the time of early imbibition exposure to 9 hours. The endosperm membrane of seeds primed for 9-18 hours in a 1% K3PO4 solution did not rupture. Rupture of the membrane was evident after 21 hours of priming. A progressive loosening of the membrane after 9 hours of priming may be indicative of membrane weakening, possibly enhancing seed germination at high temperature.
Palms (Arecaceae) are perhaps the most important tropical plant family for human use, both for utility and ornamental horticulture. The wide diversity of palm species with different seed germination characteristics necessitates tailoring horticultural practices to the needs of each. This is crucial for production and conservation horticulture. In this study, wild-collected seeds of yarey palm (Copernicia berteroana) and buccaneer palm (Pseudophoenix sargentii) were germinated in a variety of organic (standard nursery container mixes) and inorganic substrates. The yarey palm seeds were sown at two different depths, 0.5 inch and at the surface (seed half exposed). Mean maximum germination across all treatments for yarey palm was 79% and for buccaneer palm 60%. The standard nursery mixes generally fostered the best germination and long-term survival. This is likely due to a combination of the lower water availability at the surfaces of the more porous inorganic substrates (sand and perlite) and greater difficulty for coarse palm roots to penetrate the denser inorganic substrates, including fired ceramic, which otherwise had similar water-holding capacity (WHC) and even lower air space than the organic substrates. Difficulty of penetration caused roots of some seedlings to either dry up early in germination as in the surface sown yarey palm, or to “push up” the seed (buccaneer palm) rather than penetrating the substrate and this was often fatal. Thus, inorganic substrates are not recommended for germination and early seedling growth of these palm species and planting the seeds slightly below the surface may be preferable to surface sowing. For conservation horticulture of wild-collected palm seeds, this information can help prevent further genetic bottlenecks while under protective cultivation.