Search Results
Application of DCPTA as a pregermination seed treatment (DCPTA plants) increased the seedling vigor, relative growth rate, harvestable yield, and yield quality of processing tomato (Lycopersicon esculentum Mill. cvs. UC82, VF6203, H100). When compared with controls, the growth rates of roots and shoots of 30 μm DCPTA plants were increased significantly (P = 0.05) during seed germination and midexponential growth. At fruit harvest, greenhouse-grown 30 μm DCPTA plants showed a 2- to 3-fold increase in leaf, stem, and root dry weight compared with that of controls. Improvements in the uniformity of fruit maturation significantly increased the harvestable fruit yields of greenhouse-grown DCPTA plants compared with that of controls. The total soluble solids (oBrix), glucose, fructose, and carotenoid contents of red-ripe fruits harvested from greenhouse- and field-grown DCPTA plants were significantly increased compared with controls. Chemical name used: 2-(3,4-dichlorophenoxy)triethylamine (DCPTA).
While seed priming (hydration in water or osmotic solutions followed by drying) enhances seed germination performance, the longevity of primed seeds in storage often is reduced. Postpriming treatments including a reduction in seed water content followed by incubation at 37 or 40 °C for 2 to 4 h can substantially restore potential longevity in tomato (Lycopersicon esculentum Mill.) seeds. These conditions might induce heat-shock proteins (hsp) that could be involved in the extension of seed longevity. The abundance of BiP (78 kD Binding Protein), hsp70 and class I small hsp in primed seeds subjected to postpriming treatments was examined to assess this possibility. BiP mRNA and protein amounts increased during postpriming heat treatments that extended longevity of tomato seeds. Treatment of primed seeds with the calcium ionophore calcimycin (A21387) enhanced BiP protein accumulation in the absence of heat treatment and also extended potential seed longevity. Changes in the abundance of hsp70 and class I small hsps were not consistently associated with potential seed longevity. Thus, enhanced BiP expression may contribute to the improved longevity of primed seeds following postpriming treatments.
Seeds of `Berken' mung bean [Vigna radiata (L.) R. Wilcz.] were surface-sterilized with NaOCl and then either aerated 24 hours before sowing (routine procedure), planted immediately after the NaOCl treatment, or treated with hot cupric acetate and antibiotics before planting. Nine- or 10-day-old seedlings were used in rooting bioassays. Up to 10% of the seedlings and 17% of the cuttings had collapsed upper stems or wilted leaves. None of the seed treatments completely eliminated the pathogen, but the combination of hot cupric acetate plus antibiotics reduced the quantity of diseased cuttings to 3.3%. A white and two yellow-pigmented (Y1 and Y2) bacteria were isolated from diseased cuttings and used in subsequent pathogenicity tests. The Y2 strain was nonpathogenic. Stems of plants inoculated with the white strain turned brown and collapsed 2 days after inoculation, whereas leaves of plants inoculated with the Y1 strain wilted after 7 days. Electron microscopy, fatty acid analysis, and standard biochemical and physiological tests were used to identify the white strain as Pseudomonas syringae pv. syringae van Hall and the Y1 strain as Curtobacterium flaccumfaciens ssp. flaccumfaciens (Hedges) Collins and Jones. These results emphasize that seeds of mung bean should be checked for seedborne pathogens to avoid experimental artifacts.
The influence of two fungicides—captan and thiram—on growth and 45Ca absorption by roots of `Starbrite' watermelon [Citrullus lanatus (Thunb.) Matsum. and Nakai] seedlings was investigated. Unilateral application of Ca+2 and Al in agar induced curvature in roots from untreated and pretreated seeds. In untreated seeds, PCMBS inhibited Ca+2- and Al-induced root curvature by 82% and 92%, respectively. In commercially pretreated seeds (captan + thiram), PCMBS inhibited Ca+2- but not Al-induced root curvature. Captan or thiram also inhibited Ca+2- or Al-induced root curvature, and the effects of captan and thiram on root curvature were additive. Serial concentration (0, 0.01, 0.1, 1, 10, or 100 mg·liter-1) tests indicated that captan inhibited 45Ca absorption the most at 100 mg·liter-1, whereas thiram inhibited 45Ca absorption the most at 0.01 mg·liter-1. The effects of captan and thiram on 45Ca absorption were statistically additive. Thiram seemed to influence Ca+2 uptake by affecting exofacial sulfhydryl groups (a mode of action similar to that of PCMBS). DTT reversed the inhibitory effect of thiram on 45Ca absorption by 34% but did not reverse the effect of captan. A field test showed that acidic soil (pH 4.55) reduced leaf number; leaf, stem, shoot, and whole-plant dry weights; and stem length of 15-day-old seedlings. Although there was no difference in root dry weights or root: shoot ratios of plants from pretreated and untreated seeds planted in soil at pH 6.26, planting commercially pretreated seeds in acidic soil produced plants with greater root dry weights and root: shoot dry weight ratios than those from untreated seeds. Seedlings showed a greater response to seed treatment in early growth stages. Captan and thiram may have influenced growth characteristics by inhibiting Al uptake of seedlings planted in acidic soil. To our knowledge, this is the first report on the influence of the fungicides captan and thiram on mineral ion uptake in roots. Chemical names used: p-Chloromercuribenzenesulfonic acid (PCMBS), dithiothreitol (DTT), N-trichloromethylthio-4-cyclohexene-1,2-dicarboximide (captan), tetramethylthiuram disulfide (thiram).
Sweet corn (Zea mays L.) seed is commonly infected or infested with fungi that can impair stand establishment. Among these, Penicillium oxalicum Currie and Thorn is known to cause preemergence damping-off or postemergence seedling blight. Supersweet, or shrunken2 (sh2), sweet corn cultivars are particularly affected by seedborne fungal pathogens, although the effects of seed infection on seedling emergence and stand are variable under field conditions. This study was conducted to examine factors that could influence the impact of P. oxalicum on seedling stand, including P. oxalicum inoculum density on seed and in soil, soil moisture, soil temperature, and control of seed decay caused by soilborne Pythium ultimum Trow. Seed surface disinfestation usually had no effect on seedling stand under conditions favoring infection by P. ultimum. Inoculation of sh2 sweet corn seeds or infestation of soil with conidia of P. oxalicum resulted in increasing severity of damping-off and seedling blight as inoculum density increased. In pasteurized soil in the greenhouse, an inoculum density of 102 P. oxalicum conidia per seed reduced emergence and induced seedling blight. In the field, where P. ultimum was also a factor, 106 conidia per seed were needed to reduce emergence and 105 conidia per seed to reduce healthy seedling stand. When pythium seed decay was controlled by metalaxyl seed treatment, seedling emergence and healthy seedling stand were both reduced at 1 × 106 P. oxalicum conidia per seed. When sh2 sweet corn seed was inoculated with conidia of P. oxalicum and incubated in soil at subgermination moisture contents (4.2 to -7.8 MPa) for 2-4 weeks before planting and irrigating, P. oxalicum reduced seedling emergence at all soil moisture levels, but caused the greatest amount of injury after planting when seeds were incubated in soil above -5.1 MPa. As soil temperature increased from 9-25C, seedling emergence from seed inoculated with P. oxalicum was progressively reduced, with a decrease of nearly 50% at 25 C. Penicillium oxalicum has the greatest potential to reduce seedling stand when infected sweet corn seeds are planted in warm, dry soil, but the effects of this and other seedborne fungal pathogens may be masked under conditions favoring infection by P. ultimum.
Abstract
Seeds of tomato (Lycopersicon esculentum Mill.) and pepper (Capsicum annuum L.) were either germinated before planting, primed (immersed in an aerated solution of potassium phosphate and ammonium phosphate for 72 hours (tomato) or 120 hours (pepper) and dried), or left untreated (raw) and then planted with gel in loamy sand and sandy soils. There was little difference in response from the tomato seed treatments. In pepper, germinated seeds emerged much earlier and established heavier plants. Differences in emergence due to seed treatments generally were greater in loamy sand than in sandy soil.
Methods Test materials. The test material was facultative wild jujube seeds, which were provided by Yulin Jia County in northern Shaanxi. The chemical 5-aminolevulinic acid (ALA) was supplied by Sigma-Aldrich (St. Louis, MO). Culture conditions. Seed
Transcriptioal response of soybean to thiamethoxam seed treatment in the presence and absence of drought stress BMC Genomics 15 1055 10.1186/1471-2164-15-1055 Strickler, S.R. Bombarely, A. Mueller, L.A. 2012 Designing a transcriptome next-generation sequencing
Abstract
Seed treatments and soil covers were used to assess stand establishment and uniformity of direct-seeded cabbage (Brassica oleracea L. var capitata) under high and low soil temperatures. Generally, primed seeds did not result in increased or more uniform seedling emergence compared to untreated seeds. Germinated seeds sown with a magnesium silicate gel (Laponite) or a starch-acrylamide-acrylate polymer gel (Liquagel) resulted in incomplete stands under heat stress, and stands for all plantings were generally lower when cabbage seeds were sown in a gel than when sown without a gel. Peat-vermiculite (Plug-mix) and calcined clay (GrowSorb) seed covers improved stands regardless of seed treatment when average soil temperatures were ≥30°C. Under normal (25°) to cooler soil conditions stands were not improved by seed treatment or seed cover.
Abstract
The rate and total emergence of lettuce (Lactuca sativa L. ‘Empire’) seedlings incubated at 33°C for 10 hr, alternating with 23° for 14 hr, was markedly increased by seed treatment with 0.5 mM fusicoccin (FC). Neither gibberellic acid (GA) nor kinetin (K) were effective in improving emergence when used alone. The combination of FC with GA or K appeared to give a synergistic enhancement of emergence rate. The radicle elongation of seedlings was reduced by seed treatment with FC, K, or combinations of FC, GA, and K in tests at 20°. The greatest reductions were caused by combinations that included FC. The inhibiting effect of FC on radicle growth was reduced by using a concentration of 0.05 mm. Treatment with 0.05 mm FC resulted in slower emergence but gave the same total emergence as 0.5 mm FC at high temperature. Both FC and GA stimulated hypocotyl elongation.